# My DIY electrostatic headphones



## chinsettawong (Apr 16, 2018)

Hi,

I've just joined this site today.  I just want to say hi to everybody and show you my version of electrostatic headphones and amplifier.  I've successfully made the phones and the amp for about a year now.  I just love them.












I hope my work might inspire somebody here.  

Wachara C.


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## dBel84

That is fantastic , would you mind sharing more details with us. 
   
  What stator material you used, what film are you using and how are you charging it .... the usual etc etc 
   
  welcome to HeadFi ..dB


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## sachu

Indeed..that is quite an achievement..congrats!!
   
  And yes, please do share some details if you are willing. The builds of both look very nice too.


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## Uncle Erik

That is really interesting and I'm very interested in what you did. Would you mind posting some more information about the headphones and can we talk you into sharing the schematics for your amp?


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## chinsettawong

Hi,
   
  I'm more than willing to share with you my project.
   
  First of all let me tell you that I own a DIY CNC router.  It makes my work a lot easier.
   
  I use 1 mm PCB for making the stators and spacers.  Everything is cut by my CNC machine.  I have tried many different thicknesses of material for diaphragm - 11, 6, 3, 1.5, and 0.8 micron. They all sound quite nice.  With exception to 11 micron which is a food wrap material, all 6,3,1.5,and 0.8 microns have enough highs and bass for me.  I'm now using 3 microns Mylar and just love it.


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## chinsettawong

At the very beginning, I didn't know what I was doing and I biased the headphones upto 1200V and the sound was still too soft.  Today, I bias the headphones with 600V.  As for amplifier, I got the design from http://www.tubecad.com/november99/page8.html .  The design is very good and I highly recommend it to anybody who wants to build an amp for his headphones.
   
  My headphones design is open back, and I like it better this way.  However, you need a quiet room to listen to good music with this kind of headphones. 
   
  Wachara C.


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## chinsettawong

Based on the design from www.tubecad.com, I draw up a more detail schematic for the amp:
   

   
  Frankly speaking, I have no way to compare this amp to any other direct drive amp for electrostatic headphones as I don't have any other.  Oh,I just noticed that we have an eXStata DIY electrostatic amp in this forum, can someone point me to its schematic diagram, please?
   
  Wachara C.


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## dBel84

comprehensive information on Alex's web page , there is a link to the HF thread there too. 
   
  edit - he is running a group buy now, so if you are interested, I would suggest signing up. 
   
  edit again 
	

	
	
		
		

		
		
	


	




 , I see you had already found the GB
   
  What coating did you use for the mylar? 
   
  ..dB


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## chinsettawong

Hi dBel84,
   
  Thanks a lot for the link.
   
  About the coating material for the diaphragm, I use my own formula.  It consists of 2 parts of PVA glue, 5 parts of water and 2 drops of balck poster ink.  Instead of black ink, 1/10 of a part of graphite powder works well too.  What I mean "part" can be a tea spoon.
   
  I use a wet sponge to apply the coating material lightly onto the diaphram.  After the coating, the diaphragm should still be very transparent.  The formula works well for me. 
   
  Wachara C.


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## spritzer

Welcome to HF Wachara.  
	

	
	
		
		

		
		
	


	



   
  I have a similar amp to yours (as in it uses the same basic topology, basic phase splitter) but it has ECC83 inputs and a quad of 6S4A's for the output.  It runs on a fully regulated PSU with +/-350V rails and I added some feedback to stabilze it.  Certainly not a bad little amp for the tiny amount it costs to build one, plenty of grunt but a bit limited in ultimate output.


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## dBel84

Thank you Wachara C
   
  I am sure I will have many more questions as I try and think through this all, but for now, only one. 
   
  Do you have a special trick for tensioning the diaphragm evenly and how do you fix the diaphragm to the holding ring. 
   
  ..dB


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## chinsettawong

Hi Spritzer,
   
  I really enjoy being on this forum.  It's my first time to see so many people using electrostatic headphones.  I'm really excited and looking forward to building more amps for my headphones.
   
  I am not familiar with 6S4A.  I'll study about the tube and hopefully try what you suggested.
   
  Here is another amp of mine - same schematic but in different housing.
   

   
  Wachara C.


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## gurubhai

Wow! very interesting.
  Do you mind posting more pictures & some listening impressions as well ?


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## vapman

those headphones look super cool, and i'd love to hear how they sound in general (or against a pair of Stax, maybe). if you ever get a chance to hear a pair of Stax, compare the two! i'd love to build a pair of electrostats one day.
   
  i couldn't help but notice, is that just straight up foam you're using as pads? that's insane.


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## chinsettawong

Hi dBel84,
   
  I use tape to glue and tension the mylar.  For ES speakers, I use a digital weight scale to help me tension every piece of tape to the same tension.  But for headphones, there is no need to do that.  I glue the diaphragm directly to the stators.  After gluing the diaphragms for both side, I knock the diaphragm against a table to check that the sound from both diaphragm is similar.  If they are not, I use hot air to help tension the one with more loose sound.  I hope you can understand what I mean.  
   
  Wachara C.


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## robm321

Welcome to headfi! Appreciate you sharing your ideas! Subscribing to this thread.


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## VaSpn

Amazing


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## chinsettawong (May 19, 2017)

Hi Mckickflip,

  Yes, you can say that I'm insane.  In fact, the ear pad is the most difficult part for me to source.  I happened to find a piece of roof insulation material around my house.  It was quite soft, so I just used it to make the ear pad.  

  I had a chance to compare my headphone with an old closed back Koss (I can't remember the model) and a Lafayette (I can't remember the model either) .  I think my headphones sound better.  

 Wachara C.


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## chinsettawong

Hi guys,
   
  I like to build another set of headphones, and if possible I would like to have some inputs from you what to do in order to improve my previous design.  Since there are so many Stax users here, I would appreciate if some of you who have ever taken dimension measurements of the spacer and stator of Stax headphone can share with me the info.  The dimensions will be used as the reference for my future build.  I would really appreciate it.
   
  Wachara C.


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## chinsettawong

More pictures:


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## spritzer

Quote: 





chinsettawong said:


> Hi guys,
> 
> I like to build another set of headphones, and if possible I would like to have some inputs from you what to do in order to improve my previous design.  Since there are so many Stax users here, I would appreciate if some of you who have ever taken dimension measurements of the spacer and stator of Stax headphone can share with me the info.  The dimensions will be used as the reference for my future build.  I would really appreciate it.
> 
> Wachara C.


 
   
  Stax used to post this info in their instruction manuals but the older normal bias system runs on a 200-230V bias (150V for the very first SR-1 units made in 1960) and it has a 0.3mm diaphragm-stator gap.  The Pro bias system has a 580V bias voltage and a 0.5mm D-S gap.  They did experiment with 1100V bias (0.7mm D-S gap) but never made a production model. 
   
  The thinnest mylar they've ever used was 1um but they stopped using is as it was quite frankly too thin.  Went back to 1.5um and then settled on 1.35um for the current range. 
   
  Some of the Stax drivers are just works of art:

   
  That's the super rare SR-Omega driver, 90mm across. 
   
  As for the 6S4A, it's one of the best tubes you can find for driving electrostatic headphones.  It's a single triode that can handle just enough power for our needs (sits easily at 4W) and can withstand plenty of voltage too.  Cheap as well since nobody has any use for it besides us... 
   
  If you want to step up the amp game, I'd recommend building the Stax SRX design which you can find easily by googling it.  It's the same basic design used in the Single Power ES-1 which you can find a link to in my sig and it sounds very nice with some ECC83's and 6S4A's as output tubes.  Even better with EL34's.


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## chinsettawong

Hi Spritzer,
   
  Thank you so much for sharing with me the information.  90mm sounds like a nice number to try.  For the SR-Omega driver, I guess that its spacer is around 0.9 - 1 mm in thickness, and the bias voltage is probably around 600V.  Are the 2 circles in the background the stators?  I'll make a new design and post to show you later.
   
  I'll look for 6S4A and try as you suggested.
   
  Thanks again.
   
  Wachara C.


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## dBel84

Quote: 





chinsettawong said:


> I'll look for 6S4A ...


 

 I had to go and have a look, these are also the tubes used in the hybrid design by Runeight , you will have the hybrid board from the group buy so it seems a logical choice..dB


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## apatN

WOW.


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## chinsettawong

Hi dBel84,
   
  Thanks for your reminder.  I've noticed that as well.  
   
  Wachara C.


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## spritzer

Quote: 





chinsettawong said:


> Hi Spritzer,
> 
> Thank you so much for sharing with me the information.  90mm sounds like a nice number to try.  For the SR-Omega driver, I guess that its spacer is around 0.9 - 1 mm in thickness, and the bias voltage is probably around 600V.  Are the 2 circles in the background the stators?  I'll make a new design and post to show you later.
> 
> ...


 
   
  I haven't measured them in a while but the metal rings were roughly 1mm brass and the stators are recessed to make up for the difference down to 0.5mm.  That's how Stax usually does it, the Lambda driver has metal plates for stators which is held in place by a plastic piece while the diaphragm is mounted to large brass rings.  The bias voltage the Omega drivers is 580V. 
   
  Those circles in the background are the stators, gold plated copper mesh secured to a resin frame.  Very ambitious driver design but fragile and the chassis isn't robust enough to deal with the mechanical output at high volume.  Stax fixed that with the Omega 2 but also changed to PCB based stators.


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## odanas

Just want to say great job! I've been wanting to make a pair of electrostats but haven't had the money or know how to do it yet. What you have done is amazing and I can't wait to get started making a pair.  
   
  On a side note, I remember seeing you on the diy loudspeaker forum. I am very impressed with what you've done and I can't wait to make a pair.
   
  Subscribed.


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## chinsettawong

Hi Spritzer,
   
  That's what I think when I see the picture.  The stators made up of such fine wires are probably too soft.  They will require a lot of support, and will probably ring with high bass or high volume level.
   
  The spacer sitting on top of the recessed stator of 90 mm in diameter would probably have more than 0.5 mm gap to the diaphragm.  If that is so, the tension on the diaphragm would have to be very high in order to prevent the diaphragm collapses to one side, and the bass might suffer.  Plus if the stator to diaphragm space is indeed only 0.5 mm, then I think that the bias voltage of 580V is a little on the high side.  
   
  Anyway, thanks very much for your information.  I'll try to design something and come back to show you soon.
   
  Wachara C.


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## chinsettawong (May 19, 2017)

Quote: 





odanas said:


> Just want to say great job! I've been wanting to make a pair of electrostats but haven't had the money or know how to do it yet. What you have done is amazing and I can't wait to get started making a pair.
> 
> On a side note, I remember seeing you on the diy loudspeaker forum. I am very impressed with what you've done and I can't wait to make a pair.
> 
> Subscribed.


 

  Thanks Odanas.  I hope my work does inspire you more or less.  

  ES loudspeakers are a lot more difficult to make.  The biggest challenge is to make the best insulated stators you can.  I'm not shy to say that I am still having difficulties making them to sing at high volume level.   Very high voltage + poor insulation = sparks.  

  Wachara C.


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## spritzer

Quote: 





chinsettawong said:


> Hi Spritzer,
> 
> That's what I think when I see the picture.  The stators made up of such fine wires are probably too soft.  They will require a lot of support, and will probably ring with high bass or high volume level.
> 
> ...


 
   
  The diaphragm is tight as a drum, it has to be so that it will last 50+ years or when ever the SR-1's will give up the ghost.  Mine are in perfect working order so probably a while until that happens...
   
  580V for 0.5mm is actually quite conservative.  The air around us has an average insulation resistance of 3000V/mm and given the Stax sets should never see more then 1200V P-P on the stators this gap is way more then enough.  Add to this the fact that the electrostatic force decreases with the square of the distance and there is no chance in hell of arcing a Pro bias driver.


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## chinsettawong

I'm thinking of making new stators and spacers in circular shape.  What do you think?


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## spritzer

I like those but the holes are a bit too big IMO.  Also have you ever played around with unopened spaces on the stators to provide some damping for the diaphragm?


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## chinsettawong

Hi Spritzer,
   
  Thanks a lot for your feedback.  I really appreciate it.  The pictures shown are not to the scale.  I holes will be 2 mm, and the stators and spacers will be 65 mm in diameter.  I intend to make them smaller to try and see how much difference in sounding they will make compared to my existing ones.  Do you think that they will be too small?
   
  I used to play with a few materials for damping the back stator, but I like it better without any damping.  Do you have any suggestion?
   
  Wachara C.


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## spritzer

65mm could be perfect in a good housing and with a properly sealed baffle. 
   
  The size of the holes really depends on your D/S gap and really shouldn't be any larger then double the D/S gap.  For Stax that means 1mm or so given their 0.5mm D/S gap. 
   
  I for one don't like to damp much but I've gone to extreme lengths to dampen some drivers which just won't behave.  That said, airdamping is IMO a very good idea as it it traps air next to the diaphragm and can stabilize it.  Most undamped electrostatic drivers have some resonance frequency (usually in the upper midrange, lower treble) and this helps to tame it.  Take a look at the picture below, that's a Stax SR-007Mk2 driver and notice the ring with no holes around the driver.  That's still part of the stator with the diaphragm beneath it but it can't output any sound.  The small Stax SR-003 portable headset goes even further where only a small part of the stators is open.


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## chinsettawong

Hi Spritzer,
   
  That's interesting information.  I really wonder if that can really do some dampening. 
   
  I can change my design a little bit to unable some dampening ring as you suggested.  I'll come back with some pictures.
   
  Wachara C.


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## chinsettawong

Ok, I've come back with a little modification on my previous design.  This time there is some area of stators which won't have holes.  The inner circle shows where the spacer will be placed over the stator.  What do you think?
   

   
  Wachara C.


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## chinsettawong

In my opinion, the area where there is no hole actually provides the diaphragm with a more intense force.  This should enhance the driver's sensitivity.
   
  Here is another version.  What do you think?
   

   
  Wachara C.


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## spritzer

Looks good, certainly well worth the test.  
	

	
	
		
		

		
			




   
  I would also look into earpads which seal what's next to the ear from the outside completely.  Leather is the best choice here but if you do this the driver will be far more linear and you will get more bass out of it.  Even a small port to the outside is enough to create non-linear spots in the freqeuency response.


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## chinsettawong

Hi Spritzer,
   
  Thanks for your inputs.  I'll probably make both the first and the last designs and compare both to see if I can hear any differences.  Because of a less open area in the last design, I think it will be more efficient.  It might also help with the bass, but shouldn't be that much. 
   
  I'll come back when I have new progress.
   
  Wachara C.


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## spritzer

With more surface area being driven then the drivers should indeed be more efficient.  Not a bad thing IMO even if we are working on amps which can swing 2000V P-P. Hell, 1600V P-P is just the minimum we use these days...


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## chinsettawong

I plan to cut the parts this weekend.  We'll see how it goes.
   
  Wachara C.


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## robm321

We won't complain if you post pics of the process 
	

	
	
		
		

		
		
	


	




, just sayin...


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## chinsettawong

Hi Robm321,
   
  Which process would you like to see?  
	

	
	
		
		

		
		
	


	



   
  Wachara C.


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## odanas

All the proccesses!


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## chinsettawong

I'll try to take as many pictures as I can and show you the processes.  
	

	
	
		
		

		
		
	


	



   
  Wachara C.


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## robm321

Whatever is not an inconvenience. It's nice to see a picture history of things being built.


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## chinsettawong

I've been busy and couldn't find the time to cut the stators and spacers until today.  Here are the parts. 
   

   
  I think they are too small.  Anyway, let's see how they will sound.  I still need to cut the enclosure for them though.
   
  Wachara C.


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## i_djoel2000

WOW..you even made your own driver?? that is very brilliant chinsettawong! looking forward to the 'how to make your own electrostatic headphone' thread


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## krmathis

Really impressive! Looking forward to the end result.


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## tranhieu

wao the coolest thing I've seen this year! must subscribe!
  succeed or not you're still a phenomenon! Just wanna express my encouragement and I will keep track of your progress


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## chinsettawong

Thanks for viewing.  I'll try to post as many pictures as I can.  I'll still need to find the time to cut the enclosure for them.  I think it would be around next weekend before I'll have the time to do so.  
   
  Wachara C.


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## chinsettawong

Finally, I have found a suitable housing for my new drivers.  The headband and enclosures are given to me by a friend.  I think it's a replacement (spare part) for Marantz electrostatic headphones.  It's brand new.  However, it doesn't have the front covers.  I use my CNC to cut the covers using a 3 millimeter plastic sheet.


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## chinsettawong

I think they sound nice.


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## spritzer

Yup, those are for the Marantz electrostatic phones which were really just Stax OEM's.  I would suggest you add some foam or wool into the cups and line them with bitumen.  Should make them quite a bit better.


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## HeadphoneAddict

WOW!


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## Anaxilus




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## Bullseye

Impressive work! Congrats on your awesome work.


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## Aynjell

subscribed, very awesome read!


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## chinsettawong

Quote: 





spritzer said:


> Yup, those are for the Marantz electrostatic phones which were really just Stax OEM's.  I would suggest you add some foam or wool into the cups and line them with bitumen.  Should make them quite a bit better.


 

 Hi Spritzer,
   
  Thanks very much for your suggestion.  I tried the headphones for about 30 minutes yesterday, and the sound was quite good.  However, I didn't like the way the ear pads pressed on my ears.  My ears became warm very quickly and didn't feel that comfortable wearing them. 
   
  I'll try what you suggested.
   
  Wachara C.


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## sokolov91

Quote: 





chinsettawong said:


> I think they sound nice.


 

 See, the DIY guys always made me feel useless.
   
  Seeing stuff like this makes me want to go kill myself.
   
  Just kidding .
   
  This work, as tons have state is super impressive. I wish I could add something of value, but it looks like I will just have to cheer from the side lines haha!


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## chinsettawong

Thanks folks for your compliments and encouragements.  I really appreciate them.
   
  Wachara C.


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## spritzer

Those earpads really aren't all that comfortable, long live the 70's and vinyl everything... 
	

	
	
		
		

		
			





  You could have some earpads made from real leather (which should breath a bit) or copy the Sennheiser HE60/90 design which uses a fabric in contact with the head but the rest is vinyl/leather.


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## Region2

This is amazing work.  Now I'm itching for a CNC even more.  Too bad you don't live close I would have loved to auditioned them.
   
  The ear pads do look uncomfortably thin.  How's the soundstage & leakage with these as closed headphones?


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## chinsettawong

Quote: 





region2 said:


> This is amazing work.  Now I'm itching for a CNC even more.  Too bad you don't live close I would have loved to auditioned them.
> 
> The ear pads do look uncomfortably thin.  How's the soundstage & leakage with these as closed headphones?


 

 Hi Region2,
   
  CNC is an amazing machine.  I just love it.
   
  The headphones are not closed back though.
   

   
  As I'm typing this, I'm listening to them right now.  Even though the ear pads are not that comfortable, they do make pretty good seals.  The sound stage isn't as open as my previous version which has a big open back, but it's not bad - not bad at all.
   
  Now I need to find someone who can help me make a pair of leather pads.  
	

	
	
		
		

		
		
	


	



   
  Wachara C.


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## Region2

Quote: 





chinsettawong said:


> Hi Region2,
> 
> CNC is an amazing machine.  I just love it.
> 
> ...


 

 That's embarrassing.  Thanks for the correction!  Too bad the housing isn't more rounded, I wonder how they would feel and sound if you could put on some pads from the O2.  I'm sure if you can get some patterns down you can find some customs leather company to get it made for you.  I've been considering this for some of my other headphones as well.


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## chinsettawong

Quote: 





region2 said:


> That's embarrassing.  Thanks for the correction!  Too bad the housing isn't more rounded, I wonder how they would feel and sound if you could put on some pads from the O2.  I'm sure if you can get some patterns down you can find some customs leather company to get it made for you.  I've been considering this for some of my other headphones as well.


 

 Too bad that I can't find any O2 pads to try.  
	

	
	
		
		

		
		
	


	



   
  Wachara C.


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## chinsettawong

I've been listening to my new headphones for a few days.  I find that the treble on these headphones is a little better than my fully open back version.  Do you think that the less open area and a piece of sponge at the back side of the drivers cause a little coloration on the sound?
   
  Wachara C.


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## spritzer

With any obstruction to the backwave you will get a colored sound, no way around it.  The Stax 4070 is a marvel of engineering but the effect its closed shell is clearly evident in the midrange.  It's hard to say how these drivers behave in that chassis but it is certainly well worth it to try different damping setups.  Felt, wool and other semi acoustically transparent materials have worked well in the past.


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## chinsettawong

Hi Spritzer,
   
  Thanks so much for your information.  I searched your old threads, and I found that you mentioned once that you didn't like the sound from these Marantz headphones.  You said that they didin't fixed the drivers in place and the sound wasn't that good.  Could you tell me how the drivers in the original Marantz were put?
   
  May I ask something about Stax?  How do they prevent sweat from entering into the drivers?  The way I do it is to put a layer of diaphragm between my ears and the drivers.  Is this a good way?
   
  Wachara C.


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## spritzer

I'm digging way back here but I think they were built like the Magnavox unit.  There they just fitted the driver in a circular slot on the baffle and fixed it in place with the foam behind it.  No care was taken to eliminate baffle leak and thus they sounded dreadful...
   
  All Stax sets from 1960 have had a film next to the ear to seal off the driver and after 1994 all of the models also have a PVC film on the back as well.  If you want to see how the brand new Stax phones are made, Google "SR-507 investigation".  I can't give you the link as it will just be deleted...


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## chinsettawong

Hi Spritzer,
   
  Those are really nice pictures.  Seeing those pictures has answered a lot of the questions I have in mind.  Thank you so much.  
	

	
	
		
		

		
		
	


	



   
  I really appreciate all your help.
   
  Wachara C.


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## spritzer

Happy to help.  I did void the warranty doing that but it was well worth it to see what they are up to.


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## tmblack

My old headphones uses 12.7 micron polyurathane.
  Where can I get the thin mylar 2 to 6 microns in small quantities in North America?


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## chinsettawong

Hi tmblack,
   
  I have some 3 micron Mylar which sounds very nice on my headphones.  If you like I can send some to you.  
   
  Wachara C.


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## chinsettawong

Hi tmblack,
   
  You can also buy the 1.4 and 0.9 microns Mylar from http://www.indoorspecialties.com/ .
   
  Wachara C.


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## chinsettawong

I had a chance to meet with friends who own Stax headphones.  Using that opportunity, I took some measurements of different models.  Among them is the Omega 2.  I had finished making the drawing and will cut out all the parts to try.  I think it will be a fun project.  
   

   

   
  What do you think?
   
  Wachara C.


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## chinsettawong

I had a chance to meet with friends who own Stax headphones.  Using that opportunity, I took some measurements of different models.  Among them is the Omega 2.  I had finished making the drawing and will cut out all the parts to try.  I think it will be a fun project.  
   

   

   
  What do you think?
   
  Wachara C.


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## spritzer

Looks good.


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## tohenk2

WOW!
  That well and truly does look lovely.
   
   
   
  Quote: 





chinsettawong said:


> Hi Spritzer,
> 
> I really enjoy being on this forum.  It's my first time to see so many people using electrostatic headphones.  I'm really excited and looking forward to building more amps for my headphones.
> 
> ...


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## chinsettawong

Quote: 





spritzer said:


> Looks good.


 


  Thanks Spritzer.  I'll go ahead and make them then.
   
  Wachara C.


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## chinsettawong

I've got some free time this afternoon and these are what I have achieved today.
   

   

   
  As for the male connector, I found these metal rods exactly like what are used on Stax's.  With my CNC, I cut the top part using a 5 mm plastic sheet, and I use a small piece of PVC pipe as the body.  It turns out quite nice.  
   
   
  Wachara C.


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## spritzer

I like the Stax connector.  We do something similar for the sockets, copper pins from China and a CNC cut teflon body.


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## chinsettawong

Hi Spritzer,
   
  That's a good idea with female sockets.  
   
  Wachara C.


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## pabbi1

Like this.


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## chinsettawong

Hi Pabbi1,
   
  Those are really nice looking sockets.  If I can find the pins, they should be very easy to make.  Thanks for sharing.
   
  Wachara C.


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## ujamerstand

They are these sockets pins: http://cgi.ebay.com/10-CMC-8P-Tube-Socket-Glod-Pin-Hex-Snap-2x10mm-Hole-/130342224494? fits snugly on my 404 and 507 pins.


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## chinsettawong

Quote: 





ujamerstand said:


> They are these sockets pins: http://cgi.ebay.com/10-CMC-8P-Tube-Socket-Glod-Pin-Hex-Snap-2x10mm-Hole-/130342224494? fits snugly on my 404 and 507 pins.


 


  Thanks a lot!


----------



## pabbi1

The above are compliments of luvdunhill, and Kerry has also made some as well. The .75" teflon rod makes a perfect barrel.


----------



## chinsettawong

Hi Pabbi1,
   
  Thanks for your information.  I'll go ahead and order those socket pins.
   
  Wachara C.


----------



## chinsettawong

I finished cutting my spacers today. 
   

   
  The new stators are so much smaller than my first version. 
   
  Wachara C.


----------



## spritzer

Bigger isn't always better...


----------



## chinsettawong

Quote: 





spritzer said:


> Bigger isn't always better...


 
  Roger that.


----------



## Vaughn

Hi Wachara
	

	
	
		
		

		
		
	


	



   
  I'm looking forward to hearing your impressions of the new stators. I'm still listening to the 1st version but I do like the look of that new stator. It would be nice to be able to use the Stax pads too! 
   
  I obtained a sample of the Staticide but haven't stretched new diaphragms yet. I've been dragging my feet a bit as I need to rebuild the bias supply in my amp and increase the voltage a bit. I also have been sorting a large quantity of vintage stereo gear I just came into. I've got most of that sorted at this point and am ready to try my next project.
   
  Any chance you could email a pdf of that new stator design? That is if it isn't proprietary or anything...I'd like to try making a set myself.


----------



## chinsettawong

Hi Matt,
   
  I'm glad that you still enjoy the headphones. I really feel that my 1st design is a good one. Mine sounds so much better now with 0.9 micron diaphragm and Staticide coating. The good thing with this coating is that you can really coat it very, very thin.
   
  As for my design, nothing is proprietary. In fact everything is open source. Whatever you want to know about, let me know. Hell, I can even supply you with what you want. 
   
  Anyway, I think you should let me test this design first to see if it is indeed worth our while. I will have a Stax 407 coming very soon. We'll see how mine can stack up with Stax.
   
  Wachara C.


----------



## purk

Nice stuff indeed!


----------



## McGyver

Nice work Wachara! 
	

	
	
		
		

		
		
	


	



   
  I hope to some day soon have the time to make a pair off ESL-headphones, but speakers are taking all my time at the moment!
   
  /Roger (SM7UYJ)


----------



## chinsettawong

Hi Roger,
   
  How is your full range ESL project going?
   
  Wachara C.


----------



## McGyver

Hi Wachara,
   
  The ESLs are slowly taking form, but the frame was a bit more hazzle than expected.
   
  I'm so tired off inhaling MDF and painting edges! 
	

	
	
		
		

		
		
	


	



   
  I took the short road and bought a pair off Sennheiser HE60s to listen to while I build the ESLs, and a new amp is probably on the way.
   
  But as I'm new to tubes I'll probably build a simple SE class-A amp with a trafo output and se how that sounds!
   
  /Roger


----------



## LFF

Amazing stuff!
   
  Makes me feel completely useless as I have no DIY skills when it comes to building stuff.


----------



## chinsettawong

Quote: 





mcgyver said:


> Hi Wachara,
> 
> The ESLs are slowly taking form, but the frame was a bit more hazzle than expected.
> 
> ...


 

 Hi Roger,
   
  If you want to, you can try the amp design I posted.  It's very simple to make and it sounds pretty good.
   
  Wachara C.


----------



## schorsch

Great Thread,
   
  I subsribed becuase I love people who take the challenge)
   
  Regards Georg


----------



## LFF

How much does it cost to put one of these together?


----------



## chinsettawong

Hi Lff,
   
  As I have my own CNC machine, making a pair of these is really very cheap. It's more on finding the time and the mood to do it.  
   
  Wachara C.


----------



## LFF

Quote: 





chinsettawong said:


> Hi Lff,
> 
> As I have my own CNC machine, making a pair of these is really very cheap. It's more on finding the time and the mood to do it.
> 
> Wachara C.


 

 Lucky you! I wish I had the skills and time to make one.


----------



## Sky44

[size=medium]Hello Wachara,[/size]
   
  [size=medium]Yes, Stax compatible connectors are possible DIY.[/size]
   
  [size=medium]I made myself "Stax compatible" connectors and sockets easily because the diameter of the pins are 3/32 inch (or 2,381 mm). That's corresponds exactly to the diameter used in standard XLR 3 pins connectors ![/size]
   
  [size=medium]For one panel mount female 6 pins Stax compatible connector I used :[/size]
   
  [size=medium]- The metal chassis socket from one 3 pins XLR panel mount male connector[/size]
  [size=medium]- The 6 female pins from two 3 pins XLR females connectors[/size]
   
  [size=12pt]Views of a DIY 6 pins female "Stax compatible" chassis connector I made from a Neutrik NC3MP connector and epoxy from PCB epoxy plates :[/size]
   
  [size=12pt][/size]
   
  [size=12pt][/size]
   
  [size=12pt]Philippe[/size]


----------



## chinsettawong

Hi Philippe,
   
  It's so nice to see you again.  I've been wondering where you are.
   
  Thank you very much for sharing your DIY Stax connetor.  I'll try to source something similar here in Thailand.  
   
  Since you are here, may you comment on my idea?
   
  I've been playing around with the idea of making a 3 stators and 2 diaphragms headphone.  I've actually made the design and cut the parts.  I'm going to cut the enclosures soon.  What do you think?
   


   
  The size of the stators is very similar to that of Stax 407.  I make the two outer stators from single sided PCBs.  The middle stator is made from a double sided PCB.  My spacers will be made of 0.5 mm plastic.   I expect that this design will yield much better efficiency and hopefully much better bass than the conventional single diaphragm design.  
   
  Wachara C.


----------



## spritzer

With a CNC machine you could just make Stax sockets like we did for the DIY SRM-T2 project.  The whole piece is milled from a block of Teflon and the sockets are from the CMC octal tube sockets.


----------



## FrankCooter

Really interesting and innovative work! Anxious to hear how your phones compare to a 407. I have a small hoard of the Amphenol 5 pin jacks that are used  in most Stax amplifiers.  As Spritzer says, you can probably make better, but I'd be happy to contribute a few towards your projects. PM me if you're interested.


----------



## chinsettawong

Hi Spritzer,
   
  Thanks for your info. 
   
  Wachara C.


----------



## chinsettawong

Hi FrankCooter,
   
  Thank you so much for your kind generosity.  I'll PM you.   
   
  Wachara C.


----------



## jgazal

It is indeed a very interesting idea.
   
  Are you going to use some kind of crossover (low-pass filter) with the outer diaphragm? How high frequencies reflections between both diaphragms interact?
   
  Best regards,
   
  Jose


----------



## chinsettawong

Hi Jose, I've never thought of using a crossover. Anyway, that seems to be an interesting idea too. I'll try to make them sing first. Then we can think of how to play around with them later. Wachara C.


----------



## nick n

This is incredible. After you iron out whatever small stuff you want to fine tune and find a build you are happy with======> Have you thought of offering this in a D.I.Y. kit form of unassembled parts/instruction manual for tech minded people to assemble themselves? I am sure you would have a positive response. Having a D.I.Y. set of these would make a person proud.
   
  Truly inspiring.


----------



## schorsch

Dear chinsetawong,
   
  Why not build a headphone that is no longer available but has a unique design like the Stax Sigma)
   
  Regards Georg


----------



## jgazal

That arrangement is really food for thought.
   
I was wondering if you would need to pull out the diaphragms with a very accurate force. If they stay unevenly stretched, you might have distortion.
   
I was wondering if the PCB (woven glass epoxy?) shield is enough to isolate the outer layer and the inner layer of the second stator.
   

  [size=inherit]
 First Stator​  Outer Diaphragm​ (+ fixed bias polarity)​  Second Stator Outer Layer​  Second Stator Inner Layer​  Inner Diaphragm​ (+ fixed bias polarity)​  Third Stator​  +​  (Fa >) +​  -​  +​  (Fa >) +​  -​  -​  + (< Fa)​  +​  -​  + (< Fa)​  +​   

[/size] 
   
What happens if you chose to supply inverse bias polarities? You would also invert + and – signal connections in the inner balanced arrange. For instance:
   

 First Stator​  Outer Diaphragm​ (+ fixed bias polarity)​  Second Stator Outer Layer​  Second Stator Inner Layer​  Inner Diaphragm​ (- fixed bias polarity)​  Third Stator​  +​  (Fa >) + ​  -​  -​  (Fa >) - ​  +​  -​  + (< Fa)​  +​  +​  - (< Fa)​  -​ 
   
   
I was wondering the magnitude and direction of all forces and the resultant/net force acting not only in the diaphragms, but also acting in the stators. The second stator seems to be neutral in both arrangements, right?
   
I was wondering also resonation on the second stator. I do not think the air enclosed between diaphragms cause resonation, but what if you choose to make an imperfect vacuum there? Is there a way to do that? Perhaps it would be a sealed duct within the spacers so you can always reinforce the vacuum and try different air pressures. 
   
You would avoid air resistance inside the second stator mesh and may compensate occasional differences in the stretch forces applied to the diaphragms during the manufacturing. There would be also an impact in high frequencies interactions between both diaphragms as there would be little air to conduct sound. 
   
But then there would be no air to push forces between both diaphragms, which was you first disign criteria (improve sensitivity).
   
Do you think this (air pressure between both diaphragms) is some way relevant?
   
I know sometimes engineering goes in practical models, but I love to simulate or anticipate things...


----------



## chinsettawong

Hi Jgazal,
   
  Wow, that's a lot of thoughtful thoughts.  I have been thinking only doing the really easy triple stators and double diaphragms design,  I've no intention of vacuuming the air between the two diaphragms.  I want to keep it simple and try to see if it will work.  Thanks for sharing your thoughts though.
   
  I will most likely try the configuration as your first chart:
   
   

 First Stator​  Outer Diaphragm​ (+ fixed bias polarity)​  Second Stator Outer Layer​  Second Stator Inner Layer​  Inner Diaphragm​ (+ fixed bias polarity)​  Third Stator​  +​  (Fa >) + ​  -​  +​  (Fa >) + ​  -​  -​  + (< Fa)​  +​  -​  + (< Fa)​  +​ 
   
   
  Unfortunately, I haven't had the time to cut the enclosures this weekend.  So, the assembling and testing will only come next weekend at the earliest.  I'll keep you posted of the results.
   
  Wachara C.


----------



## chinsettawong

Quote: 





nick n said:


> This is incredible. After you iron out whatever small stuff you want to fine tune and find a build you are happy with======> Have you thought of offering this in a D.I.Y. kit form of unassembled parts/instruction manual for tech minded people to assemble themselves? I am sure you would have a positive response. Having a D.I.Y. set of these would make a person proud.
> 
> Truly inspiring.


 

 Hi Nick N,
   
  Thanks for your interest.  At the moment I am still experimenting with my different designs.  I hope my work inspires people.
   
  Making stators from CNC milled PCBs is just one of many possibilities.  A few people have successfully made their ES headphones out of some commonly found stuffs.  So, please do not be discouraged if you do not have access to a CNC machine.  If you need some guidance on how-to, I'll be more than willing to help.  
   
   

  
  Quote: 





schorsch said:


> Dear chinsetawong,
> 
> Why not build a headphone that is no longer available but has a unique design like the Stax Sigma)
> 
> Regards Georg


 

  
  Hi schorsch,
   
  I might just come to that one day.  Thanks for your suggestion.  
   
  Wachara C.


----------



## jgazal

One last thought now on stator’s temperature.
   
  I was reading those comments on C32 done by a Stax engineer who said they had a concern with the stator temperature so that they made a hole right in the middle of the mesh (stator). According to him that would improve air circulation (I wonder if it also improves the reproduction of certain high frequencies that will not reflect at the thinner mesh; do higher frequencies originate from the middle of the diaphragm or they come from the whole surface? A laser vibrometer would be useful to trace that…)
   
  I think woven glass epoxy boards are less prone to temperature variations than the full metal C32 stators (different specific heat capacities on the materials). And the PCB copper layer is not thick enough to increase temperatures or accumulate so much heat energy.
   
  But given the fact that your second stator will be air isolated, it would be nice to monitor its temperature along certain usage time.
   
  I am looking forward to hearing the results from you. It is a very exciting project.


----------



## chinsettawong

Hi jgazal,
   
  Personally, I do not think that there will be any issue with the temperature.  Even if it does, opening a bigger hole in the middle will not help much, IMO.  I haven't noticed any changed in temperature on the stators or headphones regardless how long I am using them.  If there is any, the temperature should more likely come from the person who wears the headphones.  It shouldn't be any higher than a person's body temperature. 
   
  Let's keep moving and worry about all these details later.  
   
  Wachara C.


----------



## spritzer

The heat would really only be an issue with a T2/BHSE pushing (relatively) massive amounts of current onto the stators and even so, only with prolonged periods of that.  Still all metal stators are more sensitive to the ill effects of temperature drift than the PCB based units.


----------



## chinsettawong

I've cut all the necessary parts and etched the unneeded copper on the PCB. If time permitted, I should be able to test them within 2 days.  
   

   

   

   
  Chemically etching a PCB to me is very difficult.  The result isn't pretty, but for an experiment, I think it will do just fine.  
   
  Wachara C.


----------



## pabbi1

Wachara, just inspirational. Watching with the keenest interest.


----------



## Uncle Erik

Wachara, that's some fine work there. Please keep us updated!


----------



## McGyver

Nice work Wachara! 
	

	
	
		
		

		
			




   
  Why dont you route the PCBs instead?
   
  Are you using FeCl or HCl when you etch the boards?
   
  I use HCl - you have to be careful and do it outside, but I find it faster and easier to get good results!
   
  /Roger


----------



## chinsettawong

Hi Roger,
   
  I'm not sure what chemical I used, but it etched out the copper pretty quickly.  The reason why I didn't route the PCB is because I have some problems of unevenness of the machine surface.  The tolerance of PCB is very small and therefore I decide to use chemical etching.
   
  Wachara C.


----------



## chinsettawong

I've just finished putting everything together.  Here are some pictures.
   

   

   

   

   

   

   
  Wachara C.


----------



## chinsettawong

The first listening impression is that these headphones are a lot more efficient than my previous version.  The main reasons should be the thinner spacers in them and having 2 diaphragms on each side.  However, I feel rather uncomfortable listening to them.  My ears feel rather uneasy.  I'm not sure if it's because of the greater force pushing and pulling the air inside my ears or I'm just too tired.
   
  Let me give them a few days to play lots of songs and I'll report back.
   
  Now I'll need to look for a proper headband for them.  
   
  Wachara C.


----------



## 00940

This is, without a doubt, the thread that amazes most on the whole forum. Outstanding work.


----------



## spritzer

Even the huge SR-Omega drivers don't push and pull the air, they excite it via vibration so I doubt that is the issue here.  What bias and diaphragm/stator spacing are you using?


----------



## elliot42

:basshead: Amazing.


----------



## jgazal

Great work!
   
   
  I wish you had access to a distortion analyzer, like the one in this system: http://www.klippel.de/our-products/rd-system.html
   
  I suspect what spritzer have in mind. Could the diaphrams be touching the stators? That could increase distortion and thus the fatigue.
   
  We are looking forward to hearing your next report.


----------



## frank2908

subscribed


----------



## chinsettawong

Quote: 





spritzer said:


> Even the huge SR-Omega drivers don't push and pull the air, they excite it via vibration so I doubt that is the issue here.  What bias and diaphragm/stator spacing are you using?


 


  Hi Spritzer,
   
  I'm using 0.5 mm plastic as spacers and the bias voltage is 600V.  The diaphragm is 1 micron Mylar.
   
  Unfortunately I can't listen to them today as I'm away for a business trip.  I was really exhausted after I put everything together last night.  I'll try them again tomorrow night and see if I like them better.
   
  Wachara C.


----------



## spritzer

0.5mm and 600V is bang on the money.  If the diaphragm were to touch the stators (or rather if it were loose enough to do so) then the distortion would be easy to hear.  Open any Stax driver and the diaphragm is tight as a drum for this very reason.


----------



## chinsettawong

Quote: 





spritzer said:


> 0.5mm and 600V is bang on the money.  If the diaphragm were to touch the stators (or rather if it were loose enough to do so) then the distortion would be easy to hear.  Open any Stax driver and the diaphragm is tight as a drum for this very reason.


 

 Hi Spritzer,
   
  I know what you mean.  I don't think I have a problem with diaphragms touching stators.  If that happens, it's very obvious.  I'll report back after I have a chance to listen to them again tomorrow.
   
  Wachara C.


----------



## chinsettawong

I have fixed the last few bugs that I have today, and I have give them a good 2 hours of listening.  They sound pretty good now.  However, I thought by using double diaphragms, I would get a significant improvement on bass response, but I don't.  I'm not sure why.   
   
  Wachara C.


----------



## spritzer

Might it be the baffle seal which is the issue?  If the front and back waves can collide then the first thing to go is the bass...


----------



## chinsettawong

Quote: 





spritzer said:


> Might it be the baffle seal which is the issue?  If the front and back waves can collide then the first thing to go is the bass...


 


  Hi Spritzer,
   
  That might be the case.  I am now listening to them by using my hands holding them against my ears.  I haven't got a headband for them yet.  I think I will go ahead and use the headband of my Stax 407 with them.  Let's see if there is any improvement.
   
  Wachara C.


----------



## c12mech

I've been watching this and am interested in doing it myself.  I don't have a cnc machine but do have above average woodworking and metalworking skills.  I like the way tat you used the pcb materials and was wondering if it would make a difference if I etched the hole pattern then drilled it with a drill press.  I know it is not as accurate as the cnc but I think it could be done.  As for the cups a nice looking piece of wood, routed properly, could do the trick.  I don't see why this would not work but let me know your thoughts.


----------



## chinsettawong

Hi C12mech,
   
  Your method will definitely work.  
   
  Yes, the enclosure, if made out of wood, would look even better, IMO.
   
  Wachara C.


----------



## c12mech

Once I get started I'm sure I will have a lot of questions. 
   
  Thanks for the inspiration to do something completely different.  I've wanted to try this for a while and seeing your work got me thinking of different ways to solve the problems I was having.  Now I just have to order the materials and do it.


----------



## chinsettawong

Hi C12mech,
   
  Please do not be shy to ask a lot of questions.  Just go for it.
   
  There are a lot of materials that you can use for making stators.  Just for fun, you can even make the stators out of metal mosquito net.  
   
  Wachara C.


----------



## c12mech

I have a large supply of aluminum but don't know that it would work so well.  I'm having trouble locating the mylar film right now.  I can find it down to 6 micron pretty easily but that is after that I can only find it in large rolls.  The sources that I have come from ESL speaker builders.  I showed my wife some of them and she liked the way they look.  Those will be on my list to do as well.


----------



## chinsettawong

Hi C12mech,
   
  Aluminum works well.  However, it is not easy to solder onto aluminum.  I would use a thin metal sheet instead.
   
  About Mylar, you can buy it off ebay.  There are many thicknesses to choose from.
   
  I also make ESL.  To me, it's a lot more difficult to make a good pair of ESLs.  But they do sound very good.  
   
  Wachara C.


----------



## chinsettawong

I borrow the headband from my Stax 407 to put my drivers on. Now they sound a lot better.


----------



## spritzer

That does look brilliant.


----------



## TheKisho

Nice!  How much did that cost you to make and when you going into production? ;D  You do very nice work.  I've been following this thread for a while now.  Would Sennheiser HD600's ear pads work on these headphones or would that ruin the sound? [I don't know much about electrostatic headphones, just curious].  How does the sound on your DIY headphones compare to commercially made dynamic and electrostatic headphones?  I cannot imagine somebody making DIY dynamic headphones from scratch, drivers and all that sound anywhere close to the quality of commercially available headphones but electrostatic headphones seem simple enough to make a really high class product.
   
   
  -Curious thread follower


----------



## chinsettawong

Quote: 





spritzer said:


> That does look brilliant.


 


  Thanks, Spritzer!

  
  Quote: 





thekisho said:


> Nice!  How much did that cost you to make and when you going into production? ;D  You do very nice work.  I've been following this thread for a while now.  Would Sennheiser HD600's ear pads work on these headphones or would that ruin the sound? [I don't know much about electrostatic headphones, just curious].  How does the sound on your DIY headphones compare to commercially made dynamic and electrostatic headphones?  I cannot imagine somebody making DIY dynamic headphones from scratch, drivers and all that sound anywhere close to the quality of commercially available headphones but electrostatic headphones seem simple enough to make a really high class product.
> 
> 
> -Curious thread follower


 

 Hi TheKisho,
   
  I make my own just for fun.  There is no plan for a production run.  
   
  If you open up a pair of commercial electrostatic headphones, you will be surprised that the parts are very similar to what I make.  Indeed, electrostatic headphones are not very difficult to make at all.  As for comparison, everyone has his own opinion.  But as for me, as you can see, I even take out the headband of my brand new Stax 407 to put my drivers in.  That should tell you something.  
   
  Wachara C.


----------



## McGyver

Good work Wachara, they look realy nice!
   
  Where did you find the cable you use?
   
  Roger


----------



## chinsettawong

Quote: 





mcgyver said:


> Good work Wachara, they look realy nice!
> 
> Where did you find the cable you use?
> 
> Roger


 

 Hi Roger,
   
  The cable is actually an extension cable of Koss ESP950.  I make my own jack.


----------



## LFF

Amazing work!


----------



## McGyver

May I ask how much the Stax cable cost?
   
  I need a extension cord to my HE60s as I had to shorten the original one due to the different leads splitting after the connector!
   
  I have measured standard RGB extension cord, and the capacitance seem to be identical to the Sennheiser original (wich cost abt. 250$ here in Sweden)
   
  I'm thinking off using only the center conductor in the RGB cable and se how this works, but a STax cable is perhaps a better way to go!?
   
  Roger


----------



## chinsettawong

Hi Roger,
   
  I use an extension cable of Koss ESP950.  It's available from Koss USA.  You have to contact the customer service and ask them about it.  It cost only about US$10 for a 2 meter length cable.  However, they do not ship it overseas.  Therefore, you will have to ask your American friend to buy and ship over to you.
   
  Stax 2.5 meters extension cable costs around US$100.  It does look a bit better than Koss, but I'm not sure about the capacitance.
   
  Wachara C.


----------



## MDR30

May I very humbly join the song of praise - that's what I call dedication. And on top of that the spirit of sharing that seems to be so very rare these days.
   
  I, for one, would be very interested to know what the music of your choice is, Mr. chinsettawong?


----------



## chinsettawong

Hi NDR30,
   
  Thank you very much for your kind words.  I do really enjoy making things.  I also enjoy sharing and exchanging knowledge with others.
   
  I listen to all kinds of music except for hard rock.  I prefer instrumental music.  Sometimes classical is nice. 
   
  What about you?  What kind of music do you like?
   
  Wachara C.


----------



## HONEYBOY

I read through this entire thread with ardent interest. Incredible work my friend. I really wish I was a DIY guy. Perhaps it's time to stop wishing..


----------



## wdiabc

Incredible work. I read through the 10 page thread and you kept shocking me. May I ask can you make one pair of those round drivers for me? (the 90mm one). I saw you made many of them and expect you would have several spares. I am just to dull to make those and I really admire your work.


----------



## reiserFS

This is one of the most interesting threads on Head-Fi, your work is amazing and very inspiring.


----------



## chinsettawong

Thank you for all your compliments.  I really appreciate them.  
   
  @wdiabc:  I'm sorry that I do not have any more spare stators and spacers at the moment.  
   
  I want to update you guys with the 3 stators and double diaphragms design that I made earlier.  Even though they sound pretty good, but I will not make them anymore.  I don't feel that they are any better than the normal 2 stators and one diaphragm design.  I've also played with a different configuration.  That is I use 2 stators and 2 diaphragms with a charge ring between the 2 diaphragms and that makes the 2 diaphragms move as one.  This configuration actually sounds better than 3 stators and 2 diaphragm design, but still, it's not as good as the conventional.
   
  In the end, the basic philosophy still applies.  Size does matter!  If you want to get good low frequencies, you make big diaphragm.  
   
  Wachara C.


----------



## d1554573r

Pure awsomeness! Man when I look at Your finish and design of both the headphones and Your amps I think You should go pro with those...


----------



## chinsettawong

Hi d1554573r,
   
  Thanks a lot for your compliments.
   
  Wachara C.


----------



## hello im sean

Hey how do your electro static headphones sound compared to the typical dynamic headphones thrown around on here?


----------



## chinsettawong

Quote: 





hello im sean said:


> Hey how do your electro static headphones sound compared to the typical dynamic headphones thrown around on here?


 


 Ever since I make my own electrostatic headphones, I quit listening to all other dynamic headphones.   
   
  Wachara C.


----------



## purk

Quote: 





chinsettawong said:


> Ever since I make my own electrostatic headphones, I quit listening to all other dynamic headphones.
> 
> Wachara C.


 


  Hi there krub!  After you completed your own stats, have you made any comparison to the top end dynamics?  If so, what is your findings?


----------



## chinsettawong

Quote: 





purk said:


> Hi there krub!  After you completed your own stats, have you made any comparison to the top end dynamics?  If so, what is your findings?


 

 Hi Purk,
   
  I'm sorry that I do not have any top end dynamic headphones to try.  
   
  Wachara C.


----------



## purk

Quote: 





chinsettawong said:


> Hi Purk,
> 
> I'm sorry that I do not have any top end dynamic headphones to try.
> 
> Wachara C.


 

 How about borrowing several from Kiertijai when you start his  T2?


----------



## chinsettawong

Quote: 





purk said:


> How about borrowing several from Kiertijai when you start his  T2?


 

 That sounds like a nice idea.


----------



## Twinster

Maybe you should send a pair of your nice headphone to Tyll http://www.innerfidelity.com/ and he will gladly do a graph test and compared them to other high-end headphones.


----------



## Maverickmonk

*bump out of nowhere* We were discussing electric field and flux in my physics Electricity & Magnetism course today, and it got me thinking about how the principles could be applied to making a DIY Electrostat. Your work is gorgeous. The engineering of the diaphragms, the circuitry in the amp, the beautiful casework, all of it.


----------



## chinsettawong

Thanks for your kind compliments, Maverickmonk.
   
  I've finished putting together Kiertijai's T2 for over a month now.  Kiertijai kindly lend me his SR007 MK1, and SR009 to tried on T2. 
   

   

   

   
  Using T2, I tested my headphones against Kiertijai's SR007, SR009 and my own SR202, SR407, and HE60.  To my ears, my headphones sound quite similar to SR007 MK1.  I think the sound is more relax than that from SR009.  With the powerful T2, headphones with big diaphragm really shine which makes my headphones, SR007 and SR009 a lot more fun to listen to than SR202, SR407, and HE60. 
   
  Wachara C.


----------



## chinsettawong

I'm making a new pair of headphones.  This time I try to make the headphones with as less copper as possible - I etched out all the useless copper.  This helps reduce the capacitance on the headphones and makes them easier to be driven by an amp on high frequencies.  It's still a work in progress, but here are a few pictures:


----------



## kiertijai

*How about borrowing several from Kiertijai when you start his  T2?*
         @Purk,  Thanks for your excellent idea.
         @Chinsettawong,   when your new DIY ES headphone has been finished please
  organize a mini meeting.  I will bring some of my dynamic and orthodynamic headphones there
  I would like to bring my Balancing Act 300B there but I need to do some modification and am looking
  for someone who do the transformer and putting 2 resistors in the BA as Craig recommended.  It
  would also be nice if we can also have the legendary Single Power amplifier.  This way you can compare
  the best of electrostatic vs dynamic setup.


----------



## chinsettawong

Hi Kiertijai,
   
  Can you forward me the information that Craig recommended to you?  
   
  Wachara C.


----------



## jgazal

Wonderful! Congratulations! 
   
  How did you do the wood working (frame)?
   
  Quote: 





chinsettawong said:


> I'm making a new pair of headphones.  This time I try to make the headphones with as less copper as possible - I etched out all the useless copper.  This helps reduce the capacitance on the headphones and makes them easier to be driven by an amp on high frequencies.  It's still a work in progress, but here are a few pictures:


----------



## chinsettawong

Hi Jgazal,
   
  I use my own DIY CNC to make everything.  
   
  Wachara C.


----------



## Flops

Which DIY CNC do you have?


----------



## chinsettawong

Quote: 





flops said:


> Which DIY CNC do you have?


 


  What do you mean?  I design and build my own with the help of a local machine shop.  I also make my own CNC transformer coil winder.
   
   

   

   
  Wachara C.


----------



## Flops

Oh ok, I thought you maybe purchased a DIY CNC kit like http://www.mydiycnc.com/. Awesome work designing it all on your own.


----------



## chinsettawong

Today I found a headband from my old and forgotten headphones.  It fits perfectly with these drivers.  
   

   

   
  With the headband, they do sound lovely.  Wish you could hear them.


----------



## bcg27

I imagine listening to them through the T2 doesn't hurt either 
	

	
	
		
		

		
		
	


	



   
  Seriously nice job, I really like the wood frame - was that an attempt to mimic orpheus?


----------



## chinsettawong

Hi bcg27,
   
  No, I am trying to mimic Orpheus.  I've been making the frames from plastic, and they turn out well.  But I want to try something new.  I look around my house and I see this small piece of wood.  So, I just try it out.  Actually I'm still worry that the wood might absorb too much moisture in the air and cause problem.  Our summer and rainy seasons here are extremely humid.  Let's see.
   
  Wachara C.


----------



## spritzer

Sennheiser used plenty of varnish on their frames but the inside is untreated,  The drivers are never in contact with the wood frame on the HE90 though...


----------



## chinsettawong

Hi Spritzer,
   
  I have noticed that about Sennheiser too.  Unfortunately, my design is a little different from that of Sennheiser.  
   
  I have been making a few pairs of electrostatic speakers as well.  From my experience, the wood frame tend to absorb moisture in the air and cause some electrical leakage. I put an O Ring in the frame.  This prevents the drivers in direct contact with the wood.  It also helps fit the drivers in the frame much tighter.  Let's see how it goes.
   

   
  Wachara C.


----------



## audio technica

Hi Wachara
   
  This is awesome.  I have been inspired to make my own electrostats now....
   
  For your CNC machine, are you using stepper motors?  What software do you use with it?
   
  This looks like something I could make to upgrade from the panasonic RP-HTF600s.  Love the picture of the DIY headphones surrounded by top-of-the-line electrostats.
   
   
  Thanks in advance.


----------



## chinsettawong

Hi Audio Technica,
   
  If you already have a CNC machine, it's very easy for you to make a pair of electrostatic headphones.  Yes, I use only PCB to make my drivers.  I use 1 mm PCB to make my stators and 0.6 mm PCB to make my spacers.  If I can find 0.5 mm PCB, I would definitely use it for the spacers.  But it's unfortunate for me that I can't find it here.
   
  Yes, my CNC machine is equipped with stepper motors.  I use an open source software, EMC2, for controlling.  It really is a great software.
   
  Wachara C.


----------



## audio technica

Hello Wachara,
   
  Thanks for the reply -- I'm definitely going to be making these headphones.
  As for the mylar, how exactly is it even affected by the fields made by the stators?  I read a post regarding a special coating, but I wasn't sure how that changes things.
   
   
  Thanks.


----------



## chinsettawong

Hi Audio Technica,
   
  Well, the reason that you want to coat your diaphragm is that you need to charge it with electricity.  As you might have known, the diaphragm is made from a very thin sheet of plastic, and plastic isn't conductive.  The stuff you coat on the diaphragm makes it somewhat conductive - not too much.  Think of the driver as a capacitor.  You want to charge it up and keep it charged for as long as you can.  That's why you coat it with a stuff that is conductive and has high resistivity.  I find Staticide 6300 to be excellent for this application.  
   
  Wachara C.


----------



## kiertijai

Now the Stax company has been taken over.  The hope of  hiend electrostatic headphones may depend
  on the DIY ES headphones and all those who are interested in this thread.


----------



## audio technica

Could you post the layout of those stators, showing measurements (hole diameter, total diameter, etc)?  I'd like to try making them myself.
   
  I wonder if I could do this with nothing but a router table, a drill press, and a ferric chloride tub...  I don't really have the time to build a cnc machine (though I do have most of the parts) and I've got a few other projects going on right now.
   
  If it doesn't work out, would you be willing to make me a few stators?  I'd be willing to pay for the copper clad if you'd like.
   
   
  Thanks
   
  Quote: 





chinsettawong said:


> I'm making a new pair of headphones.  This time I try to make the headphones with as less copper as possible - I etched out all the useless copper.  This helps reduce the capacitance on the headphones and makes them easier to be driven by an amp on high frequencies.  It's still a work in progress, but here are a few pictures:


----------



## chinsettawong

Hi Audio Technica,
   
  I think this version of mine is quite difficult for you to make an exact duplicate because the stator contains a lot of holes and they have to line up all perfectly.  You might want to look at the one in my earlier post.  That stator version has a lot less open area and it should be a lot less difficult to make if you don't have a CNC machine.  http://www.head-fi.org/t/498292/my-diy-electrostatic-headphones#post_6730417
   
  Wachara C.


----------



## chinsettawong

Here are the dimensions of stator and spacer


----------



## spritzer

Quote: 





chinsettawong said:


> Hi Spritzer,
> 
> I have noticed that about Sennheiser too.  Unfortunately, my design is a little different from that of Sennheiser.
> 
> ...


 

 I really like the o-ring since it also makes for a good baffle seal.


----------



## i_djoel2000

Quote: 





chinsettawong said:


> I'm making a new pair of headphones.  This time I try to make the headphones with as less copper as possible - I etched out all the useless copper.  This helps reduce the capacitance on the headphones and makes them easier to be driven by an amp on high frequencies.  It's still a work in progress, but here are a few pictures:


 

 very professional finish, chinsetta..
   
  have you tried sending your headphones to other users here to make a comparison review? seems interesting..


----------



## chinsettawong

Hi i_djoel2000,
   
  We had a mini meeting sometime last month, and a few Thai Head-fi members had listened to my phones.  http://www.head-fi.org/t/570050/sr-009-vs-orpheus-sr-omega-o2s/135
   
  We will have another meeting pretty soon, and they will be able to try my new headphones.  
   
  Wachara C.


----------



## chinsettawong

Today I make the last modification to my headphones so that they can accommodate the ear pads from HE-5.  They turn out pretty good.


----------



## Puranti

Wow looks comfy and stylish !


----------



## Saintkeat

This is another unbelievable piece of work.
   
  I would certainly love to have a listen some day. Heck I can't read electrical diagrams else I'd try my hand at building the amp and have you make me one


----------



## bcg27

They look really good. No offense to your other work, which is also really impressive and I'm sure sound great, but these look much more professional and polished than your previous efforts.


----------



## Hennyo

Wachara
   
  Can't wait to get underway. =) KGSSHV is about 1/4 paid for so far, headphones are to be CNC'd early January once the ET/EE guys are back from Christmas break. I hope to be done mid-January with a set (or two).
   
  Been reading you diya thread, (really helped button up 'loose ends' questions) as well as the 'sr-009 problem' thread, and a couple other threads, including this one where you make your headphones. Thanks for sharing this art, friend. It's fun to see your progression as you literally blast along with ideas.
   
  Also, congrats on your T2! 
	

	
	
		
		

		
		
	


	







 In-credible.
   
  Thanks does not justify it. Keep researching!
   
  Btw, can you send me instruction on how to make your version of a precise mylar stretcher? Or even better yet, do you have an old stretcher lying around you would'nt mind to ship to me? (I'll pay for the worth of the stetcher, of course. Has your adhesive from 3 M 77 adhesive changed?
   
   
  For anyone interested, http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=120664289524&ru=http://search.ebay.com:80/120664289524_W0QQfviZ1
   
  I've found reliable source for spacer pcb; for *.5mm, .58mm, and .6*/.64 mm's. They are a tiny bit expensive, but for spacer application they are rare and totally worth it.


----------



## chinsettawong

Hi Hennyo,
   
  Glad to hear that you're making some progresses.  About stretcher, it's nice to have one, but you don't really need one - unless you want to go into commercial.
   
  I actually don't use it.  In my last pair, I simply stretch Mylar using tapes.  I use synthetic rubber glue (contact cement) for gluing the diaphragm to the spacer.  It is the best type of glue for gluing Mylar, IMO.
   
  Good luck with your build.  Please keep us update with your progress.
   
  Wachara C.


----------



## notloc

Okay, joined the forum just for this thread 
   
  I have been interested in building my own electrostatic headphones for a while (most of my information coming from this page: http://gilmore2.chem.northwestern.edu/projects/showfile.php?file=radford1_prj.htm )
   
  Well since I first started playing with the idea, I've increased rapidly in electronics experience, and I've got some new manufacturing ability as well. I recently built myself a 3D printer and figured it would make these much easier to make (Like your CNC does)
   
  Here's the idea I'd like to contribute: Since the part that seemed to be hard for most folks is the PCB stuff, why not just let a real PCB house make the boards for you? There are two shops in China that will give you 10 5cm x 5cm PCBs for $10USD, or 10 10cm x 10cm for $25. I believe they'll even route the outside and everything.
   
  The only hurdle is you'll need to use a PCB CAD package that can output the Gerber files they use. This is something I can do if there is an interest.
   
  It seems like you guys all have amps and need the drivers. I think I can do the drivers, but I don't have a suitable amp yet. I'm playing with trying to design an all solid state (maybe class D even) amp for these things. It will be good practice in an area of electrical engineering I don't get to play with much.
   
  One other question: It occurred to me that space blankets (aluminized mylar/polyester) might be good for the diaphragm as it's tough, cheap, and already has an electrically conductive coating on it. Any thoughts?
   
  It may be worth noting that I probably have far lower audio standards than most folks here. If it's better than my beloved $50 Sony earbuds, I'll be pretty happy.
   
  Chinsettawong, great work! It's inspiring! Thanks everyone else for keeping the discussion going, it's been very informative to me.


----------



## livewire

Quote: 





notloc said:


> One other question: It occurred to me that space blankets (aluminized mylar/polyester) might be good for the diaphragm as it's tough, cheap, and already has an electrically conductive coating on it. Any thoughts?


 
   
  The aluminum on them has too low of a resistance to work well, also the mylar in question is most likely too thick.
  A coating with a resistance in the megohm range is needed along with a thin film mylar, between 6 microns and (ideally) 1.4 microns thick.
  0.9 microns has been used as well but is more difficult to work with.
   
  What I would like to see is a DIY step by step instruction on how to make these along with parts list and sources.
  These threads (here and at DIY Audio) have most of the info needed, but things are rather nebulous and not organized for a beginner to this discipline.


----------



## chinsettawong

Hi Notloc,
   
  You can certainly work with a professional PCB maker, and I'm sure that the quality of their work will be much superior than mine.  However, I do not want you to restrict yourself on just using PCB as a material for making stators and spacers.  The website you post a link to is one of the websites that I learn to make these headphones from.  It certainly has given a lot of ideas on how the phones are made.  Look around your house, and you might find a lot of things that you can use to make.
   
  I can post my design if you want to.
   
  I'm extremely interested in making a 3d printer.  Can you recommend me a good design?  How do you like yours? 
   
  Wachara C.


----------



## chinsettawong

Hi Livewire,
   
  It will just be a redundant for me to post a step by step on how to make the electrostatic headphones.  The website Notloc posted a link to has given a very detail step by step procedure.  If I will write a procedure, it will be very similar to that.
   
  I will post my designs for your reference.  It might be quite difficult to make an exact pair if you don't have a CNC machine though.
   
  Wachara C.


----------



## chinsettawong

Well, I just checked my earlier posts, and I've actually posted my design on http://www.head-fi.org/t/498292/my-diy-electrostatic-headphones/180 .
   
  The hole size is 2 mm.  The trick is to etch out most of the unneeded copper.  This really helps the phones to produce treble a lot easier.  However, you might want to do some experiment with it.  It's pretty much similar to comparing the SR007 and SR009.  If you like a lot of treble, etch the copper.  If you don't, you can just leave it there.
   
  Another thing that I like to say is that I don't use graphite powder to coat the diaphragm, because it is very difficult to make a good and even coating.  I use a permanent antistatic solution.  It is very easy to apply and has been very stable regardless of humidity.
   
  Oh, aluminized Mylar is certainly usable.  To prevent a quick discharge, you can series higher value resistors to the bias voltage.  Instead of a few mega ohm, try using 100 to 500 mega ohm.
   
  Let me know if you want more information.
   
  Wachara C.


----------



## spritzer

We have even discussed making a DIY electrostatic headphone kit in the past with fabbed PCB stators, coating, mylar and a cable to be fitted in some production headphones but it simply isn't feasible.  Same thing with the reworked and fully balanced Stax diffuse field EQ, simply too hard to DIY for the masses.


----------



## bcg27

Quote: 





spritzer said:


> We have even discussed making a DIY electrostatic headphone kit in the past with fabbed PCB stators, coating, mylar and a cable to be fitted in some production headphones but it simply isn't feasible.  Same thing with the reworked and fully balanced Stax diffuse field EQ, simply too hard to DIY for the masses.


 


  I'd sign up for that


----------



## ujamerstand

Birgir, you know I'm all up for the diffuse field EQ.


----------



## chinsettawong

Quote: 





spritzer said:


> We have even discussed making a DIY electrostatic headphone kit in the past with fabbed PCB stators, coating, mylar and a cable to be fitted in some production headphones but it simply isn't feasible.  Same thing with the reworked and fully balanced Stax diffuse field EQ, simply too hard to DIY for the masses.


 


  Hi Birgir,
   
  To DIY a pair of headphones for personal use, I think the difficulty isn't that much.  But, yes, if you want to go commercial or making a kit for the mass, it's another story.
   
  I have no idea what a fully balanced Stax diffuse field EQ is.  Could you kindly explain?
   
  Wachara C.


----------



## schorsch

Let's have a look,


----------



## schorsch

There are some stax difusse field equalizers eg Stax ed-1 (pro/signature) and they provide a special equalization for the related earspeakers.
  Rhere is also the SRM Monitor which has the equalizatuin included.
   
  For recent models pawel acoustics makes a equalizer.
   
  Regards Georg


----------



## spritzer

Quote: 





chinsettawong said:


> Hi Birgir,
> 
> To DIY a pair of headphones for personal use, I think the difficulty isn't that much.  But, yes, if you want to go commercial or making a kit for the mass, it's another story.
> 
> ...


 

 My issue was getting consistent results when people have no experience stretching and gluing mylar.  This would be a 100% DIY project but I believe that it isn't worth the bother if anybody with the minimal skill and basic instruments can't build it.  It also prevents Kevin and I from going way too deep down the proverbial rabbit hole... 
	

	
	
		
		

		
			




   
  Diffuse Field EQ is a way of expanding the soundstage of headphones and minimize the issues all headphones have i.e. being so close to the ears.  Stax did indeed make a few boxes that did this but they are all single ended and tuned for old Lambda models.  I believe the Pawel box is just a clone of what Stax did plus adding crossfeed but the pix I have are rather poor.  The problem with DIY boxes are the tools needed to adjust them but if something like this could be done in DSP then that would be far easier to implement.


----------



## chinsettawong

Quote: 





spritzer said:


> My issue was getting consistent results when people have no experience stretching and gluing mylar.  This would be a 100% DIY project but I believe that it isn't worth the bother if anybody with the minimal skill and basic instruments can't build it.  It also prevents Kevin and I from going way too deep down the proverbial rabbit hole...


 


  I will think of a simple and effective way to stretch and glue Mylar for you.  I actually have an idea.  Let me go back and do some experiments and I will post a step by step procedure with pictures for you.
   
  Happy New Year!
   
  Wachara C.


----------



## spritzer

The most simple way I used was a piece of glass and some tape with a strain gauge to measure how much force I used on the film.  Simple and very effective.


----------



## chinsettawong

Hi Birgir,
   
  That surely is one of the simplest and effective ways to tensioning Mylar.  There is another way that I would like to suggest. In this case you use a piece of glass and predraw some scales on it.  Let's say for each 1 mm you draw a line.  You cut Mylar just big enough to make a pair of headphones.  You tape the four corners of Mylar on the glass.  Draw a line on Mylar to indicate your prestretch starting point. Then you hand stretch your Mylar to your target point by observing the line on Mylar against those on the glass.  When you get to your target point, you simply tape it down. Do the same for all four sides of Mylar. I have some pictures below to show what I mean.  It's basically the same principle of how I stretch Mylar for my ESL.
   
    
   

   

   
  These pictures are taken when I use a rubber tube tensioning jig for my ESL.  It's the same principle I use here.
   
  As for gluing Mylar, I haven't found anything better than rubber glue.  I use a piece of sponge to help me apply the glue evenly.
   

   
  This is how I tape Mylar.  I use a soldering iron for cutting Mylar. 
   
  Usually, I will cut a few more pieces of spacer rings. I like to try with different tensions and different thicknesses of Mylar.  
   
  Wachara C.


----------



## spritzer

How do you heat treat the mylar?  That is indeed the biggest obstacle in making the drivers last for 50 years (how old my Stax SR-1 drivers are).  Quad used a special oven and I'm sure Stax uses something similar for the correct heat transfer properties.


----------



## chinsettawong

Hi Birgir,
   
  With enough mechanical tensioning, there is no need to use another heat treatment on the diaphragm.  On ESL building threads, there have been a lot of discussions about this topic, and it's pretty apparent that you can only heat shrink the diaphragm to a certain extend.  However, mechanical tensioning can do a much better job than heat. 
   
  I don't think that the diaphragm is to blame for when the diaphragm looses it's tension.  Most of the times, it's glue that fail.
   
  And yes, Quad did use an oven to do a heat treatment.  But, I'm skeptical about that.  They could have used heat to treat the coating material and not the diaphragm.
   
  Wachara C.


----------



## chinsettawong

Here is an example of a failed ESL driver.  When I opened it up, I found that the double sided tape that I used gave up its strength.  This was after about 3 months of usage.  When it failed, the diaphragm would collapse to one side and the sound was very much distorted.
   
  The diaphragm was initially stretched to 1.5% elongation on one side.  It's probably too much. 
   

   
  Wachara C.


----------



## Nixon

Read this and the similar thread over at DIY Audio and I think I might have to have a crack at a set. Spent the evening on Sketchup and have began designing the stator and spacer.
   


   
  Ever so slightly ripped off from one of chinsettawong's designs. Do they seem ok so far? They're both 90mm in diameter so you have an idea of scale.


----------



## chinsettawong

Hi Nixon,
   
  Your design looks great. However, you also need to have a knob on your stator so that you can solder the + and - audio signal onto. 
   
  What is the spacer thickness you intend to use?  I assume that you are going with 70 mm active diaphragm area, right?  In my last design, that is exactly the dimension I use.  But, if I were to do it again, I will increase the active diaphragm area to 80 mm.  This will give you better low frequencies response.
   
  Wachara C.


----------



## Nixon

Thanks chinsettawong. Meant to add the knob on the stator but was  a bit knacked after making all the holes it and must have forgot. I'll tweak it tonight to increase the diaphragm area and add the knob. 
   
   
   

Still undecided on the spacer thickness, modelled it at 0.5mm but that's easy to change if you think that's wrong.


----------



## Nixon

Redesigned the spacer and stator to be 10cm in diameter. Going to have a go at the enclosure next.


----------



## chinsettawong

That stator design looks interesting.  But I think that your long and unsupported opening will cause you problem.  The whole stator might not be strong enough.  You might want to reduce the length of your slots down to perhaps 2 -3 cm, IMO.  Otherwise, it looks really nice.
   
  Are you going to use a PCB to make your stators and spacers?  Don't forget to etch out all the unneeded copper on the outer circle of your stator.  With the copper out, it really make a huge difference in high frequencies response.
   
  Wachara C.


----------



## Nixon

I'll tweak the stator now. Plan to use PCB to make the stator and spacer and already planned to etch off the excess copper after reading about your test of it.


----------



## Miln

Hello, and sorry for the late reply.
  I just recently completed a small electrostatic speaker (not a headphone, sorry.)
  Good news is: SPACE BLANKET WORKED. Sounded great, played well, a little arcing didn't destroy it completely.
  Bad news is: I am not an ESL professional. It sounded great, but I haven't ever heard another ESL. Also, I tensioned/assembled it very poorly. It was only stretched about 0.7% and there was a small wrinkle in the corner.
   
  Setup: ~2500kV ballast with 15 megaohms of resistance and 1/16 inch d/s spacing on a 5inch x 7inch speaker.
  Have a nice day:
  Mike


----------



## chinsettawong

Hi Miln,
   
  DIY ESL can certainly sound as good if not better than the commercial ESL.  I have a pair of ML next to my DIY ESL, and I just leave them gathering dust.  
   
  If you are experiencing arching, you might want to lower your bias voltage down a bit.  Your d/s spacing is quite small.  If you use a good coating material, I think 2.0KV is plenty for you.
   
  To get good bass from ESL, you need to build them big.  The size you are making is certainly nice for a desktop.  You might want to pair them with an active subwoofer.  I'm sure that they will be nice together.
   
  Oh, please do not be mistaken.  I'm not a professional ESL maker at all.  I'm just doing headphones and ESL for pure fun.  
   
  Wachara C.


----------



## Avro_Arrow

Here is a nice ESL page...
  http://jazzman-esl-page.blogspot.com/


----------



## Avro_Arrow

Which ML do you have?
  I have a pair of Sequel II which I just love.
   
  Quote: 





chinsettawong said:


> Hi Miln,
> 
> DIY ESL can certainly sound as good if not better than the commercial ESL.  I have a pair of ML next to my DIY ESL, and I just leave them gathering dust.
> 
> ...


----------



## chinsettawong

Hi Avro_Arrow,
   
  Thanks for the link.  I've known Charlie for quite sometime.  
	

	
	
		
		

		
			




   
  I have a pair of ML Aerius.  I bought them just to try to compare mine with.  As it turns out, I think ML has a pretty high cross over point, and so they lack the beauty of being electrostatic, IMO.  I run my DIY ESL full range, and just love it that way. 
   
  Wachara C.


----------



## Avro_Arrow

I've heard the Aerius too. I didn't like them at all. The Sequel sounds much better.
  The Aerius are just too small.


----------



## chinsettawong

Unfortunately for me, I didn't have a chance to listen to them before I bought them.  I don't blame Aerius being small.  But I don't like the high cross over point that makes a lot of sound in the mid range coming from the sub woofer.  That totally destroys the sweetness of ESL.
   
  Wachara C.


----------



## Avro_Arrow

When I bought my Sequels, the shop let me test them home for two weeks
  before deciding if I was going to buy then or not. I guess they new the answer
  before I even took them home...


----------



## chinsettawong

Wow!  That's pretty good deal.  Unfortunately for me, I bought mine from a guy whom I didn't know at all.  At that time all I was thinking was that I really needed to do an A/B test with some ESLs. 
   
  Wachara C.


----------



## jtwrace

Being a Stax lover I must say that's amazing.  Great job and I wish I could hear them.


----------



## Headdie

I'm speechless Wachara... Reading that thread was fascinating. I didn't know someone could go that far. And even if you're light years ahead of us, you take time to answer basic questions that we ask in other threads... C'est tout à ton honneur !
   
  I wish you the best,


----------



## chinsettawong

Thanks Jtwrace and Headdie for your kind compliments.  I'm making them for fun, and I can assure you that the sound isn't bad at all.  To raise your appetite, here are a few pictures of my latest pair.  They are not yet finished though.
   

   

   

   
  The active diaphragm area is now 80 cm.  I will use 1.5 micron Mylar as diaphragms.  The spacers are 0.5 mm in thickness.  Let's see how they sound compared to O2.  
   
  Wachara C.


----------



## Headdie

May I ask you what's the effect of bad/poor coating of the diaphragm ?
  Do you loose in volume, dynamics, frequency response or something else ?
   
  Did I say I like these pictures...
   
  Thanks,


----------



## chinsettawong

Quote: 





headdie said:


> May I ask you what's the effect of bad/poor coating of the diaphragm ?
> Do you loose in volume, dynamics, frequency response or something else ?
> 
> Did I say I like these pictures...
> ...


 


  From my experience, the resistance on diaphragm surface after it's coated can affect the performance of the headphones greatly. If you have good coatings, you will have good volume and dynamic.  Bad coating can absorb moisture in the air and doesn't work well in a high humidity environment.
   
  Wachara C.


----------



## tranhieu

Hi Wachara, I'm very impressed by your build, it's really one of its kind!
  Might be a dumb question but did you run any model on your computer to predict the output before getting down on actually building it? If you did how did you find the result? Is is accurate compared with real listening?


----------



## chinsettawong

No, I don't run any model. I don't know how to.


----------



## chinsettawong

We are having a Head-fi meeting in Bangkok tomorrow and I'll make sure that my newest headphones will be ready for audition.  
   

   

   

   
  The earpads are from original Stax Omega Mesh Stator.  Thank you Kietijaib.  
   
  Wachara C.


----------



## tranhieu

Looks awesome! I'm thinking about going to Thailand one day to audition your creation


----------



## chinsettawong

Thank you tranhieu! You are welcome anytime. 
   
  Wachara C.


----------



## bcg27

Very nice! These are the ones that are supposed to sound like sr007?


----------



## spritzer

I really like the look of those.


----------



## chinsettawong

Thanks guys for your compliments.  Actually these sound more like SR009 than SR007.  I did etched out all the unneeded copper and it really brings out more heights.
   
  If you look carefully, I make something different with the way I put the drivers together this time.  I like the way Sennheiser uses plastic screws to hold the drivers together.  So, I do the same.  I will probably use this technique with my future builds.
   

   
   
  Now I need to find better cables and have to really think about how to make a good headband for them.  
   
  Wachara C.


----------



## Headdie

Sometime, the simplest design is the best.
  For me, the headband of my Lambda can't be beat.


----------



## schorsch

I really liked the headband of my sennheiser unipolar!
   
  Regards Georg
   
  I'm a little bit sorry for seling them (


----------



## chinsettawong

Well, I end up using my old headband for the time being.  I really hate to hold them against my ears when listening.


----------



## bcg27

That first picture is full of win


----------



## Phos

Wow, those look great.  One easy option for a good headband is a semicircle of spring steel with one of those replacement headband pads meant for the beyer pro line of headphones, they only cost like $10 (in the US at least) and are really comfortable.


----------



## t0nix

Hi, im a italian boy. I work in the engine engineering but I love the music. 
   
  I see the project its great work! congratulation chinsettawong!!!! 
   
  I want to make one elettrostatic headphone, can you send me the file CAD  of the best solution, the my goal is make a headphone in aluminium and fiber carbon... you can help me for my project?


----------



## chinsettawong

Hi t0nix,
   
  If you are accessible to a CNC machine, making these headphones should be very easy for you.  I can give you some data and you can design your own and we can discuss it here, if you like.
   
  1. My active diaphragm area is 80 mm in diameter. (O2 MK1 is 78 mm)
   
  2. My spacer thickness is 0.5 mm. (same as O2 Mk1)
   
  Wachara C.


----------



## t0nix

If you had a 009 stax believe that your data is best for implementation. I have a great center 5 axis CNC machining and other types.

The only inspiration I can give is: what do you think the solution to double membrane?

I would make a good headset, with materials such as aluminum and carbon and whichare at levels of 009 stax.

Do you think it can get to the performance of stax 009?


----------



## chinsettawong

Hi t0nix,
   
  Wow! You even have access to a 5 axis machine center.  That is going to be just perfect or even better than what Stax can make.
   
  The performances of the headphones depend on many factors.  Diaphragm material, diaphragm tension, and even the coating material can affect the performance.  It's just so much fun to try and try until you get it just right.
   
  Just start making it.  If you need help along the way, I'll always be here to help.
   
  Wachara C.


----------



## t0nix

Ok, so I unfortunately have not experienced these things, I'm an engineer: P My strength is knowing how to draw cad, are capable of using the composite and to have this available to the processing center. If you were to explain the characteristics that must have the material between the membrane I can advise what should I use and what kind of carryover. mechanics use hundreds of reports that have different characteristics. I look forward to your response and be able to dellecuffie best of Stax ... aesthetically! If you have any IGES drawings you can send them?


----------



## chinsettawong

Ok, PM me with your email address, and I will send you the drawings that I have made.  However, I use 2 mm drill bit to drill the holes.  If you have 1 mm drill bit, I think you should try drilling more holes using 1 mm.  That's what Stax does.
   
  For stators, I use 1 mm copper clad PCB and 0.5 mm for spacers.
   
  For diaphragms, I'm now trying 2 micron Mylar.  I will also try 3 micron later.  I've tried 0.8 and 1 micron Mylar, but I didn't like it.
   
  You should go ahead and make the spacers and stators first.  Then you will have a good idea of what to do next.
   
  Wachara C.


----------



## t0nix

The mylar 2um found it, what uses stax? for 1mm holes there are problems, they can also do 0.8 mm! for PCB thicknesses and tell me what features you must have and what can I advise you to use  the my email is: antonino.scordato @ me.com


----------



## chinsettawong

I'm not sure what Mylar thickness Stax's using.  Now I can get treble and mids as good as SR009, but for bass, mine is a little less. I've played with different tensions on 1 micron Mylar and I still couldn't get the same.  I'm now trying 2 micron, and it seems a little bit better than 1 micron.  I'll try 3 micron next.  
   
  I'll convert my design info .dxf and send to you later.
   
  Wachara C.


----------



## t0nix

You think that 3micron is better for bass, without penalizing the top and midle frequency?
   
  ok, now realizze all the headphone, for the  thinkness mylar wait the your test


----------



## chinsettawong

Hi t0nix,
   
  I've just sent .dxf files to you.  Please have a look.  
   
  I am postings the images here just in case you can't open the files.


----------



## t0nix

From this file, I change the dimension of the holes, from 2mm a 1mm?


----------



## chinsettawong

No, don't change only the hole size.  You also increase the number of holes. 
   
  Wachara C.


----------



## t0nix

Ok  thanks


----------



## t0nix

i send you the news for email OK?


----------



## chinsettawong

Hi t0nix,
   
  You can post them here and we can discuss here in the open or you can send me by email.  Either way is fine with me.  
   
  Wachara C.


----------



## Headdie

I know it's not DIY, but to begin wth...
   
  I wonder if I could take the electrostatic cell out of an SR-X/Mk3 and fit it into larger circumaural headphones ?
   
  The diameter of the cell is probably 70-80 mm. Would it be a problem to fit it into a larger cup ?
   
  Thanks,


----------



## chinsettawong

Hi Headdie,
   
  If you know what you are doing, I'm sure that can be done.  
	

	
	
		
		

		
			




   
  Wachara C.


----------



## chinsettawong

Ok, I have the result of 3 micron Mylar.  It's definitely better with low frequencies.  What I'm hearing right now is very close to what I can hear from SR009.  
	

	
	
		
		

		
		
	


	



   
  Using 3 micron Mylar, the bass just goes lower while mids and highs are not suffered.  I like it.  
	

	
	
		
		

		
		
	


	



   
  Wachara C.


----------



## Headdie

I'd like to hear it ! Lucky guys,
   
  Technical question : What's the effect of the air volume in front an behind of the driver...
   
  I mean, what's the effect if I increase the air volume in front of the driver with wider/deeper earpads ?
   
  And what's the effect if I use a larger earcup ? I assume it won't change much if it's open, but I may be mistaken...


----------



## chinsettawong

Hi Headdie,
   
  I don't have any technical data to back be up. However, from my experience, you get a deeper bass if you move the drivers further away from your ears. That is if you use thicker ear pads VS thinner ones.  Bigger or smaller ear pads affect more on comfort.
   
  Wachara C.


----------



## Vaughn

Quote: 





chinsettawong said:


> Well, I end up using my old headband for the time being.  I really hate to hold them against my ears when listening.


 

 You have made a lot of progress on these since last I checked in Wachara
	

	
	
		
		

		
			




   
  This is making me want to build another pair!


----------



## chinsettawong

Hi Matt!  It's been a long time!  If you should decide to make another pair, I can really give you some really good advices.  
   
  Wachara C.


----------



## Headdie

I've tried it and didn't get good result.
   
  Regarding the coating, I didn't find Staticide 6300, but this thing,
   
  http://www.ebay.com/itm/320548856268?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649
   
  Do you think it's the same ?
   
  I've made up my mind. I'll open the the cell and re coat the diaphragm.
   
  Quote: 





headdie said:


> I know it's not DIY, but to begin wth...
> 
> I wonder if I could take the electrostatic cell out of an SR-X/Mk3 and fit it into larger circumaural headphones ?
> 
> ...


----------



## chinsettawong

Hi Headdie,
   
  No, they are not the same.  But, I think it will work too.  But probably the life time after coating won't be as long.
   
  If you don't mind coating the diaphragms once after a while, you can go for it.
   
  Best regards,
   
  Wachara C.


----------



## Vaughn

Quote: 





chinsettawong said:


> Hi Matt!  It's been a long time!  If you should decide to make another pair, I can really give you some really good advices.
> 
> Wachara C.


 


  Hi Wachara
	

	
	
		
		

		
		
	


	



   
   
  I have been playing around with orthodynamics and love their sound, I just wish they were lighter (HE-500). 
   
  I think I might be able to set up a simple jig on a drill press for replicating the stators. It sounds like  you are using a heavier diaphragm these days?


----------



## chinsettawong

Hi Matt,

Yes, I do notice that you have move away from electrostatic to orthodynamic. I also bought a pair of HE-5 to try. However, I find that my electrostatic headphones sound better by quite a big margin. 

Until today, I still like my version 1 headphones the most. If I were to do it again, I would etch out all the unneeded copper and use 0.5 mm spacers. As for diaphragms, I think I have been wandering in a wrong direction. The thinnest diaphragm isn't always the best. For the Stax clone, I now use 3 microns and really love it. Because of the high diaphragm width to spacer thickness ratio, I have no choice but to tension the diaphragm very high. With thinner Mylar, the bass is just not as good.

Wachara C.


----------



## Headdie

What about Elvamide for a longer lasting coating ?
   
  I can only find Staticide 6300 in gallons and for the price of my earphones...


----------



## chinsettawong

I haven't tried Elvamide before, but I've heard that it's very humidity sensitive.  
   
  I've tried this and it seems pretty good:
   

   

   
  It comes with 2 bottles - gel and spray.  Gel is much better.  However, I don't know how long it can last as I have only used it for just over a month.
   
  Wachara C.


----------



## Headdie

Interesting... I already have a Philips anti-static cleaning gel for computer screen... I guess I'll try it this weekend


----------



## Headdie

Wachara,
   
  I've opened my two SR-X/Mk3 drivers and I'm ready to replace the diaphragms.
   
  (I discovered that they were damaged when I opened the drivers.)
   
  Do you have some pictures or instructions to help me do that ? First, I'll have to find and buy mylar or the proper material...
   
  I'll look for a website explaining how to do it.
   
  Meanwhile, if you know a good one, don't hesitate to tell me.
   
  Ciao !


----------



## Indread

So are DIY electrostatic headphones for sale, say, on eBay, or here at the head-fi forums? I was wondering how cheap they can go for, to avoid the hassle of building one myself. What is the cheapest + required amp setup?
   
  The non-DIY ones are definately out of my budget range.


----------



## chinsettawong

No, my headphones are not for sale.

Even if I do, they won't be cheap.

Wachara C.


----------



## Vaughn

Quote: 





indread said:


> So are DIY electrostatic headphones for sale, say, on eBay, or here at the head-fi forums? I was wondering how cheap they can go for, to avoid the hassle of building one myself. What is the cheapest + required amp setup?
> 
> The non-DIY ones are definately out of my budget range.


 


  You should start out with an old pair of Koss ESP 9 or something similar which can give you an idea of the electrostatic sound without spending too much money.


----------



## scompton

You can also look at AT electrets, or SR-3 clones from Magnavox, K-Mart, or Radio Shack.  I only paid $15 shipped for the Magnavox stat.  I wouldn't pay more than $50 for any of these.


----------



## khbaur330162

http://20cheaddatebase.web.fc2.com/SONY/ECR-800.html
   
  I thought it was interesting. Maybe you can try to incorporate it, Wachara? Really cool work, btw.


----------



## chinsettawong

Hi Khbaur330162
   
  Thanks for your info.
   
  One of these days when I have the time and mood, I'm going to make another pair of headphones with all the dimensions similar to HE90. 
	

	
	
		
		

		
			





  
   

   
  Wachara C.


----------



## spritzer

It would be very cool if you could make two versions, one flat like the HE90 and one where the drivers are angled by a few degrees.  I suspect a large reason why the HE90 imaging is so odd is down to this.


----------



## chinsettawong

That's a good idea, Spritzer. I will try your suggestion the next time I make them.

Wachara C.


----------



## dude_500

Really amazing work. I may have missed it if you already said, but what thickness PCB are you using for the middle spacers?


----------



## chinsettawong

Hi Dude_500,
   
  I now use 0.5 mm PCB as spacers.
   
  Wachara C.


----------



## chinsettawong

I just want to post this information here so that some of you that have a similar problem as mine can solve it.
   
  My DIY headphones start to develop the weird squeal.  It only happens after I've been listening to them about half an hour or more.  The longer I listen, the more obvious the squeal is.  It's very annoying.  At first I thought that there could be some loose connections or some dust in the drivers.  But on close inspection, I find that it's actually the moisture (humidity) that is the real cause.  
   
  My left driver's dust protection diaphragm was accidentally damaged and had a small hole on it.  When wearing the headphones after a period of time, the humidity inside the cup starts to accumulate.  The moisture finds its way into the inside of the driver and eventually condenses into tiny drops of water on the diaphragm causing the electrical leakage from diaphragm to stators.   
   
  My solution is to replace the dust protection diaphragm.  On Stax, there are normally two pieces of dust protection diaphragm.  One is in the front and the other one is in the back side.  If the front one has a hole and the back one is still in good shape, you might want to try to swap them.  The dust protection diaphragm isn't that critical on the back.  
   
  Wachara C.


----------



## Phos

It's my understanding that Koss's electrostats tend to get that problem after a while.


----------



## chinsettawong

I'm sure that it's a common problem for all the electrostatic headphones.  Just a small, tiny hole is enough to cause this problem.
   
  Wachara C.


----------



## HeadphoneAddict

Quote: 





chinsettawong said:


> I'm sure that it's a common problem for all the electrostatic headphones.  Just a small, tiny hole is enough to cause this problem.
> 
> Wachara C.


 
   
  What Phos is trying to say is that the Koss ESP-950 tend to do that more often than other stats, and may not have a hole in the dust cover to cause the problem.  I think my previous pair of HE Audio Jade also developed an issue with noise from high humidity after I sold them to someone in Houston, while they sounded fine in dry Colorado weather.


----------



## chinsettawong

If you are sure that the dust covers on both front and back side are good, then the case of humidity affecting the drivers is extremely small since the covers block out the moisture and dust. So the noise problem should come from either the cable or connections.

Wachara C.


----------



## spritzer

The ESP950 does not have a solid dust cover on the back so dust is the most likely issue.


----------



## hello im sean

hey im sorry but where is the dust protector? im trying to find it....


----------



## chinsettawong

Quote: 





hello im sean said:


> hey im sorry but where is the dust protector? im trying to find it....


 

 Which headphones do you have?  Have you tried taking them apart to look inside?  The dust covers are situated on the very front and very back of the driver.  In Stax SR007 and SR507, the dust covers are exactly the same for both front and back side (I guess they all are the same for other series as well, but I'm not sure).  However, for HE60, they are different, and you can't simply swap the two.  I have no idea what it is like inside Koss 950 though.
   
  Wachara C.


----------



## hello im sean

i dont have any electrostatics but id like to make a pair! did you make your own dust cover or use one off of the stax?


----------



## chinsettawong

I make my own.


----------



## hello im sean

out of what? could i see pics if that's alright?


----------



## sml1226

What are some alternatives to the traditional Stax plug for these? I was curious how something simple like a 5 or 6 pin XLR would do here. I'm trying to avoid frying something (potentially myself) and those of you with more experience surely have more of an idea of what works and what doesn't.


----------



## chinsettawong

Quote: 





hello im sean said:


> out of what? could i see pics if that's alright?


 

 Obviously you haven't read my older posts.  
   
  The dust cover is nothing special.  I use the same material as my diaphragm to make it.  It's 1 micron Mylar.
   
  You can look at some of the pictures from my older post here:
   
  http://www.head-fi.org/t/498292/my-diy-electrostatic-headphones/120#post_7330732
   
  Wachara C.


----------



## hello im sean

thank you i skimmed through the whole thread yesterday but i must have missed those pics!
   
  edit: have you considered using thicker mylar so it wont rip or is that a stupid question?
  Also some designs don't seem to include the dust cover. doesn't this color the sound? Is it only required in moist environments?


----------



## chinsettawong

Quote: 





sml1226 said:


> What are some alternatives to the traditional Stax plug for these? I was curious how something simple like a 5 or 6 pin XLR would do here. I'm trying to avoid frying something (potentially myself) and those of you with more experience surely have more of an idea of what works and what doesn't.


 
  For my own DIY headphones I simply use an easy to find 6 pin din plug.  Something like this:
   

   
  It works great for me.
   
  Wachara C.


----------



## chinsettawong

Quote: 





hello im sean said:


> edit: have you considered using thicker mylar so it wont rip or is that a stupid question?
> Also some designs don't seem to include the dust cover. doesn't this color the sound? Is it only required in moist environments?


 
   
  I do put dust covers on all my headphones.  It's a must do.  You need to put it at least on the side facing your head.  It is very critical to protect your sweat from going into the driver.  I'm now using 2 micron Mylar as the dust cover and it's pretty strong already. 
   
  Wachara C.


----------



## hello im sean

thank you very much! I did a lot of research on Stax and saw that they also use thin diaphragms on either side of the stators? for dust covers.  Do you notice it coloring the sound at all though i wonder?


----------



## chinsettawong

I do not know what kind of material Stax is using for their dust cover.  It's not the same as their diaphragm.
   
  I've tried putting dust covers on both front and back side of my DIY headphones.  I noticed that by doing so I lack quite a bit of bass.  Then later on in all my DIY headphones, I put a dust cover just on the front side.  It doesn't seem to give coloration to the sound though.
   
  Wachara C.


----------



## sperandeo

chinsettawong said:


> Hi Spritzer,
> 
> I really enjoy being on this forum.  It's my first time to see so many people using electrostatic headphones.  I'm really excited and looking forward to building more amps for my headphones.
> 
> ...




WOW!!!! I love this amp. Good work!!


----------



## FrankCooter

Quote: 





sperandeo said:


> WOW!!!! I love this amp. Good work!!


 
  I love it too! Awesome casework! 
   
  One of these days you should offer kits for your headphones.  I'd certainly buy a pair.
   
  Combining your headphones with a well executed "Volksamp"  could potentially set an entirely new price/performance standard for this hobby.


----------



## ujamerstand

Interesting. Full diy stat kit. I think there might be a ton of interest in that.


----------



## chinsettawong

Thanks guys for your compliments.  Frankly speaking, the amp case was a collaboration of a few of Thai DIYers  here in Thailand.  I made the amp, the other guys made the design and assembling.  By doing this, we brought out the best of everybody.  The case was inspired by Transformer the movie.  
	

	
	
		
		

		
		
	


	



   
  About a DIY headphone kits, I've been thinking a lot about it.  But I have to say that I just can't do it.  I have a full time job, and I'm only make the headphones for fun.  My CNC machine is a homemade one and isn't really robust.  Thank you so much for your interest.  
   
  Wachara C.


----------



## spritzer

Kevin and I have talked about DIY transducers or even full kits but it's just not a great idea along with the Stax EQ's,  Too many variables and few people have the equipment or skill required to overcome them.


----------



## chinsettawong

spritzer said:


> Kevin and I have talked about DIY transducers or even full kits but it's just not a great idea along with the Stax EQ's,  Too many variables and few people have the equipment or skill required to overcome them.




Do you have any special specifications that you would like to try?

Wachara C.


----------



## spritzer

Not really, just compatibility with the Stax setup.  The plan was to design drivers which would fit into some common frame with minimal modification needed.  I never nailed down any model I liked but pretty much anything with the right shape and driver mounting would work.


----------



## chinsettawong

Ok, I've got some time today and I managed to cut some stators and spacers for my HE90 clone.  If time permits, I will cut the wooden enclosure tomorrow.


----------



## spritzer

Those do look smashing!  
	

	
	
		
		

		
			





  Did measure the HE90 you had there and pretty much clone the drivers?  Reason I'm asking is I just got the price of the HE90 drivers and yeah... I'm not going to buy a set.  Insane is to put it lightly...  I do have a complete HE90 frame but no drivers so either something like this or a mounting plate to fit Lambda drivers.  I do think some of the better drivers, mounted properly, will be an improvement over the HE90.  Too bloody colored...


----------



## pabbi1

Just awesome.... words fail.


----------



## chinsettawong

Quote: 





spritzer said:


> Those do look smashing!
> 
> 
> 
> ...


 
  Hi spritzer,
   
  Unfortunately, the HE90 wasn't mine, and I didn't want to open it up to make the measurement.  I did took out the earpad and spent a rather long time taking the measurement from outside the can.  But I'm sure that I'm pretty close.  
   
  What parts do you need?  Do you have the exact measurements?  How about you send me the frames and I make the drivers for them?  
	

	
	
		
		

		
		
	


	



   
  Here is the frame I've managed to cut today. I'll spend the next few days putting them together.  Let's see how they compare with the real thing.  
   

   
  Wachara C.


----------



## spritzer

What I need is a plate to fit drivers to, so it does the same job as the black protective plate on the HE90.  I have a nice stash of Lambda drivers so it would be a good idea to use them.  I'd have to have a few mounting plates made to see whether I should just use the protective grill on the Lambda drivers or fashion or build one into the plate and mount the drivers flush with it.  Here are a couple of pics of the cups, they are quite big so I'll just post the links:
   
  http://i.imgur.com/l7RML.jpg
  http://i.imgur.com/Emgpt.jpg
   
  You are very close with that one and here is how it looks with a Lambda driver inside. 
   
  http://i.imgur.com/gayuA.jpg
   
  imgur clearly doesn't like that plan but I'll carry on regardless.


----------



## chinsettawong

Hi Spritzer,
   
  Thanks for the pictures.  Your idea of fitting the Lamda drivers in the frame is interesting.  Do you want me to help you make the mounting plates? In order to make them, I need the exact dimensions.  Do you think that you can make the measurement for me?  What kind of material is good for making such mounting plates?  What should be the thickness?  How would you fix the Lamda drivers on the plate?
   
  As for mine, I make the mounting plate out of a 5 mm plastic sheet (we call it plastwood here).  After fitting everything in, I found out that my mounting plate is a bit too thick.  If I were to do it again, I might go with 2-3 mm plate. But, what material is good, I don't know yet. 
   
  From your picture, I can see that the dust cover of the driver is actually made of some kind of woven fabric.  I suppose this is the side facing out, right?  The opposite side must be plastic then.
   
  Wachara C.


----------



## chinsettawong

Little by little, they are coming together.  
	

	
	
		
		

		
		
	


	



   

   

   

   

   
  Wachara C.


----------



## tranhieu

Awesome! you ever consider lacquering those woodies?


----------



## spritzer

Quote: 





chinsettawong said:


> Hi Spritzer,
> 
> Thanks for the pictures.  Your idea of fitting the Lamda drivers in the frame is interesting.  Do you want me to help you make the mounting plates? In order to make them, I need the exact dimensions.  Do you think that you can make the measurement for me?  What kind of material is good for making such mounting plates?  What should be the thickness?  How would you fix the Lamda drivers on the plate?
> 
> ...


 
   
   
  I'd love to see your measurements and compare them to mine but I'll probably bribe Dr. Gilmore with booze and cakes into helping me make the plates.  
	

	
	
		
		

		
		
	


	




  My plan is to just mimic how Stax made the Lambdas for 30 years so an aluminum plate (1.5-2mm) and the drivers then glued to the plate.  I might also try titanium plates to save on weight and also try to make the plates thicker in the center with a recess at the edges so that they fit the housing. 
   
  What will take some trial and error is the distance from the driver to the ear.  On a Lambda the driver is recessed by the thickness of the protective grill and it's support but this might not work on a HE90 frame.  So I'd either have to cut a slot into the plate like they do on the Lambda or drill holes and then mount the driver right next to the plate.  I'm worried about reflections if I do this and ditto about my idea of slightly angling the driver inside the cup.  Nobody said designing headphones was easy... 
	

	
	
		
		

		
		
	


	



   
  Those drivers came out of a Lambda Pro and all pre 1992 Lambda drivers had that type of dustcover on the back.  It's woven nylon and Stax had used it since 1960 on the back.  It only proved to be a problem with the 1987 Lambda Signature as it didn't have any damping so dust had a much easier way of getting to the dust cover and cause issues.


----------



## chinsettawong

Hi Spritzer,
   
  I'll try to make the exact measurement to show you tonight.  Before going to sleep last night, I was thinking the same as what you described.  I can use a 6-8 mm plastic and etch down to the shape of the Lamda driver. Put the Lamda driver in and fix it with a 1-2 mm aluminium or fiber glass top plate.  And you just put the whole thing into HE90 frame.  
   
  Wachara C.


----------



## chinsettawong

Quote: 





tranhieu said:


> Awesome! you ever consider lacquering those woodies?


 
  Hi Tranhieu,
   
  Yes, eventually I will lacquer the frame.  
   
  Wachara C.


----------



## chinsettawong

Hi Spritzer,
   
  Here are the measurements of my plate:
   

   
  Wachara C.


----------



## JoseClimaco

Amazing work!


----------



## Phos

Quote: 





chinsettawong said:


> Thanks guys for your compliments.  Frankly speaking, the amp case was a collaboration of a few of Thai DIYers  here in Thailand.  I made the amp, the other guys made the design and assembling.  By doing this, we brought out the best of everybody.  The case was inspired by Transformer the movie.
> 
> 
> 
> ...


 
  Have you heard of emachineshop?  They can do volume manufacturing for you.  Worth a look, at least.


----------



## chinsettawong

I just finished putting the phones together.  They sound nice!  
	

	
	
		
		

		
			





  
   

   

   
  Now I need to buy more plastic screws, make a couple of nice back covers, lacquer the wooden frames, and find a decent headband for them.


----------



## hello im sean

how is the frequency response on those compared to your round drivers?


----------



## chinsettawong

As of now, they both sound very similar.  The round one has a bit better bass, but really not that much better at all.  I like both.  
	

	
	
		
		

		
		
	


	



   
  Wachara C.


----------



## nk77

Quote: 





chinsettawong said:


> Here is the frame I've managed to cut today. I'll spend the next few days putting them together.  Let's see how they compare with the real thing.
> 
> 
> 
> Wachara C.


 
   
   
  This thread...is...brilliant! Mate very very good work!
   
  Was that made using the DIY cnc?


----------



## chinsettawong

Yes, I made my own CNC, and everything was cut by my DIY CNC.  Here is a short VDO of my CNC in action:
   
http://s611.photobucket.com/albums/tt193/chinsettawong/?action=view&current=b8c34496.mp4
   
  Wachara C.


----------



## Congo5

Hi Wachara
	

	
	
		
		

		
		
	


	



  
  I've been reading all your postings and am excited to follow your examples.
   
  I have 2um Mylar and the coating, have the plans to build a cnc. (mydiycnc.com)  will order the kit soon...
  have sourced the .5 mm PCB (http://www.ebay.com/itm/120664289524?var=420018556368&ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649)
   
  I have access to a bridgeport mill but don't like the thought of drilling those stators by hand.
   
  The plan is to use EMC2 Ubuntu..got that loaded into a virtual machine and looks good..
  Found a virtual mill that runs G code, its fun
   
  OK But how did you draw the parts/ get the G code??
   
  What software are you using?  I tried Heekscad, inkscape, CamBam and Free Cad to design with but cannot figure out how to do holes in a grid pattern?
   
  I would like to start with 80mm active round stators..
  Are your files posted anywhere?
   
  any help or suggestions would be appreciated...
   
    Thank You
    Gary


----------



## chinsettawong

Hi Gary,
   
  It's nice to hear that you are going ahead to build your own CNC.  I'm sure that you will find the CNC machine to be really fun to work with.
   
  I also use EMC2 and I love it.  For drawing the holes pattern, I actually draw them manually and use copy and paste function.  It's quite confusing at the beginning, but when you know it, it's not too difficult.  I can share with you my drawing if you want.  PM me with your email address and I will send my drawings to you.  Is general .dxf be good for you?
   
  About PCB, you will need 1 mm PCB for your stators and dust cover rings.  0.5 mm PCB is only good for making spacers.
   
  To me, my Omega clone sounds pretty good.  But, for my next headphones, I would go back to my original oval shape design.  You know - nothing beats big diaphragm when it comes to electrostatic.  The bigger diaphragm is always the better!
   
  2 microns Mylar is a good start, but you really want to have thicker Mylar to try too.  I am now using 3 microns and I like it better than 2 microns.  I will try 6 microns very soon.
   
  Wachara C.


----------



## Congo5

Wachara:
   
  Thank you for your quick reply....
   
  I trust your knowledge on this as I have followed your posts for a while..and they make sense!
   
  Will PM email and .dxf is fine as I will learn to use it..
   
  Thanks for the 1mm  stators>> correction. Will use plastic for spacers..
   
  I will try any design you think is best , just thought the Omega would be simpler
   
  what do you import the .dxf file into (what program) to make G-Code?
   
  The CNC might take a month or two to get going depending on my work schedule..
   
   
    Gary


----------



## chinsettawong

Hi Gary,
   
  If you can buy 0.5 mm PCB easily, please use it as the spacer.  It's much better than plastic.
   
  I've got your email and will send the files to you later today.
   
  Best regards,

 Wachara C.


----------



## Congo5

Wachara
   
  The same store has .5mm FR4 single sided PCB for spacers
  and .94 or 1.2mm for stators
   
  on the  oval shape ones:  2mm holes, 4mm on center ... about 400 of them
   
  many decisions.....
   
  thanks
  Gary


----------



## chinsettawong

Hi Gary,
   
  The CAD files for stator and spacer have just been sent to you.  I recommend that you make the round ones for your first pair as the ear pads are readily available.
   
  Wachara C.


----------



## chinsettawong

Just want to show how desperate one of my friends is to build his own electrostatic headphones.  
	

	
	
		
		

		
		
	


	



   
  He uses 1 mm PCB for the stators and spacers.  The diaphragm is made from plastic food wrap from his kitchen.  I give him two thumps up for his devotion and creativity.  
	

	
	
		
		

		
		
	


	



   

   
  He even records the sound from his headphones here in this VDO.


----------



## ujamerstand

He should record it with a binaural recording rig, so that the rest of us with DF type headphones can have a better idea of how it sounds like.


----------



## FrankCooter

A while back I was able to help Wachara with some components. It  wasn't a big deal and I was happy to help. You can imagine how stunned I was when a few months later he offered me a pair of his DIY Omega clone electrostatic drivers and enclosures.   It took me awhile to get them up and running, but here they are. The cable is a Stax extension cable. The earpads are Stax 007 replacements. The headband is from an HE-5. I fabricated the arcs out of aluminum bar stock. Definitely a "Frankenphone", but I think they look pretty good.
   
  How do they sound?  I've heard the original Omega a few times, it's my all time favorite Stax headphone. Maybe it doesn't have quite the resolution and linearity of the O2, but it's not far off, and it's got a bigger sound stage, slightly warmer and fuller midrange, and a powerful dynamic abilty that no other Stax possesses.  Audio memory is very transitory, but I think he has come very close here. These are wonderful headphones by any standard. I own a a pair of 507's and Koss 950's.  In the past I've owned several Lamdas. I prefer Wachara's headphones to any of them. Truely stunning work.  The journey's not over either. He's got plans for further refinements and experiments.
   
  I'll be bringing these to the LA meet. Come listen for yourself.
   
  Thanks again Wachara! These are truly a stunning accomplishment!


----------



## HeadphoneAddict

Quote: 





frankcooter said:


> A while back I was able to help Wachara with some components. It  wasn't a big deal and I was happy to help. You can imagine how stunned I was when a few months later he offered me a pair of his DIY Omega clone electrostatic drivers and enclosures.   It took me awhile to get them up and running, but here they are. The cable is a Stax extension cable. The earpads are Stax 007 replacements. The headband is from an HE-5. I fabricated the arcs out of aluminum bar stock. Definitely a "Frankenphone", but I think they look pretty good.
> 
> How do they sound?  I've heard the original Omega a few times, it's my all time favorite Stax headphone. Maybe it doesn't have quite the resolution and linearity of the O2, but it's not far off, and it's got a bigger sound stage, slightly warmer and fuller midrange, and a powerful dynamic abilty that no other Stax possesses.  Audio memory is very transitory, but I think he has come very close here. These are wonderful headphones by any standard. I own a a pair of 507's and Koss 950's.  In the past I've owned several Lamdas. I prefer Wachara's headphones to any of them. Truely stunning work.  The journey's not over either. He's got plans for further refinements and experiments.
> 
> ...


 
   
  That's very cool.  Any chance you'll be at RMAF this year with those?


----------



## spritzer

Those do look awesome and I'll be sure to pester Wachara for some parts once this project is done:
   

   
  Wachara made these for me and they are adapter plates to fit Stax Lambda drivers in a Sennheiser Orpheus shell.


----------



## chinsettawong

Hi Frank,
   
  They do really look nice with HE-5 headband.  I have a pair of HE-5 too, and I'll try to do the same as you've done.  
   
  Thanks for your review.  I am glad to hear that you like them.  If you have a chance to A/B test them with the original Stax Omega, I'm sure that you'll find the sound to be vey similar.  
	

	
	
		
		

		
			




   
  Wachara C.


----------



## chinsettawong

Hi Spritzer,
   
  I'm really looking forward to hearing how you like the Lambda drivers in HE-90 enclosure.  When you're done with all the tests, if you want, I can send you my version of HE-90 drivers to try.  Let's see how they compare to the Lambda or the real HE-90.  
	

	
	
		
		

		
		
	


	



   
  Wachara C.


----------



## spritzer

Quote: 





chinsettawong said:


> Hi Spritzer,
> 
> I'm really looking forward to hearing how you like the Lambda drivers in HE-90 enclosure.  When you're done with all the tests, if you want, I can send you my version of HE-90 drivers to try.  Let's see how they compare to the Lambda or the real HE-90.
> 
> ...


 
   
  That would be very cool.  I'm still waiting on the drivers to arrive from Japan but I'm going to get some HE60 drivers soon which should also fit.  Better than paying 6K$ for HE90 drivers...


----------



## dude_500

Just finished my second revision of drivers today which pretty much follows your design. Figured I'd share some photos of it (hopefully it's appropriate to put these in this thread, seems like the most logical place to put them). Revision 1 used stainless plates and was of much poorer construction, but still sounded very good, although the trebles seemed a bit over-bearing and a bit distorted (could have just been my amp though, which is a work in progress). I hadn't heard electrostatic headphones before, the bass presence is simply incredible. I increased the tension quite a bit on the second revision since I was having the film stick to the stators and it just seemed overall too loose.
   
  This was made entirely without CNC tools, so anyone with basic tools can make one of these (although I'd stick to rectangular drivers without CNC). Took roughly one day from start to finish to build these new drivers. The stators are 0.060 FR4 and I drilled them by using the stainless material as a drill-template while drilling them on a small drill press under water.
   

   

   

   

   
   
  Here's my old version in milled wood enclosures and with stainless stators. They were way too heavy, and i'm not going to use the enclosures anymore and just go with a minimalistic design. Every part of these were scrapped and won't find their way into my final headphones, but it was still a good first-build to figure out the tricks to making drivers.


----------



## chinsettawong

Hi Dude_500,
   
  Your drivers look very well made.  I'm sure that they sound very good too.
   
  What is the dimension of your drivers?  What is your spacer thickness?  What Mylar thickness do you use?  How much tension do you put on the film?  What is your bias voltage and what do you use to drive them? I always like to ask a lot of questions. I hope you don't mind. 
	

	
	
		
		

		
		
	


	




  Let's share our experiences with others.  
	

	
	
		
		

		
		
	


	



   
  I really like the way you manually drill your stators.  Although it's a lot of work, but you can actually get a good result doing it that way.  Very nice!
   
  Your Mylar tensioner looks really nice.  Keep us posted with your progress.  
   
  Wachara C.


----------



## dude_500

Questions are good, sharing details definitely makes projects like these better for everyone. 

 As for dimensions, attached is an image of the masks I used to etch the four layers. The grid is 0.5" / div.
   
  Spacers are 0.5mm each, 1mm stator-to-stator gap. Mylar is 2 micron. I'm coating it with a water/white glue/graphite mix of roughly the proportions you mentioned, though I didn't actually measure it. Just mixed up a bunch to last a lifetime.
   
  I tensioned my first revision with 0.26lbs on each of the 8 strings. On the new revision two, I increased that to 0.49lbs so almost twice the tension. I don't know what units of tension this all correlates to, I didn't do a percentage displacement measurement. I'm an EE, not a mech-e.
   
  I have them biased at 500V which is the minimum my bias supply adjusts to. I haven't felt the need to increase it since it's way louder than I'd ever want them at 1400V stator AC voltage out of the blue hawaii I'm working on. I don't have an SPL meter, but it'd be painfully loud to listen to for very long at the peak output with 500V bias so I'm not going to push it higher and risk blowing through the films for no benefit.
   
   
  I'm going on vacation through the end of the month, so I won't have much to update for a month or more, but I'll definitely post back when I move along with the project.


----------



## chinsettawong

Your diaphragm area is huge.  This should give you very good bass.  However, with the width of over 100 mm and the spacer thickness of only 0.5 mm, you need a lot of tension on the diaphragm otherwise it would be sucked to one side.  You might want to play with the tension.  I doubt that 0.49lb would be enough.  Actually, the best is to keep the ratio of the diaphragm width and spacer thickness to be not over 1:120.  However, on Stax Omega the ratio is around 1:156.  On my Omega clone driver, I use 1:160.  I think yours is about 1:200.  Lowering bias voltage can help. Let us know how it goes.
   
  Oh, about coating material, PVA glue formula isn't very good.  The glue tends to absorb moisture in the air and leads to water condensation.  Nowadays, I very much prefer using antistatic cleansing gel.  It's cheap and works great for me.


----------



## chinsettawong

Hi dude_500,
   
  I think that your diaphragm width is too large and your diaphragm will not be stable.  If I were you, I would increase the spacer thickness to around 0.7 - 1 mm.  And I will probably increase my bias voltage to around 800V or more.  Or you can try to inject a drop of silicone right in the middle of the diaphragm. You want the drop to be in between the diaphragm and one of the stators. When the silicone is dried, it'll act like a spacer helping the diaphragm to stabilize better.  This is how a lot of ESLs are made.
   
  Anyway, it's good to try it your way first, and if it doesn't work you can try it my way.  
	

	
	
		
		

		
		
	


	




  Let us know how it goes.
   
  Wachara C.


----------



## dude_500

I finished tuning up my blue hawaii today and hooked up the new drivers. Incredible sound, like nothing I've ever heard. Way better than my prevision version.
   
  I'm on the loud side of comfortable listening with only 50V p-p on each stator, so they seem pretty efficient at making noise. This is with 500V bias.
   
  I took away signal and blew as hard as I could on the stators and they hit the sides and make crackling sound as expected, but they bounce right back without sticking, so I guess that's enough tension? They seem to be perfectly balanced in volume and sound timbre.
   
   
  More to come as I put more time into tweaking everything.


----------



## AmarokCZ

I also made my DIY electrostatic headphones a while ago.
  I used hand-drilled PCB stators, ~8cm diameter with 2mm holes (331 holes per stator). HD-PE spacers are 0.6mm thick.
  First diaphragm was thick HD-PE (9um) with low tension, but I left it on direct sunlight and it lost its tension, also the sound quality wasn't so great (little worse than Stax SR-3 NEW).
  So I used 2um boPET instead. I tensioned it (by hot air) so the free-air resonant frequency of driver is 110Hz.
  For conductive coating I tried antistatic spray and some "hocus-pocus mix" (water, ink, glue and very little of solvent) but quality of those coating was horrible. So I ended with simple graphite powder which makes great, even coating (surface resistance across diaphragm diameter is ~100 Giga ohm).
  Bias voltage (for now) is 230V, because I'm using Stax SRD-5 energizer. But I will switch to 580V and my own electrostatic amp design after the earcups are finished. Efficiency with 230V bias is quite low (~90dB/100V), I think it's due to relatively high diaphragm tension, but I'm listening at very low voumes so it doesn't bother me.
   
  Coated boPET diaphragm:

   
  Two stators:

   
  Finished driver with dust covers and temporary earpad (borrowed from AKG K300):

   
  Sound is neutral, quite similar to SR-3NEW, but it has better bass (much deeper and more accurate), better soundstage, lover isolation (no isolation at all) and maybe something more, but final conclusion will be available with new earcups.


----------



## chinsettawong

Quote: 





dude_500 said:


> I finished tuning up my blue hawaii today and hooked up the new drivers. Incredible sound, like nothing I've ever heard. Way better than my prevision version.
> 
> I'm on the loud side of comfortable listening with only 50V p-p on each stator, so they seem pretty efficient at making noise. This is with 500V bias.
> 
> ...


 
  Using your headphones with Blue Hawaii would certainly be an ultimate system.  Nothing beats large electrostatic drivers when it comes to dynamic and sound stage.  Coupling that with a wonderful amp such as Blue Hawaii, you're in heaven.
   
  I'm glad to hear that your drivers are stable.  With that large diaphragm area, you really have no need to turn up your volume too high.  
   
  You might want to do this experiment to see if your diaphragms are really stable enough.  You hook up your headphones with the amp and leave them like that for a few hours (3-4 hours) without  playing any music.  If the diaphragms are still not being sucked to one side after that period of time, then everything is fine.
   
  Congratulations on your success and please keep us posted if you have any update.
   
  Wachara C.


----------



## chinsettawong

Quote: 





amarokcz said:


> I also made my DIY electrostatic headphones a while ago.
> I used hand-drilled PCB stators, ~8cm diameter with 2mm holes (331 holes per stator). HD-PE spacers are 0.6mm thick.
> First diaphragm was thick HD-PE (9um) with low tension, but I left it on direct sunlight and it lost its tension, also the sound quality wasn't so great (little worse than Stax SR-3 NEW).
> So I used 2um boPET instead. I tensioned it (by hot air) so the free-air resonant frequency of driver is 110Hz.
> ...


 
   
  Wow! You did a wonderful job making those drivers.  You said your drivers are 8 cm in diameter.  What is your active diaphragm area?  Your bias voltage of 230V is way too low.  With your 0.6 mm spacer, 600V is still very conservative.
   
  I'm not sure why antistatic solution isn't working well for you, but using graphite powder is fine. 
   
  Thanks for sharing.  Please keep us posted with your progress.
   
  Wachara C.


----------



## AmarokCZ

Active diaphragm area is ~40cm^2. Bias is low that's for sure, but just like I wrote I'm going to switch to 580V.
  Did you tried changing bias? If yes, did it change sound quality? (I guess, that it could improve bass quality.) Also did you measured resonant frequency of your drivers?


----------



## chinsettawong

I've never measured the resonance frequencies.  But with around 40cm^2 of active diaphragm area, you should get pretty decent bass.  Yes, when you increase the bias voltage, you increase the efficiency and you get more bass.  You might want to go even higher than 580V since you have a 0.6 mm spacer.  I've been using 650V with the my previous 0.6 mm spacer drivers with no problem.  In fact you can even go up to 800V if you want.  
   
  Wachara C.


----------



## arnaud

Wow, I just happened to stumble upon this thread today and must say I am humbled by your efforts Wachara! I am going to ask a moderator to remove my contributor title and give it to you instead!!
   
  As an acoustic engineer who spends his days simulating the vibro-acoustics of all kinds of equipment, I find fascinating the trial and errors that you've been through to come up with a good sound headphone.
   
  Among the many things you've tried, I was wondering if you had some insight about the following? (I can make guesses based on my experience, but its virtually inexistent in the case of headphones so your input is worth so much more...
   
  > Fim thickness: you've tried quite a few thicknesses and did not hear much differences at first but then found that 3 micron was better then 1 micron as far as bass rendering. What I can't get my head around is how you ensure that you have a reasonable cut-on frequency for the diaphragm (by that I mean the first free-air resonance of the diaphragm, which is typically in the 50-75Hz for Stax headphones I believe). Did you find out you had to increase the tensioning with thicker diaphragms?
   
  > Earpad cavity: you've mentioned that from experience, increased distance from the diaphragm to the ear turns into a bassier tonal balance. Since the earcup cavity is most always seal type (leather or pleather pad), indeed the height of the pads governs the stiffness of this "air spring" and likely affects the low frequency driver response. But you don't seem to play with that variable as much as actual driver design? This is something I may be able to look into with simulation.
   
  > Enclosure model: similar to the earcup cavity, the driver frame seems to act as an acoustic baffle to prevent acoustic cancellation of the front and back waves. Have you done experiments with different frame dimensions? This I could also potential look into with simulation.
   
  > Stator design: per Stax, and intuitively, one has to pay attention to the stator design (it has to be open enough but on the other hand maintaining structural integrity is key to limit distortion). You seem to be using always the same material (1mm PCB?) but I wonder if such relatively thin part doesn't vibrate within the audio range. In which case, part of the benefits with limiting the perforated region is to maintain overall rigidity. This is something I could easily simulate if you give me stator dimensions (including perforations) and material.
   
  > Dual diaphragm: we have been discussed on an other site about dual diaphragms and I was surprised to see you've already tried it! I am keen also on simulating this with an idea I had in mind (two concentric diaphragms between the same stators but with a rim spacer separating the two diaphragms and usage of a thinner diaphragm for the center "tweeter" part). I was wondering if you had any comment on this (like it makes no sense or you won't be able to assemble it...)
   
  > Perforation size: it seems like that rule of thumb is to use a perforation diameter to match the stator/stator gap, any idea where that comes from? From a physics point of view, I imagine the perforated stators help to damp the diaphragm through viscous losses (although they're typically negligible for channels smaller than 1mm). In practice, using larger perforations brings nasty colorations in the midrange as mentioned by Birgir?
   
  You may not feel like answering all these questions, I will totally understand . But if you have interest in what simulation may (or may not lol) bring to the table to help with improving the design, I'd be happy to contribute. Ideally, measurements by someone like Purrin would also dramatically help but I am not sure I can entice him into the venture .
   
  cheers, arnaud


----------



## AmarokCZ

I also done some experimenting, so here is my point of view:
  > Perforation size: I'm using 2mm holes with 0.6mm D-S gap and there is no coloration compared to STAX SR-3NEW (0.5mm holes and 0.3mm D-S gap).
  > Film thickness: I tried few films and I found, that bass is better (more controlled) if the force required to move with diaphragm is larger (this applies only to some point). This, of course, negatively affects sensitivity of driver. One of my previous driver had free-air resonant frequency ~300Hz, but I think it's not problem since it's damped by closed cavity between head and driver.
  Just for your information the free-air resonant frequency of SR-3NEW (old round earspeakers, 8cm^2 active diaphragm area) is ~160Hz and it affected low frequency response only when there wasn't good seal (see this frequency response graph: red line when resealed, yellow line is what I was listening to before resealing).
  > Earpad cavity: I tried 15mm and 40mm thick earpads and with 40mm earpad the sound was little less bassier (!!) with less controlled bass and less bass punch.


----------



## chinsettawong

Hi Arnaud,
   
  First of all, let me tell you that I don't really have much knowledge about Physics, Mechanic, or Electronics.  I make these headphones just for fun, and actually just to get me away from thinking about my day work.  I don't have any instruments for making sound measurement, and I don't do any calculations or simulations at all when I'm making a design. So, forgive me if I can't answer some of your questions, since I really don't know how to answer.  
	

	
	
		
		

		
			




   
> Film thickness: In my first few headphones, I have been using thicker spacers (0.6-1 mm) than what I use now (0.5 mm).  With thicker spacers, using thin film, the stability is good.  But when I reduce spacer thickness down, I need to increase tension to get good diaphragm stability.  With that, I lose bass.  Therefore, I have no way but to use thicker film.  With thicker film you can put more tension on it and still have good bass.  I am tempted to try 6 micron Mylar on my next one.
   
  > Earpad Cavity:  Yes, putting the drivers a little bit farther away from ear, in my experience, gives a little better bass.  Thicker earpads are certainly better, IMO.
 
> Enclosure model:  I've never done any experiment like that.  However, I don't like to have anything obstructing the back side of the drivers.  Open back is certainly better than sealed back, IMO.
   
> Stator Design:  Yes, I have been using 1 mm PCB for my stators since the beginning.  I've only found out recently when I have a chance to open up a pair of Stax 007 that Stax also uses 1 mm PCB for its stators. I haven't had any problem with its rigidity.  I've made many different types of driver.  Which one's dimension would you like to have?
   
> Dual Diaphragm:  The last time I tried it, I didn't like it.  The sound that I hear was like echoing.  I think I must have done something wrong, because I tried stacking 2 drivers and listened to them the other day, and I didn't notice that echo sound.  I'll give it a try again in the near future.  I'm thinking of putting a thicker diaphragm in the back, and perhaps make some low pass filters for that diaphragm.  By the way, I don't quite understand the kind of dual diaphragms you try to explain.  The easier way to make a diaphragm sound different frequencies in different areas is to make segmentations on the stators.  You can make two separate circuits on the stators and put a high pass filter on the center circle.  That way you can make only a small center part of the diaphragm sound like a tweeter.  
   
  > Perforation size:  I have't heard the rule of thump you mentioned before.  I always use 2 mm holes, and that's because I can find 2 mm drill bits easier.  To me the perforation size doesn't make much of a difference.  I don't think bigger holes puts coloration on the sound.  However, it might affect the efficiency of the drivers a little. 
   
  Thanks for your offering to make simulation.  I have no knowledge about that.  But if you feel like doing it, let me know what info you need.  
   
  Wachara C.


----------



## arnaud

Wachara and amarokcz, thanks for the replies! 

Wachara, you've made several designs, how about your favorite one? All I need to get started is the parts dimensions, dsf files probably being the easiest to deal with. That and the materials used. I thing I want to try is evaluate the radiation from residual stator vibration relative to the diaphragm motion. Ideally, I would like to know the free air resonance frequency rather than tensioning but it seems you're doing everything by feel (and doing a darn good job apparently!).

I may start with the existing 009 model I made and evaluate the dual diaphragms (and/or split stators excitation) before going to your headphone model.


----------



## chinsettawong

Quote: 





arnaud said:


> Wachara and amarokcz, thanks for the replies!
> Wachara, you've made several designs, how about your favorite one? All I need to get started is the parts dimensions, dsf files probably being the easiest to deal with. That and the materials used. I thing I want to try is evaluate the radiation from residual stator vibration relative to the diaphragm motion. Ideally, I would like to know the free air resonance frequency rather than tensioning but it seems you're doing everything by feel (and doing a darn good job apparently!).
> I may start with the existing 009 model I made and evaluate the dual diaphragms (and/or split stators excitation) before going to your headphone model.


 
  I'll send you the drawings when I get back home tonight.  Please PM me with your email address.
   
  Wachara C.


----------



## dude_500

Finished up building some quick headphones to go with the drivers today just so I could get some listening in on them before I leave for the rest of the month. They blow my HD600/beta-22 away. I'm not really good at describing headphone sound qualities, they're just incredible. I need to try to listen to some good Stax sometime just so I have a reference of comparison, since these are the first electrostatic headphones I've heard. I don't think I'll ever listen to magnetic headphones again (unless it's 100* out and my dorm room is on fire and 200 watts is too much to add in, which should describe the next two months quite nicely).
   
  I haven't added any moisture shield in on the ear's side of the driver, which I imagine I'll need to do to keep them working in the long run. Do you typically tension that film or just leave it loose? I would think the film vibrating and hitting the stator could be a problem either tensioned or not.


----------



## chinsettawong

Hi Dude_500,

Congratulations! With those large drivers and a BH amp, I am very sure that your headphone's sound is already on par, if not better, than those top of the line commercial headphones. You know what? I stop listening to non-electrostatic headphones for a long time already. After this you might want to make yourself a pair of good ESL. And you'll never want to listen to those boxy loudspeakers again. I'm sure. 

Yes, you definitely want to make a sweat protection diaphragm. The tension isn't crucial here. I just hard tight it and if it has any wrinkle, I don't really care. You put it on only the side that faces your ear. I don't put it on the back side, because it will trap the air and the bass isn't as good.

Wachara C.


----------



## Micaiah

After years of using Head-fi, this thread made me finally sign up. It's humbling how creative some people are and especially when they are willing to share their hard earned knowledge! Thank you!
   
  I'd like to try making a pair of electrostatics, even if just something simple at first. Only problem is what to plug them into without jumping in head first, buying or building an expensive amp. Any recommendations for an amp that wouldn't be too costly? I don't care if it doesn't sound that good as long as it's cheap. Just something to experiment with to get my feet wet. Is it possible to convert a loudspeaker amp or to make a transformer that connects to an amp for not too much money?


----------



## chinsettawong

Hi Micaiah,
   
  There are two ways to listen to electrostatic headphones.  The cheaper way is to listen to them thru the connection with step-up transformers and a normal loudspeaker amp .  You might be able to find a cheap used unit of Stax.  Depending on its age and condition, sometimes you can find it for less than US$100.  The other way is to build yourself a simple tube amp. I built 2 tube amps using a simple circuit, and they costed me around US$250 each. Either of these solutions can give you pretty good sound.  But if don't want to spend money and just want to try it out, you can also find some old, trashed toroidal transformers and put some wires in them.  Then they can be used as step-up transformers.  Together with a simple bias circuit, you can listen to the headphones for sure. They won't sound that good, but they can certainly get your feet wet. 
	

	
	
		
		

		
		
	


	



   
  Let me know if I can be of further help.
   
  Wachara C.


----------



## spritzer

Even power transformers wired backwards will work in a pinch.  The bias supply can be a simple voltage multiplier or just something simple off two back to back transformers.


----------



## chinsettawong

Quote: 





spritzer said:


> Even power transformers wired backwards will work in a pinch.  The bias supply can be a simple voltage multiplier or just something simple off two back to back transformers.


 
  Yup!  That will work too.
   
  Wachara C.


----------



## jgazal

Quote:


arnaud said:


> > Dual diaphragm: we have been discussed on an other site about dual diaphragms and I was surprised to see you've already tried it! I am keen also on simulating this with an idea I had in mind (*two concentric diaphragms between the same stators but with a rim spacer separating the two diaphragms and usage of a thinner diaphragm for the center "tweeter" part*). I was wondering if you had any comment on this (like it makes no sense or you won't be able to assemble it...)
> 
> cheers, arnaud


 
   
   


chinsettawong said:


> > Dual Diaphragm:  The last time I tried it, I didn't like it.  The sound that I hear was like echoing.  I think I must have done something wrong, because I tried stacking 2 drivers and listened to them the other day, and I didn't notice that echo sound.  I'll give it a try again in the near future.  I'm thinking of putting a thicker diaphragm in the back, and perhaps make some low pass filters for that diaphragm.  *By the way, I don't quite understand the kind of dual diaphragms you try to explain*.  The easier way to make a diaphragm sound different frequencies in different areas is to make segmentations on the stators.  You can make two separate circuits on the stators and put a high pass filter on the center circle.  That way you can make only a small center part of the diaphragm sound like a tweeter.
> 
> Wachara C.


 
   
  I have tried to draw Arnaud idea:
   




   
  Arnaud, is the rim spacer draw correct? Which material would you use with such rim spacer? Would the Mylar just be glued to the rim spacer?
   
  It is easier to "build" things virtually... 
   
  Cheers


----------



## arnaud

Quote: 





jgazal said:


> Arnaud, is the rim spacer draw correct? Which material would you use with such rim spacer? Would the Mylar just be glued to the rim spacer?
> 
> It is easier to "build" things virtually...
> 
> Cheers


 
   
  That's the idea although I thought you could have the spacers (PCB or the like) mounted on both stators (the stators would have an outer and inner ring with the same radial stiffeners, the stator outer and inner rims supporting the annular spacers). If the DS gap is the same for both diaphragms, this not sound too difficult to build?
   
  Now, to glue two different diaphragms to one of the stator/rim assembly, I'd imagine a 3 step process, such as this example (assuming same DS gap for both membranes):
  1. Stretch the tweeter diaphragm and glue to the tweeter (inner) rim, cut off the excess material on the outskirt of the tweeter spacer rim
  2. Glue the bass diaphragm (perforated with a hole of same size as the tweeter rim inner diameter) centered on the tweeter rim without tensioning (the tweeter rim could be made wide enough to ease that step) 
  3. Stretch the bass diaphragm and glue to the outer spacer rim under tension, cut off the excess material on the outskirt of the bass spacer rim.
   
  What did you use to make that cool animation?


----------



## chinsettawong

Hi Arnaud,

While it would be fun to simulate, but what are you trying to achieve? For one thing, the sound from electrostatic driver shoots out like a beam, if you miss a sweet spot some of the frequencies are gone. I mean if you make a small tweeter and a woofer, when you move the cups around your ears, the sound you hear will change. As for woofer, the critical thing is the total active area. Given the same diaphragm tension and thickness, the larger it's active area the more bass you'll get.

As for double diaphragms, if you stack two drivers back to back, the total active area becomes 2 times as much. It is possible to achieve more bass without having to increase its physical width and height. It is also possible that the efficiency increases as well. 

Wachara C,


----------



## jgazal

Quote: 





arnaud said:


> That's the idea although I thought you could have the spacers (PCB or the like) mounted on both stators (the stators would have an outer and inner ring with the same radial stiffeners, the stator outer and inner rims supporting the annular spacers). If the DS gap is the same for both diaphragms, this not sound too difficult to build?
> 
> Now, to glue two different diaphragms to one of the stator/rim assembly, I'd imagine a 3 step process, such as this example (assuming same DS gap for both membranes):
> 1. Stretch the tweeter diaphragm and glue to the tweeter (inner) rim, cut off the excess material on the outskirt of the tweeter spacer rim
> ...


 
   
   
  I cheated. I have used Google SketchUp and Microsoft Expression Encoder with Screen Capture. I did the easy way... 
	

	
	
		
		

		
		
	


	



   
  Here is more and less what you describe:
   




   
  And here are other crazy ideas:
   




   
   
   
   
  I am with Wachara, perhaps the increased complexity worsens the reflections.


----------



## arnaud

Wachara,

You may be right this design is creating compromises and I will try to see with simulation if it can go anywhere (simulation isn't easy in itself so I may get nowhere but still planning to try).

As for potential benefits:
- Better control on the diaphragm behavior by adjusting size / thickness to the frequency range
- More freedom to adjust the tonal balance by having two drivers to work with
- Take benefit of the beaming nature of transducers at HF (it doesn't matter if you split the diaphragm at the center, HF radiate from there). Not the this directivity pattern may have little meaning once you factor in the reflections from the pinna) 
- Potentially have freedom to make a larger woofer diaphragm since you're clamping it in the center (similar reasoning to something like the hd800 driver)
- Lack of spurious reflections added by a stacked drivers design

There might be more benefits (and many more drawbacks) but that's what comes to mind now...


----------



## chinsettawong

Hi Arnaud,

You don't need to make it into two diaphragms if all you want is to limit some frequencies in some area. You can do segmetations on the stators instead. You can make the stators into two seperate circuits. You run the little middle part full range and run the outter part with low pass filter. This is a very popular way that people do on their full range ESL. They do that to help fix the beamy nature of the ESL that when you listen to them you can hardly move your head because the sweet spot is so little. 

Wachara C.


----------



## Soul_Est

After reading through the the thread so far, I must type that I have the utmost respect for you Wachara. You're doing with ES headphones what John Britten did with motorcycles. You've even inspired me to try doing the same thing myself even though I'm starting from scratch with no CNC machine or vertical mill to help me yet.
   
  I did have a question about your CNC machine though. How accurate is it? I have been reading through several Instructables and that one person uses theirs for routing PCBs. The Instuctable is located here: http://www.instructables.com/id/Easy-CNC-conversion-of-a-small-mill/
   
  This picture shows what I'm talking about:
   

   
  I believe it could save you a bit on etching the stators.


----------



## chinsettawong

Hi Soul_Est,
   
  I can assure you that a CNC machine is a nice investment for your DIY hobby.  The machine can be extremely accurate.  Depending on your budget, you can start by making a very simple and cheap one, or you can put in more money and use better materials such as ball screws for an extremely accurate machine.  As for my machine, I use ball screws and the accuracy is very good.  I would say the error is not more than +/- 0.05 mm.
   
  However, using a CNC to etch a PCB isn't that easy.  To do a very nice job on that you need to have a very flat bed.  It's extremely difficult to have that on a big table such as mine.  So, I still prefer using chemical to etch a PCB.  It's pretty simple and doesn't use much time at all.  
   
  If you like to make electrostatic headphones, just go ahead and make them.  As you can see, there are a few guys here successfully make them without using any sophisticated tools.  I'm sure you can do it too.  If you need any help, please do not hesitate to let me know.
   
  Wachara C.


----------



## Soul_Est

Thank you very much for the kind words.
   
  I'll start working on the machine once I get the measurements for the place that it'll be operating in. I don't have space for it where I live so I will have to operate the system remotely. Hopefully, I can build a Gantry CNC machine once I save up enough for it. It'll probably end up being a close to the one up on http://diylilcnc.org/ but with ball screws.
   
  I do have a big question though about headband assemblies. I prefer not to use ones from pre-existing headphones as the drivers I'd need to fit the cups would be too small (JVC HA-RX900 = 495 mm, GRADO SR 60i = 400 mm?, Sennheiser HD555 = 400 mm?) and will produce little bass. I've been looking around for spare headband assemblies for STAX headphones and they are expensive. Looks like I might have to make my own as well?


----------



## Soul_Est

Quote: 





miln said:


> Hello, and sorry for the late reply.
> I just recently completed a small electrostatic speaker (not a headphone, sorry.)
> Good news is: SPACE BLANKET WORKED. Sounded great, played well, a little arcing didn't destroy it completely.
> Bad news is: I am not an ESL professional. It sounded great, but I haven't ever heard another ESL. Also, I tensioned/assembled it very poorly. It was only stretched about 0.7% and there was a small wrinkle in the corner.
> ...


 
  Where did you get the space blankets that you're using and how thin is it?


----------



## chinsettawong

I have no idea what a space blanket is.
   
  Wachara C.


----------



## liamstrain

Quote: 





chinsettawong said:


> I have no idea what a space blanket is.
> 
> Wachara C.


 
   
  Mylar with an aluminized (or other metal) face to reflect heat.


----------



## AmarokCZ

When I was searching for boPET film to replace my old PE film I asked small local company making capacitors and they send me a piece of aluminized mylar, so try contacting some similar company.
  But then I realized (correct me if I''m wrong) that this is against basic principles, because there will be constant voltage across diaphragm which is not desired.


----------



## chinsettawong

The diaphragm needs to hold the voltage constant. High resistivity on the diaphragm helps the voltage to discharge very slowly which is something that aluminum laminated Mylar can't do.

Wachara C.


----------



## AmarokCZ

So you think that aluminium is better than any high resistance coating??


----------



## chinsettawong

No, in fact I mean just the opposite. The aluminum laminated Mylar has too low resistance.

Mylar with high resistance coating is much better.

Wachara C.


----------



## AmarokCZ

OK, I thought so, but I asked to be sure.


----------



## chinsettawong

Quote: 





dude_500 said:


> Questions are good, sharing details definitely makes projects like these better for everyone.
> 
> As for dimensions, attached is an image of the masks I used to etch the four layers. The grid is 0.5" / div.
> 
> ...


 
  Hi Dude_500,
   
  I've just reread your post and found that I've actually miscalculated your dimension.  Your active diaphragm dimension is actually 2.25" x 3.5".  That comes to around 58 mm x 89 mm.  Your using of 0.5 mm thick spacer is actually perfect.  The spacer thickness to spacer width ratio is 1:116.  That's very good.  With this ratio, you don't have to put too much tension on your diaphragm and your bass can go really low.  I'm sorry for my earlier mistake.  By the way, you can up your bias voltage to at least 580V, same as Stax, with no problem.
   
  Wachara C.


----------



## dude_500

I just made new drivers today using elvamide coating instead of the white glue/graphite mix I used before. They sound like absolute crap. Zero bass, completely tinny sounding, totally worthless. Do you think this could possibly be related to the coating?


----------



## AmarokCZ

I think you have extremely high resistance of diaphragm coating (it happened to me when I was trying something different than grapfite and result was virtuallly no bass), did you measured its surface resistance?


----------



## chinsettawong

Quote: 





dude_500 said:


> I just made new drivers today using elvamide coating instead of the white glue/graphite mix I used before. They sound like absolute crap. Zero bass, completely tinny sounding, totally worthless. Do you think this could possibly be related to the coating?


 
  Yes, that is very possible.  I've tried a few coating materials, and I can only advise you to use the antistatic gel or antistatic cleanser.
   
  Wachara C.


----------



## dude_500

So, this was the first time I added a sweat screen (on the inside only). I used the same film material, 2uM mylar glued around the edge of the ear side of the stator. It was loose, not tensioned. This is what absolutely killed the bass. Took the screen off, and the bass and beautiful sounds are back. With the film, 100hz was inaudible, 200hz was barely audible, and all the high ranges sounded very muffled and tinny.
   
  What do you use as a sweat screen? I was under the impression this is what everyone else has been doing...


----------



## chinsettawong

The sweat screens don't affect the sound as long as you put them only on one side. I've tried 0.9, 1, 2, and 3 microns Mylar and all of them are fine. You might try heat shrinking them a bit and see if they make any difference.

Wachara C.


----------



## AmarokCZ

*dude_500*: I'm using the same film as for diaphragm (boPET 2um) for both "dust covers" and I have no problems with bass. But film on dust covers must be quite losse in order to keep free-air resonance frequency low as possible. Try to measure free-air resonant frequency of driver itself (without dust covers), then put both dust cover back and measure free-air resonant frequency (just run sweep with microphone near the driver, use SpectraLab to display frequency response - high peak on response is resonant frequency). If free-air resonant frequency is high you need to decrease tension or you need better earpads (better seal) to damp this frequency.
*chinsettawong*: I think that you're incorrect, even one dust cover affects free-air resonant frequency (at least mine did), hence the sound.


----------



## chinsettawong

I might be wrong, but to my ears, I don't hear any differences.

By the way, make sure that you only put the dust cover on the side facing your ear and leave the other side uncover.

Wachara C.


----------



## AmarokCZ

Any reason why to put dust cover only on one side??? How would I prevent dust coming into driver then?
  And what was the difference between two and one dust covers to your ears? (for me the difference was virtually none when using earpads with good seal)


----------



## chinsettawong

Are you sure that you don't hear any differences between putting one and both sides on?  It sure sounds a lot different to me.  I think that by putting these diaphragms on both side, you trap all the air in a tight seal.  Since the air has nowhere to go, the bass is rather bad.  Try it again.  I'm sure that you'll feel the difference.
   
  The protective diaphragm is more critical for sweat protection.  If your listening area is clean enough, you don't need to put a dust cover on the back.  I never do anyway. 
   
  If you look at old Stax drivers, the back side protective cover is actually made of some kind of cloth, which is air permeable.
   
  Wachara C.


----------



## AmarokCZ

Tried it again and it's just like I said above: no audible difference with good sealing earpads and loose dust covers. But the difference is audible with bad seal.
  Could you specify the "rather bad bass"? Does it mean lower in quality or in quantity? Or both? Or does it mean boomy bass?
  From physical point of view I don't see any problem in using two dust covers, so I don't understand why you had worse bass with two dust covers.
  BTW, I think that newer STAX earspeakers have two dust covers.
  On my 40-years old SR-3NEW there is some kind or glass wool as a back-side cover, but I think that it's used as damping too.


----------



## chinsettawong

Well, it's been a long while since I put on both sides.  I can't remember exactly how the bass was now.  But when I took off the back side last time, it was "Wow".  And since then, I just didn't put it back on.
   
  Let me show you a few pictures of HE60 driver.
   
  This first one shows the driver with front sweat cover.  The material is plastic sheet, I'm not sure how thick it is. Sennheiser injected some urethane glue spots in between the diaphragm and the stator as you can see from the small white circles.  
   

   
  The second picture shows the other side.  The material is a kind of very fine mesh cloth similar to silkscreen cloth.
   

   
  Wachara C.


----------



## dude_500

It seems the sweat screen can't be touching anything for my drivers. I put them on spacers, and that seems to work great. If they get pushed down to touch the stator, all bass goes away. Do you have them raised above the stator like this?
   
  In general, it seems that less tension has always been better for everything I've made. I'm down to 8x 0.2lbs weights which is half the maximum tension I've tried. Much more bass, and an overall richer sound with lower tension. Much lower, and it will start to become structurally unstable.
   
  I'm going to order some thicker mylar to see how that sounds.
   
  As for coatings, I've been very pleased with elvamide. It seems to make a very reliable layer and works fine. Only drawback being that it doesn't store very well once mixed, really ideally need a fresh batch each coating I do.


----------



## AmarokCZ

You didn't put sweat screens on spacer, but directly on stators??? 
	

	
	
		
		

		
			





  That must sounded like total crap. Sweat screens must be on spacers to allow them to move (just like diaphragm).
   
  EDIT: If you are using mylar as sweat screens try thin PE film. The problem is that mylar has very high Youngs modulus compared to PE. That means that the PE sweat screen doesn't affect free-air resonance frequency and sound so much as mylar film.
  Where are you goint to order thicker mylar? I was happy to find 2um mylar and that was everything I found after few weeks of searching.


----------



## wink

With regards to the conductive coating on one surface, please excuse my ignorance,
   
  What would be wrong with using something like a space blanket type material as discussed earlier, and adding a say, 2 to 5  gigohm resistor just before the stator.
  This would give an instant uniform voltage across the diaphragm.


----------



## AmarokCZ

Quote: 





wink said:


> ...This would give an instant uniform voltage across the diaphragm.


 
  And this is the problem. Constant voltage is not what you need, but it deosn't mean it wouldn't work at all.


----------



## chinsettawong

I'm so glad to see you guys getting really serious into making these headphones. 

@ dude_500 You glue the sweat screen on the spacer and make sure that there is some room for it to move. I always use 1 mm PCB as the spacers for the sweat screens. I don't hear the difference in sound whether these screen are tensioned or not. 

@ AmarokCZ. You can order films in different thicknesses here: http://www.eraudio.com.au/Components/components.html
They even sell the coating which has been proven to work very well.

@ Wink. The space blanket type material certainly works. However, the mass of the material might not be as light as Mylar with conductive coating. And as to how it sounds, I'm not sure.

Wachara C.


----------



## chinsettawong

Hi dude_500,

What is the diaphragm thickness you are using now? Yes, when you want good bass, you can't give the diaphragm too much tension. But on the other hand, lower tension results in the diaphragm being unstable. That's why now I've move up the diaphragm thickness to 3 micron, and it's so much better in low frequencies. I think 6 micron should be even better, but I haven't tried it yet. 

Wachara C.


----------



## AmarokCZ

*chinsettawong*: thanks for the link!! As for the dust covers tensioning ... it's strange, but my experience is totally different: more tension=higher free-air resonance frequency and when the tension is really high (e.g. boPET stretched to 102%) there is virtually no bass even with good seal. 
	

	
	
		
		

		
			




  That's why I'm using PE-HD films for dust covers.


----------



## chinsettawong

Hi AmarokCZ,
   
  I'm not sure why your finding is different from mine. It is very strange especially when you say that there is no difference between putting the dust cover on one side or both sides.  
	

	
	
		
		

		
		
	


	



   
  Wachara C.


----------



## AmarokCZ

Obviously, there is something important that we do differently... 
	

	
	
		
		

		
		
	


	



  If you like try to measure free-air resonance frequency of some of you driver without, with one and with two dust covers. I think that the answer could be in resonant frequency.
  I forgot to ask you earlier: is the cavity between diaphragm and dust cover air-sealed in your headphones? Or is there some intentional hole to prevent pressure building in this cavity (e.g. caused by changes of atmospheric pressure)? I had my drivers air-sealed and one day later after assembling (when atmospheric pressure was higher) the dust covers were sucked closer to diaphragm. 
	

	
	
		
		

		
		
	


	




 So I made 0.5mm hole to prevent this.
  EDIT: one driver was completely air-sealed and the atmospheric pressure change caused bass roll-off. The other driver was air-sealed only on one side so the diaphragm was pushed onto stator.


----------



## chinsettawong

Do you mean that you intentionally put a hole of 0.5 mm in one of your dust covers on each driver?  I assume that this is the back side dust cover, right?
   
  How about you try to heat shrink your front side dust cover a bit.  This is just to make sure that the dust cover won't touch your stator.  Please also try taking the back side dust cover off again and see if you can hear any difference this time.  
	

	
	
		
		

		
		
	


	



   
  Have you increased your bias voltage yet?  200V for you is way too low.  I'm listening to my headphones which has 0.6 mm spacers right now.  With 580V and eXStatA, the headphones sound very nice.  
   
  By the way, if your diaphragm sticks to the stator, you haven't enough tension on the diaphragm. It doesn't really matter if your driver is air tight.   With higher bias voltage, you also need to increase your tension on the diaphragm.  
   
  Also watch out if you're not using Mylar.  Some plastics elongate over time.  One day you have the right tension, and a few days later the diaphragm sticks to the stator.  
   
  Wachara C.


----------



## dude_500

I currently have 2uM mylar. I ordered it from ebay seller music-in-life in Taiwan. Extremely good price, and the shipping didn't take more than a week or two. They stock 2uM and 6uM, I'll probably order some 6uM from there today unless I can find a more local source.
   
  I increased my bias from 480v to 600v the other day and noticed not change in the sound other than more volume.
   
   
  Just listened to them this morning, it seems they always sound vastly better the next morning after being on the bias charging all night. Have you found the same thing?


----------



## AmarokCZ

I drilled hole not into dust cover (= not into the film), but into spacer (my spacer is 1mm thick, so 0.5mm hole is feasible) and I did it on both dust covers (0.5mm hole doesn't affect bass response).
   
  Right now I can't heat-shrink dust covers, because I'm using PE (PE doesn't heat-shrink). But I did a lot of testing and I also tried higher tension of dust cover (by heat-shrinking boPET). Before heat shrinking the "ear-side dust cover" the driver had resonant frequency of 90Hz and bass was astonishing, but after heat shrinking the free-air resonance frequency was ~350Hz and the bass was very weak (second dust cover was still loose and earpads were the same with good seal). From what I can tell there is no audible difference as long as the free-air resonant frequency isn't over ~200Hz (with good sealing earpads from AKG K300).
   
  I didn't increased bias yet, because I have time only on sundays and I'm now working on earcups, headband, etc. I'll try higher bias when I had them finished (so I can plug them to my electrostatic amplifier, right now I got them soldered to STAX SRD-5 energizer)
   
  Air-tight driver vs. sticking diaphragm: it does matter, when there is pressure in diaphragm-dust cover cavity. Because the pressure in air-tight driver pushes diaphragm to stator and the diaphragm touches stator almost by its entire surface. With 0.5mm holes drilled into spacers the diaphragm doesn't stick when playing loud music, because with loud music the diaphragm just gently touches stator. Also I painted stators with paint (I had problems with arcing even at 500V, with paint it's OK at 1800V) and this paint is quite smooth and therefore sticky.
  Do your drivers have paint on them or is it just bare copper?
  I can't increase tension to prevent sticking at extreme conditions, because right now I have free-air resonant frequency of 120Hz and it's approximately the upper limit I can accept (bass response is still excellent).
   
*dude_500*: I'm using the same film as you. Before that I contacted local DuPont dealer, but they didn't sell films for less than 100€, but for 100€ it would be ~ 1km of 3um thick and 1m wide film, so a group buy would be excellent.
  On my drivers I didn't noticed any big improvements, but I did on SR-3NEW - they sound like crap for the first hour, good sound is after one day of charging.


----------



## dude_500

I covered my earpads today in leather and also somewhat sealed them to the drivers with overhanging leather, and it seems to have brought out the bass quite a bit as expected due to sealing them up better. 
   
  I did some frequency measurements using an electret microphone cartridge mounted into a sheet of plastic. I pushed this up against the ear pad for measurement.
   
  Here's what the frequency response looked like with and without the sweat screen (green without, red with):

   
  So it does look like it removes bass slightly, although not a lot. It also looks like I do need either less tension or thicker mylar to get the bass up which is rolling off a bit right now. Might be able to get by with less tension since my resonance seems to be around 400hz which is pretty high. I ordered 6uM mylar today, will see how that affects it. I have a felt backing as an outer dust screen, this does not affect sound in the slightest.
   
  This isn't really a calibrated system for frequency response, so I'm pretty much disregarding the high end fall-off, which seems to also be like that on my HD600's. I imagine due to either microphone calibration or the fact that I'm using my laptop's internal ADC.
   
   
   
  Here is what I'm using for measurement:
   
   

   
   
  New earpads:


----------



## chinsettawong

Hi AmarokCZ,
   
  The tension on the diaphragm and the bias voltage are 2 main factors that cause the diaphragm to stick to stator.  Just imagine the stator as a big piece of magnet and your diaphragm as a thin sheet of iron.  As you increase your magnet power, your diaphragm has to be stiffer otherwise it will be sucked by the magnet.  Drilling holes on the dust cover won't help.  Trust me.  I've been there too.  
   
  Wachara C.


----------



## chinsettawong

Hi dude_500,
   
  Thanks for sharing the FR curves.  Those look interesting.  Yes, the dust cover might have just a little impact on the sound, but to me, the impact is so little that I can't really hear the difference.
   
  Your leather ear pads look really nice.  Can you share with us how you make them?  
	

	
	
		
		

		
		
	


	



   
  Let us know how you like 6 microns Mylar as compared to 2 micron one.
   
  Wachara C.


----------



## AmarokCZ

*chinsettawong*: if the diaphragm sticks to stator over night (with no signal on stators and even no bias at diaphragm) you must agree that it has nothing to do with tension or bias voltage, but it's factor number 3: air-tight driver combined with atmospheric pressure changes. So the hole in dust cover spacer helps (only) this kind of sticking.
   
*dude_500*: try the same measurement but with microphone held in space to measure free-air frequency response (from this you can read out free-air resonance frequency). I'm quite courious what is yours resonance frequency, mine is ~120Hz.
   
  Here's my frequency responses measured the same way you did (red=right channel, the other one is left channel)

   
  EDIT: *dude:500*: here's resonance frequencies = free-air frequency response of my drivers (with same film as you and two dust covers per driver!)


----------



## Phos

Does the sweat guard really need to be sealed like that?  It can't be any more permeable?


----------



## arnaud

phos said:


> Does the sweat guard really need to be sealed like that?  It can't be any more permeable?




On the sr009, it seems the dust covers are non-impervious (thin fabric like) so effectively dust covers rather than sweat guard. Acoustically, it's also hard to imagine drum tight impervious seals can do any good.


----------



## arnaud

AmarokCZ, what mic and setup are you using for your measurements? I am getting back to acoustic simulation of estat headphones but am finding out the response above a few kHz is highly sensitive to the ear cup geometry / presence of artificial ear and what not. So rather than trying to guess the dummy head geometry and properties used in published headphone performance data, I am considering doing my own measurements on simple flat backplate and go from there... 

Alternatively, I was thinking to work on simulation model for a diy unit in case measured performance data and material properties / geometry are accessible (there's lot of guessing work involved in modeling something like the 009 because of unknown internal geometry/ material properties and lack of measured data). I received some geometry from Wachara before (which I haven't got my head around yet) but he tunes everything by ear, so difficult to go anywhere on the simulation side of things (I need to calibrate my model before I can do "what if" virtual redesign studies). If one of you guys has required data are is interested in such stuff, feel free contact me!

Cheers, arnaud


----------



## AmarokCZ

*arnaud*: the mic is some cheap electret mic possibly with very curved frequency response. Those measurement vere made with flat piece of wood instead of head (similar to the picture dude_500 posted above) and the driver IS ALREADY IN EARCUP.
  It's shame that I didn't save measurements without earcups, but I think it was more flat (at least the 1.5kHz dip wasn't there). Also I read somewhere that even measurement at dummy head are not much precise above ~1kHz.
  BTW what data would you need for simulation? Is it enought if you knew dimensions of driver and its materials and dimensions and materials of earcup?


----------



## chinsettawong

Hi AmarokCK,
   
  I remember that you solder your headphones to an energizer.  So, even if you don't play any music, the bias voltage from the capacitors is still there for a long period of time.  That can cause the diaphragm to stick to stator.  I have been through this same problem many, many time.  
	

	
	
		
		

		
			





  
   
  Wachara C.


----------



## chinsettawong

Hi Arnaud,
   
  The sweat protection diaphragms on new Stax headphones are not really fabric like.  I've opened up a SR007 MK1, MK2 and 507 drivers.  And they all use the same plastic like material.  The plastic isn't Mylar though.  It's a lot more fragile than Mylar.  
   
  I've heard that there is a kind of plastic that actually is impervious but is air permeable.  That would be a perfect material for this application.
   
  Wachara C.


----------



## arnaud

Wachara: maybe this is only the 009 then? See this picture: http://cdn.head-fi.org/e/ea/eaf088ce_DSC00274.jpeg
   
  AmarokCZ: in regards to dummy head measurement, it's not so much that it's imprecise (you can get very good repeatability up to 10kHz or so if you look at a few mic positions average) that it does not really represent anything objective unless properly calibrated (e.g. normalized against FF or DF HRTFs of that particular dummy). 
   
  Also, thanks for offering to help with the simulation!
   
  For the geometry, I would need all dimensions (length, width, thickness) along with material used (if possible with reference to the product):
  - Diaphragm: dimensions/material
  - Stators: dimensions/material + perforation size / area ratio
  - Spacers: dimensions/material + DS gap / spacers location
  - Rest of enclosure: dimensions/material
  - Earpad: dimensions/materials (+approximate thickness of each layer)
  - Dust covers and grills: grills I typically ignore (considering the simulation is far from accurate enough to capture that kind of delta SPL....)
   
  The rest is:
  - All the pictures you have!
  - Any test data you have (free air, baffled, against plexiglass back plate, with/without the dust covers and other screens) including microphone model number (in case there's any rough calibration data) 
   
  Note that if you don't have calibrated microphone (at least within 3dB or so), then maybe the rest is moot point because I won't have a way to tell if the model is wrong at the measurement is biased. So, maybe just start here first because spending any time on the rest.


----------



## chinsettawong

Hi Arnaud,

That looks like the same stuff I saw in SR007 and SR507 drivers.

Wachara C.


----------



## arnaud

Wachara: ok nevermind then. 
   
  AmarokCZ: well, it turns out I just ordered a EMC8000 mic and will try to do some measurements since I have an M-Audio recording sound card with phantom power... Don't need to send your data just now, it will take a while before I can get to it.


----------



## dude_500

As for leather pads, I made them by cutting out the red lines, and folding onto a foam rectangle with hot glue which is represented by the grey area. The corners need to be super glued onto the edges. There is exposed foam inside the ear pad, since geometrically it's not possible to use a single flat piece of leather and cut it to cover every exposed surface. This isn't really a big deal though. This image is not to scale.
   
  It took about 20 minutes per side to cut and glue the leather. My foam is relatively hard so they're not all that comfortable and they don't conform to the head very well. Does anyone know what that extremely soft foam they use in many headphone pads is called? I ordered the softest stuff I could find on McMaster but it's 10+ times harder than the foam in my HD600's or any other headphone I've felt.
   
   
   
   

   
  Here are some more frequency responses:
  *Blue - With ear-pad, detector plate held about 6" away from the end of the pad
  *Red - Ear-pad removed, detector about 1cm away from the driver (and amplifier volume lowered relative to the other readings)
  *Green - Ear-pad removed, detector about 6" away from the driver
   
  Not sure what to make of it, I don't really see any resonant peak with the detector held far away.


----------



## AmarokCZ

*chinsettawong*: you won't talk me out of it, my diaphragm sticked because of atmospheric pressure fo sure. Bias voltage at SRD-5 dissapears few second after unpluging it from mains because mine is modified a bit. Also that morning the dust cover was blown-out and after piercing the dust cover with needle the dust cover was flat again.
   
  The dust cover on SR-009 (http://cdn.head-fi.org/e/ea/eaf088ce_DSC00274.jpeg) is the same as on my ancient SR-3NEW and I think it's corrugated (creasy, wrinkled or whatewer) mylar (it shrinks by heat). It doesn't require lot of force to move, so it's perfect material by me.
   
*arnaud*: dimensions and materials list won't be problem, but good mic will be a bit hard. I'll look for something and let you know if I find something. All I have now are mic that are typically flat, but the "response tolerance window" is +-5dB or more. 
	

	
	
		
		

		
		
	


	



   
*dude_500*: that frequency responses look strange. Either way you got some damping and resonant frequency is damped or you got high resonant frequency (looks like 3.5kHz, but it's not possible). How's the bass on your drivers?


----------



## dude_500

I screwed up, still learning this frequency response software. I was time-gating the signal almost completely, which was giving false readings. Disregard all my previous plots.
   
  Here are the raw frequency response readings
 *Blue - Set sideways on the ear pads with slight leakage
  *Red - Far away (amplifier volume increased)
  *Green - Ear pad sealed to detector. Really incredible how much even a tiny bit of leakage on the seal does to the bass response! Definitely need to work on that as it doesn't seal to my head all that well.
   
  So it looks like free-air resonance is around 175hz.


----------



## AmarokCZ

That's much better! Try different tensioning of dust cover (lower tension) to decrease resonant frequency or try some damping. 175Hz is too much for good low-bass response in my opinion.
   
  The frequency response with good seal is now similar to mine...


----------



## chinsettawong

*dude_500:  *Thanks for sharing how to make your leather pads.
   
*AmarokCZ:*  About the diaphragm sticking to stator problem, sooner or later you'll understand what I'm talking about.  I hope you're right though.  
	

	
	
		
		

		
		
	


	



   
  This frequencies response thing is making my hands itchy.  Actually I have an electrate mic which I bought so long ago that I've actually forgotten all about it.  I'll look for it and make some FR curves to share.  By the way, which software do you guys use for measuring?
   
  Wachara C.


----------



## dude_500

I redid the mylar on the sweat screens today, I put it on basically with no tension at all (it is wrinkled, but just enough tightness that if pushed there is a bit of resistance before it hits the stator). This lowered the free-air resonance down by about 50hz (previous blue, new screens red). I would say there is noticeably more bass, although I did both changes simultaneously so it could easily be a subjective bias:
   
   

   
   
  Here are readings of L/R channel, sealed to detector. I imagine this is the #1 problem of home-built speakers or headphones. I don't actually notice much difference between them, although my ears aren't in the best of shape to tell right now, they've been acting very strange and out of balance since coming back from some high altitude mountaineering last week:
   
   

   
  Does anyone know what's up with the 10khz drop in all my measurements? Is this likely the microphone or is this actually happening? I certainly don't hear it when doing a frequency scan.
   
   
   
  I tried making diaphragms with the 2uM mylar with slightly less tension (0.15lbs instead of 0.21lbs for the eight weights) and it was highly unstable, I had to literally peel the diaphragm off the stator, no amount of blowing ever would have gotten that off. That was the first instability I've had, pretty amazing how sudden the difference is with just a little bit less tension.
   
   
   
  I finally figured out a way to make them comfortable today, and it sure works well! I could wear these all day now easily. I put an elastic material as a band below the metal band, so the weight fully rests on the elastic band, but the metal is still there to give them the springiness and shape of headphones. They fell very different, but no less comfortable than most retail headphones I've felt. They are a bit heavy, weighing in at 1.0lbs currently. I'm going to work on shaving that down a bit since although they are comfortable, they are pretty heavy feeling.
   
   

   
   
   
  I guess I'll be waiting for the 6uM mylar to arrive before many more changes or tests, I'll enjoy the beautiful sounds and work on another amplifier for a while.


----------



## AmarokCZ

*chinsettawong*: I'm using good old SpectraLab or sometimes VisualAnalyser. About the sticking: since I drilled those holes it never sticked, but if it ever sticks I'll consider what you were advising me.
	

	
	
		
		

		
		
	


	



   
*dude_500*: those dips around 10kHz are not likely microphone in my opinion. Look at my measurements - there is dip at 10kHz too. Also when I sweep throught audible frequencies I don't hear any very noticeable peak or dips (unlike on my dynamic headphones where dips are easily audible). I think this is because the mic isn't flat and also because I (and you) measure it against flat board which is far from head+ear.
  With the same mylar as you I made driver with 90Hz resonant frequency (driver itself without dust covers) and it never sticked (except the case when one dust cover-diaphragm cavity was pumped with air). I tried lower tension and an 70Hz was unusable = it sticked even when I pressed earcups lightly to my head.
  SR-3NEW is ~1lbs (430g) and its comfortable even after ten hours of listening.
  EDIT: I also did similar headband, I'll post some pictures later when it's finished


----------



## chinsettawong

Hi dude_500,
   
  Congratulations on your headphones!  They look really nice.  
	

	
	
		
		

		
		
	


	



   
  As you have found out, the tension you put on the diaphragm is very important.  When you want more bass, you don't want to tension the diaphragm too much.  But then you probably put too little tension on it that it's not strong enough, and it's becoming unstable.  Once sucked by the stator, it can be rather difficult to pull it off.  If I were you, I would up the bias voltage to around 650V and do the test on the diaphragm tension just to make sure that it's OK.  Once at 650V is confirmed OK, going back down to 500V is certainly no problem.
   
  I wouldn't worry too much about the sweat protection diaphragm tension.  In reality, it's hardly a noticeable difference on bass whether it's stretched or not. The most critical is still the diaphragms that actually make the sound.  For me, 3 microns Mylar is very good.  But let's try 6 microns.  
	

	
	
		
		

		
		
	


	



   
  If you want to build another ones in the future, may I suggest you make them bigger size?  Good bass and big sound stage is easier to achieve by making the the drivers bigger.  The active diaphragm area of around 8 cm x 12 cm is vey interesting to me. 
	

	
	
		
		

		
		
	


	



   
  Wachara C.


----------



## MuppetFace

Subscribed.
   
  You DIYers are really something else. Thanks for sharing your creativity! I'd love to hear some of these homebrew electrostats.


----------



## dude_500

Quote: 





chinsettawong said:


> If you want to build another ones in the future, may I suggest you make them bigger size?  Good bass and big sound stage is easier to achieve by making the the drivers bigger.  The active diaphragm area of around 8 cm x 12 cm is vey interesting to me.


 
   
  How would you seal them to the head? Mine are already about as big as I feel I could easily come up with earpads that form any sort of reasonable seal. Has this been done in retail (other than the ridiculous float headphones)?


----------



## chinsettawong

Quote: 





dude_500 said:


> How would you seal them to the head? Mine are already about as big as I feel I could easily come up with earpads that form any sort of reasonable seal. Has this been done in retail (other than the ridiculous float headphones)?


 
   
  My very first version has an active dimension of 7 cm x 10 cm.  The shape is oval though.  I guess going to 8 cm x 11 cm is OK, but 12 cm can be too long indeed.
   
  I wouldn't call Float ridiculous.  In fact, it can be very good.  For electrostatic, size does matter. 
	

	
	
		
		

		
			




   
  Wachara C.


----------



## spritzer

Quote: 





arnaud said:


> Wachara: maybe this is only the 009 then? See this picture: http://cdn.head-fi.org/e/ea/eaf088ce_DSC00274.jpeg


 
   
  That is the textured PVC film Stax have used on all their drivers since 1993.  It's very, very thin and light but they never stretch it drum tight so it has no effect on the output.


----------



## chinsettawong

Quote: 





spritzer said:


> That is the textured PVC film Stax have used on all their drivers since 1993.  It's very, very thin and light but they never stretch it drum tight so it has no effect on the output.


 
  Hi Spritzer,
   
  Do you happen to know where we can buy it?
   
  Wachara C.


----------



## arnaud

Quote: 





spritzer said:


> That is the textured PVC film Stax have used on all their drivers since 1993.  It's very, very thin and light but they never stretch it drum tight so it has no effect on the output.


 
   
  Thanks for the additional info Birgir, so this can be pretty much considered acoustically transparent. Do you know the reason for not going to thin fibrous material? Sweat or fear of small fibers getting into the diaphragm as time passes by? Somehow, it would seem like a suitable method further damp the diaphragm.


----------



## AmarokCZ

Except for earpads (I'm planing velour), connector and some tuning (I'm planning to replace back-side dust cover for something similar as in SR-Lambdas to add some damping) I'm finished...


----------



## chinsettawong

Those look nice.  
	

	
	
		
		

		
		
	


	



   
  Where do you get the cable from?
   
  Wachara C.


----------



## AmarokCZ

Cable is ordinary flat cable from local electronics store but in black color instead of "rainbow" or grey ~1€/m.


----------



## spritzer

Quote: 





chinsettawong said:


> Hi Spritzer,
> 
> Do you happen to know where we can buy it?
> 
> Wachara C.


 
   
  Not a clue but a thicker alternative can be found in those clear bags you can find at the super market.  The ones I buy are marked "Fruit Bags" and come on rolls of few hundred. 
   
  Quote: 





arnaud said:


> Thanks for the additional info Birgir, so this can be pretty much considered acoustically transparent. Do you know the reason for not going to thin fibrous material? Sweat or fear of small fibers getting into the diaphragm as time passes by? Somehow, it would seem like a suitable method further damp the diaphragm.


 
   
  Ever since the first SR-1 set all Stax sets had a film dust cover next to the ear and a woven one on the back.  There were usually three of them actually, one pressed up against the grill, one next to the damping pad and one on the back of the driver.  Fast forward to 1987 and Stax releases the first headphone without damping and they have issue with dust, major issues.  That's why they switched to film on both sides.  The HE60 also has the same issues due to it's dust covers which is why I add mylar or PVC to all the sets that come through here.


----------



## AmarokCZ

So I added some damping behind the copper-wire grill and it's now much better. 
	

	
	
		
		

		
		
	


	



  Frequency response is now smooth (as far I can tell) without any noticeable peaks or dips (before that there was annoying non-flatness in midrange, especially annoing was ~1kHz peak). Also the headphones are now much less sensitive to good earpad seal because free-air resonance frequency dropped and the peak at free-air frequency response is much lower.
   
  Anyone experimented with damping too? I'd be happy to know if there's any material that provides good damping but doesn't degrade soundstage, etc.


----------



## Vaughn

Wow, this thread has really taken off since I checked in last!
   
   I'm still thinking about building another set of electrostatic phones. I'd really like to make this set special with an aesthetically matching tube amp to drive them. Something that would be visually along the lines of the SE 2A3 Morrison Micro I'm working on - http://www.audiokarma.org/forums/showthread.php?t=457931
   
  I'll probably just set up a simple jig on my drill press for drilling the stators since I don't have a cnc.
   
  What energizers are you using now for your headphones Wachara?


----------



## chinsettawong

Hi Matt,

It's been a long time. Beside the tube amp that I made long ago, I now have an eXStatA, Stax SRM007t, and a DIY T2. My next project will be a KGSSHV.

Since you already have an experience building the headphones, making another pair isn't going to be that difficult for you at all. I'm looking forward to seeing your creation soon. 

Wachara C.


----------



## dude_500

AmarokCZ, what material and thickness do you use for the metal rods that provide structure to the headphones? I've been experimenting with some materials I have laying around and haven't yet found anything that I find satisfying.


----------



## AmarokCZ

I too didn't found anything satisfying for long time. I tried some common steel wire (low tensile strength ~320MPa) but its elesticity is very poor. Reasonable choice is stainless steel (~700MPa) strip but you have to heat it before bending it if you don't want to loose its elasticity. 
	

	
	
		
		

		
		
	


	



  But I knew that the result wouldn't be worth of heating-up the forge, so I asked my friend to get me (as he calls it) "spring wire" 2.5mm in diameter. It's high strength patented steel wire (~2000MPa), it can be bent cold and still its elasticity is reasonable.
  It's good for the purpose, but it's nothing compared to the wires on AKG (K240, K270,...) headbands - you can bend them straight and they still return back to original shape (which is ~16cm circle). If you want something special just order some spare headband from AKG.


----------



## arnaud

Edit: updated graphs / corrected typos / added pics of the test rig
   
  I have been making progress on my SR009 investigation... Got a measuring rig working reasonably well it seems so I now have proper data to calibrate my models! 
   
  Here's the summary of what I've measured so far (had seal issue with the Omega 2 / plexiglass backing):
   
   
_Repeatability check:_

   
   
_Influence of backing plate used to perform the measurements:_


   

   
_Comparison of SR009 and SR007A (driven from stock 727A amp). Omega 2 is end of SZ2 series, I did not (yet) plug the ports but bend the arch and springs as step gap toward mkI version. Obviously, there's still nasty boominess which is clearly audible:_
   
   

   
_Free air resonance check:_


----------



## chinsettawong

Hi Arnaud,

Do you know why the FR fall so sharply even before 10K? 

Wachara C.


----------



## arnaud

Edit: consolidated result graphs into the original post for clarity
   
  Quote:


chinsettawong said:


> Hi Arnaud,
> Do you know why the FR fall so sharply even before 10K?
> Wachara C.


 
   
  Hi Wachara,
   
  Not yet but I am suspecting these are just acoustic resonances in the earcup with null pressure at the mic location. Having the mic centered on the earcup does not help and we're bound to see such stuff. Once you have the actual ear in there / average a few positions, these would likely disappear. At this stage, I am mostly looking for some calibration data for the simulation and will investigate the rest numerically if I can get things to line up.
   
  I have updated the graphs in the original post and added comparisons with the Omega 2 (SR007A): http://www.head-fi.org/t/498292/my-diy-electrostatic-headphones/435#post_8607847
   
  And a few pictures of the measuring rig:


----------



## ujamerstand

I like your rubber gasket.  I couldn't find one appropriate, so I used caulk instead.


----------



## arnaud

Quote: 





ujamerstand said:


> I like your rubber gasket.  I couldn't find one appropriate, so I used caulk instead.


 
  If you ever come to Tokyo, "Tokyu Hands" store is really a DIYer's friend! BTW, you caught a typo, I got confused with the labels... The "PUF" backing is actually wetsuit stuff (neoprene, 3mm). Am correcting the graphs and adding a few comparisons...


----------



## ujamerstand

Ah, you are using the same material as I am then. I am using a much thicker piece though. 5/8 inch stuff from ebay.


----------



## tranhieu

Quote: 





arnaud said:


> If you ever come to Tokyo, "Tokyu Hands" store is really a DIYer's friend! BTW, you caught a typo, I got confused with the labels... The "PUF" backing is actually wetsuit stuff (neoprene, 3mm). Am correcting the graphs and adding a few comparisons...


 
  May I ask which software you used for plotting those graphs? I'm playing around with ARTA atm but I have no idea if it's a good one to use.
  Perhaps you might want to replace that acrylic plane with something else to dampen the low frequencies. That huge peak at 200hz looks a bit weird.


----------



## arnaud

Quote: 





tranhieu said:


> May I ask which software you used for plotting those graphs? I'm playing around with ARTA atm but I have no idea if it's a good one to use.
> Perhaps you might want to replace that acrylic plane with something else to dampen the low frequencies. That huge peak at 200hz looks a bit weird.


 
   
  Homebrew using Octave, really helps to get clean results (long averaging, fine resolution...) and opens a lot of doors for subsequent processing (extract of impulse response, CSD, step response, or whatever you fancy from the same raw data). Did the recordings using the equipment in the pics (Berhinger ECM8000 + M-Audio Firewire Solo) using Audacity.
   
  For the huge peak at 200Hz, this is the open air resonance of the diaphragm, there's no backing plate in this case. We seldom see those graphs (open baffle would also be good) and I was also surprised to find it to be so high. Not quite sure what to make of the resonance shifting down / not up in frequency once the earpad seals it off since I assumed the earpad cavity acted like a damped spring in that frequency range. I guess there's also very significant mass load from the entrapped air (esp. relative to the diaphragm weight), which isn't felt when front and back waves acoustically cancel out. I am going back to the simulation soon so hopefully I can get a handle on this...
   
  arnaud


----------



## arnaud

The plot is thickening a little... Short story is that I've been banging my head against the keyboard trying to reproduce the shift in resonance between free air and loaded conditions for the 009 and got nowhere. Went back to quick and dirty measurement this morning, placing the mic on the outside grill this time and, there you go, the earcup sealed cavity does act like a spring until a kHz or so (e.g. below the first acoustic resonance in this tiny volume).
   
  By looking at this graph below, it would seem like the diaphragm resonance is pushed up from ~180Hz to about 700Hz, which would make sense and is also visible in the previous data I sent (but to a lesser extent because very damped). This is getting interesting as this is challenging my previous beliefs (that there were zillions of modes in the membrane) .
   
  Also interesting to see the effect of the ear pad and the dust pad on the inside...


----------



## tranhieu

Quote: 





arnaud said:


> The plot is thickening a little... Short story is that I've been banging my head against the keyboard trying to reproduce the shift in resonance between free air and loaded conditions for the 009 and got nowhere.


 
  does that mean when loaded the peak shifts somewhere else or it's simply not there?


----------



## arnaud

tranhieu said:


> does that mean when loaded the peak shifts somewhere else or it's simply not there?




Unclear at this time and hard to guess as it's all a matter of relative mass/stiffness between the tensioned diaphragm and the earcup cavity / pad system. 

From the graph about, I thought the free air resonance was shifted up by several hundred Hz but actually, the 700Hz resonance is visible in both free air and loaded data (looking at the SPL on the outside). Conclusion is that I am as clueless as before I started .


----------



## AmarokCZ

Just finished and installed DIY Stax male Jack, it's quite ugly, but better than nothing. 
	

	
	
		
		

		
			




   

   
  Each channel has capacity of 91pF including 3m cable, which is quite nice.
  The difference between 230V and 580V bias is (to my ears) only efficiency (8dB higher), efficiency is now 98dB/100V @ 1kHz.
   
  I also compared 230V and 580V bias using mic.
   

  White curve is normal bias and the difference between two curves is certainly effect of bias, because I didn't even get close to the phones while measuring them.
  Output level of amplifier was changed so the curves are at the same level.
  The bass bump is present because earpads was pressed to the desk only by weight of earcup = quite bad seal.
   
  Anyone got idea what's causing the sharp change in response near 30Hz? (same thing is on responses of SR-009 measured by *arnaud*)


----------



## chinsettawong

I can't comment anything about the FR curves.  I just don't know anything about them, unfortunately.  
	

	
	
		
		

		
		
	


	



   
  Wachara C.


----------



## dude_500

Got my 6uM mylar today, I made some new diaphragms using the same tensioning weights I used on my stable 2uM diaphragms, and the new ones both almost immediately went unstable. 
   
  Interestingly, the FR is practically identical to the 2uM (I managed to get this reading before it went unstable and stuck to a stator):
   
   

   
  Any differences are meaningless since I rebuilt the headphones between takes of course. 
   
   
  So, this would imply thinner is better: The same tension is unstable with 6uM, but stable with 2uM, yet they have the same FR. This means it needs more tension with a thicker material, which will push the free-air resonance up and lower bass response.
   
  This seems like the opposite of what everything I've read says though, since bass panels are almost always thicker materials.
   
   
  Also, in doing this test I took out my 2uM diaphragms which seems to have drained them. They now sound like absolute garbage compared to what it sounded like before all this. It's been about an hour and they're still crap, which implies it takes days to charge my headphones.


----------



## ujamerstand

Would be interested to see distortion and CSD graphs in addition to FR. There might be changes in distortion levels with the thicker diaphragm that is not shown in the FR graph.


----------



## chinsettawong

You know what?  I just did a test a few days ago, and I too didn't notice a difference between going from 3 micron Mylar to 6 micron either.  However, going from 2 micron to 3 micron, for me, the sounding difference is huge.  
   
  If you can afford to go with thicker spacers, thinner Mylar does sound superb. Since you don't need to put a lot of tension on it, the bass from thin Mylar is very good while the high frequencies are very nice too.  I still have a set of headphones using 0.6 mm spacer and 0.9 microns Mylar, and they sound lovely. 
   
  Wachara C.


----------



## dude_500

So a few things... first off, I had one of the drivers mounted upside-down in my headphones, which was leading to the awful sound. I can't stand phase-reversed channels!
   
   
  I turned down my bias and went back to 6-micron to try them out again, now they're stable (about 450V bias vs. 600). They sounded about the same as the last week of listening on the 2 micron. 
   
  Randomly, I thought let's take off the sweat screens (I still just don't like the concept of them being there). Within seconds, I was absolutely blown away. Felt like I was being kicked in the face by the low bass.
   
  Blue - 6 micron with sweat screen (sealed)
  Green - 6 micron without sweat screen (sealed)
  Red - 6 micron without sweat screen (a few inches away, unsealed)
   
   
   
   
   

   
  So, it looks like I have free-air resonance at 100hz, and sealed it pulls it down to an incredible 30hz. 
   
   
  6-microns it is! I'm going to sit back and enjoy the sheer beauty.


----------



## AmarokCZ

*dude_500*: the blue line is definately not sealed, there must be some leak, a large one!
  I'm using the same film as you were (2um) and with two dust covers my bass frequency response is flat just like yours with 6um (even flatter). Just look at the SR-009 measurements: free-air resonance is ~170Hz but when sealed the frequency response is flat (except the ~40Hz step).
   
  Here's my response (2um diaphragm, two dust covers, driver in wooden earcup, leatherette earpads, little bit of damping on the back side of driver, bias 580V), finally with calibrated mic:

   
  As you can see the bass is great even at 20Hz, so I think you must have some huge leak somewhere.


----------



## chinsettawong

So, do you guys like 6 microns Mylar or not?  
	

	
	
		
		

		
			




   
  I bet you can give it a bit more tension and it will be stable at 600V and the bass will be very good too.
   
  Not putting a sweat screen isn't a good idea.  You probably can only do that in the dry seasons.
   
  Wachara C.


----------



## AmarokCZ

I'd like to ask what's the benefit of 6um Mylar to 2um one?


----------



## chinsettawong

6um Mylar is supposed to give better bass than 2um one.  But for some reasons, dude_500 haven't found that to be true.
   
  As for me, 3um is already a lot better bass than 2um.  But 6um isn't very clear winner of 3um.
   
  Wachara C.


----------



## AmarokCZ

Quote: 





chinsettawong said:


> But for some reasons, dude_500 haven't found that to be true.


 
  I think he did! Now with 6um he got response flat to ~30Hz and with 2um it was flat only to 60Hz (and there was bump at ~80Hz).
  For me the 2um is great and I can't imagine it could be better.


----------



## dude_500

I do get more bass with 6-micron, but only with no sweat screens. Increased tension a little bit (about 30%) to ensure stability, and also built new 6-micron sweat screen to see how that does. 
   
  Severe bass roll-off with sweat screen, non without. Both times pushed hard into the cushion, definitely sealing in both tests. Results are highly repeatable.
   
   

   
   
  So, I guess I'll just have to see what happens with no sweat screen, unless anyone has ideas about it. I've tried 2 micron with no tension, low tension, high tension, and no tension with 6 micron and high tension with 6 micron. It all destroys the bass.
   
   
  Overall, my favorite sound thus far is no sweat screen, 6-micron.


----------



## khbaur330162

Quote: 





amarokcz said:


> Anyone got idea what's causing the sharp change in response near 30Hz? (same thing is on responses of SR-009 measured by *arnaud*)


 
   
  Quote: 





chinsettawong said:


> I can't comment anything about the FR curves.  I just don't know anything about them, unfortunately.
> 
> 
> 
> ...


 
   
http://www.innerfidelity.com/content/skullcandys-director-electrical-acoustical-engineering-dr-tetsuro-oishi-visits-innerfidelit-0
   
  This might be of some help.


----------



## arnaud

Quote: 





dude_500 said:


> I do get more bass with 6-micron, but only with no sweat screens. Increased tension a little bit (about 30%) to ensure stability, and also built new 6-micron sweat screen to see how that does.
> 
> Severe bass roll-off with sweat screen, non without. Both times pushed hard into the cushion, definitely sealing in both tests. Results are highly repeatable.
> 
> ...


 
   
  It looks like your sweat screen is as much tensioned as the diaphragm and that you get coupling between the two membranes (double slope for the roll off at LF). Depending on how lucky you are with the free air resonance frequency of both the diaphragm and the sweat screen (which acts like a passive radiator), you seem to be getting a bump before the roll off (similar to a poorly aligned bass-reflex speaker).
   
  I'd be interested to see a summary of the comparisons between the various thicknesses and tensioning. But I guess a key point when you're doing the comparisons is ensure all configurations have the same free air resonance, else all subjective impressions are likely more due to the tensioning than change in material. Theoretically, a thicker / heavier diaphragm should roll of at HF, which does not seem to be visible in your graphs? Maybe this belief is a bit "overrated" and a result of years of Stax marketing


----------



## arnaud

Quote: 





dude_500 said:


> So a few things... first off, I had one of the drivers mounted upside-down in my headphones, which was leading to the awful sound. I can't stand phase-reversed channels!
> 
> 
> I turned down my bias and went back to 6-micron to try them out again, now they're stable (about 450V bias vs. 600). They sounded about the same as the last week of listening on the 2 micron.
> ...


 
   
  Do you have the 6 micron WITH sweat screen (a few inches away, unsealed) ? Curious to see the free air resonance frequency of that one...


----------



## chinsettawong

Ok, I think that we can now confirm that the sweat screen tames down the bass somewhat.  Perhaps its' time to look into what better material is suit for this purpose.  Stax uses a different material for all it's sweat screens.  The material is really thin and fragile.  It has some wrinkles on the surface.  What it is, even Spritzer doesn't know.  
	

	
	
		
		

		
		
	


	



   
  I have a quick and simple idea.  If we really don't want to use a sweat screen, then maybe we can swap the direction of the energized Mylar to facing outward.  That way the humidity in the cup won't affect the diaphragm so much.  Let's try it.
   
  Another idea is to make the double diaphragms design.  We encapsulate the energized sides of the diaphragm in the middle.  The two diaphragms serve as protective diaphragms on either side.  We need to make a special bias ring that would gives the bias voltage to both diaphragms. Let's say make it using a thin sheet of copper of 0.1 mm.  This idea sounds rather funny, but I've actually tried it.  At that time, I just did it for fun and didn't think about not using the sweat screen.  The sound was pretty nice.  I was hoping to gain a bit of efficiency from using two diaphragms, but that wasn't the case.  The idea was from an ESL expert who whispered softly to me.  
	

	
	
		
		

		
		
	


	



   
  Wachara C.


----------



## chinsettawong

By the way, we can also try playing with the distance of the sweat screen and the diaphragm.  I'm not sure if we move the screen further away from the diaphragm will cause any better or worse effect.  What do you guys think?
   
  Wachara C.


----------



## AmarokCZ

*dude_500*: The response on the last picture you posted is now with good seal because there is no visible resonance (unlike the previous one). What's the tension of the sweat screens? It seems to be high and it's causing the roll-off (I've been there). This is the reason why I'm not using Mylar for sweat screen (I already wrote here that the sweat screen must have low youngs modulus or must be similar to the Stax sweat screens).
*khbaur330162*: thanks for the helpful link! The good thing is that this "spring effect" gets almost canceled with good seal (see my frequency response at the top of this page). If you look at my response on the top of the page, there seems to be the "Voice Coil Wobble" at ~500Hz, so I guess that has nothing to do with coil (from what I can tell it't also caused by the same "spring")
  EDIT: *chinsettawong*: I tried it, but the effect of diaphragm-sweat screen distance is small.


----------



## ujamerstand

I don't know what stax uses for their dust screen, but from this post, they seem to slowly hand rub the material (for a staggering 30 hours?!) to add folds into the film.


----------



## dude_500

Quote: 





chinsettawong said:


> I have a quick and simple idea.  If we really don't want to use a sweat screen, then maybe we can swap the direction of the energized Mylar to facing outward.  That way the humidity in the cup won't affect the diaphragm so much.  Let's try it.


 
   
  I have always been careful in my designs to have the charged side facing outwards, for exactly this reason. After wearing after a shower, I have seen the entire diaphragms covered with visible condensation on the inside from water in my hair evaporating, it had no impact on performance. And since it's condensation, it's pure water and will just evaporate away in time leaving nothing behind. Time can only tell if it would work in the long term, though.
   
  I'm mainly worried about hair grease building up from the few hairs that penetrate the stator. If one were bald or had extremely short hair, I see no reason why you would need a sweat cover. Even evaporated sweat should be pure water.


----------



## AmarokCZ

Quote: 





dude_500 said:


> If one were bald or had extremely short hair, I see no reason why you would need a sweat cover.


 
  I see a reason - short hair gets between stator and diaphragm. Only way to get it out is disassembling the driver.


----------



## chinsettawong

Hi dude_500,
   
  Try it for a few days and let us know if it's really stable enough not to put the sweat screen on.  I always have my conductive side facing inward and a sweat screen to protect it.
   
   
   
  Hi ujamerstand,
   
  Thanks for the link.  That's interesting information.


----------



## chinsettawong

Quote: 





khbaur330162 said:


> http://www.innerfidelity.com/content/skullcandys-director-electrical-acoustical-engineering-dr-tetsuro-oishi-visits-innerfidelit-0
> 
> This might be of some help.


 
  Hi Khbaur330162,
   
  Thanks for the link.  It's really an informative read,  
   
  Wachara C.


----------



## spritzer

Quote: 





chinsettawong said:


> Ok, I think that we can now confirm that the sweat screen tames down the bass somewhat.  Perhaps its' time to look into what better material is suit for this purpose.  Stax uses a different material for all it's sweat screens.  The material is really thin and fragile.  It has some wrinkles on the surface.  What it is, even Spritzer doesn't know.


 
   
  It's very thin PVC film but I have no idea where to source it.  I use the slightly thicker variant found in grocery bags for dust covers or just very thin mylar with almost no tension applied.


----------



## AmarokCZ

*spritzer*: any idea what they used on older earspeakers? (e.g. on SR-3?)


----------



## khbaur330162

Quote: 





spritzer said:


> It's very thin PVC film but I have no idea where to source it.  I use the slightly thicker variant found in grocery bags for dust covers or just very thin mylar with almost no tension applied.


 
  Quote: 





amarokcz said:


> *spritzer*: any idea what they used on older earspeakers? (e.g. on SR-3?)


 
   

   
  Picture taken of a Sony ECR-500. There are sweat screens on both sides, they're made of extremely thin ?PET? film at very low tension with millions of crinkles in it, spaced perhaps a cm away from the metal mesh (which is just outside -and I believe in contact with- the stator), and they have roughly the same radiating area as the diaphragm, perhaps slightly larger.
   
  Hope this helps.
   
  And a beauty shot of the diaphragm just to heat things up a bit. Somebody's gonna make a DIY stat with a scalene pentagonal diaphragm, right...? Riiight?!

   
   
  I might take the SR-5 apart for you guys if you're truly interested and there's meritable cause, although I wasn't exactly planning on it for myself.


----------



## dude_500

It looks like everybody wrinkles their sweat screens in retail electrostatic headphones. Maybe the industry experts figured something out?
   
  Works great! red before addition, green after
   
   

   
   
  Crumpled up some 2 micron mylar, loosely tensioned it (basically just enough to get it to lay flat with maybe a few millimeters of extra displacement) and glued it on. Turns out crumpled mylar is a really awesome material. It stays relatively rigid in space in that it's not flopping around, but if you even exhale on it from a foot away you can see it displacing significantly. So it has structural rigidity, but virtually no net tension across the whole screen.


----------



## chinsettawong

Wow! What a nice accomplishment. I'll have to try that. With you guys shimming in, this thread is becoming more interesting.

Wachara C.


----------



## AmarokCZ

Nice job! One year ago I also used wrinkled film to repair my SR-3 and I also didn't noticed any bass roll-off which is quite something since SR-3 have weak low bass even without dust covers.


----------



## chinsettawong

Hi Dude_500,
   
  Can you make another set of the sweat covers and put them at the back side of the drivers?  Let's see if they will make any difference in FR at all?
   
  Wachara C.


----------



## AmarokCZ

Also listen to slow sine sweep (~ 20Hz to 200Hz, ~5sec) at high volume. The thing is that I always heard resonances at some frequencies when using creasy film. That's why I'm now using PE film which doesn't resonate and doesn't degrade bass performance too.


----------



## dude_500

I didn't notice any resonances in the sweat screen, but currently my headphones are retired while I develop completely new ones. Some issues came up that I deemed not worth repairing. Done with prototyping, the next edition will look aesthetically good and be made with 100% CNC and laser cut parts to ensure channel matching. Going to make an airbrush mounted above a linear motion table to create perfectly uniform and matched coatings.
   
  Will post results here when done in a few weeks.


----------



## arnaud

dude_500, neat work you've done there and looking forward to future developments!


----------



## dude_500

Do any professionally made headphones have the sweat shield directly exposed to the outside, or is there always another mesh?


----------



## chinsettawong

There usually is a mesh protecting the sweat screen.
   
  Looking forward to seeing your new design.  Good luck.
   
  Wachara C.


----------



## SigmaAcoustics

Quote: 





chinsettawong said:


> Hi,
> 
> I've just jointed this site today.  I just want to say hi to everybody and show you my version of electrostatic headphones and amplifier.  I've successfully made the phones and amp for about a year now.  I just love them.
> 
> ...


----------



## AmarokCZ

Finally, it's finnished. 
	

	
	
		
		

		
			




   

   
   

   
  Now just hours and hours of listening...


----------



## chinsettawong

Those look super lovely. I really like your ear pads too. Do you make them yourselves?


----------



## khbaur330162

Edit: Holy schinkes, I'm a page behind. Those are beautiful Amarok. Intense.
   
   
  Sweat screen from an AT-707. To my understanding these are similar to AT-705, PWB electrets, SR30/40/50/etc. and I'm sure others.

   
  Front grill of AT-707

   
   
  The Sony ECR-500 and Stax SR-5 have sweat screens protected by a plastic mesh, but no fabric that I remember seeing. The more acoustically invisible the protective mesh is the more it will allow dust and dirt in hence the dust covers you see on the 707's, I'd assume.


----------



## nick n

To give some perspective on that picture khbaur posted above here are Stax SR-40 and SR-50 electret drivers ( same driver as AT shown above ) that do not have the silver crinkled moisture guard in place.
   There is a transparent dustguard on these a thin transparent rubbery thing under enough tension it is hard to notice( can't see it in the pictures at all ) just above where the stator dips down on the driver side of that spacer ring. I measured the spacer ring seen just after the housing lip there and it seems to be no more than 1 mm thick. So the silver thing there is instead of one of these transparent things possibly or on the very top of one if you compare pictures.
   
  Hope that shows some distances and roughly how the Stax/Audio Technica electrets are constructed. The diameter is ~57mm so how that moisture guard spacing varies with bigger driver size who knows.


----------



## chinsettawong

Thanks guys for sharing your photos.  
	

	
	
		
		

		
		
	


	



   
  Wachara C.


----------



## Congo5

More pic's of Stax SR-40


----------



## khbaur330162

Cool photos Congo!
   
  While skimming the old ECR-500 Impressions thread I re-stumbled over this post of ericj's. Gives meaning to the wire mesh outside the ECR-500 stators.
http://www.head-fi.org/t/183017/sony-ecr-500-impressions/45#post_3347954
   
  No idea if any of this interests you guys, but it seems like it could be incorporated into your designs. For planar magnetic drivers, use flux plates whenever possible. Could the same be said for electrostatic drivers and electrostatic shielding? I've never heard of an electrostatic loudspeaker manufacturer using this technique, although I admit I'm not that informed.


----------



## AmarokCZ

Interesting, but if I understand it correctly this wire-mesh is useless for electrostatic drivers with non-electret diaphragms, am I right?


----------



## chinsettawong

I really don't see how a wire-mesh can help to keep the charge on either electrostatic or electrate diaphragms.

Wachara C.


----------



## chinsettawong

Purrin was so kind to help me make a FR measurements on my Omega clone headphones that I sent to Frank Cooter.
   

   
   
  The sweat protection on this one is damping the lower bass somewhat.  
   
  Wachara C.
   
  P.S. I think the roll off isn't that bad.  It's only about -5 dB from 50hZ.


----------



## Phos

Looks pretty nice, did he make THD graphs or anything?


----------



## chinsettawong

He also makes a CSD measurement as below.
   
   
   
   
  Actually, I've found the FR measurement to be very similar with that of SR Omega that Purrin measured
   
  Wachara C.


----------



## ujamerstand

That's a terrific FR response. CSD curves are remarkably similar to the 007s as well. Congratulations!
   
  Did he happen to take distortion measurements for the headphones as well?


----------



## chinsettawong

Purrin said that he would run a few more measurements for me including the THD. Let's wait and see.

Thanks Purrin!

Wachara C.


----------



## AmarokCZ

Here's something to compare to:
   

   
  First one is CSD (different time and amplitude scale than the one above!), second is burst decay, third is distortion in % (more like distortion of my crappy microphone 
	

	
	
		
		

		
		
	


	




 ) And the last one is frequency response of left and right channel with new earpads.
   
  And a last thing (interesting maybe only for _arnaud_), I decided to use just calculator instead ANSYS due to "time deficiency". 
	

	
	
		
		

		
		
	


	



  My calculator results are: peaks at 4.8 + 2.4kHz, dips at following frequencies: 13.1kHz, 2.7kHz, 6.5kHz, 10.6kHz and 1.7kHz.
  Except the 2.4kHz and 1.7kHz all frequencies are correct and I think that's nice result.


----------



## chinsettawong

My second pair of Omega clone will be singing very soon.


----------



## Congo5

Warning: reading may cause upset stomach.​    I have not been able to get a CNC yet but wanted to try anyway. ​ some of below can be used for *"What not to do"*​  ​ Have tried several times but nothing works right yet.​ Go ahead and laugh. I am.​  ​   Ok here goes: ordered perf metal from Amazon Stainless Steel 304 Perforated Sheet, ASTM-A-176-99, Straight 0.045" Round Perfs, 0.066" Center Spacing, 0.0187" Thick, 12" Width, 24" Length 
   
    Machined a 3" PVC coupling to have 93mm opening with shelve on a lathe.
  cut metal with snips and sanded with belt sander to size.
   
   Bought Mylar C 2um 20M + Elvamide 60g and made the formula.
   
    Am trying to follow Andrew Radford's guide.....http://gilmore2.chem.northwestern.edu/projects/showfile.php?file=radford1_prj.htm
   
    I do not have a Pro Bias adapter so built one ( with a little help from the Stax Mafia )

  It has 610v before the ballast resistor...and is made from a SRD-4 & radio shack parts.
    The radio shack 110v -24v trans shown shorted out on the primary,, so am now using an HVAC 20va trans that I had..
   
    As far as glue, I have tried:
  Elmer's rubber cement -  too thick,not enough holding power on mylar.
  Gorilla Glue - too thick, foams and make a big mess, thinned down right it does seem to work . does stick to mylar but hard to control application.
   
    Then I read about 3M yellow weatherstrip adhesive #2 thinned down 3 to 1 with MEK,  this seems good,
   
  On sweat screens:
    Having read the recent discussion on screens - made the crinkle out of the 2um Mylar..

   
  About spacers:
  want .5mm
  looked for something the right thickness and found two- the plastic For Sale signs - the early glues did not stick- tried pvc glue- that did not stick to Mylar.
  plain old file cabinet folder - yep
   
    The problems are:
  metal is not flat, may be close enough.
  hard to cut film so Bias can not leak to stators,
   
  The diaphragm coating does seem to work - unplug and hear the sound go away slowly.
   
  How do they sound - BAD BAD BAD max volume is 85DB 
	

	
	
		
		

		
		
	


	



  (other than volume- they do work)
   
  What do they look like?
   

   
  the paint is missing from scraping off old glue..and you can see my homemade Stax connector..
  coat hanger wire is the right size and Hot glue with tape around it....
   
  At this point you might wonder why this guy doesn't just go earn some money and buy the real Stax...me too 
	

	
	
		
		

		
		
	


	



   
  gonna try again today ---this is what labor day weekend is for right?


----------



## dude_500

A few things... As for glue, Elmer's contact cement works well, as dose probably any contact cement. I tried another brand, I forget which and it provided an even stronger bond. That said, I'm done with contact cement and am using double sided VHB 3M tape in my new build which is in progress.
   
  As for using paper for holding the film, I don't think that is going to be rigid enough. The tension will most likely be lost in paper deformations. Are the drivers stable? If the film is sticking to one of the stators (a sign of too little tension) it will sound terrible and have lowered volume.


----------



## chinsettawong

Very nice try Congo5!  Reading this reminds me of the beginning of my making of the headphones.  While it's frustrating, it's fun too.  Who wants to spend the money when we can have so much fun doing it ourselves, right?
   
  Keep trying, you're getting there.
   
  There are a few points I would like to suggest.  The Elvamide coating isn't really good.  It's difficult to make, and it tends to absorb too much moisture.  A lot of the people that have used it don't like it.  I would recommend you to try the antistatic cleaner.  It should be readily available in computer stores.  I have used it for a few years now and I really like it.
   
  Using 0.5 mm spacers, while it's good, it's rather difficult to get it right.  You might want to try a little thicker spacer for the start.  In the very beginning, I use 1 mm spacer with a bias voltage of around 900V-1200V and it turns out very well.  This is just to get your feet wet and then you can do further experiment to get everything as you want.  
   
  The perforated metal sheet might not be flat enough.  From the picture, I'm guessing that you're using 80 cm diameter active diaphragm, right?  With 0.5 mm spacer, even a small warp on the stators can cause problem.  You can either increase the spacer thickness as I suggested above or you can try inject a small drop of silicone right in the middle of the diaphragm.  This will act like a small spacer in the middle.  The diaphragm will be more stable, but will not make very deep bass. 
   
  Please keep us posted of your progress.  Keep trying!
   
  Wachara C.


----------



## dude_500

Quote: 





chinsettawong said:


> There are a few points I would like to suggest.  The Elvamide coating isn't really good.  It's difficult to make, and it tends to absorb too much moisture.  A lot of the people that have used it don't like it.  I would recommend you to try the antistatic cleaner.  It should be readily available in computer stores.  I have used it for a few years now and I really like it.


 
   
  Where have you read that Elvamide doesn't work well due to moisture? I've been using it for a while and I find it fantastic. It's quite simple to make (I'm not sure why people online seem to say it's really hard, putting pellets into a cup of alcohol and heating it isn't very difficult) and it bonds extremely well to the mylar (another thing people seem to not usually find true... I don't even usually clean the mylar before application, not sure why I'm lucky here)
  
  You can also reheat it and use the same mixture several times before it starts to go bad (yet another thing few people online seems to have mastered... reheat, and it's good to go!)
   
   
  If anyone hasn't tried it, I would suggest doing so. If you have and had problems, I'd be curious to hear your story about it. As far as I know it is a current industry standard product and is used even in some retail products, so I find it hard to believe moisture is a problem for it. The material datasheet says it can only absorb 3.4% in moisture content, and that is if soaked in liquid water.


----------



## chinsettawong

If it works well for you, I am glad to hear that. At an ESL DIY forum over at diyaudio.com, I haven't heard anybody using it for a while. Many feel that it's a pain to prepare, add too much mass to the diaphragm and too humidity dependent. I guess my information is wrong then. 

Wachara C.


----------



## Congo5

thanks Guys for the input..
  I am going to try some things today.
  there is something I'm missing, or not doing.
   
  Last night I looked for movement on diaphragm when applying bias but
  could not see any displacement..
   
    These sound exactly like the Stax SR-3N that I got on ebay.
  until they were charged several hours. low volume, bad distortion.
   
  I have read the arguments on Elvamide, found it slow but easy to cook up.
  reheating was obvious to me.
  still using the first batch from june.
  Have you seen the video of melting it into the Mylar with a heat gun?
  Its hard to control the heat- made a few holes- but it can be done.
  I also have antistatic spray and use it too.
  I like the way Elvamide sticks and coats the surface.
  if you spray antistatic on the Elvamide it has an interesting chemical reaction
  but I have no way to know what is the result except trial and error.
   
    In Andrew Radford's guide he says:
   
  [size=x-small]use 115:24 transformer then a 12:115 transformer to get 230V.[/size]

  well the transformers run hot so gonna try adding a resister in series between them to lower current.
  I have some 10ohm 5w or a 25ohm pot...
  what do you think?
   
  thanks.


----------



## dude_500

If it sounds good for a while, then later sounds bad with no bass and lower volume, that is almost certainly the diaphragm going unstable. I've never had it immediately go unstable, always minutes to hours later. You can often tell if it's stuck to a stator by blowing through each side. If blowing on both sides displaces it a little, then it's still centered. If blowing on it doesn't make it displace, it's probably stuck.
   
  As for 110>24 into 12>110, that's not going to work. A resistor won't fix it. That will drive the second transformer way into saturation because you're trying to put 24V onto a 12V winding. The image is not actually suggesting doing so, though. It is showing 230>24 into 24>230, basically an isolation transformer. There is no correct way to get 230V out of a 110V winding, so you'll need a different transformer configuration than what you already have.


----------



## jcx

Radford's text advice is wrong - likely he never tried it - or used such small transformers the abuse wasn't obvious - physically small xfmr have more surface to volume ratio, high winding resistance/poor regulation - can radiate away the heat from abuse better than larger xmfr
   
  dual primary "universal" line transformers can be used if step up from 110/120 AC is needed - a single 1:1 line isolation xmfr can be used, or 2 back-to-back, the smallest VA you can find with *matching* secondary V
   
  the dual primaries may be wired for 110/120 one side, 220/240 the other
   
  I would only use "double/reinforced insulation" xmfr here, tested to 4 kV
   
   
   
  a Y1 "double/reinforced insulation" safety rated cap based, "capacitively isolated" bias generator would be more compact - may want lower leakage diodes than 1N4007 to keep C values down, diode leakage can be biggest load on ESL membrane bias supply


----------



## Congo5

Thanks JCX
   
  I do not understand everything you said --- will google.
   
  I do have a triple primary 20va trans for HVAC.
   
  Well I did not know the primary's could be used like that,
  so one is 208v and one is 240v. now it makes sense.
  will check on double/reinforced insulation..
   
  thank you


----------



## nick n

Re-read this entire thread again making notes until late into the night, and it looks like I may have found a use for these Philips 6326 driver stators ( 80mm too ! ).

   

  As you can see here above the green coating is the bonded spacer in this setup.
   But it's only 2mm wide and very shallow not even .3mm i wouldn't think from a rough measurement ( no electronic capliers ) As well due to the poor shot I took there you can't see them, but there are* tiny dots of this green stuff between each of the holes on this same side*. I assume because it was so close the the electret diaphragm that it hit that thing or had the potential to hit it so this must prevent it from sticking. Sort of see that on the diaphragm there.
   
  I'll have to see whether I want to use this face of it and how tall that green spacer ring is. Ideally I am looking for 0.5mm.  If I kept that face towards the diaphragm it has the bonus of all those tiny green dots to prevent sticking just in case, although I plan to avoid that and tension as best as possible, still nice to know some extra insurance in that aspect.
   
   
  As the driver these came from is only_ a single sided one_ I will need to sacrifice the mint second set of electrets ( yikes ) to get another matching set, but it will be worth it I think considering the possible end result. ( or *wait* around and pick up a cheapo pair?).
   This way I have factory made  burr-free evenly spaced and perfectly sized stators . Just a matter of getting the rest of the stuff rolling, and time. They are aluminum it seems so I may opt for attaching the leads with the MG Chemicals Electrically Conductive Silver Epoxy. Worked great before on another similarly drivered set i have with absolutley no noticeable difference and the product specifications say the same.
  Certainly it had better be good it's_ not cheap stuff_ for the miniscule amount you get in the tube.
   
  Even have aged Alder wood for the housings.
  Whenever I get to these , I can run them from both normal and pro bias stax adapters, so i will be recabling for that. Most likely the Pro. ( SRD-6 and SRD-7Pro boxes.)
   So for now it's a bit before I can start, have to begin collecting the materials.
   
  Was going to give the 3.5 or 4.2 micron mylar a shot from that ER Audio site.  Hmm which one to try.
   
  Torn between using the Computer anti static application, the stuff rom ER Audio, or simply the old graphite powder rub. With the graphite is it just a general application and how precise to do have to get the resistance on each I assume close. This was the part that was bothering me. The posts i have seen they seem to just do it without regard to precise amounts (?)
   
  Has there been any degradation with the antistatic cleaner application? I was wondering how long that will last as obviously it isn't an "apply it once for the lifetime of your computer screen " type of stuff. At least in my mind. I'd rather not rebuild a year down the road.
   
   
*Thanks to all* in here who have painstakingly narrowed down the materials to find the best solutions for this. Particularly impressive was the set made from shopping bags. Incredible DIY.
  And the square drivers are certainly interesting also ( _*heck everything in here is great!*_ ), for some reason I have always thought that round was the only way to go, but then again the Sony ECR electrets use the offset pentagon shape to minimize resonances caused by the driver shape, and offhand I think there might be one or two orthos like that just can't recall.
   
  Just a matter of time now on this end.( so many projects getting burned out )
  Have to figure out how to get the pcb spacers ( If I even need spacers due to the already applied green ones ) cut nicely and what to use for the diaphragm ring . Also the spacers for the dust guard on the front. Thinking the green spacers are simply not high enough. Is there a standard width for that also? Have to go back and look again.


----------



## khbaur330162

Whoops. Delete.


----------



## chinsettawong

My second pair of Omega Clone is done.


----------



## spritzer

So... where can I place the order for a set?  
	

	
	
		
		

		
		
	


	




  Drill a couple of holes in the sides and the SR-Omega headband should fit perfectly.


----------



## chinsettawong

Hi Birgir,
   
  Thanks for your interest.  As you might have known, I don't sell my headphones.  
	

	
	
		
		

		
		
	


	



   
  How is your fitting of Stax drivers into Orpheus wooden cup project going?  When you are ready, I would rather let you try the Orpheus clone drivers that I made.  Let me know. 
	

	
	
		
		

		
		
	


	



   
  Wachara C.


----------



## spritzer

I know you don't sell them but I'd be up for something like that soon.  I guess I'm just bored with the commercial stuff...  
	

	
	
		
		

		
			




   
  The HE90 project has been stalled because my stash of drivers has shipped from Japan yet.  Partially my fault because I keep buying more and more stuff... 
	

	
	
		
		

		
		
	


	




  It should all ship next week so impressions due soon


----------



## tigon_ridge

This thread is Head-Fi's truly well hidden gem. Just read those all 36 pages with much interest and awe, within a period of 3 hours or so. You guys give a whole new dimension to this hobby. To think that someone can so easily build something that compares to the $5k 009 with such inexpensive materials is quite staggering. I hope you guys allow others to have a taste of your creations in future meets. It would be a real shame if the only people allowed to experience such fine fruits of labor be those who built them.
   
  Anyways, here's an idea for your future creations. Regarding the issue of sweat/vapor guard (even though you guys seem to have it mostly solved), take a look at this neat product:
   




   
  Spray this on a thin fabric (perhaps pantyhose) then use that as your guard. It should repel moisture far better than the mylar film, while being air-permeable!
   
  Mr. Chinsettawong, kudos to you, Sir, for being the pioneer, as well as being so willing to share your knowledge and experience.


----------



## chinsettawong

Hi tigon_ridge,
   
  Thanks for pointing out such an interesting product.  It looks like something that might actually work.  
	

	
	
		
		

		
		
	


	



   
  I only hope that my posting here inspires people to start making their own electrostatic headphones.  Seeing you guys interested and actually make them makes me very happy.  
	

	
	
		
		

		
		
	


	



   
  Wachara C.


----------



## dude_500

I'm almost done with my new headphone build, but I'm having what seems to be a very atypical resonance. Here's the FR:
   
  Red - free air
  Blue - no damping
  Green - a few layers of felt on the back
   

   
  So, what is that peak at 1khz? any idea? I've not had anything like this in previous builds I've done. The only thing I've really done is adding in two 1/4" ABS mounting plates as can be seen in the CAD drawing below (The black are ABS plastic 1/4" thick to support the PCB and make sure everything stays flat, the brown represents the driver). I have not yet installed a sweat screen.


----------



## chinsettawong

Very nice!  I have no idea where the 1khz peak is from, but have you tried listen to them?  
   
  Wachara C.


----------



## dude_500

Quote: 





chinsettawong said:


> Very nice!  I have no idea where the 1khz peak is from, but have you tried listen to them?
> 
> Wachara C.


 
  I have, and the 1khz peak really destroys the sound. In a frequency scan 1khz is extremely noticable, and I can tell that range is way too present in music.


----------



## bidoux

This a very interesting thread, quite an original work. It might come in handy with my studies so I wouldn't like to see it disappear.
   
  Does anyone know how to save the whole thread on my computer ?


----------



## dude_500

It appears there is a limit to bigger being better... the 1khz turns out to have been caused by my earpad inner cavity being too large. I tried out my old earpads, and it's pretty much flat again. You can see the difference between the two sizes below, as well as a frequency response for the smaller earpads. The driver is the same, just the earpad size is the difference:


----------



## tigon_ridge

That's very interesting findings, dude_500!
   
  Here's an interesting idea:
   
  Have you guys thought about shaping the plate and/or earpad so that it concentrates the sound somewhat towards the ear canal? Not necessary anything drastic; maybe just a gentle slope towards the center. I think it would increase the phones' efficiency, to alleviate the need for a crazy-expensive electrostatic amp. I think it might also make the cans sound warmer (low frequency waves are easier to direct with soft padding material than higher frequencies?). Just a 2-cent.


----------



## tigon_ridge

Quote: 





dude_500 said:


> It appears there is a limit to bigger being better... the 1khz turns out to have been caused by my earpad inner cavity being too large. I tried out my old earpads, and it's pretty much flat again. You can see the difference between the two sizes below, as well as a frequency response for the smaller earpads. The driver is the same, just the earpad size is the difference:


 
  This sorta explains why Stax chose a more concentric shape for their flagships, while their affordable line-up has a more rectangular shape. The rectangular model is easier to construct; but in the end, the concentric design focuses lower frequencies towards the ear canal better, thus being warmer sounding than the rectangular models! I think I just had a eureka moment. It must be true that a concentric design allows for warmer sound. It explains why Chinsettawong's cans have the Omegas' warm sound! I feel smart.


----------



## chinsettawong

Hi Dude_500, 
   
  Maybe your pads are too wide that they somehow obstruct or reflect the sound.  As for what I have experimented, I like thicker pads better.  They don't have to be that wide.  Thicker pads bring out a little more bass, and better comfort for wearing.
   
  Wachara C.


----------



## dude_500

I know almost nothing about acoustic engineering, as I know many of us in this thread don't. Does anyone know what the theoretically ideal inner-edge of the earpad would be?
   
  My new earpads that don't work well (1khz resonance) are approximately the red outline for inner-edge of the pad. My old pads which work well are approximately (but not quite) the green line.
   
  Based purely on reasonless theorizing, perhaps the extra volume that is not in front of the driver has to be somehow filled with sound, and that filling can have resonance whereas if the inner area is entirely in front of driver, this filling effect doesn't occur. Building on that theory, I wonder if the yellow rectangle would be worse since it would cause some damping of the diaphragm, or possible even better than green since the very outer edge of the diaphragm probably doesn't actually move much compared to the center.
   
   
  Anyone know if any of this is even remotely on with the science of the situation?


----------



## chinsettawong

I think it has more to do with the kind of material you use for making the pads.  Perhaps the leather is too stiff?  If you don't cover your pads with leather, would the result be the same?
   
  Wachara C.


----------



## arnaud

Dude_500, I agree with wachara. You can estimate the first acoustic resonance in the earcup cavity assuming rigid walls but it doesn't line up. The frequency is such that half a wavelength fits across the largest dimension. So, in SI units: f0 = 340 / ( 2 * L ). At 1kHz, this corresponds to about 15cm and I don't believe you made that big an enclosure . The pads are not rigid walls which shifts the first resonance frequency down (but hard to estimate by how unless one knows the foam elasticity). The other possibility is a resonance in the ear pad structure (affected by the foam you use and its dimensions). Where does the foam come from?


----------



## dude_500

The inner earpad area is 6.1x9.7cm. The foam is memory foam, with a density of 5.8 lbs./cu. ft. and and a softness classification of "very soft".
   
  I remember trying it before I added leather and it still had a resonance around 1khz, although I neglected to save the plot so I don't know how the magnitude compares. I might be able to try it out later, but it was definitely still there and significant.


----------



## spritzer

This resonance issue crept up in the first SR-007Mk2 revision Stax did.  They increased the height of the earpads for extra comfort which in turn meant extra space and there were some midrange issues with that change.  As soon as I lowered the pads to their normal position the coloration was gone.


----------



## odanas

I love this thread so much. Thank you everyone for all the information and experience you've gathered up on one thread. I am just about ready to build my own pair but I'm kind of stuck because I don't have an electrostatic amp. 
   
  Does anyone know of a fairly quick and cheap design that I could use to just drive whatever headphones I make? Basically I just want to be able to hear sound coming out of it. I've seen a few simple amps for ESLs but I figure the high bias and perhaps other things would make those not so good for headphones.
   
  I'm a mechanical engineer and I know some stuff about electronics but the simpler the design the better. 
   
  Thanks guys and amazing job! I can't wait to make a few pairs.


----------



## .Sup

very interesting thread indeed! Keep it up lads!


----------



## dude_500

Odanas, the simplest way to drive electrostatic headphones is a pair of audio transformers. All you need in addition is a bias supply which can be made from a transformer connecting to 110/220 and perhaps a voltage multiplier.
   
   
  As for pad material, I took a measurement just now of with and without the leather on the too-big pads. Blue is with leather, red is without. Doesn't have much impact:
   

   
   
  I'll make some new frames that hold smaller earpads hopefully sometime this week to try out. Does anyone know any good software that is free/cheap for modeling geometries like the headphones we make? I've found quite a few pieces of software online, but they're all targeted at either modeling buildings or more aimed at analyzing various magnetic speakers and don't have a lot of support for custom raw geometries of drivers and enclosures. I found VA One, but I can't find a trial or any discussion of price, I can only imagine how much it costs.


----------



## AmarokCZ

*odanas*: just use power amplifier (speaker-amp or some powerful head-amp) two output transformers for tube amps (~1:50 vinding ratio) and some simple bias supply (Delon multiplier or any other).
*dude_500*: just for information: I tried thin rectangular earpads (just to test impact of earpads on sound) with inner dimensions of 9x10cm and final version of earpads is with 6.5cm circular hole and there is virtually no difference in responce below 3kHz (could be measured, but it's not audible since it's no more than 1.5dB in narrow bands - e.q. 1.5dB dip from 800 to 900Hz).
  EDIT2: *dude_500*: just saw your last measurements, and I'm wondering what foam are you using. I tried similar yellow foam (polyurethane) as found in many headphones and bass response without leatherette was bad - almost no bass.
  How does the free-air FR (this one) change if you change earpad for "good one" and if you remove earpad?


----------



## arnaud

dude_500 said:


> Does anyone know any good software that is free/cheap for modeling geometries like the headphones we make? I've found quite a few pieces of software online, but they're all targeted at either modeling buildings or more aimed at analyzing various magnetic speakers and don't have a lot of support for custom raw geometries of drivers and enclosures. I found VA One, but I can't find a trial or any discussion of price, I can only imagine how much it costs.




I am unaware of free / cheap software at this time. As for VA One, you will not find a free trial version license easily and the cost is prohibitive at the amateur level. There is a cheaper education version but these are only sold to universities not private individuals afaik. If you give the dimensions if your headphone (driver, stator, earpad) including thickness and materials list, I can give a shot a simulating the response. 

The only issue is that I am having trouble finding time for this and haven't finished the revisit of my own 009 and haven't started wachara's and amarakcz's models. On the other hand, these guys build seem finalized already so the need for simulation isn't really there . Your resonance issue is interesting because I see it with the stax headphones as well.


----------



## dude_500

Quote: 





> EDIT2: *dude_500*: just saw your last measurements, and I'm wondering what foam are you using. I tried similar yellow foam (polyurethane) as found in many headphones and bass response without leatherette was bad - almost no bass.
> How does the free-air FR (this one) change if you change earpad for "good one" and if you remove earpad?


 
  It is memory foam, which seems to me to have very good sealing qualities to air (after all, if air easily permeated through it it wouldn't do the memory foam thing very well).
   
  Here are all the free-air responses. They are all about the same, which really reinforce the concept that the whole 1khz thing must be a resonance related to the new earpads, in a sealed state:
   
  Blue: New large earpads, leather removed (1" thick memory foam)
  Red: No earpad at all
  Green: Old smaller good earpads that I'm going to replicate


----------



## tigon_ridge

Quote: 





dude_500 said:


> It is memory foam, which seems to me to have very good sealing qualities to air (after all, if air easily permeated through it it wouldn't do the memory foam thing very well).
> 
> Here are all the free-air responses. They are all about the same, which really reinforce the concept that the whole 1khz thing must be a resonance related to the new earpads, in a sealed state:
> 
> ...


 

 The fact that they look almost identical tells me it has nothing to do with earpad material, as I had implied. It has everything to do with the shape/size of the earpads; as you said, resonance. There is no reason to have such a large and wide space between your ears and the drivers. You effectively create a chamber where sonic waves are bouncing around canceling each other. The more direct the sound transfer, the better.


----------



## arnaud

I am not sure the answer is as simple. Below the first acoustic resonance, the cavity acts like a mass and spring and restrain the diaphragm motion. As such, te low frequency extension / fundamental resonance of the diaphragm is affected by the effective volume and probably ear pad stiffness. It also prevents front / back wave cancellation but I think any combination of leather / foam thickness with a good seal can achieve the same effect.


----------



## AmarokCZ

I agree with _tigon_ridge._
  Also if you look on previous measurements (red curve) there are some HUGE swings below 400Hz. But on those three free-air responses you posted now there is nothing in 200 to 400Hz region. So you must have changed something between those two measurements.


----------



## dude_500

Quote: 





amarokcz said:


> I agree with _tigon_ridge._
> Also if you look on previous measurements (red curve) there are some HUGE swings below 400Hz. But on those three free-air responses you posted now there is nothing in 200 to 400Hz region. So you must have changed something between those two measurements.


 
  Indeed, all my measurements (especially free air) lack precision. They should be taken as approximations with disregard to fine details. I have not built a test-jig to hold both the driver and microphone in precisely the same position each time, nor do I have any means of canceling ambient noise which can be fairly loud at times in my dorm room.
   
  That said, there is absolutely no doubt the 1khz peak is huge and always present with the new earpads when sealed. It is also true that those bumps at 400hz you speak of are always there, and almost identical when sealed (naturally, sealed is easy to repeat and my measurements have very good repeatability even day to day. Free air, not so much.)
   
  Since it is now completely clear that it is a resonance, I'm not wasting any more time with these large earpads.


----------



## schorsch

Fantastic thread )
   
  I read it for quite a while now.
  You should try to make a Sigma housing for the sennheiser HE 90 clone! Should be an interesting try.
   
  Regards Georg


----------



## wiinippongamer

@Dude-500 are you using your own compensation curve for measuring them?


----------



## dude_500

Quote: 





wiinippongamer said:


> @Dude-500 are you using your own compensation curve for measuring them?


 

 No. I'm using an electret microphone element which is +-1db below ~8khz. Above that, I don't really care all that much anyways at this point since it seems the way we measure has issues in that frequency range. Maximum deviation within audio range is a +3db peak below 20khz so it should be fairly good even in that range anyways.


----------



## dude_500

Do any of you heat treat your mylar films? I've read that that is done in professional products to help keep the mylar from losing its tension.
   
  I've had some drivers built for a couple days that I've been listening to, and I noticed today that they've gone unstable, and there are wrinkles and a lack of tension in the films. Has anyone else experienced this problem?


----------



## chinsettawong

Hi Dude_500,
   
  Different people might have different technics.  As for me, I only heat treat Mylar when I feel that the tension isn't enough. 
   
  Most of the times, if the Mylar loses its tension, it's because of the glue.  Mylar normally wouldn't elongate by itself.
   
  Wachara C.


----------



## chinsettawong

I've finally drilled a couple of holes on the side of the cups and put the headband on.  
   

   
  This concludes the making of my 2nd pair of Omega clone.  My next one will be a revisit of my very first version of oval shape headphones.  From time to time, I still go back to listen to them, and I still really like them.  I'm going to redesign a new enclosure, etch out the unneeded copper, and improve the way I'll hold the drivers together.


----------



## spritzer

I've always done heat treatment as that's what the pro's do and according to Dupont, it's the only way to get a stable film over any period of time.  It fixes the tension in place by annealing the membrane.


----------



## chinsettawong

Quote: 





spritzer said:


> I've always done heat treatment as that's what the pro's do and according to Dupont, it's the only way to get a stable film over any period of time.  It fixes the tension in place by annealing the membrane.


 
  Hi Birgir,
   
  How do you do the heat treatment?
   
  Wachara C.


----------



## Maverickmonk

Any thought on using a sputter coater to coat the mylar? I know it might be hard to keep the mylar stable on the vacume chuck, but it would be possible to get very thin coatings with nanometers of accuracy


----------



## spritzer

Quote: 





chinsettawong said:


> Hi Birgir,
> 
> How do you do the heat treatment?
> 
> Wachara C.


 
   
  I use the large stone oven in my bakery at its lowest setting which is about 140°C.  Leave it there for a few minutes (depends on the size of the frame) but I put them in a box due to what's normally in those ovens.  Quad used an oven as well to cook their panels.


----------



## dude_500

Quote: 





maverickmonk said:


> Any thought on using a sputter coater to coat the mylar? I know it might be hard to keep the mylar stable on the vacume chuck, but it would be possible to get very thin coatings with nanometers of accuracy


 
  I may some day try this. Unfortunately all my vacuum equipment is at home and not with me at college. I'll probably sputter some when I'm back home for winter break, or maybe get around to setting up a high vac station in my dorm room (been meaning to for a while).
   
  I'm not sure what you mean by getting it stable on the vacuum chuck. I would put the entire thing within a vacuum chamber then pump down and turn on an ion source, so there would be equal pressure on both sides of the film and it would feel no forces.
   
  I believe the Sennheiser Orpheus is sputtered gold.


----------



## Maverickmonk

Quote: 





dude_500 said:


> I may some day try this. Unfortunately all my vacuum equipment is at home and not with me at college. I'll probably sputter some when I'm back home for winter break, or maybe get around to setting up a high vac station in my dorm room (been meaning to for a while).
> 
> I'm not sure what you mean by getting it stable on the vacuum chuck. I would put the entire thing within a vacuum chamber then pump down and turn on an ion source, so there would be equal pressure on both sides of the film and it would feel no forces.
> 
> I believe the Sennheiser Orpheus is sputtered gold.


 
  That makes a lot more sense, procedure wise.... Man, now I want to try this in the schools nano lab.


----------



## chinsettawong

While you guys are busy discussing what you're discussing, I'm busy making more headphones.  
	

	
	
		
		

		
		
	


	



   
  A friend of mine fried his HE-6 drivers, and he asked me to utilize his HE-6 cups and make them into electrostatic headphones.  Fortunately, the inside of HE-6 has the dimension close to that of the drivers of my Omega clone.  So, I'll modify the design of my drivers a little, cut them, and put them in his headphones.  Stay tune.


----------



## jcx

doesn't the membrane coating want to be highly resistive so the charge "stays put" at audio frequency http://www.audiocircuit.com/DIY/Electrostatic-Speakers/Material:Coatings
   
  sputtering gold would have to be very carefully monitored to hit the GigaOhm/sq decade of sheet resistance
   

http://www.nanoscalereslett.com/content/6/1/96


----------



## Arfan

I'm going to be trying my hand at creating electrostatic transducers very soon too, I'm not sure yet whether to create a loudspeaker or a pair of headphones yet though. But I have a few quick questions, I know pretty much exactly how to assemble the transducers but I'm pretty clueless on how to drive them properly.
   
  I only have a highschool level knowledge of the electronic side of things*, although I could follow guides to assemble materials. I was wondering exactly how difficult it was to actually create the amplifiers, the step up transformers and any circuits I'll need. I had a look around I've found some schematics but I think they might be too complex to create in the time frame I have. And I thought if I'd find anyone could help me with this i'd find them here considering all the success you guys have had with your electrostatic transducers. 
   
  I thought I could work around this problem however by just using an ordinary solid state amp and using the RCA output to step up the voltages using a toroidal transformer, maybe one for each channel, to make it suitable for the electrostatic transducer's stators, and use another circuit to supply the bias to the diaphragm which shouldn't be too hard to do. I was wondering if this would sufficient to drive the small speakers/ headphones. Does anyone have anything to say on the easiest and most cost effective method to drive these transducers? I don't mind using mid-fi here and there too. 
   
  Any help would be greatly appreciated, I can't wait to get started on these too.  
   
  * although I have access to one of my physics teachers who is an oxford graduate who could help me through some of the electronics, although he's very busy all the time so I don't have much time with him so I thought I'd find out as much as I could myself before consulting him.


----------



## dude_500

Quote: 





arfan said:


> I'm going to be trying my hand at creating electrostatic transducers very soon too, I'm not sure yet whether to create a loudspeaker or a pair of headphones yet though. But I have a few quick questions, I know pretty much exactly how to assemble the transducers but I'm pretty clueless on how to drive them properly.
> 
> I only have a highschool level knowledge of the electronic side of things*, although I could follow guides to assemble materials. I was wondering exactly how difficult it was to actually create the amplifiers, the step up transformers and any circuits I'll need. I had a look around I've found some schematics but I think they might be too complex to create in the time frame I have. And I thought if I'd find anyone could help me with this i'd find them here considering all the success you guys have had with your electrostatic transducers.
> 
> ...


 
   
  A pair of audio step up transformers is indeed the easiest way. In fact, this has been used in numerous retail products. Just connect it to a standard speaker amp and it makes it higher voltage. All you need in addition is a bias supply which is trivial to make. Transformers aren't necessarily the best for audio quality, though. There are several diy designs for amps if you want to take it to a higher level. Electrostatic amplifiers tend to be difficult to build given the high voltages, though. I have hundreds of hours invested in my Blue Hawaii. Unless you actually want an amplifier to be a project in itself, transformers definitely might be the way to go.


----------



## Nixon

I can't find any 0.5mm pcb board, but would 0.4mm work instead or would that be too narrow?
   
http://uk.rs-online.com/web/p/prototype-development-boards/2926932/


----------



## chinsettawong

Try Ebay:  http://www.ebay.com/itm/FR4-Copper-Clad-Laminate-PCB-Printed-Circuit-Board-Material-FREE-SHIPPING-USA-/120802756087?pt=LH_DefaultDomain_0&var=420050924083&hash=item1c2067c5f7


----------



## bidoux

Could these work too ? (shipping is really expensive with amt33461 )
http://www.ebay.com/itm/360377165165?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2648 and http://www.ebay.com/itm/360377165921?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2648
   
  And as for the stators, how important is their thickness ? I thought that it wouldn't matter as much as with the spacers.


----------



## spritzer

The thickness of the stator and the size of the holes are crucial parts of the design and they are tied together.


----------



## Nixon

Quote: 





chinsettawong said:


> Try Ebay:  http://www.ebay.com/itm/FR4-Copper-Clad-Laminate-PCB-Printed-Circuit-Board-Material-FREE-SHIPPING-USA-/120802756087?pt=LH_DefaultDomain_0&var=420050924083&hash=item1c2067c5f7


 
   
  Found that, but postage to the UK is £30


----------



## bidoux

Quote: 





nixon said:


> Found that, but postage to the UK is £30


 
  I thought that the seller I pointed out to offered free shipping but it isn't the case. So if you find a cheap enough source for the printed circuit board, let us know


----------



## chinsettawong

Quote: 





nixon said:


> Found that, but postage to the UK is £30


 
  Yea.  Unfortunately, the postage is quite expensive.


----------



## chinsettawong

Quote: 





bidoux said:


> Could these work too ? (shipping is really expensive with amt33461 )
> http://www.ebay.com/itm/360377165165?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2648 and http://www.ebay.com/itm/360377165921?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2648
> 
> And as for the stators, how important is their thickness ? I thought that it wouldn't matter as much as with the spacers.


 
   
  I always use 1 mm PCB for stators and 0.5 mm PCB for spacers.  Since Stax also uses the same, you can't go wrong with those.


----------



## dude_500

Quote: 





chinsettawong said:


> I always use 1 mm PCB for stators and 0.5 mm PCB for spacers.  Since Stax also uses the same, you can't go wrong with those.


 
   
  What model has 1mm stators? All the pictures of electrostatic headphone products I've seen appear to have nearly paper thin stainless steel stators.


----------



## chinsettawong

dude_500 said:


> What model has 1mm stators? All the pictures of electrostatic headphone products I've seen appear to have nearly paper thin stainless steel stators.




How many have you seen? Try to look into those of SR007 MK1 and MK2.


----------



## dude_500

Quote: 





chinsettawong said:


> How many have you seen? Try to look into those of SR007 MK1 and MK2.


 
   
  I always imagined the SR007 driver to be very thin. The picture looks like it has tiny holes, and you would never want the hole diameter to approach the thickness or resonances could form within the stator holes.
   
   
  Anyways, on my progression of building headphones I've completed my first pair that are effectively done. Of course, I'm already building my next pair! I've concluded large and rectangular simply isn't the way.  Since I now have access to a laser and router, I have SR007 earpads on the way and will be making headphones quite similar to chinsettawong's omega clones. If anyone wouldn't mind sending me the dimensions and mounting system for the SR007 earpads so I don't have to wait a week to start the CAD process, I would greatly appreciate it!
   
   
  Here are some pics of the headphones I recently finished (bulky, extremely heavy, and a bit ugly... not exactly the direction I had hoped they'd go from the beginning, but I learned a huge number of things to do and not to do):

   

   
   

   
  Most important lesson in these was that earpads are everything. Change the material, the method of covering the foam, just about anything and the sound changes completely. Hence why I chose to go with a pre-manufactured earpad.


----------



## chinsettawong

Hi Dude_500,
   
  Your headphones look really nice and well made. How do you make the plastic enclosures?
   
  About your comment on the hole size should not approach the thickness of the stator or the resonance could form within the stator holes, is there an article about this that you could point me to?
   
  Do you suggest that the hole size should be larger or smaller than the thickness of the stator?
   
  Wachara C.


----------



## dude_500

Quote: 





chinsettawong said:


> Hi Dude_500,
> 
> Your headphones look really nice and well made. How do you make the plastic enclosures?
> 
> ...


 
   
  The main enclosure is all laser cut 0.25in ABS. Spacers in this build are not FR4. Instead I used 0.02in styrene sheet so that I can laser cut it. Works just as well, I put a strip of copper foil tape on one side to contact the diaphragm.

 I was suggesting the holes be larger than the thickness, but I may be imagining all of this. I can't find a reference. Perhaps my memory became distorted and I was recalling that the hole spacing must be much smaller than the smallest wavelength.


----------



## arnaud

I believe it's not so much about the resonance in the holes (nowhere near te audio range) but the damping. The small DS gap and perforations contribute to the damping of the diaphragm because of thin layer viscous effects. I believe some comment was made on the headwize reference. 

By the way, Dude 500, I started to make a VA One model of your geometry, the old one that was causing a resonance. Trying to see if I can reproduce the problem with a simplified model. Utterly useless for you at this stage, it's mostly learning experience for me .


----------



## dude_500

Quote: 





arnaud said:


> I believe it's not so much about the resonance in the holes (nowhere near te audio range) but the damping. The small DS gap and perforations contribute to the damping of the diaphragm because of thin layer viscous effects. I believe some comment was made on the headwize reference.
> By the way, Dude 500, I started to make a VA One model of your geometry, the old one that was causing a resonance. Trying to see if I can reproduce the problem with a simplified model. Utterly useless for you at this stage, it's mostly learning experience for me
> 
> 
> ...


 
   
  It ended up being more an issue of the material than the geometry. Memory foam of softness "very soft" causes terrible resonance, be it raw foam, or foam covered in leather. Polyurethane foam of softness 25% deflection @ 1PSI is great either raw or covered with leather. Polyurethane foam of softness 25% deflection @ 0.3PSI is great as raw foam, but has very bad resonances when covered with leather or velvet.
   
  All tests were very repeatable, and although obviously I couldn't test every possible geometry, it seemed to be a material issue rather than geometry (of course, the geometry will set what the resonances are... but my point is same geometry with varying materials had these varying effects on the intensity of the resonance).
   
   
  If anyone knows even the diameter of the circle that the SR-007 earpad mounts to, it would be much appreciated!


----------



## chinsettawong

The outer circle of the cup is 110 mm. If you need other measurements, let me know.

Wachara C.


----------



## dude_500

Quote: 





chinsettawong said:


> The outer circle of the cup is 110 mm. If you need other measurements, let me know.
> Wachara C.


 
   
  Only other thing is how it mounts, pictures look like it's just a friction fit slide onto the cup. Is this the case? Or if it's some elaborate mounting mechanism that's difficult to describe, just let me know and I can patiently wait for my pads to arrive to analyze.


----------



## chinsettawong

For Stax 007, the sleeve on the pad simply goes into a small opening on the side of the cup.  As for my design, I use the same mounting mechanism as HE-5.  It's rather difficult to explain.  I can take a few photos to show if you want to.
   
  Wachara C.


----------



## dude_500

Quote: 





chinsettawong said:


> For Stax 007, the sleeve on the pad simply goes into a small opening on the side of the cup.  As for my design, I use the same mounting mechanism as HE-5.  It's rather difficult to explain.  I can take a few photos to show if you want to.
> 
> Wachara C.


 
  If I understand correctly, the cross section would look something like this? That could actually work quite well for my design. Do you know what D measures for a good tight fit? Don't know if you actually have a pair of 007's to measure.
   
  If you don't mind taking pictures, I'd definitely be curious to see other mounting methods that have worked for you.


----------



## chinsettawong

Hi Dude_500,
   
  What you understand is correct.  I'll take a few pictures later on today and will post to show you how mine looks like.
   
  Wachara C.
   
  P.S.  D is quite thin.  It's about 1 -1.5 mm.  However, the sleeve can go in deep.  The inner diameter of the sleeve is around 90.  I'll check it for you later just to make sure.


----------



## chinsettawong

Here is a simple drawing of how my pad is put on.  I hope you can understand. 
   

  Here is a picture of my cups before putting the pad on.
   

   
   
  After putting the pads on, they look like this:


----------



## chinsettawong

Here are some more photos:
  

  
  

  

  

  
  
 Wachara C.


----------



## arnaud

I have been looking further into the 1kHz resonance issue of dude500's previous iteration. I will show the headphone simulation results later on, but basically, the earpad cavity is not responsible for the 1kHz resonance, and it indeed comes from the pad / leather arrangement. For now, have a look at this simulation of the earpad absorption (the first peak is the foam/leather fundamental resonance, like a mass/spring system if you will).
   
  These results are for an infinite size sheet (1mm leather - 10mm foam - 1mm leather) so it's not quite was is happening with the actual earpad geometry but this highlights the potential resonance when using soft memory foam:
   

   
  The simulations I've run so far where for melamine foam / no leather, I will try with "soft PUF + leather" next. The one strange point about this is that, considering only the absorption effect of the pad, you should get a dip at 1kHz, not an extra resonance. Hopefully, the actual simulation including 3D earpad model will tell...


----------



## arnaud

Finally, here are the simulation results of dude500's previous phones (large earcup, thin pads). One important thing is that I realized how critical the pads construction / configuration / size affects the results, in particular the fundamental resonance of the diaphragm (it is heavily influenced by the effective mass and stiffness of the earpad cavity which in turns depends on the earpad to some extent).
   
  Since I only had one dimension with work with (old earpad inner surface area), everything else is approximate base of the pics posted by dude500 and of coarse I did not have any of the materials properties so I don't expect things to line up with tests. However, it was very good learning experience to find out about the importance of the pads.
   
  First, a simulation of the response of the headphone in free air for mics along the vertical axis between the diaphragm and base of the earcup. A couple of notes: this type of simulation is based on "Boundary Element Method" in which you only mesh the boundaries of the domain, compute the pressure and particle velocity at every nodes of the surface(s) and can then post-calculate the SPL at any point in the domain. The nice thing is that this enables calculation in free field / over large volumes:
   

  Below is a contour plot of the diaphragm velocity and SPL around the headphone at a single frequency (~100Hz, the free air resonance of the diaphragm):
   

  And here is the 3rd resonance of the diaphragm (+/-/+ across the length) at about 300Hz. 
   

  Note that the 2nd resonance (+/- across the length) isn't visible in the SPL response because this "mode" is a very poor "radiator" (+/- cancellation over the surface).
   
  Next step consisted in comparison the results from "BEM" simulation above to those of more traditional "Finite Element Method" where the whole acoustic volume is meshed. In that case, "rigid walled" acoustic modes are first computed and combined to "in-vaccuo" structural modes of the diaphragm during a coupled structural/acoustic solution. The main limitation is that you cannot resolve the response outside the meshed domain and computations get expensive with increasing domain size. Special care needs to be taken to make sure you don't get reflections from the boundary of the exterior domain, it then returns reasonably close results to the BEM approach (red vs. black curve). Note the drastic shift in the diaphragm resonance frequency compared to free air response:
   

  Contour plot around 3.5kHz where the SPL dips at the center of the earcup (this is an acoustic resonance in the earcup). First the BEM model, next the FEM model:


   
  Then comes the question why bother with FEM instead of using BEM? The reason is to be able to include more complicated earpad dynamics. In particular, in the BEM and FEM simulations above, the earpad effect was modeled as just a surface impedance (using infinite size trim model discussed in previous post) with every node acting independently of the other. It turns out this simplified earpad model totally misses the physics at low frequency, in particular because the earpad has such large influence on the first diaphragm resonance frequency. Here's a comparison with a "FEM/PEM" coupled model with the earpad (PU foam + leather) modeled in 3D using "Porous Finite Elements". The pad is assumed bounded to on the diaphragm side and "sliding" on the base (the surface in contact with the skin). You can see the diaphragm resonance (above 25Hz) shifted back to about 100Hz and you barely see the blip (I now understand why Stax headphones measure like they do below 100Hz: this is actually a coupled diaphragm / earcup cavity / earpad resonance):

  FEM model (rigid earpad) at ~25Hz (note the SPL response inside / outside is quite boring, this is because we're at very low frequency):

  FEM/PEM (3D earpad visible in grey color below) at ~100Hz:
   

   
   
  So, this brought me to the next stage. Now, it was clear I couldn't cut corners and had to include a full 3D model of the earpad. I did the rest of the simulations using this coupled FEM/PEM approach and investigated the sensitivity of the response to the earpad. I first changed the foam (PU foam) stiffness drastically. The disappointing thing is that I could not reproduce the huge 1kHz peak in dude500's response (it's rather easy to imagine though since I probably used the wrong material properties, foam dimensions, leather properties/dimensions and especially mounting configuration...). But the interesting thing was how sensitive the low frequency response was to the foam used. Below I am showing the SPL in the middle of the earcup, diaphragm velocity response and contour plot at 60Hz (soft foam only):
   
   


   

   
   
  At last, I investigated the effect of removing the leather and having a porous ("unsealed") or smooth foam surface ("sealed", impervious...). The motivation was that I did not know the actual leather properties / thickness and noticed that dude500 was only partly covering the foam with leather. Below are the SPL and diaphragm velocity, effect is pretty drastic:

   

   
   
  Conclusion: well, it's no surprise to some of you maybe but indeed the earpad matters a lot more than I thought! This actually has taught me a thing or two and I will be able to revisit my 009 model next...


----------



## chinsettawong

Hi Arnaud,
   
  I'm impressed of your simulations.  You really have spent a lot of time and effort into this.  Thanks a lot for sharing the info with us.
   
  As I have no knowledge about this subject and I cant't really understand the graphs (I'm sorry), could you kindly summarize the simulation results?  Can you conclude whether a soft or hard earpad is better?  Does the thickness of the earpad have any impact on the sound?  A few of my friends and I like thicker pads better than thinner ones.  We find that thicker pads give better bass.  But I don't know why.
   
  Wachara C.


----------



## arnaud

Hi Wachara,
   
  Thank you for your kind comments. Unfortunately, there's no easy answer I am afraid. The simulations I have run show that the earpad materials have a large influence on the low frequency extension of the response. Although I haven't visited this yet (I originally planned to but ran out of time), the earpad thickness most likely also has a significant influence, so does the mounting conditions (glued or not, using a thinner or thicker leather skin, how compressed it gets in seated position).
   
  As for rigid vs. soft foam, the simulation for the geometry above, and a particular PU foam used as baseline (there are so many variants of PU foam actually), the harder foam was beneficial to the low frequency extension (no roll-off, invisible fundamental diaphragm resonance, the lowest excursion of the diaphragm below 200Hz which should decrease distortion). But again, use a different material, different thickness, different "skin" and results will shift drastically.
   
  If anything, this reinforces why earpads are so meticulously manufactured by Stax and eventually so expensive... Note also that all the simulations above neglected the leakage from the earcup (improper seal or by design), this is another important variable (although I believe only a good sealed design will ensure a clean / extended bass).


----------



## chinsettawong

Apart from the pads and their construction materials, do you think that the distance between the driver and the ear has a significant impact on the bass as well?  This simulation should be quite interesting to see too.
   
  Wachara C.


----------



## arnaud

The baseline model (prior to meshing) is parametric so I will be able to investigate earpad depth and thickness without too much trouble. Maybe next week end...


----------



## dude_500

I've got most of the parts made for my new headphones. Even though it's all CNC at this point, it still takes lots of time to get everything made, so it's been slow going with school work.
   
  Pretty much a copy of Wachara's design concepts.
   

   

   

  Active area is 88mm diameter.
   
  Still lots of work to put into them before they're making any sound. Finding access to a router for the stators really took my design possibilities to the next level from what I've been making in the past.


----------



## chinsettawong

Wow, those look super cool!  With active area of 88 mm, you are going to need a lot more tension on the diaphragm.  But, you'll get a huge sound stage and unbelievably deep bass.  Let us know how they go.
   
  By the way, are you not going to etch away the unneeded copper around the stators? 
   
  Wachara C.


----------



## dude_500

I was debating whether or not to get rid of the extra copper. I have an 0.5mm lip of copper removed to avoid leakage around the edge, which I did on the router. I didn't want to take away a bulk of copper on the router since that'd take away some thickness of FR4 which would make squeezing the package less reliable. That just leaves etching. The problem there is at this point I'm not sure how to get an etch resist on it in any repeatable manner. Typically I'd user a laminator with toner transfer, but it wouldn't really be repeatable positioning. I guess I could just eyeball it and get it pretty close.
   
  Do you think it's definitely worth doing? My thought is driving them with a blue hawaii, it won't make much if any difference.


----------



## chinsettawong

You might have noticed that I etch out the unneeded copper on all my later version stators. The amount of copper really makes a big difference in high frequencies. I think it is worth it to remove it.

I have a DIY T2. It's more powerful than a Blue Hawaii, and yes, I still can hear the difference.

Wachara C.


----------



## jcx

Cu foil can be peeled off too - don't always need to etch
   
  try a compass cutter to scribe thru the foil, then peel up an edge with a exacto blade - with enough width to support the stress you can sometimes get a flap that can be grabbed with pliers and pull


----------



## dude_500

4-day weekend, so I figured I'd finish these up so I can stop being distracted by the project. After about 16 hours over the last two days, out come my omega clones.
   
  I decided that I should etch away that copper. I just did a standard toner transfer lining it up by eye. Upon typing up my last post, I realized it'd be correct within a millimeter or two, which is more than enough precision for this.
   

   
  Next, I assembled the plastic mount for the earpad. This is made of 1/8" ABS as the rigid structure, with a 0.02" styrene spacer and a mounting loop of the same thickness. The slit allows for the earpad to easily rotate into place:
   

   

   
  Diaphragm's were made by my typical method of hanging weights as I've discussed earlier.
   

   
  Next, I cut a spray mask on a styrene sheet and airbrushed elvamide solution onto the mylar. The mask is to keep the elvamide off of the edges to prevent any leakage of charge. I really like the airbrush technique... hook it up to a compressor, spray uniformly, and in a couple minutes of work effectively perfectly matched coatings can be accomplished.
   

   
  I used my crumpled mylar sweat screen design, since it seems to be completely acoustically transparent:
   

   
  And, the final product:
   

   

   
   
  I need to play with damping a bit, may need to add a felt sheet to the outside. But that's it pretty much.
   
  Weighting in at 0.60lbs, they feel weightless compared to my previous builds (in fact they can be comfortably worn with the elastic head strap not present just pushing against the ears). Free air resonance is 75hz.
   
  I'm not going to bother posting analysis graphs yet, since honestly I'm too tired to even think about analyzing them. I'm going to play with damping first anyways since there is some distortion in the 300-600hz range as is typically seen in fully undamped headphones.
   
   
  As for the sound, they are fantastic. noticeably better than my previous rectangular builds, I imagine largely due to the quality earpads (a purchase that I most certainly do not regret!) and the large driver area.
   
   
  This will probably be the last pair of headphones I make in the foreseeable future (right... like that'll happen).


----------



## chinsettawong

Hi Dude_500,
   
  Congratulations on your fantastic build.  Your headphones look great!  I'm sure that they sound great too.
   
  Since your active diaphragm diameter is 88 mm, do you have any problem with the stability of the diaphragms?  
   
  I'm looking forward to seeing a lot more DIY headphones from you.  
	

	
	
		
		

		
			




   
  Wachara C.


----------



## .Sup

Very nice Dude. What's the weight of those?


----------



## Soul_Est

Quote: 





.sup said:


> Very nice Dude. What's the weight of those?


 
   
  Quote: 





dude_500 said:


> . . . Weighting in at 0.60lbs, they feel weightless compared to my previous builds (in fact they can be comfortably worn with the elastic head strap not present just pushing against the ears). Free air resonance is 75hz. . . .


 
   Or 0.27 kg if we're talking metric.


----------



## chinsettawong

Hi Dude_500,
   
  Do you put a dust cover on the backside of your driver?  From the picture, it looks like you don't.  
   
  For damping, I know I few people who build their ESL attach a piece of cloth to the stator.  They really glue the cloth on the stator. If you want to, you can try that.
   
  As for me, I don't like any damping.  I feel that it adds coloration.  
   
  Wachara C.


----------



## dude_500

As for stability, I haven't had any problems yet, but time will tell. I increased the tension over what I've used on previous headphones (that tension was hopeless for such a large diaphragm) and it seems pretty stiff, so I have pretty good hope that it'll remain stable. I'm shocked how low the resonant frequency is, I guess it's related to size as well as tension.
   
  In the past I haven't liked damping, so I most likely won't add anything. I do hope to find a grill to put in, though. Do you know of anywhere to get those circular grills with the bent lip that can friction fit into a hole? I'd even go with a custom order if it were affordable.
   
   
  Interestingly, I still have a 1.5khz resonance and bass rolloff below it! L/R channel:
   

   
  I really need to figure out some way to get rid of that phenomenon, it definitely affects sound. I think I'll carry my amp to the shop today to test and convince myself it's not the amp that's causing the rolloff, but I'm guessing it's fine since I've tested it many times.


----------



## .Sup

thanks soul, I missed that!


----------



## dude_500

Is there perhaps something bad about having too little tension that I'm not aware of (other than losing stability, of course)? It seems every pair of headphones I make is worse than the last, and these are about as bad as it's gotten on frequency response. There's pretty much no bass there at all. In general, the FR seems to ramp up at about 3-4db/octave up to 1.5khz, which is obviously not a very pleasant listening experience.


----------



## AmarokCZ

Lower tension = better bass, because of lower resonance frequency. As proof I had a pair with extremely low tension (diaphragm sticked to stator even at 230V at certain conditions), but the bass was amazing even with bad sealing. By the way: SR-404 has free-air resonance frequency 207Hz and bass is super flat (just like on my headphones).


----------



## arnaud

Have you tried to tape the edge of the earpad along the sim with the driver frame? I am wondering about leakage there as I don't understand your pad mounting method. Another possibility I want to investigate is stator effect. what is the stator thickness, material, holes diameter and holes separation distance?


----------



## dude_500

Tape didn't change anything. I think it's a pretty good seal.
   
  Stators are 1mm FR4, holes are spaced at 0.155in from each other and have a diameter of ~0.115in (was supposed to be 0.125 but the router made them a bit smaller, don't have calipers around right now).
   
   
  I'm going to try making stators with more tension to see what that does. I had a pretty sparse covering of elvamide and added some dish soap (I know, not a good long term solution... just wanted to see how it'd affect it) and it instantly goes unstable with that coating, so I guess more tension will be good regardless.


----------



## arnaud

dude_500, what is the overall diameter of the fr4 stator and diameter of the perforated area?


----------



## dude_500




----------



## dude_500

I doubled the tension (blue line) and it's pretty much the same, so it doesn't seem to be an issue related to tension.


----------



## chinsettawong

Hi Dude_500,
   
  What's wrong?  I thought you liked them.  You mentioned earlier that the free air resonance was at 75Hz.  I thought that was terrific.
   
  Why did you rebuild your diaphragm?  Did you run into instability?
   
  I don't like using dish washer.  While it's alright, it tends to absorb moisture in the air.  Is alvamide not working very well?  If you want to try something different, you can try a few drops of black ink or antistatic gel into your alvamide solution.  I think they work better.
   
  I notice that the two frequencies response curves are very much different from one another.  Do you know why?
   
  Wachara C.


----------



## dude_500

I initially was blown away by the sound stage, but after a bit of listening and then going back to my HD600's, I realized they really are almost completely lacking in bass. This is well explained by the FR.
   
  I rebuilt it just to see if more tension would fix it, since at this point I have no clue what's wrong. It did not help the FR to have more tension. Although they are somewhat different, in the grand scheme, they're both largely qualitatively the same in that they have rolloff below 1.5khz.
   
  The elvamide is working well, it's just a more resistive coating than others and it takes a while for them to charge up. I don't mind this, I was just checking if perhaps that was somehow contributing to the frequency rolloff. It also had no effect on the FR with regard to the rolloff problem.
   
   
  So, basically I have no idea what's wrong. The first electrostatic headphones I made had almost flat frequency response right down to <50hz (unfortunately these headphones are long gone and scrapped, I don't really keep old ones together), then every new model I've built have had more and more rolloff below 1.5khz. Unless I figure out what I must be doing wrong, pretty soon I'll just be building electrostatic high pass filters!


----------



## arnaud

dude_500 said:


> I doubled the tension (blue line) and it's pretty much the same, so it doesn't seem to be an issue related to tension.




I can see the diaphragm resonances in this graph (for instance what I suppose is the second radial mode in the diaphragm shifted from ~175Hz to ~250Hz when you increased the tension. I am pretty confident I can reproduce this with simulation (see my previous post about your old can simulation). It doesn't address the roll off below 1kHz but I may be able to see if this is an issue with the airpad cushion and/or earcup volume (or lack there of). It takes me a while to get to this but if you provide me all dimensions, I can give it a shot. Is this an omega 2 pad?


----------



## chinsettawong

How is your FR compared to what Purrin measured on mine?  
   

   
  As for the coating, it makes a lot of difference in sounding.  My headphones would charge up instantly.  
   
  If you are sure of alvamide, let the diaphragms charge up for about an hour and take another FR measurement.  If you see any difference, then it's the coating problem.
   
  Wachara C.


----------



## dude_500

Quote: 





arnaud said:


> I can see the diaphragm resonances in this graph (for instance what I suppose is the second radial mode in the diaphragm shifted from ~175Hz to ~250Hz when you increased the tension. I am pretty confident I can reproduce this with simulation (see my previous post about your old can simulation). It doesn't address the roll off below 1kHz but I may be able to see if this is an issue with the airpad cushion and/or earcup volume (or lack there of). It takes me a while to get to this but if you provide me all dimensions, I can give it a shot. Is this an omega 2 pad?


 
  The rolloff does seem to get quite a bit better, although it's still there a little, when using soft uncovered foam earpads. This graph was using the SR007 earpad.
   
  My only thought is that perhaps it has something to do with the fact that a large portion of the diaphragm is hidden behind earpad cushion, although I'm not sure exactly what acoustic effect that'd have. It would surely add some frequency-dependent damping since higher frequencies would see a volume under there but lower frequencies wouldn't.
   
   
   
  Quote: 





chinsettawong said:


> How is your FR compared to what Purrin measured on mine?
> 
> As for the coating, it makes a lot of difference in sounding.  My headphones would charge up instantly.
> 
> ...


 
   
  Mine overlayed on yours is as follows:

  As you can imagine, not much bass there, and way too warm midrange.
   
  I did let the elvamide charge up, overnight even... it did not change the FR. I also tried both soap and PVA-graphite (again, I know both are bad for longterm... just doing shortterm testing here to get my FR working) and both charge almost immediately but have the same rolloff. So it's got to be acoustic dynamics.


----------



## chinsettawong

I don't know why you still don't want to try the electrostatic cleaner gel.  I've tried PVA glued with graphite powder, PVA glue with black ink, liquid soap, and a few other kinds of coating too, and nothing works better.
   
  The coating does make a big difference.
   
  Wachara C.


----------



## spritzer

I second altering the coating and I would also look into backwave cancellation.  I've been working on the HE90 with Lambda drivers project over the last two days and one of the sets I tried just sounded odd with a strange reverb in the bass.  Very little low level bass too which quickly led me to find a small gap in the glue holding the driver to the baffle creating this odd effect.  If the earchamber isn't completely sealed it can lead to some very odd behavior. 
   
  Btw. Wachara, the HE90''s sound amazing with Lambda Nova Signature drivers.  Some of the odd imaging from the HE90 remains but it's a minor effect and quite similar to the HE60.  The rest is just brilliant.


----------



## dude_500

I really like elvamide because it doesn't go unstable even when blown onto a stator with the same tension where other coatings would immediately go unstable upon plugging in. I assume this is because it's higher resistance at least in the way I apply it (takes a few minutes to charge up, and a few hours to reach full sound quality.
   
  It also doesn't seem to affect the sound signature in my experience, and it doesn't affect the FR in any major way (if it does, it's below the threshold of repeatability in my measurement techniques)


----------



## chinsettawong

Quote: 





dude_500 said:


> I really like elvamide because it doesn't go unstable even when blown onto a stator with the same tension where other coatings would immediately go unstable upon plugging in. I assume this is because it's higher resistance at least in the way I apply it (takes a few minutes to charge up, and a few hours to reach full sound quality.
> 
> It also doesn't seem to affect the sound signature in my experience, and it doesn't affect the FR in any major way (if it does, it's below the threshold of repeatability in my measurement techniques)


 
   
  One should not have to plug and wait an hour before using his headphones.  While high resistivity is good, but if it's too high, your diaphragm might never get enough charge at all.  When the charge isn't optimal, you won't have good bass.
   
  It took me at least 2 years after so many trials and errors to find out this cheap and good coating material.  I just wish you could give it a try.
   
  Wachara C.


----------



## chinsettawong

Quote: 





spritzer said:


> Btw. Wachara, the HE90''s sound amazing with Lambda Nova Signature drivers.  Some of the odd imaging from the HE90 remains but it's a minor effect and quite similar to the HE60.  The rest is just brilliant.


 
   
  Hi Spritzer,
   
  Please share with us a few photos of your headphones.  I really look forward to seeing them.  Congrats on your success.
	

	
	
		
		

		
		
	


	



   
  Wachara C.


----------



## dude_500

Quote: 





chinsettawong said:


> One should not have to plug and wait an hour before using his headphones.  While high resistivity is good, but if it's too high, your diaphragm might never get enough charge at all.  When the charge isn't optimal, you won't have good bass.
> 
> It took me at least 2 years after so many trials and errors to find out this cheap and good coating material.  I just wish could you give it a try.
> 
> Wachara C.


 
   


 Yes, I have some in the mail arriving tomorrow. I'll give it a shot this weekend and report back on it.
   
  I'm also planning to make a pair of stators to test that have holes restricted to the center of the area where there is earpad opening. I've noticed that Stax appears to do this, and preliminary testing with duct tape indicated that it may help and/or solve my rolloff issue.


----------



## dude_500

A few interesting findings this weekend:
   
  First off, I tried out the anti-static cleaner. Not a chance, will never use that. In about half a second, went unstable to a degree that I had to literally peel it off the stator. And that was on the highest tension diaphragm I've ever made. Love Elvamide, and will probably use it forever.
   
  More importantly, back to the key issue with my new headphones. I made a pair of stators with holes that approximately line up to the opening of the earpad. Makes a huge difference! Here are the FR's of the two channels, one built with the old stators and one with new stators. Everything else (tension, coating material, and sweat screen configuration) is identical between the two. Red is new stators with fewer openings, blue is old stators:
   

   

   
   
  This is no measurement glitch, highly repeatable and listening to them definitely shows that the bass is approximately identical between the two ears, but one has painfully strong midrange. It's nothing subtle, just a few minutes of listening causes physical pain to me having that imbalance in the midrange.
   
  I can only stipulate that it must be some sort of resonance forming in the volume between the diaphragm and the backing of the earpad. Would be very curious to hear any thoughts on what's really going on. I know Stax claims having some extra copper area with no holes increases the force on the diaphragm, but that shouldn't really cause this sort of issue I wouldn't think.
   
  Also of interest is the dip at ~6khz. Again, it is definitely real and not some result of my measurement setup. I can hear a pretty big dip in that area when running a frequency sweep. Any idea what causes this to form?


----------



## chinsettawong

Hi dude_500,

I'm very interested to hear from you what the problem with the antistatic cleaner is that makes you think it is so bad. If I were you, I would increase diaphragm tension even more until the diaphragm is stable, listen to it, then judge if it's good or bad. My point is that with electrostatic cleaner as a coating, your electrostatic field on the diaphragm is much stronger. That's what it should have been in the first place.

Without good efficiency, you won't get good enough sound.

Wachara C.


----------



## arnaud

Dude500: very very interesting! Besides stax comment (to increase the force), another thing that comes to my mind is the increased rigidity of the stator. This is the reason why I asked you the dimensions and properties of the stator, but as usual I am lagging behind with the simulation... That or increase damping in the DS gap which severely affects mids/highs response. I have hard time imagining this relates to the earpad covering part of the driver (but what do I know eh  ).

The 6kHz dip requires investigation but are there any dimensions within 50-60mm range like the inner pad diameter? Else a dimension in 25-30 mm range? What is the perforated diameter in your revised stator?


----------



## dude_500

Quote: 





chinsettawong said:


> Hi dude_500,
> I'm very interested to hear from you what the problem with the antistatic cleaner is that makes you think it is so bad. If I were you, I would increase diaphragm tension even more until the diaphragm is stable, listen to it, then judge if it's good or bad. My point is that with electrostatic cleaner as a coating, your electrostatic field on the diaphragm is much stronger. That's what it should have been in the first place.
> Without good efficiency, you won't get good enough sound.
> Wachara C.


 
  Well, the thing that was bad was the instant instability. It required probably about a half a pound of laterial force to get if unstuck from the stator. I can't even imagine how much tension that would require to keep stable. I doubt my tensioning jig is capable of making such a tension. I put a bit thicker of an elvamide coating on and now those charge up in about 10-15 seconds.
   
  Quote: 





arnaud said:


> Dude500: very very interesting! Besides stax comment (to increase the force), another thing that comes to my mind is the increased rigidity of the stator. This is the reason why I asked you the dimensions and properties of the stator, but as usual I am lagging behind with the simulation... That or increase damping in the DS gap which severely affects mids/highs response. I have hard time imagining this relates to the earpad covering part of the driver (but what do I know eh
> 
> 
> 
> ...


 
  Many of the earpad opening dimensions are at least on the order of 50-60mm, although I haven't found any measurements that are dead-on the wavelength of 6khz. There is still that void between the now-covered part of the stator and the back of the earpad. I filled that in partially and the dip lowered in magnitude slightly and went up to 7khz. I'll cut some plastic parts to fully fill it and see if that changes anything. Also possible that void is related to the 2khz dip, perhaps a quarter-wavelength issue. At least in electrical engineering, quarter wavelength is a short circuit.
   
  The new stators have an opening diameter of about 2.5in.


----------



## chinsettawong

Quote: 





dude_500 said:


> Well, the thing that was bad was the instant instability. It required probably about a half a pound of laterial force to get if unstuck from the stator. I can't even imagine how much tension that would require to keep stable. I doubt my tensioning jig is capable of making such a tension. I put a bit thicker of an elvamide coating on and now those charge up in about 10-15 seconds.


 
   
   
  How can you blame the coating for your diaphragm instability?  
	

	
	
		
		

		
		
	


	



   
  Well, I have done my part.  It's all up to you now.  I won't give you anymore comment.
   
  Wachara C.


----------



## dude_500

Quote: 





chinsettawong said:


> How can you blame the coating for your diaphragm instability?
> 
> 
> 
> ...


 
   
  Quite simply, one coating causes instability while the other doesn't, when applied to a stator of the same tension. Since most coatings go unstable at said tension (like soap and PVA/graphite) I can only assume it's because elvamide has a bit higher of a surface resistance preventing the charge from quickly spreading to where it is contacting the diaphragm. The differences between the coating is massive in stability performance, but seems to have no effect on sound (so long as you're willing to wait for the elvamide to charge for a couple of minutes, which I couldn't care less about - I've heard even some retail headphones take some time to charge up).


----------



## arnaud

Dude500, I finally got around to make vibration simulation of your recent omega clone stator. I was surprised by the result but essentially the smaller size of perforated area did not seem to increase the effective stiffness of the stator and both versions exhibit resonances at similar frequencies. It does not mean stator resonances are not an issue in absolute sense, but at least, it doesn't seem to be the cause of your current issue with the old stator... Else something went awfully wrong with my simulation lol.
   
  Examples below with the first 2 stator resonances at about 750Hz and 1400Hz, left is the old stator, right is the new one with smaller perforated area. In both cases I ignored the copper trace / etching so this is assuming 1mm FR4 (also I used isotropic average properties for the material even though its mechanical properties are actually somewhat direction dependent):
   
  Mode 1 (730Hz for both stators):
   

   
   
   
  Mode 2 (1460Hz for old stator, 1350Hz for new stator):
   

   
  I will probably try to investigate acoustic resonance within the DS gap next, have to think of the most efficient way to model it...


----------



## J-Pak

Terrific thread, thanks for all the useful information everyone.


----------



## chinsettawong

For those who are interested to learn about the diaphragm coating:  http://www.diyaudio.com/forums/planars-exotics/109789-esl-diaphragm-coating.html
   
  Wachara C.


----------



## dude_500

Here's some potentially interesting data, although I'm not sure what to make of it.
   
  Made new stators today with 0.042in holes, with 0.055 hole-to-hole spacing.
   

   
   
  Red is the new smaller hole stators, blue is the old large hole stators. This is with no damping fabric anywhere, so it's a bit more peaky than previous FR's I've posted recently. I was wondering if the huge narrow peak in the large-hole stator FR is something like the ~30th harmonic of the diaphragm resonance. If the resonant geometric diaphragm pattern matched up with the holes in the stator, I could see that creating some pretty serious resonances.

   
   
  My ears can not notice any difference between the two.


----------



## arnaud

Dude500, it's very difficult to see the consistency with your measurements. Last week, you show us results from the new smaller diameter perforated zone which alleviated the 1kHz or so peak / lack of bass. Yet the results today with smaller holes but same "reduced" perforated area seem to show again the same problems as your original stator. Am I missing something?

Also, a couple pages back you showed some comparisons of 2 diaphragms tensioning with very large variation above 5kHz or so (which might be as much due to microphone placement variation as it is to diaphragm change). Hence, I am wondering how repeatible your narrow band measurements really are. From experience with simulation, you don't need more than a few mm shift in mic placement to get 5-10dB shifts in narrow band response above a few kHz (past the first few acoustic resonances in the earpad cavity).

Results today (small perforated area, small vs large perforation holes): http://www.head-fi.org/content/type/61/id/702419/
Previous result (small vs large perforated area, large perforation holes): http://www.head-fi.org/content/type/61/id/700423/
Older result (large perforated area, large holes, change in diaphragm tensioning): http://www.head-fi.org/content/type/61/id/697112/flags/LL


----------



## dude_500

I agree it is quite strange how the bass rolloff seems to be coming back. All measurements and comparisons I do on one day I do many times with microphone placement adjustments to ensure repeatability against major FR changes or random measurement glitches. Day to day, I really can't claim repeatability.
   
  My diaphragms seem significantly lower in tension today than last week, which may be one explanation. This may or may not be related to the fact that the temperature has increased substantially in my room since, and humidity is much higher today than the last FR I posted.
   
   
  Moving the microphone around does seem to change the treble peaks, but not hugely or on the scale of the difference between the two traces. There is no doubt in my mind that the larger holes result in a sharp peak. Tomorrow, who knows 
	

	
	
		
		

		
		
	


	




... Maybe I should just start tuning to sound and personal preference.


----------



## J-Pak

Quote: 





notloc said:


> I have been interested in building my own electrostatic headphones for a while (most of my information coming from this page: http://gilmore2.chem.northwestern.edu/projects/showfile.php?file=radford1_prj.htm )


 
   
  This link has now gone down, just curious if it is the same article as this one: http://headwize.com/projects/cmoy3_prj.htm
   
  Thanks


----------



## Congo5

Quote: 





j-pak said:


> This link has now gone down, just curious if it is the same article as this one: http://headwize.com/projects/cmoy3_prj.htm
> 
> Thanks


 
   


 changed to:      http://headwize.com/projects/radford1_prj.htm


----------



## dude_500

The cause of the inconsistencies in bass roll-off day-to-day seems to have been how well I was sealing to the detector panel. What's strange, is the better I push it down to seal it, the more roll-off I get. The relative flat FR pictures I posted before are reproducable by basically setting the headphone onto the detector, if pressing at all then with very light force.
   
  Do Stax headphones or the ones you guys DIY have any sort of vents on the earpad side of the driver? It almost seems as though very slight leakage is preferred. Mine are so sealed that if I push them into my head while wearing them, the diaphragms are slammed into the outer stators for a few seconds due to the air pressure.


----------



## AmarokCZ

Mine DIY ES are air-tight as much as possible, just like the SR-404. With better seal (=more pressure towards detector panel), there is LESS rollof: with 2kg force pressing towards detector panel, there is -10dB rollof at 10Hz (white curve) compared to flat range between 50Hz and 500Hz.
   
  BTW, does anyone have STAX SRM-006t amplifier? I'd like to check some parameter on another amp - I think mine is "not all right". 
	

	
	
		
		

		
		
	


	



   
EDIT: link


----------



## chinsettawong

The diaphragm slamming on the outside stator is normal.  With such a large diaphragm diameter to stator thickness ratio such as Omega's, this problem is quite unavoidable.  However, the diaphragm must be tensioned enough so that it will never stick to the stator.  It should just touch and bounce right off.  The diaphragm touching the stator for a few seconds is a sign that the tension isn't enough.
   
  Wachara C.


----------



## chinsettawong

The HE-6 to Omega clone conversion is finally done.


----------



## J-Pak

Very nice! Are those 80 mm diameter stator?


----------



## chinsettawong

The active diaphragm diameter is 80 mm, and the diaphragm thickness is 3 microns.
   
  Wachara C.


----------



## spritzer

Any issues with drivers that big?  They do look awesome!!


----------



## chinsettawong

Thanks, Birgir. 
   
  The size of the drivers is very similar to that of Stax SR007.  The actual active diaphragm diameter of SR007 is 78 mm while mine is 80 mm.  With the diaphragm width this much, the tension on the diaphragm has to be very high to keep it stable.   
   
  The only other issue I have while making this conversion is that the cups are coated with conductive paint underneath the black paint.  I only find out this after I've cut all the parts.  Therefore, I have to be extremely careful.  I etch out all the copper that could possibly come into contact with the cups, and I tape the outer perimeter of the drivers as an extra precaution.
   
  The sound is similar to my previous Omega clone.  However, the comfort is a big issue to me.  They just aren't that comfortable to wear.  The earpads are rather bad too.
   
  Wachara C.


----------



## spritzer

Having held my fair share of SR-Omega diaphragms... yup you need plenty of tension.  I'm sure the brass mounting rings would bend before that diaphragm.  
	

	
	
		
		

		
		
	


	



   
  Pretty much all black paint is somewhat conductive due to the carbon die in it, something people rebuilding Quad ESL's have learned the hard way. 
   
  Are those the HE-6 earpads?  They are really nasty indeed.


----------



## chinsettawong

Yes, they are HE-6 earpads. Nasty is the right word indeed. 

The first layer of paint looks very much like chromium. The resistance is very low. I guess they want the black color surface to look shinny, and with the chromium underneath, it helps. 

Wachara C.


----------



## dude_500

I've been doing lots of tweaks to get the sound more how I'd like it to be. Been continually increasing tension, and also decreasing the active area (tried 78mm like Stax uses and I like it much better than the 90mm I'd been using in the past). 
   
  But I've been running into a problem. I've pretty much never made a diaphragm that after a couple days, didn't have a high pitched squeal develop. It is an inconsistant and fairly quiet squeal that comes and goes. It is not in the amplifier, because unplugging the headphones keeps the squeal going for quite some time from the stored charge. I have quite uniform and high tension, with no wrinkles even along the glue edge. Has anyone run into this issue? It always develops slowly after several days or weeks after assembly. When I take the diaphragm out and check the tension, it's the same as day 1, and nothing visually changed. The only thing I can think of is maybe dust getting in since I don't have a protection screen on the outer face. My coating material is anti-static cleaner.
   
  Turning bias down to about 250-300v always clears it up indefinitely (at least to time lengths that I've tested, I have no way of knowing if it'd come up months later), but I would like to run at higher bias to keep efficiency up.


----------



## spritzer

That would be dust causing those issues.


----------



## chinsettawong

Hi Dude_500,

Have you given up on your elvamide already? 

The squeal has nothing to do with the diaphragm tension. The sound that you hear is from the electrical discharging. In my experience, it can only happen when you either have some dusts inside the driver, or there is a small hole on your dust cover.

Yes, it can really be a pain to look for the dusts inside the driver. The dust can be so small that it can't be seen with naked eyes. I normally use a big magnifying glass to help me look for it. A simple and effective way to clean your stator is to use a piece of sticky tape to stick the whole surface of the stators. When you pull the tape up, the dusts come up together with the sticky side of the tape. I do that a few times just to make sure all the dusts have been removed. 

Another way is to spray paint your stator with some plastic paint. Since the stators surface is now non conductive, the dust won't make the squeal. 

Water condensation inside the driver is another major cause of the squeal. If your headphones start up with no squeal, but the squeal only comes after you've been listening for a while, then I think this is the problem. It takes only just a small pin hole to cause it. When you're listening, the humidity inside the cup can be quite high. The humidity eventually finds its way inside the driver and condenses into water. So, do not overlook a small pin hole on the dust cover. 

By the way, may I ask you to tell us why you decide to use anti static cleaner? Is Elvamide not performing well?

With your active diaphragm diameter of 90 mm, it's extremely difficult to keep the diaphragm stable, right? If I were you, I would increase the spacer thickness a little more - say 0.6 mm. 0.1 mm sure makes a lot of difference.

Wachara C.


----------



## frank2908

sorry, I have no experience with DIYing electrostatic, love to try one day though, but from my experience with diy thunderpants, you should try out the LCD-2 pads, i strongly believe that the quality of the bass from the Audeze has 80% to do with the pads ( of course to benefit, the driver should have fast bass, which i think electrostats have plenty) It need a few teak as the mids might become too thick, but worth trying


----------



## dude_500

I do have my stators painted with a relatively thick coat of spray primer. I have read that many spray paints are actually quite conductive though, I should check if the stuff I used is as that may be one reason it doesn't help much with the squealing. I do also notice the squeal coming up after long listening, and often it will come on quite badly after showering and still having wet hair. I have what I would consider to be a perfectly sealed sweat shield over the inside stator, but nothing on the outside stator. What do you use to keep dust (and possibly moisture) out of the outside? I recall at one point putting a mylar screen on both sides was discussed, but I think it was determined that caused a bit of bass rolloff (and as far as I know even most retail headphones don't have a film on the outside). 
   
  90mm was indeed very difficult to get stable, 78mm is a huge difference in stability. I had it stable for about 350V bias, but never bothered get the tension high enough to get it stable higher. 
   
  And yes, you're right... anti-static cleaner is great. I still would argue that if what you're after is ultra low tension then elvamide is the way to go (which is what I was going for early on, but at this point I like the sound of higher tension more anyways, and it's much easier to work with). The elvamide holds a much weaker charge so it's vastly more stable, of course it also is less efficient being that it has less charge, so it's all a balancing act where you have to pick your priorities.


----------



## chinsettawong

We can argue all day long about the coating materials.  As for me, if I want to use lower tension on the diaphragm, I would still use the same coating material, but I would lower just the bias voltage.  That's how I would do it.
   
  What bias voltage are you using now with your 78 mm diaphragm?  Stack uses 580V.  I use 580-650V.
   
  About the squeal problem, it's either dust or humidity that is causing it.  Be very patient.  Use a big magnifying glass, if you have to.
   
  Good luck.
   
  Wachara C.


----------



## dude_500

Quote: 





chinsettawong said:


> We can argue all day long about the coating materials.  As for me, if I want to use lower tension on the diaphragm, I would still use the same coating material, but I would lower just the bias voltage.  That's how I would do it.
> 
> What bias voltage are you using now with your 78 mm diaphragm?  Stack uses 580V.  I use 580-650V.
> 
> ...


 
   
  Right now I'm sitting at about 250V to keep the squeal down until I fix that, I've gone up to 400V on the 78mm stators, and can switch a wire in my supply to get adjustment up to 700V when I fix the squeal.
   
  I could go through the work of cleaning the dust out, but I don't see the point... won't it just fill up again? There are stator holes exposed to the atmosphere on the outside face.


----------



## chinsettawong

dude_500 said:


> Right now I'm sitting at about 250V to keep the squeal down until I fix that, I've gone up to 400V on the 78mm stators, and can switch a wire in my supply to get adjustment up to 700V when I fix the squeal.
> 
> I could go through the work of cleaning the dust out, but I don't see the point... won't it just fill up again? There are stator holes exposed to the atmosphere on the outside face.


 
 Hi Dude_500,
  
 If you don't listen, nobody can help you.  I've made many electrostatic headphones, and I know what I am doing.
  
 If you're so worried about the dust, you can certainly put another dust cover on the backside.  
  
 Wachara C.


----------



## dude_500

Quote: 





chinsettawong said:


> Hi Dude_500,
> 
> If you don't listen, nobody can help you.  I've made many electrostatic headphones, and I know what am doing.
> 
> ...


 
  Not sure what I'm not listening to... I fully accept that it is dust and am glad to learn that is definitely the issue. My question was what people are using for dust covers. I may have missed it, but unless I'm mistaken nobody has discussed what they now use with the exception of a second mylar film, which was determined many months ago to quite likely inhibit bass response.I have used felt, but that changes the sound signature quite a bit.


----------



## chinsettawong

For what I know, you are making your headphones exactly the way I make mine.  I only use the dust cover to cover the inner side of the driver.  I leave the other side completely open to the atmosphere.  I've been doing that for many years.  The reason for me is that when I cover the outer side with another Mylar dust cover, I tend to get less bass, and I don't like it. 
   
  If you want to, you can cover the outer side with very fine screen mesh cloth.  I think that's what Sennheiser did on their HE-60.  Here are some pictures of the HE-60 driver.
   
  This first photo shows the dust cover that is facing your ear.
   

   
  This second photo is the other side of the same driver.
   

   
   
  Wachara C.


----------



## spritzer

If you are loosing bass due to the back dust cover then it's simply too tight and bounces back some of the low frequencies causing them to cancel out.


----------



## arnaud

It was also demonstrated in this exact thread at around the same time he was working out his issues: use a wrinkled mylar film with no tension and you shouldn't see this bass drop / membranes coupling effect. That's what stax has been doing for decades it seems and they are covering both sides of the stator it appears.


----------



## chinsettawong

Thanks Arnaud an Birgir for your inputs. I'll try the back side cover for my next build. But just for you know, I have no issue with squeal even without the back side dust cover. Since the bias supply is only applied to one side, there is no electrical charge on the back side and therefore no electrical leakage to make the squeal.

Wachara C.


----------



## chinsettawong

I'm moving ahead with my new headphones.  This time I'm revisiting the very first version of my headphones.  Of all the headphones that I've made so far, I really like my very first version the best.  They are oval shape similar to Orpheus, but the active diaphragm area is much larger (100 mm x 70 mm compared to 100 mm x 50 mm of Orpheus).  
   

   
  There are two weak points that I'll fix on my new build - low efficiency and high capacitance.  At the time I made these headphones, 0.6 mm PCB was the thinnest I could find.  This time I will be using 0.5 mm PCB.  To reduce the drivers' capacitance, I'll etch away all the unneeded copper on the stators.  This will make the headphones sound brighter.
   
  Taking this opportunity, I'll increase the size of the active area a little.  The new size will be 104 mm x 74 mm.  Here is how the new drivers will look like:
   

   
  I've started cutting my wood cups today.
   

   
  This is how the new cup compares to the Orpheus clone cup I made earlier.
   

   
  Yet, there are still many parts to cut.  
	

	
	
		
		

		
			




   
  Wachara C.


----------



## spritzer

I can't wait to see how these come out.


----------



## tigon_ridge

Since this is the ultimate DIY head-fi thread, I thought maybe you guys could go further with this idea I have, and make earpads custom-molded to your head/ears. This might be the solution for obtaining the closest-to-perfect seal and comfort; and also will allow you to use a harder material for the "core" of the earpads, such as wood, to reduce absorption of bass frequencies. You can then, place a thin layer of softer material as the interface between your head and the hard layer of the earpads. This might entail that you should make the earpad component easily detachable; as to be able to switch over a standard pad, in case you wish to compare the sound differences, or share your creation with friends who will invariable not have the same shape as your head/ears. Just an idea for you guys.


----------



## chinsettawong

Quote: 





tigon_ridge said:


> Since this is the ultimate DIY head-fi thread, I thought maybe you guys could go further with this idea I have, and make earpads custom-molded to your head/ears. This might be the solution for obtaining the closest-to-perfect seal and comfort; and also will allow you to use a harder material for the "core" of the earpads, such as wood, to reduce absorption of bass frequencies. You can then, place a thin layer of softer material as the interface between your head and the hard layer of the earpads. This might entail that you should make the earpad component easily detachable; as to be able to switch over a standard pad, in case you wish to compare the sound differences, or share your creation with friends who will invariable not have the same shape as your head/ears. Just an idea for you guys.


 
   
  Thanks for your recommendation.  But, I think I'll just move on for the time being.  It's more fun for me to feed my DIY CNC machine with something new.
   
  Wachara C.


----------



## dude_500

Quote: 





tigon_ridge said:


> Since this is the ultimate DIY head-fi thread, I thought maybe you guys could go further with this idea I have, and make earpads custom-molded to your head/ears. This might be the solution for obtaining the closest-to-perfect seal and comfort; and also will allow you to use a harder material for the "core" of the earpads, such as wood, to reduce absorption of bass frequencies. You can then, place a thin layer of softer material as the interface between your head and the hard layer of the earpads. This might entail that you should make the earpad component easily detachable; as to be able to switch over a standard pad, in case you wish to compare the sound differences, or share your creation with friends who will invariable not have the same shape as your head/ears. Just an idea for you guys.


 
   
  That's a very interesting idea. The problem I see is that the shape of your head in that area changes substantially when opening your mouth, which would make a rigid earpad feel terribly restrictive. In fact I can hear rises in the ~200hz resonance when I open my mouth since it reduces the quality of the earpad seal.
   
  Might not be a problem if you only use them for dedicated listening, but I use my headphones for internet phone conversations, listening to stuff while eating breakfast, etc.
   
   
  Anyways, I thoroughly cleaned dust out of my drivers today and put a dust screen (wrinkled 2um mylar) on the outside with a protective plate over it. Doesn't affect the FR at all as Wachara predicted, and I don't hear any discharges noise anymore.
   

   
  I quite like the color contrast and decided to not paint the covers black, although I'm sure many would disagree with that decision


----------



## chinsettawong

Congrats!  Next, you need to boost up your bias voltage to 580V.  If everything is stable, it's done. 
	

	
	
		
		

		
		
	


	



   
  Wachara C.


----------



## tigon_ridge

Quote: 





dude_500 said:


> That's a very interesting idea. The problem I see is that the shape of your head in that area changes substantially when opening your mouth, which would make a rigid earpad feel terribly restrictive. In fact I can hear rises in the ~200hz resonance when I open my mouth since it reduces the quality of the earpad seal.
> 
> Might not be a problem if you only use them for dedicated listening, but I use my headphones for internet phone conversations, listening to stuff while eating breakfast, etc.
> 
> ...


 
  It seems the gap between adjacent holes is quite large. Might contribute to unnecessary resonance. You might benefit from "bunching" the holes closer together, by squeezing in more holes, or increasing the size of each one.


----------



## chinsettawong

Here are some updates of my progress.
   
  All the parts are cut.
   

   
  The unneeded copper is etched.
   

   
  The parts fit in the cup perfectly.
   

   
  I'm learning how to oil the wood.  I've put 5 coats of linseed oil on the cups so far.  I think I'll finish them off with vanish.
   

   
  I'm making this pair together with another friend who's responsible for making the headband and headpads.  We hope to finish the project before New Year holidays.  
	

	
	
		
		

		
		
	


	



   
  Wachara C.


----------



## smart

Hi everyone,
   
  I'm new to this thread, but being a head-fi member for quite a while.  I've been working with Wachara for the leather work to make ear pads, and headbands.  I used black sheep skin for ear pads, and brown sheep skin for head bands.
   

   
  The cutting plan was designed in an AutoCAD.  A skill I learned from a technical college.
   

  An ear pad consists of 5 pieces of leather.  Thanks to my wife who taught me how to use sewing machine (that I bought for her over a decade ago).
   

  With soft sponge and 3mm. sheet foam, the ear cups turn out to be as good as I expected.
   
   

  The final look is really satisfying 
	

	
	
		
		

		
		
	


	



   
  I should get new ear pads and head bands for our new project done soon, to make sure we have another good pair of headphones to celebrate christmas and new year holidays.


----------



## smart

leather work for headphones was done
   

   
   
  closed-up shots show more details.


----------



## chinsettawong

Quote: 





smart said:


> leather work for headphones was done
> 
> 
> 
> ...


 
   
  Nice work!  
	

	
	
		
		

		
		
	


	



   
  I'm looking forward to putting everything together soon.
   
  Wachara C.


----------



## SmittyHalibut

I've been lurking in/reading this thread for several weeks now and finally got around to creating an Head-Fi account.
   
  First off: Wow, those look AMAZING. You have done such a wonderful job.  I have a (crummy) CNC mill and have been resisting the urge to build myself a set of these.  I may not be able to hold out much longer.
   
  But before I do that, I am borrowing a pair of Stax SR-5s with SRD-6 transformer box from a friend.  As one might expect, the detail is PHENOMENAL, but the frequency response is mid-heavy and bass-light.  I'm wondering how much of that is influenced by the transformers in the SRD-6.  I'm not afraid of DIY amps or high voltages in tubes, so I'd like to build a simple OTL amp for them to see how it changes the sound.  Of course, the amp I build would also (hopefully) be usable with the phones described in this thread if/when I break down and give them a try.
   
  I'm posting because the last talk about the amplifier design I've been able to find using the search feature was back in post #7: http://www.head-fi.org/t/498292/my-diy-electrostatic-headphones#post_6732478  There are _A_LOT_ of posts in this thread; I have NOT read them all.  I'm curious whether there is more discussion about the amplifier used, or if anyone knows of another DIY ES OTL amp thread where I should move my questions.


----------



## chinsettawong

Hi SmittyHalibut,
   
  Don't resist your urge!  Go for it!  
	

	
	
		
		

		
		
	


	




  With your own CNC mill, making parts for your headphones shouldn't be that difficult at all.
   
  I'm not sure how familiar you are with electrostatic headphones.  With them, you hear very detail sound.  The bass can go very deep, but it won't be as heart pounding as dynamic headphones.  Some people like them, while some people don't.  Yes, the quality of transformers has a big influence on the sound.  To me, direct drive amps are better than amp and transformer.
   
  There are many DIY electrostatic headphones amp projects that you can build.  Some are very easy to build.  And some are very expensive and quite difficult to build. 
   
  For a beginner, I would recommend the one on my post #7 that you mentioned or the one design my Frank Cooter.  The two amps are quite similar on the working principle.  However, Frank's has a higher voltage swing.  It's also simple and can be built at quite a reasonable price.  Please contact Frank for his schematic.
   
  There were a few group buys for electrostatic amp PCB.  If you can get hold of eXStatA or KGSSHV PCB from group buys,  you can build those too.  They are more advance, and should be very good sounding amp for the budget.
   
  Wachara C.


----------



## smart

I had a lot of progress during the weekend.  The cups are ready for drivers, and one of the two headbands was done.
   

   
  A final look of the cups.

   
  I use stainless steel wire and a small section of PVC pipe to make the main part of the headband.  
   

   
   
   
  Almost done!  The lamb skin is so soft and beautiful.  I still need to do double stitching to finish the band.


----------



## mungwi

wow, that looks impressive. good job sir!


----------



## livewire

WOW!
   
  Cant wait for the final product impressions.


----------



## 234537

That leather band look super comfortable!
   
  I am sure you could listen without fatigue for hours!


----------



## thelion

Amazing work that you guys have done! This sounds like a very interesting project.
   
  I'm thinking of trying this myself; but I have several questions:
   
  1. Will perfectly circular headphone enclosure work, or is an oval better? Stax uses circles, but they have more holes in the mesh they use.
   
  2. Several of you are making the mesh out of copper.
   
  Suppose I machine aluminum or copper mesh from thick foil with extremely many holes very close together, to extent that the plate is not rigid by itself under stress.
   
  To make it very rigid, suppose that at distant but regular points I braze stamped triangles from steel for instance, with thin bars brazed on top of them them (like a bridge truss structure) across the entire surface: it will look like pyramids made of thin trusses. This will cover very few of the holes, as it will be raised from the mesh plate, and if optimized like in a music hall, it will not cause the sound to bounce around too much theoretically.  
   
  Has anyone tried this sort of thing? That is, joining a rigid support system to the electrically conducive plates while maximizing the number and closeness of holes on the plate without concern for its individual rigidity under stress?
   
  3. Speaking of mylar? Will 2 micron thick mylar that is already metalized work as diaphragm material?
   
  Cheers!
   
   
  Edit: I also don't have time to make the electrostatic amp itself, and would like to buy one. Which one would work best for home-made electrostats, if anyone knows? I have a usb dac, and mostly have been listening to wooden closed dynamic headphones.
   
  I'm mostly interested in making several home-made electro-stats, driver and enclosure, largely because that's what I have tools for making.


----------



## n3rdling

I don't know how small you intend to make the holes, but they shouldn't be smaller than the stator thickness. 
   
  Metalized mylar will work, but the resistance is much, much higher than what most recommend ( ~ 10^6 - 10^9 Ohm/in IIRC).  Current will be higher on the diaphragm and thus metalized Mylar is more prone to flammable arcing than other common solutions.


----------



## n3rdling

Awesome thread btw. 
	

	
	
		
		

		
			





 I've been putting off reading this thread until I had more free time - about halfway through, gonna read the rest tonight.


----------



## spritzer

Metalized mylar is too conductive to work on a constant charge basis.  You can get it to work but distortion will be higher.


----------



## chinsettawong

Hi thelion,
   
  You probably haven't read through the whole thread.  
   
  1.  Yes, the circular shape sounds very nice too.  Actually you can make them in any shape you like.  The most important thing is that they should have sufficient diaphragm area so that they can play full range.  With small diaphragm area, your headphones won't have good bass. 
   
  2.  I always make my stators using copper clad PCBs. They are good and cheap.  I'm sure your method works too.  If you like to try it, just do it, and let us know how it goes.
   
  3.  You can try.  There is a guy that I know making his ESL with metalized diaphragm and he says it sounds very nice.  However, he puts very high series resisters into his bias circuit (a few hundred million ohms).
   
  Wachara C.


----------



## chinsettawong

My New Orpheus is officially done. Thanks to the headband and ear pads from Smart, not only that they sing wonderfully but they are also so comfortable to wear.  This is so far the best pair of headphones that I've made.  
	

	
	
		
		

		
		
	


	



   

   
  As expected, the sound stage is big and the bass impact and efficiency is just right.
   
  I have a pair of SR007 MK2 with me to compare.  My New Orpheus sounds much brighter in comparison.  The sound stage is wider and the sound is a little louder at the same volume level.  I think that they must come from the larger diaphragm area.  However, SR007 MK2 still has just a little better bass. 
   
  Wachara C.


----------



## spritzer

The HE90 is pretty bright and weak in the bass so you might just have nailed it then.  
	

	
	
		
		

		
		
	


	




  What did you for the cable on these?  I like it, very retro Stax.


----------



## chinsettawong

Quote: 





spritzer said:


> The HE90 is pretty bright and weak in the bass so you might just have nailed it then.
> 
> 
> 
> ...


 
   
  Thanks, Birgir!
  I use Koss 950 extension cord.  It's cheap and good.  
	

	
	
		
		

		
		
	


	



   
  I'm sure you like my ear pads too.  They are made thicker at the back just like Stax Omega's.  
	

	
	
		
		

		
		
	


	



   
  It's too bad that I don't have HE-90 to compare right now.  Will report on that when I have a chance to compare.
   
  Wachara C.


----------



## spritzer

Angled earpads are a must have.  
	

	
	
		
		

		
		
	


	




  I must say I attributed the diffused imaging of the HE90 to the flat earpads for all this time but our FrankenSennStax shows it's mostly due to the drivers as these image just fine.


----------



## ForzaPC

Dammit man, you make me want to build my own CNC mill!
   
  Great build!


----------



## peterroumian

me too
   
  wachara, i had an idea for improving the design of the holes. here it is - tell me what do you think. Left is the "original", right i think might improve air flow. it's important that the copper is untouched because if we go deeper it may start to peal


----------



## n3rdling

Keep in mind doing so alters the strength of the electrostatic force and thus decreases efficiency.


----------



## jgazal

I believe copper surface still remains the same.
   
  Nevertheless, the diameter of stator holes is still constrained at the copper face. 
   
  I am afraid the "mouth" you propose may reduce the stator rigidity and that could increase distortion.
   
  Let’s hear from Wachara.


----------



## n3rdling

You're right, I was reading it upside-down.


----------



## peterroumian

Quote: 





jgazal said:


> I believe copper surface still remains the same.
> 
> Nevertheless, the diameter of stator holes is still constrained at the copper face.
> 
> ...


 
   
  i think you are right
   
  it was just an idea - like i said "it might improve SQ"


----------



## chinsettawong

Quote: 





peterroumian said:


> me too
> 
> wachara, i had an idea for improving the design of the holes. here it is - tell me what do you think. Left is the "original", right i think might improve air flow. it's important that the copper is untouched because if we go deeper it may start to peal


 

 Hi Peterroumian,
   
  Thanks for sharing your interesting idea.  I really don't know if the shape can improve anything.  You can try though.
   
  For what I know, the sound from the diaphragm shoots out like a beam.  It goes in a straight line.  Are you suggesting that by making the holes like that the dispersing of sound will improve?  Why would you want to do that?
   
  While we are on this topic, I think there is something that really worth looking into.  As you can notice, the stator of SR007 is partially closed and the open part covered with perforated holes is only 55 mm in diameter out of 78 mm diameter of total copper covered area (active area).  I have been listening to a SR007 MKII against my new Orpheus, and I find that the bass of SR007 is quite punchier.  While mine can go as deep, they just don't sound as punchy as SR007.  I'm not sure if it has anything to do with the stator that is partially closed making the air inside compressed and thus punchier.
   

   
   
   
  Wachara C.


----------



## arnaud

Wachara, I had looked at some point at the stiffening effect on the stator when reducing the perforated diameter (stator flexion is a known issue) but I could not see any significant changes in stator mechanical resonances (I posted in this thread some time ago). So, I now wonder about the increased / more homogeneous force on the non-perforated conductive surface which would improve the transduction.


----------



## n3rdling

Is the 007 the only headphone by Stax with such a large non perforated area?


----------



## spritzer

Nope, SR-001 is mostly solid copper with openings just where the went is at the back and the port into the ear.  The intent is clearly improved control via airdamping to get rid of the dreaded HF etch.


----------



## Tjj226 Angel

Hello,
   
  I recently have been trying to get into stax headphones, but let's just say I am not the greatest at winning auctions. I am however good at DIY stuff, and I would like to put together my own headphones. 
   
  Before I do that though, I need an amp...otherwise what is the point of making electrostats. 
   
  Can someone point me in the direction of a DIY amp for electrostatic headphones? Preferably one that uses tubes?


----------



## jgazal

Quote: 





arnaud said:


> Wachara, I had looked at some point at the stiffening effect on the stator when reducing the perforated diameter (stator flexion is a known issue) but I could not see any significant changes in stator mechanical resonances (I posted in this thread some time ago). So, I now wonder about the increased / more homogeneous force on the non-perforated conductive surface which would improve the transduction.


 
   
  Does a second completely etched PCB glued to the first PCB improve stiffening?
   
  I am imagining both PCB glued to form one stator.
   
  Then the transducer would also have that bigger center hole.
   
  I have drawn it, but not to scale. First the "color code": 
   

 "beige" for etched PCB (inactive stator area);
 "yellow" and "fence texture" for active not perforated and perforate area.
   
  Here it is:
   





   
  Do you think that center hole is prone to flexion?
   
  And here I have another draw from Arnaud idea of different diaphragm masses (in this case three different diaphragms):
   




   
   
  Just in case someone finds a way to produce it, here it is another idea. A rounded perforated stator, which I can't even draw correctly. It also has a center ring for two different diaphragms masses:


----------



## Tjj226 Angel

Here is an idea for you guys. Why not electroplate your PCB in silver. Your headphones will probably be more efficient.


----------



## chinsettawong

It's fun to have you guys comment on new ideas. 
   
  Arnuad, is it possible to do a simulation on the SR007 style stator?  I really wonder if the closed part makes a difference in low frequencies.
   
  Tjj226 Angel, I recommended a simple to build tube amp here: http://www.head-fi.org/t/498292/my-diy-electrostatic-headphones#post_6732478
  The efficiency of the drivers is greatly dependent on the bias voltage.  The bigger size of the driver helps the sound volume too.
   
  Jgazal, I don't think segregating the diaphragm into smaller sections is a good idea.  While the middle circle can indeed produce good treble, the outer bigger circle won't do a good job producing good bass.  Good bass comes from large active area.  By limiting the diaphragm with additional spacers in between might just make the driver becoming a big tweeter.  Well, unless you can make your driver very, very big.  
	

	
	
		
		

		
		
	


	



   
  Happy New Year!
   
  Wachara C.


----------



## Tjj226 Angel

Quote: 





chinsettawong said:


> It's fun to have you guys comment on new ideas.
> 
> Arnuad, is it possible to do a simulation on the SR007 style stator?  I really wonder if the closed part makes a difference in low frequencies.
> 
> ...


 
   
  Yeah, I read that post. But I don't know how to read a circuit map and turn it into a thing. 
	

	
	
		
		

		
		
	


	



   
  I was wondering if there was more of a tutorial with pictures. 
   
  Edit: Or a good guide on how to read circuit maps because all the guides I find aren't all that great.


----------



## jgazal

Quote: 





chinsettawong said:


> It's fun to have you guys comment on new ideas.
> 
> (...)
> 
> ...


 
   
   
  I agree that segregating the diaphragm into three sections is not a good idea. 
   
  I was just brain storming...  
   
  Anyway, I like the first draw most, since it is feasible with your current techniques.
   
  Happy New Year!


----------



## n3rdling

Quote: 





tjj226 angel said:


> Here is an idea for you guys. Why not electroplate your PCB in silver. Your headphones will probably be more efficient.


 
   
  Silver is only like 6% more conductive than copper IIRC.  I don't think it'd be worth the cost difference.


----------



## Salm0n

If stator rigidity is one of the major issues than you could try electroplating a different substrate. The imidiate material that springs to mind is corundum - it's very hard, very rigid, inert and non conductive. I have no idea where you would get it, or how you would machine it, but the rigidity means that you could get thinner stators that flex much less. I imagine that there are other materials out there with similar properties, so you could look at different materials to machine and electroplate. It seems to me that the standard PCB substrate might be one of the major things holding back these designs.


----------



## Tjj226 Angel

Quote: 





n3rdling said:


> Silver is only like 6% more conductive than copper IIRC.  I don't think it'd be worth the cost difference.


 
  ????
   
  Silver plating is only like 20 dollars more? Plus it is 9% more conductive. 
   
  For other projects that need silver plating, I will go down to a independent jewelry store and see if they have scrap silver. Pawn shops work well too. I get like 15 bucks worth of silver. You could also spend a bit more and get silver wire. Make a coil to place your copper drivers in and you are good to go. 
   
  Then silver nitrate is pretty easy to find online. You can get a bottle of the stuff for about 45 bucks, but the container is so big that you are pretty much set for life.  
   
   
  On a separate note, I do not have access to a CNC machine. I have read that people have been having success with drill presses, but what about a plain old dremel tool with a 1mm drill bit and a lot of luck. Any chance that would work?


----------



## Salm0n

Quote: 





tjj226 angel said:


> Plus it is 9% more conductive.


 
   
  5.7% more conductive, if the conductivity figures from Wikipedia are accurate.
  EDIT: or 8.6% if you're comparing to IACS. I think the first is more accurate compared to the copper used in these headphones.


----------



## Tjj226 Angel

Quote: 





salm0n said:


> 5.7% more conductive, if the conductivity figures from Wikipedia are accurate.
> EDIT: or 8.6% if you're comparing to IACS. I think the first is more accurate compared to the copper used in these headphones.


 
  Yeah, my chem teacher I guess wrote down the figures wrong on the board. I went back to look for other metals and I saw that chart.


----------



## arnaud

Quote: 





salm0n said:


> If stator rigidity is one of the major issues than you could try electroplating a different substrate. The imidiate material that springs to mind is corundum - it's very hard, very rigid, inert and non conductive. I have no idea where you would get it, or how you would machine it, but the rigidity means that you could get thinner stators that flex much less. I imagine that there are other materials out there with similar properties, so you could look at different materials to machine and electroplate. It seems to me that the standard PCB substrate might be one of the major things holding back these designs.


 
   
  The SR-009 is made of 3 layers that are "fused" together under high temperature and pressure. The main perforated surface is thin but it is stiffened by ribs that are significantly thicker. It's interesting to note though that you then get less viscous damping from the perforations so this can cause an issue with too little damping from the diaphragm (thin air layer damping is critical in this application because mylar resonances in the mid/highs are not particularly pleasant to hear I believe .


----------



## Tjj226 Angel

@chinsettwong: I noticed your friends attempt at electrostatic headphones. They look cheap and right up my alley. Obviously they work, and they don't sound bad, but in your opinion, how well do they work/sound. Is it worth the effort to make a cheap test pair? Or should I just go for the gold and build a full scale electrostatic headphone.


----------



## jgazal

PCB's are usually made with glass-reinforced epoxy laminate sheets, also known as FR-4, which seems to have reasonable strength. Wachara or Spritzer can confirm that, but I think one of them once posted that SR-007 stator is also an etched PCB.
   
  Although we can find non-metallic materials with better strength (glass, diamond, graphene...), it seems to me that they are still not very suitable when we want to mass produce an electrostatic stator. 
   
  Pure metal (titanium) or metal alloys (for instance maraging steel, CO-CR etc) vary in strength and production process. I for one would love to know which metal alloy is used in the SR-009 stator. The metal alloy Stax uses might be suitable for mass production, but unless someone show up with a "poor man" process, they are not very suitable for DIY.
   
  For that purpose (DIY), FR-4 PCB's seem to be the most convenient material available (which does not mean the best material available…).


----------



## Salm0n

Quote: 





arnaud said:


> The SR-009 is made of 3 layers that are "fused" together under high temperature and pressure. The main perforated surface is thin but it is stiffened by ribs that are significantly thicker. It's interesting to note though that you then get less viscous damping from the perforations so this can cause an issue with too little damping from the diaphragm (thin air layer damping is critical in this application because mylar resonances in the mid/highs are not particularly pleasant to hear I believe .


 
   
  I'm slightly confused by this reply. Do you mean that a thinner perforated surface provides less 'resistance' (not sure what the correct term would be) to the flow of air, thus reducing acoustic damping on the diaphragm, leading to an underdamped diaphragm with harsh high frequency resonance? That's what I think you're saying, correct me if I'm wrong.
  Given that the SR-009 uses (at least this is what I took from your comment, once again correct me if I'm wrong) standard PCBs that are fused, the use of a material such as corundum may be senseless overkill. However, I still think that for small scale production, where quality over all else is most important, that using different materials would at least be worth some experimentation.
   
   
  Quote: 





jgazal said:


> PCB's are usually made with glass-reinforced epoxy laminate sheets, also known as FR-4, which seems to have reasonable strength. Wachara or Spritzer can confirm that, but I think one of them once posted that SR-007 stator is also an etched PCB.
> 
> Although we can find non-metallic materials with better strength (glass, diamond, graphene...), it seems to me that they are still not very suitable when we want to mass produce an electrostatic stator.
> 
> ...


 
   
  Thanks for the info on PCBs. Just a side note, the strength isn't all that important, it's the rigidity that counts here. tht's assuming I understand the issue correctly.
  What I'm thinking about is a pipe dream of what would be the best possible. When I find something new that interests me I almost always think immediately of what ridiculous ways it could be improved. For instance, when I first saw a carbon fibre dynamic driver I thought about doing the same with a tri-axial CNT weave, something that would be hideously expensive if even possible with todays technology.
  So, while PCBs seem to be very good when properly implemented it's still possible that there is something better. I might not be easy for either mass production or DIY, but I'm just thinking out loud here. I find that thinking out loud means that you only have to come up with half an idea - others who are more experienced, knoledgable, or who are just thinking the right way at the time are able to either finish off the idea into something useful, or explain why it's stupid before too much time is wasted on it.
   
  I freely admit that I likely don't know enough about electrostatic drivers to contribute anything that is of significant help, which is why I have thus far read and learned, rather than posted and cluttered, on this thread. I simply saw a number of posts discussing how stator flexion caused distortion and added my $0.02.
  Throwing out another off the cuff idea, if a pure metal stator will work (ie one that is conductive in it's entirety rather than just a film on the surface) than BeCu would have the right mix of mecanical and electrical properties for the job. Again, it's expensive and difficult to source and difficult to work with. just a thought.


----------



## chinsettawong

Before we all get confused, I must say that there is nothing wrong with using PCB to make your stators. As I see it, it's strong enough for this application. Stax use it with their SR007, and SR007 is considered one of the best electrostatic headphones that is out there.

It's not the first time that Stax is using some reinforcement with their SR009's stator. The original SR Omega also has the similar backing for their wire mesh stators. It's simply for the purpose of making the stator strong and to avoid ringing in certain frequencies.

While the stators need to be conductive, we are better off to lightly insulate their conductive surface. With a very high diaphragm tension, high bias voltage, and a small air gap between the stators and the diaphragm, it's much better for your driver to operate more reliably by coating the stators with some plastic paint for insulation. For those who do not know about how the electrostatic driver operates, it might sound strange. But it's not the conductivity on the stators that matter much for efficiency. It's rather the bias voltage and air gap that really play important roles.

The good reasons for using PCB for making stators IMO are:

1. PCB is strong.
2. PCB is very flat.
3. The fiber glass side of the PCB is a good insulator. You want 100 percent sure that your ears won't be shocked by electricity. 
4. It's cheap and easy to drill.

Wachara C.


----------



## Nemeske88

After reading the entire topic, I am just curious how your tools are made that made your DIY tools that made your DIY CNC that made your DIY Electrostats spacers.......


----------



## chinsettawong

nemeske88 said:


> After reading the entire topic, I am just curious how your tools are made that made your DIY tools that made your DIY CNC that made your DIY Electrostats spacers.......:bigsmile_face:




LoL. All that you need is the will to do.

Wachara C.


----------



## SmittyHalibut

Quote: 





tjj226 angel said:


> Yeah, I read that post. But I don't know how to read a circuit map and turn it into a thing.
> 
> 
> 
> ...


 
   
  I'm considering building an ES amp kit loosely based on the ciruit in this thread.  Rather than assembling the amp Dead Bug style, where you wire components point-to-point between the tube socket terminals and other stand-offs, I'd make a board that you could just populate with components and put in a box.  I'm borrowing a set of SR-5s from a friend and the frequency response through the converter box really isn't very good for the majority of what I listen to.  I'm hoping that driving them directly without those huge inductors in series with the audio, would make it sound better.
   
  As a SWAG, I'm guessing it would be in the range of $300 to $500 in parts (more of a WAG than a SWAG, I confess)  Is that something that would interest you?  Would anyone else be interested in such an ES amp kit?


----------



## SmittyHalibut

Quote: 





chinsettawong said:


> Based on the design from www.tubecad.com, I draw up a more detail schematic for the amp:
> 
> 
> 
> ...


 
   
  What modifications have you made to this circuit (if any), Wachara?  Are your phones still operating with the (220vRMS * 1.7vPtP/1vRMS * 2 (full wave)) = 748vDC BIAS?  I notice you don't have any DC blocking caps on the inputs, is that still the case?
   
  Do you know if anyone has already made a kit for an ES direct drive amp like this one?  I'm not in it for the money, I just want the amp and it's cheaper to make circuit boards in quantity than one offs.


----------



## chinsettawong

Hi,
   
  I haven't made any changes to the circuit.  But the bias voltage isn't as high as you calculated, I think.  I calculate out to be around (220 x 1.414 x 2) 622vDC.  
   
  There was a group buy a while back on KGSSHV PCB.  I think it is a very good and easy to build amp.  You might want to contact Lilknight to see if he still has some left.
   
  Here are a few pictures of my KGSSHV that I just finished building recently.  I really like it.


----------



## arnaud

Wachara, this looks so cool!


----------



## SmittyHalibut

That does look very nice.  I've been chatting with Lil'Knight in DM.  Turns out, he's out of the boards but has more on order.  They'll be delivered in a couple weeks he said.  I looked at the low-end build cost and decided it out of my price range right now.  (yes, I know, I'm in the wrong hobby if that's out of my range...  
	

	
	
		
		

		
			





 )  I'll spend a bit of time putting together a board for the tube design you posted here and see what that would cost.


----------



## chinsettawong

If you really want to go with the tube amp, you can just hard wire the circuit together.  I didn't use a PCB either.
   
  Oh, about KGSSHV, if you want to build a cheap version, you can really make it without the voltage regulator.  I'm sure it'll sound very nice too. However, I'm not sure if Dr. Gilmore and Spritzer will agree with me on that.  
	

	
	
		
		

		
		
	


	



   
  Wachara C.


----------



## Kuba4

Second pair DIY electrostats by AmarokCZ


----------



## chinsettawong

The headphones look really nice. Congratulations!

Wachara C.


----------



## spritzer

Quote: 





smittyhalibut said:


> What modifications have you made to this circuit (if any), Wachara?  Are your phones still operating with the (220vRMS * 1.7vPtP/1vRMS * 2 (full wave)) = 748vDC BIAS?  I notice you don't have any DC blocking caps on the inputs, is that still the case?
> 
> Do you know if anyone has already made a kit for an ES direct drive amp like this one?  I'm not in it for the money, I just want the amp and it's cheaper to make circuit boards in quantity than one offs.


 
   
  No DC blocking caps needed on the input as the two stages are AC coupled.  A couple of changes I'd make for anything more than a dirt cheap build is to add a trim in series with the 5965 cathode resistor to null out DC offset and you can also add some low value trims on each of the front end cathodes before they are joined up to adjust the front end balance.  100r should be plenty for that role. 
   
  I could also regulate the PSU which is well worth it.  Simple resistor-pass transistor-zener string is more than sufficient. 
   
  Quote: 





chinsettawong said:


> If you really want to go with the tube amp, you can just hard wire the circuit together.  I didn't use a PCB either.
> 
> Oh, about KGSSHV, if you want to build a cheap version, you can really make it without the voltage regulator.  I'm sure it'll sound very nice too. However, I'm not sure if Dr. Gilmore and Spritzer will agree with me on that.
> 
> ...


 
   
  I'd never build anything full size that isn't regulated (or some odd vintage tube design) but the main reason to regulate is to make sure the parts aren't operated past their limits.  Even Stax put a regulated PSU in the SRM-300 as the parts are used right on the limit.


----------



## FrankCooter

Quote: 





chinsettawong said:


> Hi,
> 
> I haven't made any changes to the circuit.  But the bias voltage isn't as high as you calculated, I think.  I calculate out to be around (220 x 1.414 x 2) 622vDC.
> 
> ...


 

 Great casework Wachara! Very clean and understated, yet elegant at the same time. A difficult combination to pull off. Really, really nice!


----------



## SmittyHalibut

I was considering trimmers on the plate resistors, but I confess I'm still learning tube circuit analysis. Trimmers on the cathodes would allow me to balance the bias, right? Would both be beneficial, or would trimming the plate resistor not accomplish much?


----------



## FrankCooter

Quote: 





smittyhalibut said:


> What modifications have you made to this circuit (if any), Wachara?  Are your phones still operating with the (220vRMS * 1.7vPtP/1vRMS * 2 (full wave)) = 748vDC BIAS?  I notice you don't have any DC blocking caps on the inputs, is that still the case?
> 
> Do you know if anyone has already made a kit for an ES direct drive amp like this one?  I'm not in it for the money, I just want the amp and it's cheaper to make circuit boards in quantity than one offs.


 

 If you dig around, on this and other forums, you'll find that a fair number of simple tube based electrostatic amp designs are out there. Most either originate or have been modernized by Spritzer or Dr. Gilmore. There's also the Egmont, the Exstata, the Stax SRX, and some transformer based designs. A good place to start is the Broskie articles.
   
  Having heard Wachara's headphones, I have the highest respect for his abilities.  Having built a couple of similar amps, there are a few things I did differently that I thought improved the basic design.
   
  First, incorporate all of Spritzer's suggestions about regulation and trimmers.  An amp like this really needs all the help it can get to maintain proper balance and off-set.
   
  I would up the HV rails to at least 350V. 400V is even better.   I would change the plate resistors on the output tubes to IXYS10m90 based CCS.  Output tubes would be changed to an ECC99 to better handle the increased plate voltage and allow for increased plate current, which will improve slew rate.  I'd eliminate the cathode bias on the output tubes in favor of adjustable "fixed" bias.  A 12AX7 has a lot of gain, but to get it reasonably linear, you'll probably require some global feedback. You might want to look at a 12AT7 for the first stage.
   
  If I was going to produce a board run for an amp of this type , I think I'd use the Stax SRX design as a starting point.


----------



## SmittyHalibut

Forgive my ignorance, I'm still learning how to read and design tube circuits.
    
  Quote:


> Originally Posted by *spritzer* /img/forum/go_quote.gif
> 
> A couple of changes I'd make for anything more than a dirt cheap build is to add a trim in series with the 5965 cathode resistor to null out DC offset and you can also add some low value trims on each of the front end cathodes before they are joined up to adjust the front end balance.  100r should be plenty for that role.


 
    
  The trimmer on the 5965 is just a single trimmer in series with the 650 that's there, just to adjust the 650?  As opposed to a trimmer where each side goes to the cathodes and the wiper to the 650 to balance between the two cathodes?  That would create a different current path between the two cathodes and therefore allow a voltage to form across the cathodes.  Is that what you're suggesting?  Or, just making it so I can adjust the precise value of the 650?
   
  Similarly for the 12AX7, you said "low value trims on each of the front end cathodes before they are joined up."  Could I do this with a single 100ohm trimmer split across the 38k as described above?  100 vs 153k is pretty negligible so I wouldn't expect the voltage formed across those two to be very significant.
   
  Quote:


frankcooter said:


> Having built a couple of similar amps, there are a few things I did differently that I thought improved the basic design.
> 
> I would up the HV rails to at least 350V. 400V is even better.   I would change the plate resistors on the output tubes to IXYS10m90 based CCS.  Output tubes would be changed to an ECC99 to better handle the increased plate voltage and allow for increased plate current, which will improve slew rate.  I'd eliminate the cathode bias on the output tubes in favor of adjustable "fixed" bias.  A 12AX7 has a lot of gain, but to get it reasonably linear, you'll probably require some global feedback. You might want to look at a 12AT7 for the first stage.
> If I was going to produce a board run for an amp of this type , I think I'd use the Stax SRX design as a starting point.


 
   
  What are you attempting to do by increasing the HV rail?  Just give me a higher output voltage for the ES 'phones?   Or are you trying to stay closer to the middle of the gain curve to keep it more linear?  Or something else?
   
  When you say "use the Stax SRX design as a starting point," Google returns a ridiculous number of hits for that.  But the one that seems most referenced elsewhere is this: http://www.bonavolta.ch/hobby/en/audio/hdgsta.htm   Is that what you're talking about?


----------



## spritzer

You would use a 500R resistor plus a 500R pot on the cathode and then adjust the output WRT ground.  This removes the DC offset so better driver control. 
   
  Those low value trim pots are just for fine tuning the balance of the tubes so they can be much smaller than the actual circuit values.  See here:
   

   
  The higher rail voltages mean more voltage swing but that also means the amp will be more linear under normal conditions.  More headroom and all that. 
   
  That is indeed the SRX design, you can also look for ESX here on HF for the modified version that Kevin Gilmore and I did back in 2010.


----------



## chinsettawong

Quote: 





frankcooter said:


> Great casework Wachara! Very clean and understated, yet elegant at the same time. A difficult combination to pull off. Really, really nice!


 

 Thanks FrankCooter for your compliments.  I didn't do much on this chassis.  I simply utilized what I had on hand.  
	

	
	
		
		

		
		
	


	



  @SmittyHalibut:  I can't help you much with amp designs.  Please listen to what Spritzer and FrankCooter have to say.  They really know what they're saying.  
	

	
	
		
		

		
		
	


	




  Good luck.
   
  Wachara C.


----------



## 12517

Quote: 





chinsettawong said:


> Hi Gary,
> 
> If you can buy 0.5 mm PCB easily, please use it as the spacer.  It's much better than plastic.
> 
> ...


----------



## chinsettawong

Hi 12517,

Can you at least let us know a little about yourself? Do you have a CNC mill? 

As you can see, I have built so many different versions. Which version would you like to build?

Wachara C.


----------



## 12517

Quote: 





chinsettawong said:


> Hi Khbaur330162
> 
> Thanks for your info.
> 
> ...


 
   
  Quote:


chinsettawong said:


> I'm making a new pair of headphones.  This time I try to make the headphones with as less copper as possible - I etched out all the useless copper.  This helps reduce the capacitance on the headphones and makes them easier to be driven by an amp on high frequencies.  It's still a work in progress, but here are a few pictures:


----------



## chinsettawong

I just want to show you guys just how much weight you have to pull on the diaphragm.  When I tried to glue my diaphragm last week, this was what I did.
   

   
  The Mylar I used was 3 microns.  I used a total of 8 bottles each with 650 ml.  That's about 650 grams on each bottle.  Still the stretch was barely enough.  If I were to do it again, I would probably increase the weight on each bottle to 800 -1,000 grams.
   
  Wachara C.


----------



## Brapp

that's awsome!!
  im' kinda new in diy so im easily impressed but those are awsome!!!


----------



## koikoi

chinsettawong said:


> Hi Spritzer,
> 
> I really enjoy being on this forum.  It's my first time to see so many people using electrostatic headphones.  I'm really excited and looking forward to building more amps for my headphones.
> 
> ...


The design of the amp is just amazing.


----------



## koikoi

chinsettawong said:


> Hi 12517,
> 
> Can you at least let us know a little about yourself? Do you have a CNC mill?
> 
> ...




Dear chinsettawong,
This is a really long post and I have not finish reading the whole post yet. 

I did not see any scheme design of the earphone. According to the information I have learnt from the first 22 pages of this post (this is so far I have read), I draw this picture. Did I understand correctly to your design? 


Thanks. 
koikoi


----------



## chinsettawong

Hi koikoi,
   
  Your understanding is correct.  The only thing that I will add to your drawing is that I glue the dust cover on a 1mm spacer.
   
  I coat only one side of the diaphragm that is the one facing the ear.  The bias voltage now is at 570V which is similar to what Stax is using.
   
  Wachara C.


----------



## koikoi

chinsettawong said:


> Hi koikoi,
> 
> Your understanding is correct.  The only thing that I will add to your drawing is that I glue the dust cover on a 1mm spacer.
> 
> ...



Hi Wachara C,
Thank you very much for the reply! I never expected to get your reply so fast. Everything you shared on the forum helps DIYers like me to save a lot of time and money. 

You coat on the facing-ear side of the diaphragm only, so the 570V bias voltage is only connected to the PCB spacer that contacts the coating side of the diaphragm? 

Do you put glue on the other side at where it contacts the spacer or you glue on both sides? Have you tried to coat on both sides? I guess this may increase the sensitivity of the speaker. Just a guess, I have forgotten everything learnt from electronics courses in school.

I have some more questions, please forgive me, while reading the post, I have got lots of questions. How do you apply the staticide to the diaphragm? Do you spray or use a tool like a brush? How much staticide should be applied on to the diaphragm?

You mentioned previously, the size of diaphragm is important. I am planning to make some pairs portable headphones with smaller diaphragm, eg. Φ=40mm or even smaller like the Stax SR-001. While I reducing size of the diaphragm, what other elements do you think I need to change in order to maintain the SQ in a good level? At least you can give me some directions I can do experiments with. 

These are a lot of questions. I will thank you for your time to reading my post first.

Best wishes,

Koikoi


----------



## koikoi

Following my last post, I have read only about half of the post(22 pages). If you have answered my questions somewhere in the post already, please just tell me to go back to read. I know to keep answering everyone's questions in a long time is a hard work. 

Thanks again for sharing everything. 

Koikoi


----------



## chinsettawong

Hi koikoi,
   
  There have been some experiments done by other DIYers that show no noticable difference between coating one side versus 2 sides.  I didn't bother to try it.
   
  I always glue the diaphragm to only one of the spacers.  The other spacer is used as a charge ring for the diaphragm. 
   
  About the diaphragm size, if you are going to make a pair of full size, over the ears headphones, go for the biggest diaphragm size you can make.  To achieve good low frequency response, you need a large diaphragm area.   Diaphragm diameter of 40 mm won't give you good bass.
   
  I don't know anything about SR-001 type headphones.  I've never listen to them.  
	

	
	
		
		

		
			




   
  Please feel free to ask anything you like.  I don't mind at all.
   
  Wachara C.


----------



## koikoi

Hi Wachara,

Thanks for your good advises. I think it is a safe way to just follow your steps while building my first pair of ESL headphones. 

And, how do you apply the staticide to the diaphragm? Do you spray or use a brush? How much staticide do you apply on to the diaphragm?

Best regards,
Koikoi


----------



## chinsettawong

I put a small drop of Staticide on the diaphragm and wipe it with a sponge.  You only need a very thin coating on the surface. 
   
  Wachara C.


----------



## koikoi

Thanks Wachara. It is very kind of you. I think now I am able to make my own ESL headphones. 
Best wishes,
Koikoi


----------



## chinsettawong

Go for it!  
	

	
	
		
		

		
		
	


	



   
  Wachara C.


----------



## koikoi

Is there anyone has an idea that can I use a 5-pin XLR connector and 2 x 3-pin mini XLR connectors (on the headphone side) to make a custom ESL headphones cable? I am not sure about the breakdown strength between the pins of XLR connectors. They are not designed to carry the 570V high voltage. 

Thanks 
Koikoi


----------



## bidoux

I have been using a 3 pins XLR connector for my mono prototype. Although this is not respecting the XLR's datasheet I am not sure it is an actual issue. On a related thought, as anyone found male stax plug ? I still have the female sockets Franck Cooter gave away but can't match it yet ...


----------



## spritzer

Allied Electronics have the male plugs. 
   
  http://www.alliedelec.com/search/productdetail.aspx?SKU=70144660


----------



## bidoux

Thanks Spritzer
  Though it seems that this connector needs to be inserted in some sort of housing to make it usable. Maybe a XLR shell ?


----------



## KimLaroux

Are the XLR connectors even rated for such high voltages? It seems a bit dangerous to me.


----------



## bidoux

The setup I'm describing is only temporary. If think it would be clearer as to why I am no too worried about the xrl connectors if you saw it entirely 
	

	
	
		
		

		
			





 Eventually I want to build something that looks as much as possible like a pair of headphones, that is why I'm looking for the original stax male plug.
   
  If you glance at chinsettawong first diy headphones, you will se that the cable and plug he is using aren't really recommended either (this is how i interpret the picture anyway).


----------



## koikoi

bidoux said:


> I have been using a 3 pins XLR connector for my mono prototype. Although this is not respecting the XLR's datasheet I am not sure it is an actual issue. On a related thought, as anyone found male stax plug ? I still have the female sockets Franck Cooter gave away but can't match it yet ...


i have two solutions.

1. To buy a Stax extension cable. Cut off the female plug at one end-- this can be your headphone jack on your DIY ES amp. Then you get one Stax headphone cable with a male plug. You can make it to your headphone cable.

2. Use the air plugs. Air plugs (I am not sure if there is a more proper name in English for them) are originally used in aircrafts. They are designed to carry very high voltage (400V?) which is much safer than the XLR connectors.


----------



## koikoi

Air plug is something like this. What do you call it?
http://bestdragon.en.made-in-china.com/product/IBEnwhSVYQWx/China-Air-Plugs.html

If you are making a DIY headphone and amp, and do not require them to be compatible with the Stax headphones, the air plug may be a good choice for your cable and amp.


----------



## KimLaroux

These don't really have a technical name. In America, their generic name is "CB microphone connector".
   
  And from the experience I have with those, I highly doubt they are better than XLR. There may have been high quality ones at some point that were rated for 400 V, but the cheap ones available today probably aren't.


----------



## spritzer

Quote: 





bidoux said:


> Thanks Spritzer
> Though it seems that this connector needs to be inserted in some sort of housing to make it usable. Maybe a XLR shell ?


 
   
  That's exactly what I do.  You need to cut off the "lip" on the back for it to fit inside the XLR shell.  Here is a pic of a ESP950 adapter I made:


----------



## koikoi

kimlaroux said:


> These don't really have a technical name. In America, their generic name is "CB microphone connector".
> 
> And from the experience I have with those, I highly doubt they are better than XLR. There may have been high quality ones at some point that were rated for 400 V, but the cheap ones available today probably aren't.


I think those plugs are widely used in occasions that need highly secure connections. 

e.g. I found these ones with rated current 25A and rated voltage 500V. They are definitely not for "microphone connectors". and they are not expensive at all. 



In terms of sound quality, I think the XLR connectors may be better. There must be some XLR connectors with high rated voltage, If I can find, I will use XLR connectors.


----------



## chinsettawong

When I started making my headphones, I used only materials which could be bought easily locally.  The cable was ordinary paired cable and the jack was a cheap 5 pin DIN jack.  Surprisingly, they worked without problem.  
   
  Nowadays, I use the extention cord from KOSS.  It's good and cheap.  
	

	
	
		
		

		
		
	


	



   
  Wachara C.


----------



## chinsettawong

For connectors, something like these work fine too:
   

   
  Wachara C.


----------



## spritzer

Yup, many manufacturers used DIN plugs for electrostatic models.  All low bias though.


----------



## koikoi

Hi Spritzer and everyone,
  Do you guys have any idea why all ES headphones are with parallels cables not twisted ones? Is it because to avoid interference brought by the bias voltage wire?
   
  I am about to make my own ES headphone cable and found that it is difficult to find parallels cables. The only thing I found is the Nordost flat cables. But the Nordost cables are not soft enough to make headphone cables.
   
  Thanks,
   
  koikoi


----------



## livewire

Only use Stax or Koss cables. The Koss extension cable is the cheapest, around $10 from the factory.
  Stax cables can be found on ebay, but are not cheap.
   
  Electrostatic cables are double insulated (with the correct materials) to withstand the high voltage,
  the conductor spacing is designed to maintain low impedance and low capacitance.
  Very important parameters when one considers the electrical load an electrostatic headphone represents. 
  Any old cable isn't going to do the job.


----------



## koikoi

Hi livewire,
Do you know where can I find the $10 Koss cable? I googled a lot but cannot find anything on the internet. 
Thanks,
koikoi


----------



## livewire

At Koss of course.
  Call their customer service at 1-800-USA-KOSS,
  Ask for a replacement "extension cable" for a ESP-950 headphone.


----------



## koikoi

Hi livewire,
Thanks. I am not in US, but I will try with local Koss branch.


----------



## bidoux

I also sent a message to Koss regarding this matter.

 Now I want to build a tube amp for my stats (the eXStata does its job, but you see, it doesn't glow softly red in the dark 
	

	
	
		
		

		
			





 ). I have the egmont clone in mind (the schematic can be seen on the 7th post of this thread) for which the 6S4A are on their way. I have a small question regarding the power supply. The transformers I am ordering are custom and it really doesn't cost more to go with 25VA, 35VA or even 40VA rather than 16VA. I thought it could be something like this :

 2*250VAC for a current of :
                       - 5mA per 6AS4  at idle
                       - 1mA per 12AX7 at idle

 1) 16 VA  (using 7mA for each  6AS4 and 2mA for each 12AX7 )
   
  or

 2) 25 VA ( using 10mA for each 6AS4 and 5mA par 12AX7)

 (I also have to mind the size of the transformer though)
   
  Also regarding the power supply, I understood I needed to separate the heater supply of the 12AX7 from the 6S4A. Are two windings enough ? I mean, feeding the four 6S4As with the same heater winding isn't a problem ?


----------



## spritzer

I always over spec by at least 1.5 and for something like this I'd go double. 
   
  I would also not use the 6S4A in that circuit as it is, they need different plate resistors.  The circuit could also use some extra gain and adding feedback is a good idea.  Not much you can do about the gain and adding feedback kills some of it. 
   
  You need two windings, one for the front end and another one for the ouput tubes.  Since the amp is run off a bipolar PSU the tubes are way over their cathode-filament limit. 
   
  Personally I'd not build this as an Egmont but rather build a scaled down version of the ESX.  You need another pair of tubes but not a whole lot of extra parts.  You also need a simple 40V DC supply which is left floating on top of the -350V supply to properly bias the amp.


----------



## bidoux

Hello spritzer
   
  Thank you very much for your input. I am definitly following your recommendations for the transformer
   
  I followed the link in your signature. The schematic is not much more complicated, but the power supply gets bigger. Casing will also be a pain. I think I will be satisfied by building a small but working amp (and I have no high end phones that require more). The bigger things might come later ...
   
  Do you think i should try to use a pair of 7n7 (they are cheaper than the 6AS4 
	

	
	
		
		

		
		
	


	




 ) instead of the 6AS4 ? I think you have both versions, that is why i'm asking. As for the feedback, two 60k resistors from plate to cathode as done on tubecad is correct ?


----------



## spritzer

I've had signatures turned off for so long I forgot about the link...  
	

	
	
		
		

		
		
	


	




  The PSU only gets a bit bigger, one extra tap to feed a small PSU attached to the - side of the HV supply.  It's a far better amp though... 
   
  The 7N7 can't handle as much voltage and power as the 6S4A but it is a nice tube.  Same goes for the 5968 Tubecad used in his amp.  I had a PCB made for that version of the amp back in the day. 
   
  I used 200K and a 1uf/630V cap for the feedback line, plate of the 6S4 to cathode of ECC83.


----------



## bidoux

You are tempting me and that is no good 
	

	
	
		
		

		
		
	


	




 I am not sure I will have the time, money or skills to build something like a ES1/2 ... I am a bit puzzled by this ...
   
  I see you used the old bh supply. Are there equivalents to for the 2SA1968 ? It seems that these are long gone ...


----------



## dude_500

You can use any PNP in that spot as long as it has sufficient breakdown, and enough gain.
   
  Breakdown doesn't actually need to be the full input voltage, just Vin - Vout (although it should have quite a bit of headroom in this position). I use a 375V PNP in my BH supply and have never had problems with it.
   
  The gain needs to be high enough so that the base current is low enough as to not starve the LED of bias current through the 200K resistor.


----------



## spritzer

We've modified the PSU to use 10M90's a while back.  It just acts as a CCS for the pass fet and the 10M90 is ideal for this role. 
   
  The A1968's aren't gone, it's just that KG and I have half the world supply... 
	

	
	
		
		

		
		
	


	



   
  You can use what ever PSU you want though.  I just used the BH supply since it was the only one that fit the odd Single Hour box. I have a mini ESX that I will be casing up sometime soon and it will probably use some very simple PSU.


----------



## bidoux

It was the stax mafia all along depleting the transistors ... Knew it 
	

	
	
		
		

		
		
	


	



  Thank you both. If I carry on one project or the other I will certainly have more questions, but I will make sure to post in the right topic  ...
   
  To catch up with the original subject, I am trying another small cell experiment. The first one didn't have big enough holes seeing how tchick the pcb actually is. I also reduced the spacer thickness to 0,4mm. Still need to drill the second stator though.


----------



## spritzer

Somebody has too keep these transistors...  
	

	
	
		
		

		
		
	


	



   
  If you haven't got your heart set on tubes then we have made a new version of the KGSSHV with transistors in current production.  As it stands now you can buy everything for the amp from Mouser minus transformer and PCB.


----------



## AmarokCZ

*spritzer*: what's your opinion on STAX SRM-006t (the old one - now discontinued)? I had it borrowed for few months and I compared to my amp (JFET-MOSFET: see signature) and I was quite dissapointed how bad the SRM-006 sounded.


----------



## spritzer

It's the same as the SRM-T1 and all the other Stax tube amps.  Good circuit hampered by the costs of building amps such as these and the parts available.  The tubes are the worst culprit as they are asked to operate at 700V which is far above their comfort zone.  Then we have the PSU and how the tubes are used.  Take the same circuit with some 6S4A's with CCS and a good PSU and it is a very nice amp indeed.


----------



## chinsettawong

I would highly recommend KGSSHV.  It's easy to build and sounding very nice.  
	

	
	
		
		

		
		
	


	



   
  Wachara C.


----------



## dude_500

Has anyone ever actually tried to make an SR009 style diaphragm? I'm finishing up the design work on my next pair of headphones and got the idea that maybe this could be done, at least to limited extent, in a DIY manner.
   
  Something like the following:
   
   

   
  The two characteristic thicknesses would have to be dependent on material. I'm thinking for FR4, might be able to use 1.6mm stock and mill the openings down to maybe 0.4 or even a bit thinner. Stainless could of course go a lot thinner, but manufacturing would be harder.


----------



## AmarokCZ

What should be the effect of this "reinforced" stator? Lower distortion?


----------



## dude_500

Quote: 





amarokcz said:


> What should be the effect of this "reinforced" stator? Lower distortion?


 
   
  The goal is to have the majority of it be very thin. To be honest, I don't know all the technical acoustic reasons, but I've read all over the place and in this thread that the SR009 gets a lot of its benefit over the SR007 by having the stators be extremely thin.


----------



## spritzer

I think the the effect of the stators is greatly overestimated on the 009.  They are the reason why the 009's are so expensive so they must be the reason they sound so.... well odd.  The diaphragm is the largest contributor to this though.  Change just the tension slightly and the whole character of the drivers changes completely.
   
  The goal of the SR-009 stators is the same as the SR-Omega units, provide the maximum open area possible from a highly stable/strong platform.  The SR-Omega did succeed in this regard but they did cost a fortune to produce and the rejection rate was high.  The resin Stax used as a support for the mesh also has some issues such as it's a bad conductor of heat and the drivers must be kept cold at all times.  Contrary to some people electrostatics do need to dissipate a bit of power and thermal expansion at these tolerances is a big no, no.  The SR-Omegas main problem was with the housing though, metal screws into plastic are never a great idea and that bias connector...


----------



## AmarokCZ

I also read it "all over the place", but nobody ever supported it by something that would make sense. IMHO I think that differences between those two are "hidden" elsewhere.


----------



## arnaud

Only thing I can say is that, theoretically, a thinner stator assembly would add less damping to the diaphragm (viscous damping occurs in the thin DS gap and going through perforated holes in the stator). On the other hand, there clearly are mechanical resonances in the stator that should be avoided (the stator gets the same electrostatic force as the diaphragm), hence the requirement to use rib stiffeners in case the main surface is too thin to provide its own rigidity (which is the case of the 009 afaik from the stax interviews in japanese).

Having said that, as spritzer mentioned, the diaphragm material, thickness and tensioning are just as if not more critical to the voicing so who knows which is the main driving factor for what the 009 sounds like. Stax certainly mentioned you couldn't achieve the low distortion they got with the 009 without going the expensive route they went (the electrode remains expensive and painful to manufacture, even 2 years down the road).


----------



## chinsettawong

I'm not sure if you can get any benefit of having very thin stators.  Open up more open area, on the other hand, does make a difference, IMO.  
   
  Wachara C.


----------



## dude_500

It looks like its very practical to get these manufactured in small quantities in stainless. I uploaded the design of the picture I posted to mfg.com, and the best quote I have so far is only $45 per stator, with 1mm overall thickness and 0.1mm thickness in thin areas.
   
  I'd of course change the design quite a bit if ordering it in stainless, but it might be worth trying. I wonder what quality it'd come like. Only tolerance I gave was 0.05mm flatness to make it better than 10% the DS spacing.


----------



## chinsettawong

Why do you need the stator to be so thin?  
	

	
	
		
		

		
		
	


	



   
  I can cut the stator out of 0.1 mm copper sheet and glue it to a 1 mm fiberglass frame.  But I really don't see an advantage of that.


----------



## dude_500

Quote: 





chinsettawong said:


> Why do you need the stator to be so thin?
> 
> 
> 
> ...


 
  For no reason other than to see if the world is right that the thinness of the SR009 contributes to its sound quality/sound signature. It sounds like the view of this thread is that its not.


----------



## chinsettawong

I don't think so too.  The brightness of sound comes mainly from the minimal of capacitance of the drivers.  Some people like the sound, but some people don't.


----------



## AmarokCZ

Quote: 





chinsettawong said:


> I don't think so too.  The brightness of sound comes mainly from the minimal of capacitance of the drivers.  Some people like the sound, but some people don't.


 
  It's not simple as that. The electrostats I made for Kuba4 (picture somewhere in this thread) are quite dark, my old SR-3 are bright compared to them, but capacitance of SR-3 driver is larger than that DIY.
  Also when I was experimenting a was able to create dark or bright sound with the same driver - only change was enclosure/earcup.


----------



## chinsettawong

Quote: 





amarokcz said:


> It's not simple as that. The electrostats I made for Kuba4 (picture somewhere in this thread) are quite dark, my old SR-3 are bright compared to them, but capacitance of SR-3 driver is larger than that DIY.
> Also when I was experimenting a was able to create dark or bright sound with the same driver - only change was enclosure/earcup.


 

 I've done several pairs of headphones, and I know for sure that it's mostly from the capacitance.  Well, the diaphragm material can somewhat affect too, but not as much as the capacitance.
   
  Did you etch out the unneeded copper on your stators?  Have you compared the copper area on your DIY phones with SR-3?  How about open areas of the two?
   
  P.S. If you cover the back side of your enclosure, the sound can also get brighter.


----------



## AmarokCZ

I also done more than one pair and lots of experimenting and from what I can tell the most influental is the earcup. 
   
  Yes, I etched copper on stators (copper left only around area with holes) and it still sounded dark (it's not HD650 dark, but it surely isn't SR-404 bright-star). On the other hand the SR-3 stators are brass (so no etching and hence high capacity) and they sound bright...


----------



## arnaud

The distance from the electrode to the ear, size of the earcup and especially the properties of the earpad all effect the response (the acoustic resonances in the earcup definitely can't be ignored, nor the absorption of the pad. The pad shape and properties affect the low frequency extension (as it is determined by a coupled pad/earcup cavity/tensioned diaphragm resonance).

 So to me, nothing is simple in headphone world and estat in particular .


----------



## wakibaki

Made a 'best offer' bid on a Chinese 3020 CNC mill, so I guess I'll be making some stators and diaphragm supports, as I intend to get one of these mills, I'm just trying to get the best price.
   
  I was going to make these parts by hand, I've got a scroll saw and a bench drill press, but the milled parts look so good.
   
  Mylar is in the post.
   
  I've also got some fine stainless steel gauze that I bought, it looks like a piece cut from some grey tights, I've been thinking about some way of making a support for it that will hold it rigid.
   
  I never really thought that I'd have a pair of electrostatics, but I recently took an interest in designing an amp over in this thread, http://www.head-fi.org/t/655489/dirt-cheap-stax-amp-diy-new-schematic-updated.Perhaps buying a mill is a bit extravagant, I can't see me buying a pair of Stax phones, but the mill will get use making enclosures and PCBs so that's how I justified it to myself.
   
  What I'd like to know is can anybody recommend a pair of phones to cannibalize to put these electrostatic capsules into? I've got a pair of cheap Behringer studio phones here I'm eyeing up, but I can't see how to get them apart, and anyway they're closed back, which I don't think is what's required. Perhaps somebody could comment on that.
   
  Anyway, still waiting to see if this guy will accept my offer.
   
  Thanks Wachara, I wouldn't have got into this without your thread.
   
  w


----------



## bidoux

Maybe a cheap DT880 clone ? something like a Superlux HD-330 ? No idea if it would work alright.

 But if you do get the CNC you could build everything from scratch


----------



## chinsettawong

Quote: 





wakibaki said:


> Made a 'best offer' bid on a Chinese 3020 CNC mill, so I guess I'll be making some stators and diaphragm supports, as I intend to get one of these mills, I'm just trying to get the best price.
> 
> I was going to make these parts by hand, I've got a scroll saw and a bench drill press, but the milled parts look so good.
> 
> ...


 
  Congratulations on your purchase of the CNC mill.  I hope you'll enjoy making your own headphones like I do.  In fact with the CNC mill, you can also make your own enclosures.  
	

	
	
		
		

		
		
	


	



   
Wachara C.


----------



## wakibaki

Quote: 





bidoux said:


> Maybe a cheap DT880 clone ? something like a Superlux HD-330 ? No idea if it would work alright.
> 
> But if you do get the CNC you could build everything from scratch


 
   
  Hadn't thought of that...
   
  The Superlux look like they might be a good bet though.
   
  w


----------



## spritzer

I'd be worried about that band in the middle of the earcups.  Backwave reflection is a pain and does a lot of harm.


----------



## wakibaki

So an open back is essential? That's something I wondered about, but never having had my hands on any electrostatics, I just didn't know, and nobody has said explicitly in the thread (I think). I've read most of it, but skimmed a few pages.
   
  Maybe the phones would survive having the band cut off. Or maybe a layer of absorbent material stuck on. Sheepskin? They look useful for the price.
   
  w


----------



## spritzer

Electrostatics are true dipoles so equal radiation front and back.  If anything reflects the backwave towards the front then there are numerous issues.  That is not to say it can't be done but the only good closed electrostatic is the Stax 4070.  There they used a clever bass reflex system to minimize the effect plus the neat chassis design.  Koss went a different route, they grounded the back stator or drove it at a diminished level to minimize the backwave.  Essentially single ended but the effect is minimized with the grounded back stator.


----------



## wakibaki

Interesting. I wonder what happens if you don't perforate the rear stator, except for a small hole to allow equalization of atmospheric pressure, like an acoustic suspension speaker. Half a millimeter is a wavelength at 640.58kHz. Or a delay of 1.5 uSec. Something to try when I get moving with this. 
   
  First CNC guy came back with a counteroffer 1.5% down on original price, second place I tried still hasn't responded to my best offer. At this rate I might as well pay the full asking price.


----------



## AmarokCZ

Do you hate bass and mids? No? ...then don't even try it.


----------



## arnaud

Acoustic reflections occur with both an open and close back design (against popular belief) but the reflections are much worse in case of a closed back / affecting all frequencies and need to be handled by some acoustic sound absorbers.

In estat, there's another implication: the acoustic load the configuration presents to the diaphragm. A quasi non-perforated rear stator would certainly do something, not sure it'd be of any advantage though...

And another implication: the damping of the diaphragm motion through viscous effects in the DS gap / through the perforations / through the nearby felt or foam. Arguably, the foam/felt being the most influencial on the damping, with a closed back stator you'd loose the opportunity to damp the diaphragm from the rear stator.

About the delay for reflections, you should also consider those from the pinna.


----------



## chinsettawong

Quote: 





amarokcz said:


> Do you hate bass and mids? No? ...then don't even try it.


----------



## wakibaki

I've never been put off an experiment by the fact that it might produce a negative result. A negative result is still a result.
	

	
	
		
		

		
		
	


	



   
  If you're saying you've _tried_ it...
   
  2u mylar arrived today. I bought the CNC mill.
   
  w


----------



## chinsettawong

Quote: 





wakibaki said:


> If you're saying you've _tried_ it...


 
   
  Oh yes, I have.


----------



## wakibaki

So you must have thought it was a good idea at one time?
   
  w


----------



## spritzer

I've tried it as well.  Not a good idea but it had to be tested.  Same as applying bias to the stators and drive the diaphragm SE, reduced operation on one stator etc. etc. 
   
  Personally I'd just stick with the classic setup.


----------



## chinsettawong

I'm sure W will try it somehow.


----------



## bidoux

I have a question about the type of glue that can be used to attach the diaphragm on the stator. I have been using epoxy glue but it is hard to do something clean. I was thinking of trying super glue, which is more liquid but I am not sure if it is a good idea. Any input ?
   
  Quote:


wakibaki said:


> 2u mylar arrived today. I bought the CNC mill.
> 
> w


 
  I think you will be drilling lots of tiny round holes in the near future 
	

	
	
		
		

		
		
	


	




 Congrats


----------



## chinsettawong

The best glue that I've found so far is contact cement (yellow rubber glue).  
	

	
	
		
		

		
		
	


	



   
  Wachara C.


----------



## bidoux

I saved your picture with the uhu por tube a while back but didn't remember it until now ... Have you tried the two other type of glue I mentionned as well ?


----------



## chinsettawong

I am so very tempted to make a pair of Jacklin Float clone.  What do you guys think?  My guess is that the dimension of the diaphragm is around 12 cm x 10 cm.  Can someone confirm it?
   
  I have some 0.75 mm PCB which I think should be perfect for this.  The bias voltage should be around 1,000V.
   
  To get good bass, I think 3 or 6 microns Mylar should be good.
   
  Wachara C.


----------



## chinsettawong

Quote: 





bidoux said:


> I saved your picture with the uhu por tube a while back but didn't remember it until now ... Have you tried the two other type of glue I mentionned as well ?


 
   
  Yes, I've tried so many different types of glue in the past.  I like contact cement the most.
   
  Wachara C.


----------



## wakibaki

How is the electrical connection to the diaphragm itself made? I was under the impression that the wire went to the copper on the PCB ring.
   
  I have some of this: http://www.ebay.co.uk/itm/CONDUCTIVE-REPAIR-WIRE-GLUE-PAINT-ADHESIVE-NO-SOLDER-FOR-MODS-REPAIRS-/221201404191?pt=UK_Home_Garden_PowerTools_SM&hash=item3380a1911f ...carbon loaded conductive glue.
   
  w


----------



## bidoux

That's funny you ask, I spent half an hour worrying whether I screwed up my last cell, then I realized the diaphragm wasn't electrically connected to the spacer. So I put a tiny amount of solder on the other stator, the one on which the diaphragme isn't glued on, so this blob of solder insure the electrical connection. But I think there are more elegant ways of doing this ...

 I though this new version would improve the sound a lot but I am quite disapointed with it, though it is only a naked cell. It still has this "plastic like" (not sure how to describe it) sound which is not good enough, even my SR30 sound better


----------



## chinsettawong

Quote: 





wakibaki said:


> How is the electrical connection to the diaphragm itself made? I was under the impression that the wire went to the copper on the PCB ring.
> 
> I have some of this: http://www.ebay.co.uk/itm/CONDUCTIVE-REPAIR-WIRE-GLUE-PAINT-ADHESIVE-NO-SOLDER-FOR-MODS-REPAIRS-/221201404191?pt=UK_Home_Garden_PowerTools_SM&hash=item3380a1911f ...carbon loaded conductive glue.
> 
> w


 
   
  Wow, coming this far and I thought you had learned all about how to make electrostatic headphones. 
	

	
	
		
		

		
		
	


	



   
  Anyway, the way I do it is that I glue the diaphragm on one of the spacer and use the other spacer as a charge ring.  Remember, I use PCB to make stators and spacers.  So, it's very easy for me to do that.
   
  These pictures hopefully can give you better understanding of my arrangement.
   

   
   

   
   
  Don't use the conductive glue.  Your glue doesn't need to be conductive.  And it should not be.
   
  Wachara C.


----------



## wakibaki

So you apply the antistatic fluid to one side of the diaphragm only? I would have thought you could double the force on the diaphragm if there is twice as much charge distributed on it...
   
  w


----------



## bidoux

Quote: 





wakibaki said:


> So you apply the antistatic fluid to one side of the diaphragm only? I would have thought you could double the force on the diaphragm if there is twice as much charge distributed on it...
> 
> w


 
  The equation that rules the way the diaphragm moves only considers the difference in voltage thus it is not necessary to double coat the diaphragm.


----------



## wakibaki

Quote: 





bidoux said:


> The equation that rules the way the diaphragm moves only considers the difference in voltage thus it is not necessary to double coat the diaphragm.


 
   
  No, this is not true. The force is proportional to the charge. See Coulomb's law. 
   

   
  w


----------



## bidoux

Well yes but the parameter that you can easily control and impose to the headphone is not the charge, it is the voltage. You have to see an electrostatic speaker as a capacitor, but since the diaphragm is mobile, the capacity is not constant. Once you have imposed the voltage, you can deduce the force applied to the diaphragm by using the law that links the charge and the voltage in a capacitor :




  (v is imposed, q is linked to the position of the diaphragm and the geometry of your cell)


----------



## dude_500

Finished up a new pair of headphones this weekend (with the exception of the top band which needs some work).
   
  Since I had some laying around, they are built with the HD600/650 earpads. They are built with 2uM mylar with 0.5mm spacers. I have them biased at 400V since that's what my amplifier puts out, but I'm sure they could go higher its not even close to instability. Open-air resonance is 175hz.
   
  I'll have to do a lot more listening before I do any real comparisons to my SR007 clones, but upon first impression they seem to be more forward in the midrange (might be hearing the 7khz dip that's always been in my other pair that is not present in these). The soundstage is quite a bit wider than the SR007 clones which is good.
   
   

   
   

   
   
  Some pictures of construction:


----------



## wakibaki

Quote: 





bidoux said:


> Well yes but the parameter that you can easily control and impose to the headphone is not the charge, it is the voltage. You have to see an electrostatic speaker as a capacitor, but since the diaphragm is mobile, the capacity is not constant. Once you have imposed the voltage, you can deduce the force applied to the diaphragm by using the law that links the charge and the voltage in a capacitor :
> 
> 
> 
> ...


 
   
  Yes, a capacitor. The capacitance is dependent on the plate area. If you have charge distributed on both sides of the diaphragm instead of one, you effectively double the plate area. For any given voltage the charge will be doubled. This is why the foils in capacitors are rolled up, to take advantage of both sides of the plates.
   
  w


----------



## chinsettawong

Quote: 





dude_500 said:


> Finished up a new pair of headphones this weekend (with the exception of the top band which needs some work).
> 
> Since I had some laying around, they are built with the HD600/650 earpads. They are built with 2uM mylar with 0.5mm spacers. I have them biased at 400V since that's what my amplifier puts out, but I'm sure they could go higher its not even close to instability. Open-air resonance is 175hz.
> 
> ...


 
   
  Wow, those look awesome!  What is the size of your diaphragm?  Your holes look big and are very close to each other.  I think you must have a very high open area.  Do you like them better than your previous pair?
   
  Congratulations!
   
  Wachara C.


----------



## dude_500

Quote: 





chinsettawong said:


> Wow, those look awesome!  What is the size of your diaphragm?  Your holes look big and are very close to each other.  I think you must have a very high open area.  Do you like them better than your previous pair?
> 
> Congratulations!
> 
> Wachara C.


 
   
  The active area is a 3.225 x 2.2075 oval. The open-area is somewhere around 60%, haven't precisely calculated it. The stators are 1.6mm instead of my typical 1mm in order to keep them plenty rigid.
   
  I don't think I like them better, although not necessarily worse either. I think both will probably remain in my active headphone collection. They are much, much brighter (too much for my taste), but I really love the sound stage which is so far beyond my old pair. I need to experiment with damping foam, as right now they are wide open, which might help a bit to calm the brightness. I'll probably also play with lower tension, since I have a ton of headroom on stability.


----------



## chinsettawong

Quote: 





dude_500 said:


> The active area is a 3.225 x 2.2075 oval. The open-area is somewhere around 60%, haven't precisely calculated it. The stators are 1.6mm instead of my typical 1mm in order to keep them plenty rigid.
> 
> I don't think I like them better, although not necessarily worse either. I think both will probably remain in my active headphone collection. They are much, much brighter (too much for my taste), but I really love the sound stage which is so far beyond my old pair. I need to experiment with damping foam, as right now they are wide open, which might help a bit to calm the brightness. I'll probably also play with lower tension, since I have a ton of headroom on stability.


 
   
  You used to make much larger active diaphragms.  Why do you make them smaller this time?  
   
  With the driver of this size, you won't get much bass and the sound would certainly be brighter - due to less capacitance.  
   
  How muh weight have you put on this time?  If I were you I would increase the bias voltage instead of lowering the tension.
   
  This was how much weight I used with my 3 microns Mylar with active diaphragm size of 78mm x 118mm.  The spacer thickness was 0.5 mm and 580V bias voltage.  The tension was only barely enough.  If I were to to it again, I would use use a few more water bottles or increase the weight of each bottle to around 1 kg (1000 ML).
   

   
   
  Wachara C.


----------



## arnaud

Dude500, looks awesome.

If you can get your hands on some leather pads (and make sure the earpad cavity is well sealed), you might gain in bass region (unless the rolloff is due to your microphone and not an actual illustration of back wave concellation due to transmission through the porous pad). However, whatever you may gain in the LF, you'll get even less sound absorption so the MF/HF response will get even more tilted up. 

The most effective method would probably be the foam layer agaisnt the driver on the ear side. It might quickly get dark sounding (and the soundstage width suffer), but surely it will tame the highs. With the very large diameter perforations, I suspect you get little damping from the thin air layer, which may seem like a good thing at first but end up hearing the diaphragm's resonances.

Awesome DIY stuff though, really enjoying reading you guys updates!


----------



## bidoux

Quote: 





wakibaki said:


> Yes, a capacitor. The capacitance is dependent on the plate area. If you have charge distributed on both sides of the diaphragm instead of one, you effectively double the plate area. For any given voltage the charge will be doubled. This is why the foils in capacitors are rolled up, to take advantage of both sides of the plates.
> 
> w


 
  I have read another time the way you put the diaphragm's movment into equation, and I still don't see how you can account for coating both sides of the diaphragm. The only change it would induce is a better symmetry but that is 5µm of diaphragm thickness regarding to the 500µm of DS spacing, so it is not really an issue.

 The force one stator applies to the diaphragm is F_E1, given by  :   (F_E2 is the force applied by the other stator to the diaphragm)
   

   
  where Σ is the surface of both, e is the distance from stator to diaphragm, U_0 is the bias voltage, u is the drive voltage and x is the distance from the middle between both stators to the position the diaphragme actually is (so it measures the diaphragm position from where it would be if there was no force at all)
   
  Here you have a change in sign because you have two stators so there is a symmetry.
   
  If you sum these two forces and say that the diaphragm is more or less a resilience (which has a certain constant named k), add a force induced by the air friction (which is, in the end, responsible for sound) also given by a constant h you end up with this equation, after simplifying a bit :
   

  M is the mass of the diaphragm. That is the equation I was talking about a few posts earlier, you only have to consider voltages, the charges are hidden underneath 
	

	
	
		
		

		
			




   
  Maybe that explains a bit better why you can't think in terms of charges, it will lead you nowhere. If you read Roger sander's book, you will see he has the same opinion ; that is about double coating the diaphragm, he doesn't explain the equations I have just given, and they are not taken from his book.
   
  (iirc the foil in a cpacitor isn't rolled to take advantage of both sides, only to manage to fit a lot of surface into a given volume but that is not really relevant here)
   
   
  And of course, if you want to try to double coat your diaphragm, go ahead and let us know what you find out


----------



## chinsettawong

Quote: 





bidoux said:


> And of course, if you want to try to double coat your diaphragm, go ahead and let us know what you find out


----------



## dude_500

Quote: 





chinsettawong said:


> You used to make much larger active diaphragms.  Why do you make them smaller this time?
> 
> With the driver of this size, you won't get much bass and the sound would certainly be brighter - due to less capacitance.
> 
> ...


 
  I think I have something like 8-10lbs of total weight on it. Haven't checked the weight of the weights for a while and don't remember precisely what they are. It's the identical weights I used on my 78mm SR007 clone diaphragms. Those operate on the edge of stability, whereas these are far beyond stability (as expected, since the diaphragm is a bit smaller in these new ones).
   
  This is the largest diaphragm the HD600 earpads can support. As seen in this picture, all the area is active (could maybe squeeze in a couple more millimeters, but nothing of any significance):
   

   
   



arnaud said:


> If you can get your hands on some leather pads (and make sure the earpad cavity is well sealed), you might gain in bass region (unless the rolloff is due to your microphone and not an actual illustration of back wave concellation due to transmission through the porous pad). However, whatever you may gain in the LF, you'll get even less sound absorption so the MF/HF response will get even more tilted up.


   


  With summer coming up, one of the major reasons for this build was to have a pair of electrostatic headphones to go to when I just can't take leather anymore. I really dislike leather earpads


----------



## chinsettawong

Let me correct my mistake.  The latest oval shape headphones that I made has 74 mm x 104 mm active diaphragm area.  It's been a while and I forgot.  
	

	
	
		
		

		
		
	


	



   
  I've been doing an extensive listening comparison between my Omega clone and this oval shape one, and I really like the oval shape one better.  Not only that the bass goes deeper, the sound stage is wider with very good treble.  And it's just more relaxing and fun to listen to.
   
  I also compare them with my very first oval shape version.  They have slightly smaller active diaphragm - 70 mm x 100 mm.  Again the oval shape ones are more relax to listen to.  With the spacer of 0.6 mm, they are a little less efficient.  But with a powerful amp such as KGSSHV, they sing out really well.  
   
  So I strongly recommend those who want to make headphones make the oval shape and try for yourselves.  I'm sure one of the reasons why they sound better is that they have bigger diaphragm area.  So, if you can make them even bigger, go for it.
   
  This is the picture of the three headphones I'm talking about:


----------



## spritzer

HD600 pads are a bad choice for planar duty as they leak... a lot.  HE60 pads would be a far better fit and they are the same size.  Here is a HE60 I built from spare parts and a HD650 capsule holder... 
   

   
  Different mounting fixture though.  If you want 100% velour then look into the Hifiman pads as they use a much denser foam to achieve more isolation.  Dirt cheap too...


----------



## Chazman

Hello!
   
  Long time reader (especially as this thread is soooo massive) and all this talk has inspired me to make my own headphones after getting a pair of Koss ESP-6a's and restoring them to their former glory. A number of years ago I was very lucky to be able to try a full Sennheiser HE90 / HEV90 set up and was blown away by them so I am going to base my designs on the basic design of those with Oval drivers in the 100 x 70mm ball park and want to try to use some premium materials in persuit of a great sounding pair of phones!
   
  So I have a couple of questions (and I sincerely apologies if they been asked before but been trying to digest my way through all this amazing information):
   
  - I have access to CNC capability so going to have the cups machined out of wood, was thinking Spruce, Rosewood or Mahogany. Any opinions on these for this purpose?
   
  - After reading details of the HE90's it appears the stators are made with a gold coating, has anyone tried cutting the fibre board and laying gold leaf on it? Any opinions on this? The electronic engineers at my work suggested it might be good due to the low resistance and ability to get quite a lot of material off thus reducing potential capacitance.
   
  - On the gold leaf topic I was wondering if you had the boards cut and then lay the leaf on top and when trimming out the holes cut them a tiny fraction bigger than the holes in the board - theory being it would be like the etching to remove the sharp edges and reduce arcing - crazy / stupid idea?
   
  - I suspect that I may end up going for machining PCB board to make them in the end and a really novice question (mostly for Chinsettawong - You are an inspiration by the way!) when using the PCB as the spacer & connection to the diaphragm do you use 0.5mm board as in your early posts you suggested you used the same type of 1mm board you did for the stators (single sided obviously) but wouldn't that mean there was a 1mm gap to one side and a 0.5mm on the other or am I missing something? On this topic what is the best way - get 0.5mm fibre board for the spacers and put some thin foil type material to get the contact to the diaphragm (sorry know this is a stupid one!)?
   
  Again an inspirational thread and thanks in advance for any assistance!
   
  Chaz


----------



## chinsettawong

Hi Chaz,
   
  If you have access to a CNC machine then go for it.  I'm sure you'll like what you make a lot.
   
  I think any wood is fine.  Just pick the one you like best.  I personally use whatever hardwood I can find here locally.  I really like zebra wood, but can't find them here.  
	

	
	
		
		

		
		
	


	



   
  Don't try to do a gold coating by yourself.  I don't think that you'll get a good result.  Actually making the stator very low resistance doesn't help.  I find it's better to use copper cladded PCB for the stators and coat them with a few very thin layers of Acrylic paint to be the best.  The paint insulates the stator which protects them against rusting and possible short in case some small dusts find their way into between the stator and the diaphragm.
   
  I use 1 mm PCB for my stators and 0.5 mm PCB for my spacers.  The copper sides of the stators are facing each other with two spacers sandwiching the diaphragm in the middle, so the spaces between the diaphragm and the two stators are the same on both side.  Please look at my arrangement from this picture.
   

   
  You want the 2 spacers to be of equal thickness.  So, using a fiberboard as spacers and putting a foil in between isn't a good idea.
   
  Wachara C.


----------



## chinsettawong

By the way, I also did a listening comparison among HE60 and all my DIY headphones.  Unfortunately HE60 just isn't good enough to be in the same league.  It's now back in the box. 
	

	
	
		
		

		
		
	


	



   
  Wachara C.


----------



## wakibaki

Quote: 





bidoux said:


> And of course, if you want to try to double coat your diaphragm, go ahead and let us know what you find out


 
   
  Exactly. Like I intend to try with one stator unperforated.
   
   

   
  CNC machine arrived today.
   
  w


----------



## chinsettawong

What do you guys think of something like these?
   

   

   
   
  With simple enclosure and headband, they could very well be something very similar to the Jacklin Float.  I'm targeting a spacer of 0.75 mm and a bias voltage of 1000V - 1200V.  They should be able to be driven by my KGSSHV and DIY T2.  
	

	
	
		
		

		
		
	


	



   
  By the way, the active area on this design is 100mm x 120mm.
   
  Wachara C.


----------



## Chazman

Wachara,


Thank you very much for the advice!!

I will go for the pcb material idea then (though struggling to find 0.5mm board that isn't pre sensitised, which I am sure isn't good is it?), another possibly silly question, when you sandwich your 0.5mm pcb board spacers I assume you face them in to the diaphragm so you get a contact on both sides and assume you glue it down? If so how do you do that and get a good connection?

I was thinking when I make them to sand the side facing the ear of the cup by a couple of degrees downward (in towards the ear canal) to help reduce any standing waves inside, good idea?

Again sorry for the novice questions but don't have access to the cnc machine for long so need to plan these bits before I get making. Will post some basic plans when I have drawn them up....

Thanks,

Chaz

P.s. which ones are you favourite out of your army of phones?


----------



## ayaflo

> CNC machine arrived today.


 
   
  how much did you get that for?


----------



## dude_500

Quote: 





chazman said:


> I will go for the pcb material idea then (though struggling to find 0.5mm board that isn't pre sensitised, which I am sure isn't good is it?), another possibly silly question, when you sandwich your 0.5mm pcb board spacers I assume you face them in to the diaphragm so you get a contact on both sides and assume you glue it down? If so how do you do that and get a good connection?


 
  This is the place to get 0.5mm and 1mm copper clad: http://www.ebay.com/itm/Copper-Clad-Laminate-PCB-Printed-Circuit-Board-Material-/120664289524?pt=LH_DefaultDomain_0&var=420018556366&hash=item1c1826f0f4
  It's a bit expensive, but I think its the best you can do without ordering in bulk from a supplier.
   
   
  How do the floats work? Isn't there zero seal since they 'float' over your head without any sort of earpad at all? I'd think the open air resonance would be completely present and they'd sound like total crap (like how it sounds when you hold the earpad of standard electrostatic headphones a centimeter away from your ear).
   
   
  Regarding more listening, the new headphones are much more enjoyable to listen to. My old pair sound so flat now in comparison. Probably won't have a chance to try until at least the weekend, but hoping for more bass from lower tension.


----------



## Chazman

Dude_500 - thank you, another forum legend 

I am in the UK so will have a look about on eBay and see if there is anything like that a bit more local. On that note is there anyone in the uk who would like to see some Mylar , I have found some (2um) on eBay but I don't necessarily need 20m of it?!

I was not thinking of them floating they would still have a pad as per normal but if you imagine it is normally a tube that is perpendicular to the side of your head these would be angled a little so the driver does not face head on and might help reduce any standing waves inside the cup. I will draw a quick image later to better describe. 

Thanks,

Chaz


----------



## ayaflo

Hope to listen to Mr. Wachara's DIY e-stats when I go to Thailand this MAY!! FINGERS CROSSED!


----------



## spritzer

Quote: 





chazman said:


> Hello!
> 
> Long time reader (especially as this thread is soooo massive) and all this talk has inspired me to make my own headphones after getting a pair of Koss ESP-6a's and restoring them to their former glory. A number of years ago I was very lucky to be able to try a full Sennheiser HE90 / HEV90 set up and was blown away by them so I am going to base my designs on the basic design of those with Oval drivers in the 100 x 70mm ball park and want to try to use some premium materials in persuit of a great sounding pair of phones!
> 
> ...


 
   
  The HE90 stators were etched glass and most of the sound comes from how they were made.  Also why there is a huge variation between sets and the reject rates were sky high back in 1991.  The stators were then coated to become conductive.  Gold plated diaphragm is just marketing BS. 
   
  Quote: 





chinsettawong said:


> With simple enclosure and headband, they could very well be something very similar to the Jacklin Float.  I'm targeting a spacer of 0.75 mm and a bias voltage of 1000V - 1200V.  They should be able to be driven by my KGSSHV and DIY T2.
> 
> 
> 
> ...


 
   
  That would work but I'd try the "ear pad" setup use don the later Floats where they have a leather L shaped back at the back and bottom. 
   
  With drivers this big I would remove or just bypass the output resistors on the T2/KGSSHV.  I'll check my data to see if Precide ever used any resistors on their sets...


----------



## chinsettawong

Quote: 





spritzer said:


> That would work but I'd try the "ear pad" setup use don the later Floats where they have a leather L shaped back at the back and bottom.
> 
> With drivers this big I would remove or just bypass the output resistors on the T2/KGSSHV.  I'll check my data to see if Precide ever used any resistors on their sets...


 
  Hi Spritzer,
   
  I'm just having this itchy feeling after seeing many people posting about how great the new Jacklin Float sounds.  To me they are just big, and I'm sure that the size does matter.  It would be fun to try and see how good they can sound.  I can play around with the bias voltage to see what the most suitable voltage should be.  Without earpads, I'm sure that the headphones need to play a lot louder in order to sound decent.  By the way, do you think that the diaphragm size of 120 mm x 100 mm is close enough to the real thing?
   
  Using series resistors shouldn't be a problem.  When I built my ESL speakers, I used 20 mega ohms series resistors.  They are just to prevent the possibility of large current going through.  I'm sure they won't hurt.
   
  Wachara C.


----------



## Chazman

Quote:Spritzer 





> The HE90 stators were etched glass and most of the sound comes from how they were made.  Also why there is a huge variation between sets and the reject rates were sky high back in 1991.  The stators were then coated to become conductive.  Gold plated diaphragm is just marketing BS.


 
  Ah that makes sense, did wonder if there was actually anything in that rather than just "Look at my gold bling headphones"
   
  So I have opted for the more traditional set up, basics are going to be:
   
  - Oval drivers - total size 105mm x 75mm (took some steer from my HD-580's in terms of size and personal fit) with an active area about 93mm x 63mm (6mm basic clearance space for screws and spacer area), using 2mm holes with a total of 462 holes per stator - 63% open on 1mm thickness 35um PCB glass fibre board.
   
  - 0.5mm PCB spacers and will try to source some 2um Mylar. Still not sure on what anti static to get (in the UK that is) but open to personal suggestions on this? Do we reckon about a 1-2% stretch is a good place to start?
   
  - Cherry wood oval cups with 15 area on back side which I will put a grill on and possibly play with various damping materials about the sound when I have put them together. 5mm lip on the front side of the drivers so I can get a really nice fit on the pads which I intend to make with thin leather running along the inside to help with bass exntension and then soft material next to the head.
   
  I will try to get a snap shot of the CAD at some point and post it but having the stators made in the next week and hopefully the cups and spacers in the next week or two when I get the materials I need.
   
  So just a couple of questions for the forum:
   
  - Cabling, good to find a Koss extension cable to start with?
   
  - Amp, right so I have not yet got round to making an Amp, I want to eventually make myself a tube amp for these but in the mean time I was thinking of trying to source something like a Stax type thing. Any help on this would be amazing, based on the dimensions and expereince what do you guys think would be a good place to start (I am not going to lie I am an electronics novice, I have some experience but mostly in IC's rather than passive type stuff)....
   
  - Gluing the diaprham to the the spacers, how is this best done to ensure there is an electrical connection?
   
  Again many thanks to the experts 
   
  Chaz


----------



## dude_500

Quote: 





> - Cabling, good to find a Koss extension cable to start with?
> 
> - Amp, right so I have not yet got round to making an Amp, I want to eventually make myself a tube amp for these but in the mean time I was thinking of trying to source something like a Stax type thing. Any help on this would be amazing, based on the dimensions and expereince what do you guys think would be a good place to start (I am not going to lie I am an electronics novice, I have some experience but mostly in IC's rather than passive type stuff)....
> 
> - Gluing the diaprham to the the spacers, how is this best done to ensure there is an electrical connection?


 
  From what I've heard, yes the Koss cable is good. I just use generic ribbon cable, but I've had it go bad with broken connections inside the wire near the headphones after a few months of use. Also they're not the safest option, although at these voltages honestly they have plenty of insulation for realistic safety.
   
   
  I've always glued the mylar to a spacer that has no copper on it at all, then put the conductive coating on after gluing, and sandwich a copper covered spacer down onto the mylar. This leaves the mylar with 0.5mm on both sides as desired, and the mylar is contacted without having to glue it to copper.


----------



## chinsettawong

chazman said:


> Ah that makes sense, did wonder if there was actually anything in that rather than just "Look at my gold bling headphones"
> 
> So I have opted for the more traditional set up, basics are going to be:
> 
> ...




-Seriously, if you can make your drivers bigger, then do it. I would stick with active area at least 70x100 mm.

-3 micron Mylar is the best one for me so far.

-I don't like to have any damping on my headphones. I feel they sound better that way. But you can try.

-I did post a picture showing the configuration of my driver a few posts back. Please have a look, and you should understand how the Mylar is glued to the spacer and how the other spacer is used as a charge ring.

Wachara C.


----------



## Chazman

Quote: 





chinsettawong said:


> -Seriously, if you can make your drivers bigger, then do it. I would stick with active area at least 70x100 mm.
> 
> -3 micron Mylar is the best one for me so far.
> 
> ...


 
   
  - Thanks, I have pushed the space envelope quite a bit (in terms of the number of holes and spacing, so its actually a bit over the number I said in places) and tried to make sure they would be pretty rigid. I will see how these ones go and then play with the active area on the next pair, also I did some measurements on my head, perhaps I have quite a small head but this was already quite a bit bigger in size to my HD-580's which are pretty big on my head.
   
*On an interesting note* I spoke to an Acoustics engineer about the stators and if there would be any advantage to putting minor radiuses on the non copper side of the stators - offical word was with over 60% open (these will be 63%) they are considered acoustically transparent and putting little horns on them effectively would increase the distance of the holes and take more energy from the sound wave. Additionally I am not sure I want to put tiny 0.2mm rads on 1848 holes!! 
   
  - I can not for love nor money find a readily available source of 3um Mylar that I can get in the UK. Where do you get yours and I might be able to see if I can get I shipped over? What stretch do you put on your sheets?
   
  - I have heard a few people say they don't any damping and some that do but its all pretty easy to put them on and off the back side of the phones so might as well give it a go (based on the closed back Koss ESP-6A's which have felt and paper backing to stop the rear wave, of course they are closed completely so not the same but maybe a middle ground)
   
  - Thanks, I have gone back and with Dude_500's response below I have stopped being stupid and worked out how you did it, for some reason I had it in my head to glue both spacers on to the sheet but of course you only need to do one and just put the other on! Again apoogies for being a bit slow! 
   
  Quote: 





dude_500 said:


> From what I've heard, yes the Koss cable is good. I just use generic ribbon cable, but I've had it go bad with broken connections inside the wire near the headphones after a few months of use. Also they're not the safest option, although at these voltages honestly they have plenty of insulation for realistic safety.
> 
> 
> I've always glued the mylar to a spacer that has no copper on it at all, then put the conductive coating on after gluing, and sandwich a copper covered spacer down onto the mylar. This leaves the mylar with 0.5mm on both sides as desired, and the mylar is contacted without having to glue it to copper.


 
   
   
  I have emailed the distributer to find out if I can get one - I am clearly in the wrong country to get hold of anything to do with Electrostatics, they don't even stock the 950's in the UK apparently!!
   
  - Anybody got any advice on the Amp side of things?
   
  Thanks,
   
  Chaz


----------



## Chazman

Wachara C - Also how are you getting on this those enormous Jecklin Float type phones you mentioned a few posts ago? The drivers on them look instanely big


----------



## chinsettawong

The place to get 3 micron Mylar is at www.eraudio.com.au 

if you want, you can also get the diaphragm coating material from them too. I've heard that it works well too.

About the Jecklin Float type headphones, it's just an itch I have right now. I might or might not build it. But believe me, for electrostatic type of headphones or speakers, size does matter. 

Wachara C.


----------



## spritzer

If you want to know anything about DIY electrostatic amps just ask away.  Tubes, SS or crazy transformer hybrids... we've done it all.  
	

	
	
		
		

		
		
	


	




  I have one planned which has only two triodes in total for a fully balanced amp.  Not cheap and probably will sound quite... ehhh... special.  
   
  Quote: 





chinsettawong said:


> Hi Spritzer,
> 
> I'm just having this itchy feeling after seeing many people posting about how great the new Jacklin Float sounds.  To me they are just big, and I'm sure that the size does matter.  It would be fun to try and see how good they can sound.  I can play around with the bias voltage to see what the most suitable voltage should be.  Without earpads, I'm sure that the headphones need to play a lot louder in order to sound decent.  By the way, do you think that the diaphragm size of 120 mm x 100 mm is close enough to the real thing?
> 
> ...


 
   
  The real thing was originally designed around RTR tweater panels and they were something like 5"x5" so 120x120mm is very close.  The biggest issue is the limited baffle range so that lack of bass that goes with it.  They don't go deep and the bass is all over the place. 
   
  With the talk of cloning the HE90 I finally tried to install the present I got from you on Christmas yesterday and they are just a bit too big to fit in the HE90 frame.  I trimmed the connection tabs a bit and with the drivers mounted like the stock HE90 units (connections at the top) there is no way for the cable entry to work.  I'll try it the other way around and see if I can make it work but it is very tight indeed.


----------



## chinsettawong

Quote: 





spritzer said:


> The real thing was originally designed around RTR tweater panels and they were something like 5"x5" so 120x120mm is very close.  The biggest issue is the limited baffle range so that lack of bass that goes with it.  They don't go deep and the bass is all over the place.
> 
> With the talk of cloning the HE90 I finally tried to install the present I got from you on Christmas yesterday and they are just a bit too big to fit in the HE90 frame.  I trimmed the connection tabs a bit and with the drivers mounted like the stock HE90 units (connections at the top) there is no way for the cable entry to work.  I'll try it the other way around and see if I can make it work but it is very tight indeed.


 
   
  Thanks for the info on the Jecklin Float.  I understand that without good seal the bass won't be that good.  But it would be nice to try to see just how good they can actually sound.  To me, they're very easy to build since I don't have to find them the proper ear pads. 
   
  I'm sorry about the HE90 clone not fitting into the cup properly.  When I had my hand on HE90 the last time, I didn't want to open them up since they weren't mine.  So I did my best guess of how the drivers should be.  I think I must have made them a little bigger than the real thing. 
   
  Wachara C.


----------



## insert-here

Cudo's to you man, this is amazing!  I love it!  Making your own equipment.  Did you learn this stuff in school or are you a born tinkerer?


----------



## chinsettawong

Let me know if you can find a school where they teach you to build all these.  
	

	
	
		
		

		
		
	


	



   
  Wachara C.


----------



## spritzer

Quote: 





chinsettawong said:


> Thanks for the info on the Jecklin Float.  I understand that without good seal the bass won't be that good.  But it would be nice to try to see just how good they can actually sound.  To me, they're very easy to build since I don't have to find them the proper ear pads.
> 
> I'm sorry about the HE90 clone not fitting into the cup properly.  When I had my hand on HE90 the last time, I didn't want to open them up since they weren't mine.  So I did my best guess of how the drivers should be.  I think I must have made them a little bigger than the real thing.
> 
> Wachara C.


 
   
  Forgot one thing about the Jecklin, it's not the ballast resistor in the bias supply that I'm worried about but the 5K1 output resistors on each of the four outputs.  These are setup for the Stax load and will cause issues with much larger drivers.  I would just jumper them as we would need to do a lot of testing to find a suitable value for Jecklin's.  I just checked the Ergo amp schematic and there were no resistors in that one.  They did use 32M for a ballast resistor though. 
   
  It took some creative cutting of the connecting tabs and violating the HE60 cable but I got them to fit.  
	

	
	
		
		

		
		
	


	




  The connection tabs are now less than 1mm strips but that's enough.  The problem was that when I mount them the correct way (tabs at the top) there is no way for the cable entry to fit as the bottom of the driver is right next to it.  Shave 1mm off the driver all around (so 2mm from top to bottom, side to side) it will fit just fine. 
   
  I fitted them with loose fitting PVC dust covers but I need to clean them out as they squeal a bit.  They do sound good though, a bit "slow" compared to the Lambda Nova drivers I had before but pretty good over all.  Nice amount of bass though it rolls off a bit down low.  Top end has some bite to it but it's otherwise nice a smooth.  Midrange good as well but a bit... vague, diffused if you will.  I just realized after I wrote that that I was pretty much describing the HE90, though in broad strokes.  
	

	
	
		
		

		
		
	


	



   
  I do have one suggestion, you could apply more tension to the diaphragm.  It's nice and stable but the HE90 and the Stax Omegas use even more tension.  Now back to some more listening...


----------



## chinsettawong

Quote: 





spritzer said:


> Forgot one thing about the Jecklin, it's not the ballast resistor in the bias supply that I'm worried about but the 5K1 output resistors on each of the four outputs.  These are setup for the Stax load and will cause issues with much larger drivers.  I would just jumper them as we would need to do a lot of testing to find a suitable value for Jecklin's.  I just checked the Ergo amp schematic and there were no resistors in that one.  They did use 32M for a ballast resistor though.
> 
> It took some creative cutting of the connecting tabs and violating the HE60 cable but I got them to fit.
> 
> ...


 
   
  Thanks for all the infos.  If I move ahead with the Float project, I might have more questions that need your help. 
	

	
	
		
		

		
		
	


	



   
  As for HE-90 clone, when I played with it, I used 0.85, 1, and 2 microns film.  When I stretched them too much, I didn't get good bass.  At that time, I didn't tried them with 3 micron film.  With 3 micron film, I can certainly tension it a lot more and still have good bass.  If you already have some differnt Mylars, please try them and see what you like best.
   
  About the squeal, I really think that spraying the copper side of the stators with a couple layers of laquer paint helps a lot.  The paint also protects the copper against the possible oxidation.  Please try.  
	

	
	
		
		

		
		
	


	



   
  Wachara C.


----------



## spritzer

Ask away, plenty of information locked away in this head... 
	

	
	
		
		

		
			




   
  What film did you end up with, 3um?  Did you heat treat it at all?  That might help... I do have some ovens to play with.  
	

	
	
		
		

		
		
	


	




   I was also toying with the idea at work today to design a PCB driver and have it made at a fab house.  Those guys can do amazing tolerances and different materials.  I did do this once but the design was flawed.  Now it would be just one design for the stators and another one for the spacers. 
   
  About the squeal, first attempt will be cleaning the diaphragm as they are dusty.  The copper oxidizing is an issue but I'll probably first try some polish liquid which forms a protective barrier that stops oxidation.  I used it on my KGSS back in the day and the bare aluminum is still nice and shiny. 
   
  Edit, some pics:


----------



## chinsettawong

I sure will ask a lot of questions.  
	

	
	
		
		

		
		
	


	



   
  The headphones look really good.  So, have you fixed the squeals?  Do you mean to clean the copper with polishing liquid and that would leave some protective shell on it?  That seems like a good idea.  
	

	
	
		
		

		
		
	


	



   
  Today, I tried to put more tension on the diaphragm of my oval shape headphones.  The last time I had 9 x 600 ML of weight on the diaphragms, and they were not good enough. Today I used 12 x 600 ML, and it's a bit too much.  
	

	
	
		
		

		
		
	


	




  I'll try 10 x 600 ML next time and will report back.


----------



## chinsettawong

My Oval shape Orpheus clone is a lot bigger than the real one.


----------



## dude_500

Quote: 





chinsettawong said:


> My Oval shape Orpheus clone is a lot bigger than the real one.


 
   
  What is the active area of the actual Orpheus?


----------



## chinsettawong

Here are two more pictures comparing my Omega clone against my version of Orpheus.


----------



## chinsettawong

Quote: 





dude_500 said:


> What is the active area of the actual Orpheus?


 
   
  I don't really know, but I guess it's around 55 mm x 95 mm or 50 mm x 90 mm.  The ones I made for Spritzer are a bitt larger at 60 mm x 98 mm.
   
  Wachara C.


----------



## spritzer

The HE90 is a bit smaller than these drivers so Wachara's estimate is about right.  It would be fun to build drivers like these and have them gold plated and put them together with black peek screws.  Almost impossible to tell them apart from the real thing... 
   
  Quote: 





chinsettawong said:


> I sure will ask a lot of questions.
> 
> 
> 
> ...


 
   
  I took a nap instead of cleaning the diaphragms...  
	

	
	
		
		

		
		
	


	



   
  I always use a larger piece of mylar when stretching so that might help.  It can take an incredible amount of tension but a small tear at the sides and all is lost.  Amazing material though...


----------



## Chazman

spritzer said:


> If you want to know anything about DIY electrostatic amps just ask away.  Tubes, SS or crazy transformer hybrids... we've done it all.     I have one planned which has only two triodes in total for a fully balanced amp.  Not cheap and probably will sound quite... ehhh... special. .




That's great thanks! So I have managed to source some lovely Cherry wood (only piece the entire timber yard had and is just big enough for the two cups with a little spare!

So in terms of the energiser I was thinking of making a nice basic one to get used to it and work out exactly what voltages I need then later on make something like a tube based amp. 

- I saw a while ago (but been searching for hours with no luck!!) a very basic design for an energiser that had two step up transformers and a potential divider for the stator and a simple transformer with a bridge rectifier from the mains to get the bias voltage. Does anyone have a circuit diagram / parts list for one like this? Also I take it would be possible to make one where the bias voltage just comes from a rectified signal from one of the stator transformers (like I assume my Koss ESP-6a's do as there is no powered input)?

Any help on this one would be massively appreciated! 

Chaz

P.s. lovely pics of the HE90 clones on here, I hope mine will at least half compare to you guys!


----------



## spritzer

What you want is the Stax SRD-7 Mk2 schematic.  You can find it online but basically it is just two transformers for the audio (1:25 in ratio or there about) and a basic bias supply.  The bias supply is just a 100V harmonic suppressor (100V zener diodes back to back) that limit the input voltage and then a six fold multiplier.  It's a neat circuit and easy to build. 
   
  If you want to build a tube amp then the Egmont is a good choice.  It's dead simple but you need a transformer with two filament windings, one for each stage, or the amp won't behave and chew up tubes.  There is an alternative, this one I recently built:
   

   
  Not high end by any means and the PSU voltages are a bit too hot but I just used the transformer I had at hand.  This one works with a single filament supply and can be built quite small.  Fully balanced too... 
   
  My HE90 is the real thing...


----------



## dude_500

After probably 20-30 hours of listening to both of my builds, there is no doubt the new ones just don't have enough bass (maybe due to the size, maybe due to the use of HD600 earpads, probably a bit of both). That said, I'd describe them as very fun to listen to, especially for classical music where bass isn't so important.
   
  A few minutes ago while wasting time online reading about the SR007, I read about someone removing the cloth dampening built into the earpad. I didn't realize this was possible, and immediately tried it. Wow! What a difference. It really opens up the sound, dramatically increasing the sound stage and brightness. I guess not everyone would want it given that by default they come with those sheets in, but I'm really quite excited about the new sound without them.
   
   
  I think I'm going to retire the new 'electrostatic HD600' headphones and put some effort into making my SR007 clones structurally better and more more aesthetically pleasing (replace some plastic with wood and improve headband).


----------



## chinsettawong

Hi dude_500,

The simple truth is the bigger, the better. 

I don't like to do any damping on the drivers too.

Wachara C.


----------



## Chazman

Quote: 





spritzer said:


> What you want is the Stax SRD-7 Mk2 schematic.  You can find it online but basically it is just two transformers for the audio (1:25 in ratio or there about) and a basic bias supply.  The bias supply is just a 100V harmonic suppressor (100V zener diodes back to back) that limit the input voltage and then a six fold multiplier.  It's a neat circuit and easy to build.
> 
> If you want to build a tube amp then the Egmont is a good choice.  It's dead simple but you need a transformer with two filament windings, one for each stage, or the amp won't behave and chew up tubes.  There is an alternative, this one I recently built:
> 
> ...


 
   
  Great stuff spritzer thanks, quite similar to a diagram I found previously.
   
  In terms of Transformers found these: http://www.maplin.co.uk/miniature-250ma-transformers-3688 (if you look at the 9v application because with a bit of quick math 240v primary and a 9v secondary is a ratio of 1:26 ish), they take 250mA current, do you think that would be ok for the main transforer from the speakers? The next transformers up (double the cost) can take 18w of power so a loooot more beffy and dont think they are needed?
   
  Possibly silly question about the SRD-7 diagram (I found on a previous post) it has 6 diode and capacitor for the multiplication system to get the bias voltage. The circuit diagram is for the japanese market so has an input voltage of 100v so does the 600v come from 6 x 100v (from the input) or because the diodes are 100v rating each and it will be limited to this across each regarless of input voltage? Reason I ask is that I am in the UK so input voltage will be 220-240v so would only need half the amount of diodes but higher voltage if it is mearly a product of multiplication.... Also I will put a coupld of taps off the diodes so I can play with different bias voltages.
   
  Thanks,
   
  Chaz


----------



## spritzer

That amp is just the Stax "A" model from 1968 with a new front end.  I'll probably draw up a PCB one of these days as it would be a good beginners amp, super cheap too. 
   
  I would never use power transformers for audio unless it's just for testing or just some silly experimenting.  The cores are just supposed to run at 50Hz and you run into DCR issues.  Old tube output transformers are much better fit, just wire them backwards.  Just remember to divide the primary and secondary impedance and then take the square root of that to find the ratio. 
   
  The Stax boxes are universal so any voltage higher than 100V is cut off via the two zener diodes and then multiplied.  It also calls for cheaper parts as the voltage rating is just 2*inputV.  If you are just going to use this at 230V then you can just leave out the limiter or use something like 200V.  I would recommend an isolation transformer though.  Stax or any of the others never used one but it helps with hum issues and safety.


----------



## Chazman

spritzer said:


> I would never use power transformers for audio unless it's just for testing or just some silly experimenting.  The cores are just supposed to run at 50Hz and you run into DCR issues.  Old tube output transformers are much better fit, just wire them backwards.  Just remember to divide the primary and secondary impedance and then take the square root of that to find the ratio.




Good advice, not especially easy things to just source so I have found so far. What is the actual difference between and Audio and power transformer (I know one is designed to carry decent current and one to match impedance but what makes them different)? Reason I ask is so I can spot which ones to use from other places and I could buy some cores and make my own transformers....

Chaz


----------



## spritzer

Very different winding techniques and core materials used.  Electrostatic step up transformers are an even further twist on this as they have their own requirements.


----------



## Chazman

spritzer said:


> Very different winding techniques and core materials used.  Electrostatic step up transformers are an even further twist on this as they have their own requirements.




Hmmm sounds like a bit of mine field of actually getting the right bits. Annoyingly I know a bit of the theory of how all these bits and pieces work but its information like this that is the real difference between something technically working and sounding great - so again thanks. 

Think I will concentrate on getting the mechanical side of the phones done and perhaps keep my open for parts to plunder from relative things like other energisers or phones....

Chaz


----------



## chinsettawong

Winding your own step up transformers is indeed very difficult.  It might be easier just to look for some used Stax units.  It's cheaper than building it yourself too, IMO.
   
  Wachara C.


----------



## Chazman

Yeah I think that is what I will end up doing (or find a pair of Koss ESP-6's, which are pretty cheap and simple dimantle for parts).
   
  At the moment there is a Stax SRD-7 (around $125 USD) and a Stax SRM - T1 (around $500-600 USD) on ebay at the moment, obviously I know they are very different things but do you reckon the T1 is worth the extra money in terms of quality I might be able to acheive from this as opposed to a good Amp and SRD-7 set up?


----------



## chinsettawong

Quote: 





chazman said:


> Yeah I think that is what I will end up doing (or find a pair of Koss ESP-6's, which are pretty cheap and simple dimantle for parts).
> 
> At the moment there is a Stax SRD-7 (around $125 USD) and a Stax SRM - T1 (around $500-600 USD) on ebay at the moment, obviously I know they are very different things but do you reckon the T1 is worth the extra money in terms of quality I might be able to acheive from this as opposed to a good Amp and SRD-7 set up?


 

 The best person to answer your question is Spritzer.  
	

	
	
		
		

		
			




   
  Wachara C.


----------



## spritzer

The Koss ESP6 transformers are not a good fit.  Too small and too high a ratio.  Get a SRD unit to try out as you can always get an amp later on.


----------



## Chazman

Quote: 





spritzer said:


> The Koss ESP6 transformers are not a good fit.  Too small and too high a ratio.  Get a SRD unit to try out as you can always get an amp later on.


 

 Good advice thanks, do you know what the step up ratio is on the Koss? I know there bias is about 320v which is a little low for this headphone.
   
  Also take it I probably want to be aiming for using the Pro bias from the Stax to get the 600v range rather than 230v?
   
  Chaz


----------



## spritzer

The Koss were 1:60 but they were meant to be used from a headphone socket and are also used to supply the bias voltage.  Another small bit, they need the extra ratio since the back stators are grounded due to the closed back design. 
   
  It's easy to get 0.5mm spacers but 0.3mm is less so.  The higher bias has obvious performance advantages as well so I'd go with that.


----------



## hifi2all

Hello
   
  A question to discuss - is there any sence to expertise in a laboratory a broken Stax 007 membrane in order to determine the chemical composition of the original coating? ... may be it's known?


----------



## chinsettawong

Quote: 





hifi2all said:


> Hello
> 
> A question to discuss - is there any sence to expertise in a laboratory a broken Stax 007 membrane in order to determine the chemical composition of the original coating? ... may be it's known?


 
   
  Nowadays, there are many coating materials that can work just as well as the one Stax is using.  I don't see a real need to do that.
   
  Wachara C.


----------



## Chazman

Quote: 





spritzer said:


> The Koss were 1:60 but they were meant to be used from a headphone socket and are also used to supply the bias voltage.  Another small bit, they need the extra ratio since the back stators are grounded due to the closed back design.
> 
> It's easy to get 0.5mm spacers but 0.3mm is less so.  The higher bias has obvious performance advantages as well so I'd go with that.


 

 Spritzer, may I lay down my hat in honour of your exceptional knowledge of everything headphone 
	

	
	
		
		

		
		
	


	



   
  I would post a wanted out on the forum for something like the SRD-7 but I have not posted enough yet (couple more to go!) but if anyone knows of one that would like to sell I would be exceptionally interested please......
   
  Quick question about the stators (possibly towards to Wachara C as I seen pics of his), is painting them essential to their operation / protection? Also I take it you make the coating very thin? Does it not get in the holes and reduce the open area?
   
  Thanks,
   
  Chaz


----------



## chinsettawong

Hi Chaz,
   
  You don't have to coat your stators if you don't want to.  It doesn't really make any difference in sound whether you coat them or not.  The reason why I coat is that the acrylic paint helps me with squeal problem.  With the paint act as an insulator for stators, a little dust that might find it's way inside the driver is less likely to cause a short between the diaphragm and stators.
   
  I usually spray only a few light layers of acrylic paint on the stators.  The paint is so thin that it doesn't reduce the open area, IMO.
   
  Wachara C.


----------



## Chazman

Quote: 





chinsettawong said:


> You don't have to coat your stators if you don't want to.  It doesn't really make any difference in sound whether you coat them or not.  The reason why I coat is that the acrylic paint helps me with squeal problem.  With the paint act as an insulator for stators, a little dust that might find it's way inside the driver is less likely to cause a short between the diaphragm and stators.
> 
> I usually spray only a few light layers of acrylic paint on the stators.  The paint is so thin that it doesn't reduce the open area, IMO.
> 
> Wachara C.


 
  Ah right, well I plan to put a moisture protector (or whatever it is called) between the ear and the driver but guess dust can get in to the backside that is not covered. On the moisture protector, I was thinking of using some EPDM self adhesive foam and mount the 2um mylar to that, taught but not especially tight, I am thinking this might be quite good (if I can get it stablise and not just collapse when it is in place) as the slight amount of flex in the EPDM will seal the driver in nicely to the head and will allow the mylar to move a little thus reducing any colouration, what do you think?
   
  Sorry another one while I think about it, I have some anti static wipes (computer monitor ones) that I was going to give a go on the mylar, an idea if these will be ok? I guess I am looking to get a resistance across the sheet of a few mega ohms? Do you find a difference in using the gel rather than just the soaked wipes?
   
  Thanks,
   
  Chaz


----------



## chinsettawong

It's only fun to try. Just go ahead and try whatever idea you have and let us know how it goes. 

Wachara C.


----------



## Chazman

Oh just another quick clarity point is the coating purely to get a high resistance coating or are there other properties required from it?
   
  Chaz


----------



## spritzer

The coating has to be highly resistive and also impervious to moisture in the air.  Being super light wieght is also a plus. 
   
  About coating the stators, the HE90 clones Wachara made for me are now pretty much free of any noise after a good clean.  The Stax Omega drivers are all uncoated and I just cleaned up a SR-007 set that had seen better days.  All the dust covers were gone when they got here and it took some trial and error to clean them properly but it can be done.


----------



## jcx

you don't need enough Gold atoms at the required resistance for the weight to matter - just awesome control in the metalizing process to put down so few, uniformly - not everybody's home diy option
   
  organic coatings could be a problem
   
  it has been speculated that getting a batch of polymer with the right carbon black loading so the conductivity is a bulk property would be a good option - anyone need a few tons of esl membrane material? - maybe a group buy?


----------



## jcx

you don't need enough Gold atoms at the required resistance for the weight to matter - just awesome control in the metalizing process to put down so few, uniformly - not everybody's home diy option
   
  organic coatings could be a problem if overdone
   
http://www.quadesl.org/Hard_Core/PanelCoatings/OriginalCoating/originalcoating.html
   
   
   
  it has been speculated that getting a batch of polymer with the right carbon black loading so the conductivity is a bulk property would be a good option - anyone need a few tons of esl membrane material? - maybe a group buy?


----------



## Chazman

Thought I would just quickly share a little screen shot of the exploded view from CAD of the phones I am currently making (obviously they are the machined blanks and will make some minor alterations like removing the tab from one of the spacers so I can get to the copper on one of them, radiusing, drilling holes for cables and headband). Will be held together with Nylon screws, Outer cup is Cherry wood, spacers are 0.5mm each, main stators just over 1mm thick, 462 x 2mm holes leaving 63% open area but with good stiffness, main active area is about 63x93mm, sheet is 2um thick (will try to get 3um and try that when I can get some) and will use either Anti static spray / gel or Evalamide. Additionally there will be a moisture cover with the 2um mylar on a EPDM spacer and the pads will be custom made leather (on the inside profile from the drivers to get good bass extension) and velvet against the ear......
   

   
   
  Quick questions:
  - I noticed the preference of etching as much copper away on the stators as possible around the edge, do you guys do this buy sanding them after machinng then colouring it in with a sharpie before putting in the etching solution (Ferric chloride I would imagine)?
  - Does this help get rid of the sharp corners on the holes and reduce any arcing?
  - Do you bother etching the copper off one of the spacers to make it completely blank board or just turn it around so the copper is facing one of the stators?
   
  Thanks,
   
  Chaz


----------



## chinsettawong

Hi Chaz,
   
  Your design looks really good.  But, if I were you, I would make them bigger.  
   
  The reason for etching out the unneeded copper is to reduce the capacitance on the drivers.  The capacitance makes a lot of difference on high frequencies.  When you have high capacitance, it's more difficult for an amp to drive high frequncies.  Nowadays, I always etch out all the copper which is not covering the active diaphragm area.  The way you describe about etching the copper is fine.
   
  Etching copper using etching solution can help get rid of sharp corners on the holes, but I think using sand paper does a better and quicker job.
   
  I do not bother to etch out the copper off one of the spacers.  I want to make sure that these two spacers are of the exact same thickness.
   
  Wachara C.


----------



## Chazman

If I went bigger now where I would I be able to get on the next pair! 
   
  Actually I did have a nice thought about being able to maximise the area and keep the same basic shape (which I quite like) and that is to make the elipse slightly square sided, just a bit and should help increase your actual open area in the 10% range with little shape change.
   
  Great stuff, good to know I am on the right lines. Did you notice quite a bit of difference when you etched them?
   
  I just wondered if you might get some corrosion or capacitance between the two pieces of copper facing each other from the stator and the spacer but if you dont think it will be an issue then will try that.
   
  Chaz


----------



## Chazman

Hello all,

Progress is getting there on the phones (had some of the wood cups made but weren't quite perfect so having some more done) and more importantly finally got the Mylar through so plan to do some experiments before I actually make up the films but as always I have some questions for the group please 

- I am going to try a few coatings as I have the stuff so might as well. I have some Elvamide but was wondering if I could use isopropanol (rubbing alcohol) as the dissolvant? 
- Do you clean the Mylar first and what with?
- What is the resistance band I am aiming for? I was thinking of applying the coating and putting some copper coins 95mm apart and seeing what the read out was....
- With the graphite powder method could I just shave a thick pencil lead for this (as I randomly have quite a few)?
- Right..... Stax plugs! Seen the threads about where to get things similar but only in the US and they want to charge nearly the same in postage as a whole Extension cord!!! Does anyone have the pin dimension and positions so I can make my own please?
- Cabling (seeing as I have access to electronics labs) I have found some nice 3mm 600v cabling, going to be quite chunky but resistance will be super low, anyone see any issues with using thicker cabling?

Will keep you posted as I progress....

Thanks as always forum gurus...

Chaz


----------



## chinsettawong

Hi Chaz,
   
  I know the fun of doing experiments.  I've been there and done a lot of those.  Do whatever you feel like doing and come back and tell us your experience.  
	

	
	
		
		

		
			




   
  If I were to tell you what you should do, would you still want to experiment?  
	

	
	
		
		

		
		
	


	



   
  Wachara C.


----------



## Chazman

Well normal I would be all up for the endless experimentation but having tried the rubbing graphite and anti static with no luck (though not sure if that is due to my cheap multimeter) and an hour and a half trying to get the elvamide to dissolve according to the instructions and not a single change in it might possibly need some help 

Do you still use the mix you specified in the first posts with PVA and graphite or just on the anti static now? Once I have the bits together can try them and mount them in the drivers and see what happens.... What are the obvious issues / what's the best way to tell if the sheets are too conductive / not conductive enough (e.g. Lack of sound, cracking or something)???

Anybody got any info on the cabling and connector please?

Chaz


----------



## chinsettawong

Hi Chaz,
   
  The resistance is normally too high for a normal multimeter to be able to measure.  You'll need a high voltage resistance meter to check it.  I normally don't bother to do that.
   
  I only use antistatic gel cleanser nowadays for coating.  It's much better and a lot easier to use.  Don't use my PVA glue formula anymore.  About elvamide, no comment.  
	

	
	
		
		

		
		
	


	



   
  Thick cable is fine, but it's a waste of resource since the current is so very little.  
	

	
	
		
		

		
		
	


	




  Do a search and you'll find the dimension for the connector.  But if you are just going to make an amp by yourself too, you don't have to use the connector like the one Stax's using.  I like the 5 pin DIN connetors, and I use them on my headphones.
   
  Wachara C.


----------



## bidoux

You should find graphite pretty much anywhere. It is used to lubrificate doorknobs and is not expensive at all (~5$). Maybe grinding pencil leads would work, but you should be careful not letting bigger bits go through.
   
  Quote:


chazman said:


> - Cabling (seeing as I have access to electronics labs) I have found some nice 3mm 600v cabling, going to be quite chunky but resistance will be super low, anyone see any issues with using thicker cabling?


 
  What you have to worry about is not resistance. Most amplifiers have a 5k resistor in serie with the output. What little resistance the cable adds does not really matter after that. But if you choose a bigger cable, you will have to deal with a bigger parallel capacitance and that might be annoying. See stax's website, the cable's capacitance is very close to the headphone's capacitance.
   
  Quote: 





chazman said:


> - Right..... Stax plugs! Seen the threads about where to get things similar but only in the US and they want to charge nearly the same in postage as a whole Extension cord!!! Does anyone have the pin dimension and positions so I can make my own please?


 
  KG posted some informations about the female plug a while back :
  "
  If you have the right tools you can make your own out of a piece of teflon and some of the yamamoto tube socket pins.

 Imagine the socket as a 6 pin with the 6th pin missing, but at position 0,0 (x,y)
 The rest of the pins are at
 0,.2175
 -.2175,0
 +.2175,0
 -.1087,-.1883
 +.1087,-.1883

 (in inches)
   "
  here is the image used to make the female plug :

  (btw the pins themselves are exactly identical to octal pins used in EL34 or 6AS7 for example)


----------



## AmarokCZ

Resistance across my diaphragm (7cm diameter, measuring points 5mm diameter) was about 10 gigaOhm, so you're gonna be smarter than your multimeter to measure it.
  Connector dimensions are in mm:


----------



## Chazman

amarokcz said:


> Resistance across my diaphragm (7cm diameter, measuring points 5mm diameter) was about 10 gigaOhm, so you're gonna be smarter than your multimeter to measure it.
> Connector dimensions are in mm:




Thanks for the diagram very useful  That is some serious resistance across the sheet, perhaps this is the issue as mine is only a normal multi meter and goes up to 2000k which is apparently no where near!

Guess I will just have to give them a go and see what works. Again any steers on symptoms of the coating being rubbish?



bidoux said:


> What you have to worry about is not resistance. Most amplifiers have a 5k resistor in serie with the output. What little resistance the cable adds does not really matter after that. But if you choose a bigger cable, you will have to deal with a bigger parallel capacitance and that might be annoying. See stax's website, the cable's capacitance is very close to the headphone's capacitance.




Hmmmm not something I had considered before. Do you have any advice on the best way to match these (e.g. Measure capacitance over the stators then then certain aspects of the cable)?



bidoux said:


> You should find graphite pretty much anywhere. It is used to lubrificate doorknobs and is not expensive at all (~5$). Maybe grinding pencil leads would work, but you should be careful not letting bigger bits go through.




I have read some articles about using graphite with different methods and some suggest just rubbing the powder on then wiping it off (others involving glue), is this right? I did some earlier and none of the graphite seems to stick to the membrane (it's 2um DuPont Mylar) but perhaps there is some there and it's enough...



chinsettawong said:


> I only use antistatic gel cleanser nowadays for coating.  It's much better and a lot easier to use.  Don't use my PVA glue formula anymore.  About elvamide, no comment.




I am getting the impression this Elvamide is a PITA! Going to get some pure Ethanol from work (I am trying to use Surgical spirit which is 90% ethanol, 5% methanol and some other stuff including castor oil which might be the thing causing the issues) and see if that works, might as well as I have the stuff!

Will hunt down the gel stuff! With these if you try them and don't work can you just use Isopropanol or acetone to take it off rather than ungluing the sheet? 



chinsettawong said:


> But if you are just going to make an amp by yourself too, you don't have to use the connector like the one Stax's using.  I like the 5 pin DIN connetors, and I use them on my headphones.
> 
> Wachara C.




I decided to chicken out for now on finding the bits for the Amp and use a Stax SRD-7 Pro to power them until I can work out how to build (or earn enough money!!) to get a nice tube amp.

Many thanks,

Chaz


----------



## chinsettawong

Quote: 





chazman said:


> I am getting the impression this Elvamide is a PITA! Going to get some pure Ethanol from work (I am trying to use Surgical spirit which is 90% ethanol, 5% methanol and some other stuff including castor oil which might be the thing causing the issues) and see if that works, might as well as I have the stuff!


 
   
  Working with Elvamide isn't easy.  Good luck!
   
  You can certainly clean out your coating using alcohol or acetone.  There is no need to redo your diaphragms.
   
  Wachara C.


----------



## bidoux

Quote: 





chazman said:


> Hmmmm not something I had considered before. Do you have any advice on the best way to match these (e.g. Measure capacitance over the stators then then certain aspects of the cable)?


 
  I guess you want a lot of space between the conductors and thinner wires in order to reduce the cable's capacitance. I don't know how stax does it.
  Another option is to use a spare cable from koss, they are quite cheap.
   
  BTW  you are not supposed to match the capacitance of the cable to the capacitance of the stator (or are you ???). More capacitance for an amp to drive means worse slew-rate so ideally the cable should present no serie resistance (but as I said it is not a real problem) and zero parallel capacitance.
  Quote: 





chazman said:


> I have read some articles about using graphite with different methods and some suggest just rubbing the powder on then wiping it off (others involving glue), is this right? I did some earlier and none of the graphite seems to stick to the membrane (it's 2um DuPont Mylar) but perhaps there is some there and it's enough...


 

 I simply rubbed the graphite onto the mylar using a paper towel, no acetone, glue or alcohol needed. It should take no more than two minutes rubbing it and then the mylar definitely changes color, it looks greyer.
  Before doing so you have to stretch the mylar over a piece of glass that you have cleaned as much as possible (I use acetone for this) then you have to expel the air between the mylar and the glass by rubbing it. Once it has attached to the glass it won't scratch (or maybe it will 
	

	
	
		
		

		
		
	


	




 , but it is less likely) so you can put much more pressure on the mylar when you will spread out the graphite.

 (at least that is why I understood from Roger R Sander book's. It has worked ok for me)


----------



## Chazman

Here's some of the first bits from the CNC and makings, hopefully will be able to get on it next weekend when I am back from holiday


----------



## shipsupt

One of our DIY'ers?
   
http://blog.shewu.me/2013/05/the-birth-of-homemade-electrostatic.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+DoesntExist+(Doesn't+Exist)


----------



## dude_500

Quote: 





shipsupt said:


> One of our DIY'ers?
> 
> http://blog.shewu.me/2013/05/the-birth-of-homemade-electrostatic.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+DoesntExist+(Doesn't+Exist)


 
   
  Those are my headphones, posted about them several pages back. The website is not mine though, as someone else took the photos.


----------



## shipsupt

Very cool. I hope you don't mind me posting your handy work again. I think we've got a few bytes left on the interweb and I think these efforts are so cool they deserve lots of post! Really well done.


----------



## chinsettawong

Quote: 





chazman said:


> Here's some of the first bits from the CNC and makings, hopefully will be able to get on it next weekend when I am back from holiday


 
   
  Wow!  They look really nice.  What''s the size of the active area?
   
  Wachara C.


----------



## chinsettawong

Quote: 





shipsupt said:


> One of our DIY'ers?
> 
> http://blog.shewu.me/2013/05/the-birth-of-homemade-electrostatic.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+DoesntExist+(Doesn't+Exist)


 
   
  Nice work!  Thanks for sharing.
   
  Wachara C.


----------



## Chazman

The active area is about 95mm x 65mm eliptical using 2mm holes and around 63% open area. Have made them quite up to the edge so there shouldnt be much etching needed. They are quite compact and perhaps the active area could be a bit bigger but will look in to that next time. 

Question - when you did the etching did you do it after you put the wholes in it? Was thinking about sanding them nice and flat and just going over all of it needed with a perm marker but worried it might etch under the marker around the holes...?


----------



## chinsettawong

I'm still learning how to etch PCB properly. 

The easiest way for me to do is that I use my spacer to cover the edge of PCB where I want to chemically etch out and spray paint the active stator area. The part where the wire connection is, I use permanent marker to paint over it.

Yes, I drill all the holes and cut them into shape before doing chemical etching. Dude_500 seems to do a better job of etching. Let's hear his method.

Your active area of 95 x 65 is good.

Wachara C.


----------



## chinsettawong

I bought this Stax SRM252A amp from a friend for a while now.  I never thought that it could sound this good.


----------



## frank2908

Quote: 





chinsettawong said:


> I bought this Stax SRM252A amp from a friend for a while now.  I never thought that it could sound this good.


 
  What's that shiny thing inside the ear pads? Did you make the dust protector on the ear side out of mylar or cling film?


----------



## chinsettawong

Yes, it's the dust protection diaphrgam and it's a must have.  I use 0.9 micron film for it.


----------



## dude_500

For etching away, I do it after machining the stators. I print the appropriate oval and contact tab on a laser printer, toner-transfer it on right over the holes, etch it, and then clean the toner off with your solvent of choice. Problem is sometimes it leaves a bit of paper residue in the holes, so I often run a drill bit through all the holes with a hand drill to clean the paper out which is a pain but only takes a few minutes. 
   
  Sharpie works alright for touchups, but often times it'll be partially etched through so it looks really bad and you get less copper density remaining. I would not advise using a sharpie for the full mask. You can buy transfer pens though that don't etch through, they may even have them at radioshack (they used to, but likely stopped carrying that stuff by now).


----------



## Congo5

For etch resist:    Sharpie Paint pens,  oil based...
   
  they work for me and are at the "office stores"
   
  I like the fine tip....


----------



## Chazman

Thanks for the advice all - I went and used the sharpie option (after doing some test runs) so I could get nice a precise with the copper I wanted to remove. Seemed to work well and left the rest of the material in good shape. 

Also been putting together the cabling, bought a set of Stax Lambda Signature with a SRD-7 pro (which to my delight I am exploring!) but going full custom for now with 3mm high insulated 600v cable (advantage of being able to get large amounts of high quality cable from work!!) and spent several hours putting it in to a nice pattern which I will terminate with a custom Stax plug I am building - here is a little peak -  - in progress (it's much tidier now)

 - finished waiting to be fitted to plug and phones

2m, 6 cable braid, took about an hour after learning how to do it from a guide on the net, whatever it looks different!! 

Oh for reference found a better thing than the extension cable for Stax and that is to get a replacement 202 cable, little tricky to find but only £30 rather than £70 for extension cable....

Chaz

P.s. RadioShack doesn't exist in the UK anymore, pretty sure they went bankrupt here, real pain but have something similar called Maplins


----------



## dude_500

That cable looks like it will probably work pretty well. With all that space in between braids, capacitance will probably be even lower than a typical ribbon cable. 
   
  I just replaced my poorly performing generic ribbon cable with Koss ESP950 cable last week and the cable seems to work very well. You can call Koss customer service and get it for $13 per 2 meter extension cable, plus $3 shipping. Pretty good price, much better than any stax cable options.


----------



## chinsettawong

Koss cable is indeed good and cheap. 

@Chaz: Your cable looks really nice. I'm sure that it'll be very good with your headphones. Now, just put everything together. I'm really eager to see your finished headphones. 

Wachara C.


----------



## Chazman

Thank you for the compliments!

Just waiting for the 0.5mm spacer parts now and pretty sure I will have everything ready to put them together though I fly out to sit of a beach in Malta till Friday so maybe next weekend I will get a chance 

Koss is an even bigger problem in the the UK! They don't sell the 950 here or parts, no luck with distributer and Koss was $15 for the cable and about $60 for shipping!!!!! Tell you what guys someone in the US should buy a load and sell them on eBay worldwide as a service and to make some good profit....! 

Chaz


----------



## chinsettawong

Today I welcome our head-fi member, Ayaflo, who comes all the way from Bangalore, India to visit me.  I let him listen to my Omega clone and my version of Orpheus.  Playing songs through Macbook and KGSSHV, he likes the Orpheus better.


----------



## Chazman

Welcome and they look great!

So put together one of the drivers this morning to see how it goes and makes a sound (yay!) but a couple of things I could do with some advice on:

- bass response seems ok but treble is low- need more tension on the diaphragm?
- needs a lot of volume to drive them with from a pro bias Stax SRD-7 - just the config (using Elvamide etc) or again the tension?

Cheers 

Chaz


----------



## chinsettawong

Hi Chaz,

I don't really like using Elvamide. Your problem could be too high resistance on the diaphragm and therefore the bias voltage isn't at its optimal. I would keep plugging it in for a while and listen to see if it gets louder. 

I would advise you to get some electrostatic gel clenser. It'll make your build a lot easier.

Wachara C.


----------



## ayaflo

had a great time mr. Wachara.
   
  I am still listening to Skylark now. addicted to that song at the moment. 
   
  your collection of music is kinda nice too 
	

	
	
		
		

		
		
	


	




... love both the cans they are amazing!, best things I put on my ear - especially the comfort of the orpheus clones were so amazing.
   
  thanks!!


----------



## Chazman

chinsettawong said:


> Hi Chaz,
> 
> I don't really like using Elvamide. Your problem could be too high resistance on the diaphragm and therefore the bias voltage isn't at its optimal. I would keep plugging it in for a while and listen to see if it gets louder.
> 
> ...




Think you hit the nail on the head, tried graphite (don't have any cleanser gel but will try to get some) and that bought the volume needed right down and seemed to bring out the full range nicely!

Just putting the bits together now but you know how long the sewing bits around the pads takes but will post some pics soon

Cheers again,

Chaz


----------



## dude_500

I got some 0.9 micron mylar last week and finally had time tonight to make some diaphragms out of it. What a profound improvement! Trebles are much more pronounced, although there may be a very slight reduction in bass. I also notice the soundstage moving more forward away from the center of my head, which is awesome. Certain female vocals sound as much as a foot in front of me.
   
  I very much still prefer 2um dust/sweat shields than 1um. I think they provide just enough damping to suit my taste.
   
  Although the price to pay is that the material is a nightmare to work with. Procedures that work on 2um mylar (which comparatively is as strong as brick) will likely not work on 0.9um. I had to add tape where each tensioning clip goes in order to balance the load to prevent it from immediately sheering the whole sheet of mylar as seen in the following photo. With 2um mylar, I can just clip directly to the film.
   
   

   
  I wonder if there are sources of even thinner mylar. I've worked with 0.1um films and they are certainly too fragile for electrostatic headphones, but I imagine something in the range of 0.5 - 0.7um could be made to work with sufficiently well constructed tensioning jigs.


----------



## chinsettawong

Nice to hear that you like the 0.9 micron Mylar. But you will find out later that this material is too temperature sensitive. I played with it for quite a while but never could get it to be stable enough. The sound from it is amzing though.

Wachara C.


----------



## Chazman

A few work in progress pics, need to make a new headband pad, ear pads and sweat guard and work out a few kinks with the balance of the drivers but initial impressions are good, very deep bass and articulate with reasonably reserved mids. Any fellow builders got any advice on what modifications (tension, coating etc) made to the different properties so I can make some informed experiments?

Also after hearing how loud these little beasts can go I am certainly thinking of electrostatic loudspeakers at some point in the future 



dude_500 said:


> I got some 0.9 micron mylar last week and finally had time tonight to make some diaphragms out of it. What a profound improvement! Trebles are much more pronounced, although there may be a very slight reduction in bass. I also notice the soundstage moving more forward away from the center of my head, which is awesome. Certain female vocals sound as much as a foot in front of me.




I have a pair of Stax Lambda Signatures which I believe use the 0.9um film and they are very impressive headphones, interested to hear your experiences with them on the home built versions....

Chaz


----------



## chinsettawong

I like your headband. It looks nice!

Believe it or not, I also go from electrostatic headphones to electrostatic loudspeakers amd now back to headphones. Building ESL is fun too. 

I have tried 0.9, 1.5, 2, 3.5, and 6 microns Mylar. While the thin ones sound pretty good, you'll find them to be a little bass light. The 0.9 mircron Mylar has a problem with temperature. The tension tends to change with the change in temperature. But it sounds really nice.

Wachara C.


----------



## ayaflo

"he likes the Orpheus better."
   
The vocals on those were just crazily ecstatic if anything


----------



## Chazman

chinsettawong said:


> I like your headband. It looks nice.




Thanks, not finished yet, want to put a nice foam pad on it but its just one of these ear defenders taken apart - http://www.clarkforest.com/shop/safety-clothing/ear-defenders/peltor-optime-2-ear-defenders

Quite nice a light, easily adjustable and fits our size of phones really well (luckily I found some at work!)

Chaz


----------



## chinsettawong

Quote: 





chazman said:


> Thanks, not finished yet, want to put a nice foam pad on it but its just one of these ear defenders taken apart - http://www.clarkforest.com/shop/safety-clothing/ear-defenders/peltor-optime-2-ear-defenders
> 
> Quite nice a light, easily adjustable and fits our size of phones really well (luckily I found some at work!)
> 
> Chaz


 
   
  Good idea!


----------



## Chazman

Right so I know it's been quite a long time since I last posted that I've been progressively working on them in between getting a new job.

Wachara- I hasve got some antistatic gel and seems you working reasonably well, it's got rid of all the problems that I was having with rubbed graphite (was having in terms of discharge, hum and crackling things like that) however I do find the resistance is very high and I need to turn the amplify quite high to get any decent volume also although very very precise (even more so than my Lambda signatures!!) the bass is lacking using the same 2um sheet and similar tension. Do you only put one coat of the gel on (all I have done so far)? Just one side? I think the bass issue is to do with the resistance because when it was much lower with the graphite it was very very punchy!

Thanks for the help,

Chaz


----------



## chinsettawong

Hi Chaz,

I don't know for sure what your problem is. But you can try a few more coatings so that you get very homogenous surface resistance. Yes, you coat only on one side of the diaphragm. 

If you have to turn up the volume much more when using the antistatic gel, then the stuff you're using might have too high resistance. A good resistance would be around 1 x 10^7 ohm per square.

Wachara C.


----------



## dude_500

I've been having a dust squeal in my right channel for weeks. I've brushed off the diaphragm dozens of times, checked and cleaned the stators for surface dust, and just don't know what's up. Has anyone had any difficult-to-eliminate squeals and found any tricks? It's usually only present in high humidity (almost continuous squealing if I try to wear them after showering and having wet hair, otherwise the squeal is somewhat rare occurring only a few times a day)
   
  There is a fair bit of dust on the diaphragm because I don't have a cleanroom so it's effectively impossible to get fully clean, but it's no different form the left channel which rarely if ever squeals.


----------



## Chazman

Not sure if it is the same thing but I was having this with some diaphragms that had too low a resistance (ones coated with graphite). Using the other coatings like the anti static gel has got rid of that, perhaps trying acetone and then recoat?

Chaz


----------



## chinsettawong

The easiest way to deal with the squealing issue is to insulate the active stator area.  I always spray a few layers of acrylic paint over the copper on my stators.  This helps prevent the possible exidation on the copper and at the same time help fix the squeal.  
   
  Anyway, after insulate the stators, you still need to clean everything up though.
   
  Try it.  
	

	
	
		
		

		
			




   
  Wachara C.


----------



## chinsettawong

We had a mini meeting among headphones lovers here in Bangkok yeterday.  We had a few different Stax headphones and my Omega clone and Orpheus clone to try.  We unanimously agreed that the oval shape Orpheus clone won over the Omega clone.  
	

	
	
		
		

		
		
	


	



   

   

   

   

   
  At least now I'm not alone who thinks that my oval shape headphones, which have bigger diaphragm area, sound better than the Omega clone. 
	

	
	
		
		

		
		
	


	



   
   
  Wachara C.


----------



## purk

Quote: 





chinsettawong said:


> We had a mini meeting among headphones lovers here in Bangkok yeterday.  We had a few different Stax headphones and my Omega clone and Orpheus clone to try.  We unanimously agreed that the oval shape Orpheus clone won over the Omega clone.
> 
> 
> 
> ...


 
   
  Are we talking about the original Omega or OII?
   
   
  BTW, that gotta be an awesome meet!!  Those folks are so lucky checking out to your creations in person.  Wonderful work again krub.


----------



## chinsettawong

Stax Sigma sounded very interesting.  To clone it would be fun.


----------



## chinsettawong

Quote: 





purk said:


> Are we talking about the original Omega or OII?
> 
> 
> BTW, that gotta be an awesome meet!!  Those folks are so lucky checking out to your creations in person.  Wonderful work again krub.


 
   
  I'm talking about comparing my Omega clone to the Orpheus clone.  
	

	
	
		
		

		
		
	


	




  
   
  I don't want to talk about how mine sound as compare to other Stax headphones, because they already sound good enough to me.  
	

	
	
		
		

		
		
	


	




  
   
  Wachara C.


----------



## jackcarver

Yesterday we have many cans not just electrostatic but dynamics and portable as well. 


My Stax Sigma normal bias and 507 were set up to drive by Electrostatic Driver + 300b amp+ interstage preamp.


Stax Omega2 Mk-I and Mk-II were driven by my Kgsshv.


----------



## purk

The KGSSHV looks so bad ass next to other amps.  The behemoth rainbow KGSSHV that is!


----------



## n3rdling

That guy is wearing the Sigmas backwards


----------



## chinsettawong

Quote: 





n3rdling said:


> That guy is wearing the Sigmas backwards


 

 Oh, yea.


----------



## jackcarver

haha. this is inside of the rainbow kgsshv.


----------



## purk

Quote: 





jackcarver said:


> haha. this is inside of the rainbow kgsshv.


 
   
  Thanks for the pic.  Are those on or off-board version?  The chassis reminds me of the Audio Reserch gear.


----------



## chinsettawong

Quote: 





purk said:


> Thanks for the pic.  Are those on or off-board version?  The chassis reminds me of the Audio Reserch gear.


 
   
  Those are on-board version.


----------



## vr1

Cool.


----------



## spritzer

Quote: 





dude_500 said:


> I've been having a dust squeal in my right channel for weeks. I've brushed off the diaphragm dozens of times, checked and cleaned the stators for surface dust, and just don't know what's up. Has anyone had any difficult-to-eliminate squeals and found any tricks? It's usually only present in high humidity (almost continuous squealing if I try to wear them after showering and having wet hair, otherwise the squeal is somewhat rare occurring only a few times a day)
> 
> There is a fair bit of dust on the diaphragm because I don't have a cleanroom so it's effectively impossible to get fully clean, but it's no different form the left channel which rarely if ever squeals.


 

  Get all the dust off the diaphragm with compressed air and a brush , that's the only way to do it.


----------



## dude_500

Squealing seems to have been a little bit of mylar extending past the edge of the diaphragm holder. Ran a soldering iron around the perimeter and it seems to be silent now. 
   
  I'll try compressed air if I have any more dust problems. I try to avoid brushing as it disrupts the coating surface. The coating still works fine, but it is visibly disturbed. It rarely matters, but I have had it affect balance slightly.


----------



## chinsettawong

A few friends here in Thailand have auditioned the JF and liked them.  I think it's interesting and will try to make a similar pair to see how mine can sound as compared to them.  I don't like the idea of using 1200V bias voltage as JF.  So, I change the width and height a little and will be using 0.5 mm spacer and 580V bias voltage as Stax.  Let's see how mine'll sound.
   

   
   


  What I'm aiming at is the active diaphragm area of 78 mm x 120 mm.  They'll be BIG!  
	

	
	
		
		

		
			




   
  Wachara C.


----------



## spritzer

Those are truly earspeakers...


----------



## dukeskd

Can't wait to see the final prototype Wachara


----------



## chinsettawong

Quote: 





spritzer said:


> Those are truly earspeakers...


 
   
  If I stack a couple of them up and find a good subwoofer, I'm sure that they can make a pair of good desktop ESL.


----------



## vr1

Can't wait to see and listen to them.


----------



## chinsettawong

I listened to the new JF at a friend's place yesterday.  The JF sounded really nice.  It's like listening to a pair of ESL and was very comfortable to wear since they're very light.
   
  However, I don't really like it's built quality.  With such a high price tag, it deserves better quality.  The frame is actually made from some plywood.  
	

	
	
		
		

		
		
	


	



   
  Anyway, the listening session gives me the inspiration to move on ahead with my version of these ear speakers.  I'm sure I can make them as good if not better.  
	

	
	
		
		

		
		
	


	



   
  Wachara C.


----------



## ayaflo




----------



## AnakChan

jackcarver said:


> haha. this is inside of the rainbow kgsshv.


I don't think I recall ever seeing a transformer like -that- in a KGSSHV.


----------



## chinsettawong

Quote: 





anakchan said:


> I don't think I recall ever seeing a transformer like -that- in a KGSSHV.


 
   
  There is nothing wrong with an EI core transformer.  
	

	
	
		
		

		
		
	


	



   
  Wachara C.


----------



## spritzer

Quote: 





chinsettawong said:


> There is nothing wrong with an EI core transformer.
> 
> 
> 
> ...


 
   
  Yup, better is some ways than the toroids.


----------



## wink

But,   but,,, toroids are supposed to be "State-Of-The_Art"


----------



## chinsettawong

wink said:


> But,   but,,, toroids are supposed to be "State-Of-The_Art"




Why do you think so?


----------



## spritzer

I think he was joking.  If you want state of the art then there is C-core wound properly.


----------



## jcx

toroids had some caché decades ago before the automated winding machinery became cheap - now they are commodity parts that are designed to work right at the edge of usability to skimp on materials, shipping costs
   
  anyone with audiophile pretensions should probably spec a custom winding xmfr with reduced Bmax compared to the standard industry practice
   
  EI do require some extra magnetic shielding (end caps in the photo are a start) - but split bobbin windings come with lower pri-sec parasitic C than toroids as a tradeoff to consider
   
  more air spacing, careful routing, twisting/common centroid cabling are more important with higher leakage flux xfmr geometry - but careful wiring is useful in any design where rectifier/cap charging current also generate interfering mag fields


----------



## chinsettawong

If you guys read my post about tensioning the diaphragm using bottled water from many posts back, I wrote that I used 600 ML bottled water to tension my 3.5 microns Mylar.  Well, I have to report to you guys that after using the diaphragm for a while, I think that the tension isn't enough.  Once in a while, my diaphragm would get suck by a stator.  I tried the same weight with 1.5 micron Mylar yesterday, and it's just about right for it.  The spacers after gluing the diaphragm on warped a little, but they're fine.
   
  With 3.5 microns Mylar, I'll try 0.8 or 1 Kg of weight next time.  I hope it'll be the right weight.
   
  By the way, I still don't quite like the 1.5 micron Mylar that I have, the lower bass is not as deep and too sharp height to my liking.  Once again, I'll go back to 3.5 microns.
   
  Wachara C.


----------



## chinsettawong

Got my first cut of the new stators today.  Look at the size and how it compares with my version of Orpheus and Omega clone.  
  When they're done, they can easily be my ultimate ear speakers.


----------



## spritzer

Those a quite big.  
	

	
	
		
		

		
		
	


	




  If you are going to use them with a limited baffle (i.e. like the Floats) then the 600V bias will become an issue.  Simply not enough force to use without sealing them.  
   
  ... and yes, more tension is better.  Too lazy or rather occupied with other things to replace the film in my Christmas present but they sound too rolled off and to thick for my tastes.


----------



## chinsettawong

Hi Spritzer,

I can always use thicker spacers and go with higher bias voltage if that becomes an issue. I also might try both seal and unseal to see which sounds better. 

Wow, you haven't changed those diaphragms yet? I'm not sure which diaphragm thickness I put on those. But it could be 1.5 micron. The good think about DIYing is that you can tailor made the phones to your liking. To me the 3.5 microns sounds just right. 

Wachara C.


----------



## spritzer

It would be interesting to try 600V as I'm not sure this was ever tried with the Floats.  The first ones used off the shelf drivers (RTR or something like that) so perhaps they just locked into that range.  1500V is the same bias as the Quad ESL uses on the tweeter panel so it's certainly up there. 
   
  I haven't used the HE90's at all for the last few months but in my defence, I have a lot of projects going all the time.  
	

	
	
		
		

		
		
	


	




  The PCB's for my subminiature tube electrostatic amp shipped yesterday...


----------



## chinsettawong

Quote: 





spritzer said:


> It would be interesting to try 600V as I'm not sure this was ever tried with the Floats.  The first ones used off the shelf drivers (RTR or something like that) so perhaps they just locked into that range.  1500V is the same bias as the Quad ESL uses on the tweeter panel so it's certainly up there.
> 
> I haven't used the HE90's at all for the last few months but in my defence, I have a lot of projects going all the time.
> 
> ...


 
  Hi Spritzer,
   
  Since I've already come this far, I'll just stick with my plan to try them at 600V.  If they're good, great.  If not, I'll just make thicker spacers and try them with high voltage.
  I'm really looking forward to your subminiature tube electrostatic amp.  Good luck.  
	

	
	
		
		

		
		
	


	



   
   
   
   
  I managed to cut the 4 stators.  But now I'm not sure if the stators will be strong enough once put together.  Because of the much open area, the stators don't feel to be very strong.  
	

	
	
		
		

		
		
	


	



   
  I made a small mistake on my spacer design.  So, I'll need to redo them


----------



## spritzer

You really are at the end of what the FR4 material can give us.  Add to the strength issues the extra tension needed to support the larger diaphragms and it becomes a bit of a problem.  Still there are no other good materials that come to mind which offer just extra strength with no weakness off their own.


----------



## dude_500

Quote: 





spritzer said:


> Those a quite big.
> 
> 
> 
> ...


 
   
  Never quite understood the concept of higher bias affecting the sound even slightly (assuming an ideal amplifier). If you halve the bias, all you have to do is double the drive voltage and you should get exactly the same forces, the same bass, the same everything. Of course your amplifier might lose linearity at higher voltages, but I believe you're making the point that there's actually less force at the same audio volume. How can there be more force if it's the same overall volume?
   
  I've listened to my headphones from 200V to 600V bias and I don't think I've ever really heard a difference. Can't imagine why there would be one!


----------



## chinsettawong

Quote: 





dude_500 said:


> Never quite understood the concept of higher bias affecting the sound even slightly (assuming an ideal amplifier). If you halve the bias, all you have to do is double the drive voltage and you should get exactly the same forces, the same bass, the same everything. Of course your amplifier might lose linearity at higher voltages, but I believe you're making the point that there's actually less force at the same audio volume. How can there be more force if it's the same overall volume?
> 
> I've listened to my headphones from 200V to 600V bias and I don't think I've ever really heard a difference. Can't imagine why there would be one!


 

 Of course, if you go with low bias voltage, your headphones would be less efficient and need more voltage swing to get the same audio volume.  Therefore, with different bias voltages, you're only playing with efficiency and not the sound difference.
   
  Wachara C.


----------



## spritzer

In an ideal world where to just leave aside the issues we are facing then yes, bias shouldn't be a factor.  With real world parts and most importantly, a finite baffle OTOH it is a large factor.


----------



## arnaud

I also can't get my hand around the influence of bias on transducer performance besides efficiency. On the amplification side, I have no idea, but for the estat force, I am not aware of non linearities and such with "mild" bias.


----------



## spritzer

More bias isn't really the issue, it's just a side product of the grater D/S spacing and greater drive voltages.  Remember the Floats are open so massive roll off issues which means the designers tried to compensate with more bias and more diaphragm excursion.  Naturally it doesn't work as they hoped but that is the theory.  It's also why ESL makers have been chasing the bias dragon for so long with ever crazier design ideas.


----------



## chinsettawong

I finished cutting my parts today.  I'll still need to etch out the unneeded copper on the stators.
   
  These are the front and back plates of the frame.
   

   
  I use a 10 mm plastic sheet to make the frames this time.
   

   
  This will be the side facing the ear.
   

   
  This will be the back side.
   

   

   
  I might cover the front and back plates with some kinds of cloth and foam for some damping.


----------



## spritzer

You will probably get some reflection issues from that back plate.  Could lead to even less bass output.


----------



## chinsettawong

Hmm. Thanks Spritzer for your input. Let me try. If it's no good, it's pretty easy to change it later.


----------



## spritzer

You could always try it by placing it behind any of your other sets and see if there is any difference.


----------



## chinsettawong

Hi Spritzer,
   
  I've tried what you suggested by placing the plates at the back of my Orpheus.  What I noticed was a little (very little) change in sound stage.  The bass wasn't affected at all.
   
  I intended to etch out the unneeded copper on the stators yesterday, but was too lazy. 
	

	
	
		
		

		
			





 
   
  Wachara C.


----------



## spritzer

That's good to know but one can never be too careful with the backwave reflections.  One of the precursors to the Jade used a slotted backplate such as that and it was panned for sounding very strange indeed.


----------



## MrTechAgent

Amazing job


----------



## chinsettawong

The new ear speakers are now singing.  
	

	
	
		
		

		
		
	


	



   

   

   

   
  I use 0.5 mm spacer and 3 micron Mylar.  The bias voltage is 580V. 
   
  It was very late last night when I finished it, and I only had just a short listening.  Overall, the ear speakers played plenty loud.  The amp I used was eXStatA with my iphone as its source.  Playing songs at 1 o'clock volume was more than I could bare.  There was still some noise in the right driver, and I wll fix that tonight.  Will update again later.  
	

	
	
		
		

		
		
	


	



   
  Wachara C.


----------



## shipsupt

Did you have a frame rigged up, or were you just holding those speakers up with your hands? 
   
  Looking good!


----------



## chinsettawong

At the moment, I'm holding them by hands against my ears. I'm still thinking of a good way to frame them up. 

Wachara C.


----------



## shipsupt

With earspeakers that large you'll get tired quickly!


----------



## spritzer

Looks good.


----------



## chinsettawong

Quote: 





spritzer said:


> Looks good.


 
   
  Thanks.   Just so you know, Playing them using a KGSSHV or DIY T2, they can be a pair of good desktop speakers too.  
	

	
	
		
		

		
		
	


	



   
  Wachara C.


----------



## dude_500

Quote: 





chinsettawong said:


> Thanks.   Just so you know, Playing them using a KGSSHV or DIY T2, they can be a pair of good desktop speakers too.
> 
> 
> 
> ...


 
   
  How do these speakers/headphones handle their resonance? I thought free standing speakers had to have two panels, one bass and one treble with intentionally non-overlapping-resonances. And it's no different being headphones with no seal. The FR must be atrocious!


----------



## spritzer

I don't think he meant speakers of reference quality.  Still if you mount them in a fairly large baffle then the sound would be ok.  Maybe some light damping on the back end would help with reflections.


----------



## chinsettawong

Hi Dude_500,
   
  Just as Spritzer said, they weren't meant for full range speakers of reference quality.  All I wanted to point out was that they were able to be driven easily by a good Stax amp.  However, I really think that that if you can bi-amp them with a seperate subwoofer, they can be pretty good desktop ESL.
   
  Wachara C.


----------



## dude_500

Quote: 





chinsettawong said:


> Hi Dude_500,
> 
> Just as Spritzer said, they weren't meant for full range speakers of reference quality.  All I wanted to point out was that they were able to be driven easily by a good Stax amp.  However, I really think that that if you can bi-amp them with a seperate subwoofer, they can be pretty good desktop ESL.
> 
> Wachara C.


 
   
  But isn't sitting on your desk or suspended an inch away from your ears with no earpads or damping practically the same thing? I know every electrostat I've ever made sounds pretty bad when held an inch away from sealing


----------



## chinsettawong

Quote: 





dude_500 said:


> But isn't sitting on your desk or suspended an inch away from your ears with no earpads or damping practically the same thing? I know every electrostat I've ever made sounds pretty bad when held an inch away from sealing


 
   
  Please remember that size does matter.
  You've got to try listen to a pair of good fullrange ESL.  
	

	
	
		
		

		
			




   
  Wachara C.


----------



## chinsettawong

I played around with bicycle inner tire diphragm tensioning method again yesterday.  The diameter of this jig was 400 mm, and I stretched the diaphragm to 1%.  Apparently 1% was too much.  I'll try 0.5 and 0.75% next time.


----------



## arnaud

What an interesting way to apply the tensioning wachara!! This seems so much cleaner method than the discrete weights.


----------



## spritzer

I love that last picture...  
	

	
	
		
		

		
		
	


	



   
  "You want tension..?  I'll give you tension...  "


----------



## chinsettawong

Quote: 





arnaud said:


> What an interesting way to apply the tensioning wachara!! This seems so much cleaner method than the discrete weights.


 
   
  It's actually a pretty good and easy tensioning method.  Once you get the right tension amount, you can repeat the same tension again and again with ease.  However, it wastes too much material.  
   
   
  Quote: 





spritzer said:


> I love that last picture...
> 
> 
> 
> ...


 
   




   
  Too much tension isn't good.  With these diaphragms, what I hear is that the dynamic and bass aren't as good.  Tomorrow, if time allows, I'll try 0.5% or 0.75% tension (2 or 3 mm) and will report back.  By the way, the Mylar I used was 3.5 micron.
   
  Wachara C.


----------



## chinsettawong

I made a smaller jig today.  I made a stupid mistake again by tensioning the diaphragm to 1% elongation(2 mm on this one is about 1%).  So I had the same result as the last ones.
   

   

   

   
  Well, I had to redo them again.  For this second time, I tensioned the diaphragm to 1 mm (0.5%) and they're better.  They sound very nice and stable now.
   
  If you guys want to try this technique, 0.4%-0.5% elongation on the 3.5 micron diaphragm seems to be right on target.
   
  Wachara C.


----------



## wakibaki

I just bought a 4 inch embroidery hoop:-
   
http://www.ebay.co.uk/itm/Elbesee-Wooden-Cross-Stitch-Embroidery-Hoop-Choice-of-Sizes/160923561289?_trksid=p2045573.m2102&_trkparms=aid%3D555003%26algo%3DPW.CAT%26ao%3D1%26asc%3D16548%26meid%3D477708376818621753%26pid%3D100034%26prg%3D7839%26rk%3D4%26rkt%3D4%26
   
  I was going to use it to tension some very fine wire mesh I bought to attach to a spider-type stator, but I guess it can be used for a tensioning jig for the diaphragm too.
   
  I still haven't got my CNC machine to cut the stator and diaphragm spacers yet, there were some problems with the electronics that I didn't get fixed before I went into hospital for surgery and I've been feeling a bit down 'cause I've started on chemotherapy. I'm still very interested in this project though, and I'm working on PCBs for a very straightforward amplifier I've designed using depletion-mode mosfets. The amp has a very low component count and cost and is intended to run off a 12V AC wallwart.
   
  w


----------



## chinsettawong

Hi Wakibaki,

Wishing you a speedy recovery. I'm very much looking forward to seeing your new amp.

About the wire mesh stator, believe it or not, I've bought the similar hoop that you bought and intended to do the same. But I haven't done it yet. 

Good luck.

Wachara C.


----------



## chinsettawong

I've got some updates on the inner tire tensioning jig method that I'm using.  Apprently, 1% elongation on Mylar is too much.  Since the elongation is so little using this small jig that it's very difficult to measure, I've found a new way to identify the right tension amount.  This time I purposely make some wrinkles on the Mylar.  I've found out that if you tension Mylar enough, all the wrinkles would be gone.  But when you see all the wrinkles are gone, the tension is too much already.  So, I tension the Mylar until the point where the wrinkles are almost gone, and this is what I get.
   

   
  Notice the wrinkles on the Mylar.
   

   
  This is before I pump the air into the tube.
   

   
  This is after I've pumped in some air and the wrinkles on Mylar are almost gone.  The elongation is so small that it's very difficult to determine the right amount by observing these lines.
   

   
  These are what I get.  Still the tension is just a little too much, but it's not too bad. 
   
  Wachara C.


----------



## shipsupt

Just a question out of pure curiosity... how much tension are you putting into the material?  Do you need to pump the tire up to a pressure like it was being used on a bicycle, or is it just getting slightly inflated?


----------



## chinsettawong

That's a question that I'm trying to find an answer myself.  At the very beginning, I was aiming for 1% elongation.  Then it was too much.  Anything less than 1% would be very difficult to make an accurate measurement.  If I have to guess now, I would say 0.3-0.5% elongation should be just right.  
   
  You can't really look at how much pressure you're putting into the tire, since you don't really put in that much at all. 
   
  Wachara C.


----------



## shipsupt

Quote: 





chinsettawong said:


> You can't really look at how much pressure you're putting into the tire, *since you don't really put in that much at all*.
> 
> Wachara C.


 
   
  That's exactly what I was wondering.  Thanks.
   
  This thread is always fun to read!


----------



## arnaud

Wachara, you've always been making your transducers like this? I mean gluing the tensioned mylar to the spacers rather than one of the stators.

Reason I ask this is that I don't imagine how such kind od spacer cam hold it's shape unless it's like 2mm thick aluminum ...

This current spacer looks like copper, but is it different from usual or you typical 1mm PCB?


----------



## chinsettawong

A little warping isn't a problem.  When I put everything together, I use plastic screws to hold them in place, and the spacer will be flat.  
   
  The spacer is my usual 0.5 mm PCB. 
   
  The trick is really to get the best suitable tension.  It's not so easy, but let's try.
   
  Wachara C.


----------



## Salm0n

Hey guys, sorry for a somewhat off topic post, but I can't think of anywhere better to post this question.
  I'm building a set of planars from scratch, parts are in the post, but I'm unsure as to how I should mount the mylar diaphragm to the frame holding the magnets. I was thinking about just using epoxy, but I dont know a lot about glues. What method(s) do you use for attaching the mylar?


----------



## chinsettawong

I use contact cement (rubber glue).


----------



## arnaud

And forget about magnets while you're at it, these are stators


----------



## Salm0n

Thanks for the advice Chinsettawong, I'll look into it.
   
  Haha, perhaps one day I'll get into e-stats, likely when I have the knowledge and money to build an amp to go with them, but 278 NdFeB cubes sitting on my desk tells me that this project is going to be about planars. If I can get a camera I may post a build diary to the DIY forum, but I'll stop with off topic posts to this thread for now, just couldn't think of a better place to ask.


----------



## wakibaki

Thanks for the good wishes Wachara C. I can't figure out which is your family name, and which is your given name.
   
  I fixed the electronics for my CNC mill, so got started trying to make some things.
   
  Here's my first attempt to cut a spider-type stator:-
   

   
  I think it needs slight changes to the dimensions, some mounting holes and some contact points, but it's definitely progress.
   
  Arrow sent me the IXYS depletion-mode mosfets eventually, but they charged me $44 for the shipping, the parts only cost $22 for 8.
   
  Here's the current state of the amplifier PCB design, they're 100*100mm, the PSU board (red tracks) sits on top of the amplifier board (blue tracks), the copper groundplanes are in between the tracks, on the bottom of the top board, and on the top of the bottom board, the supplies (680V and +/- 15V) drop down vertically to where they are required on the amplifier.
   
  The mosfets are driven by NE5332 opamps, and are arranged as a CCS-loaded long-tailed pair, with the IXTP01N100's doing duty in the CCS's as well as being the active devices.
   
  The amplifier has asymmetric voltage feedback taking advantage of the -15V negative rail, as in the Broskie 6SN7 electrostatic amp (http://www.tubecad.com/november99/page9.html). This maintains the bias conditions as well as providing distortion-cancelling feedback in the conventional sense.
   

   
  Simulation shows plenty of bandwidth and 0.08% THD at 250Vpk-pk differential, and although I have been stuck with using the Supertex DN2540 and hacked-about IXCP10M90 spice models, I think the sim. is probably not unrepresentative.
   

  The amplifier is AC coupled, hence the huge Wima polyester capacitors, but these are recommended as being distortion-free by Doug Self, and I see Broskie is not averse to using AC coupling in _his_ 6SN7 electrostatic amplifier
   
  The power supply uses just 2 transformers driven from a 12V AC wallwart, a 240~12V and a 240~15+15V. Roughly 680V is derived by using a conventional voltage-doubler.
   
  It's probably best not to say any more about the amplifier until I actually get one working. Perhaps that should be if, rather than until...
   
  w


----------



## jcx

for coupling to the ES stators I'd try NP0/C0G ceramic - say 2x 22nF 630 Vdc in series - better dielectric properties than Mylar and less chance of polarization induced piezo behavior - especially compared to the "squashed" oval wound film types which have varying tension, can "sing"
   
  for the IXTP01N100D I use the LTspice triode symbol and have a hand fitted gm subcircuit with fixed internal C, R0 from datasheet >25 Vds, ~10 mA Id curves
   

   
   
   
   
  hm - when did we lose file attachments?


----------



## chinsettawong

Hi Wakibaki,
   
  That ring looks really nice.  Have you measured the thickness of the wire mess that you're going to use?  What kind of glue will you be using to glue the wire and the ring together?  Epoxy?  
	

	
	
		
		

		
			




   
  I have really very little knowledge about electronics, so I can't give any comments on your amp design.  I'm just really looking forward to seeing your finished amp.  Good luck.
   
  By the way, my name is Wachara.  Chinsettawong is my surname.  Thai people call each other by their first name.  
	

	
	
		
		

		
		
	


	



   
  Wachara C.


----------



## spritzer

Same thing here but in Iceland we don't have surnames in that sense.  It makes checking into hotels very odd when nobody has the same last name...


----------



## chinsettawong

Quote: 





spritzer said:


> Same thing here but in Iceland we don't have surnames in that sense.  It makes checking into hotels very odd when nobody has the same last name...


 
   
  So there is no no family name in Iceland?  Then how can you tell that people are from the same family?
   
   
  I have just made two more pairs of diaphragm using the same technique I discussed before, and they turned out pretty good.  When you have enough tension on the diaphragm, if you press the headphone cup against your ear, you'll hear the noise of diaphragm collapsing to the stator and bouncing right back.  It's similar sound to that of the famous Stax's fart.  
	

	
	
		
		

		
		
	


	




  If not enough tension, then the diaphragm would be stick to the stator.
   
  Wachara C.


----------



## wakibaki

OK Wachara
   
  I have 2 sheets of stainless mesh, one is specified as 25 micron, the other is 30 micron as per this advert:- http://www.ebay.co.uk/itm/Super-Fine-400-E-Cig-Stainless-Steel-Mesh-0-3mm-A4-210-x-300mm-Bargain-/151102693460?pt=UK_Crafts_Other_Crafts_EH&hash=item232e6c2054. 
   
  I don't know whether this is the spacing between the wires or the thickness of the wires, but they are like a fine cloth. Quite heavy in the hand but feeling like silk. I think they will be pretty much transparent to audio. I need to pretension them before attaching them to the stator.
   
  Of course there are many types of mesh available, some of which are stiff and self-supporting, and I could easily obtain a different type.
   
  I was thinking of attaching the mesh to the copper using carbon conductive glue, like this:- http://www.ebay.co.uk/itm/Conductive-Wire-Glue-Paint-NO-Soldering-Iron-Gun-Solder-/320599571856?pt=UK_Home_Garden_PowerTools_SM&hash=item4aa5393d90 which I have already. I bought it to see if I could use it for making vias in doublesided PCBs but it didn't work.
   
  Thanks for the suggestions re. the capacitors jcx. 
   
  I've already bought these 0.1u 1250/600V Wima Polypropylene caps http://www.maplin.co.uk/polypropolene-capacitors-with-metal-foil-98162 since I have 1M resistors loading the amplifier outputs (on the schematic). I felt that the 1M res would be necessary to provide a defined ground return path for the bias voltage. I could of course change these to a higher resistance. I bought the caps on the basis of the tests in Doug Self's 'Small Signal Design' book.
   
  I do have some 0.1u 1kV ceramic disk caps on order, but these are intended for use as PSU decoupling for the amplifier proper, and they are not NP0/C0G.
   
  Broskie did complain about his output caps 'singing' which forced him to make a change. I wasn't aware, however, that NP0/C0G types were available in nanofarad ranges. I will probably proceed with the build using the caps I have in hand, but if I order the boards from a manufacturer rather than milling them myself, I will be sure to use a dual footprint to enable a change if it turns out to be necessary.
   
  Fred


----------



## spritzer

Quote: 





chinsettawong said:


> So there is no no family name in Iceland?  Then how can you tell that people are from the same family?


 
   
  Our last names are the first name of our fathers with son (son) or dóttir (daughter) added to the back.  There are some family names but they have always been frowned on. 
   
  As for the family, we have been isolated on this rock for 1000 years so pretty much everybody is related to some extent...


----------



## chinsettawong

Quote: 





spritzer said:


> Our last names are the first name of our fathers with son (son) or dóttir (daughter) added to the back.  There are some family names but they have always been frowned on.
> 
> As for the family, we have been isolated on this rock for 1000 years so pretty much everybody is related to some extent...


 
   
  That's so interesting.  I hope to visit Iceland someday.


----------



## chinsettawong

Quote: 





wakibaki said:


> OK Wachara
> 
> I have 2 sheets of stainless mesh, one is specified as 25 micron, the other is 30 micron as per this advert:- http://www.ebay.co.uk/itm/Super-Fine-400-E-Cig-Stainless-Steel-Mesh-0-3mm-A4-210-x-300mm-Bargain-/151102693460?pt=UK_Crafts_Other_Crafts_EH&hash=item232e6c2054.
> 
> ...


 
   
  Hi Fred,
   
  Looking at the picture, I think the mesh could be too fine.  But since you have it already, please try it.  
	

	
	
		
		

		
		
	


	



   
  By the way, if you think about it, the surface of wire mesh stator can't be absolutely flat due to the weavings of the wires.  The unevenness and irregularity of the electrostatic field might somewhat influent the sound.  Do you think that if we can find a piece of thin copper sheet and perforate it, won't it make better stators?  I have been thinking about this for a while and I have got a sheet of 0.1 mm copper on hand.  If time allows, I might just try it out.  
	

	
	
		
		

		
		
	


	




  What hole size do you think is good?  I wonder what the hole size is on SR009.
   
  Wachara C.


----------



## wakibaki

I think some of the Stax designs use wire mesh. Perhaps somebody could tell us the wire gauge and spacing. I'm thinking Stax must have done some research, and they should know what is best.
   
  I have some copper and brass sheet in various thicknesses, from ~0.1mm to ~0.5mm, I use it for making solder stencils for SMT soldering in a toaster oven. I use toner transfer and etch it to get the holes.
   
  I will certainly be trying a few different stator types when I get better at programming the CNC machine. I think I might make the first one PCB with holes like the many you have done so I can get started with something that other people have tried first, so I can get some advice if I have problems. The spider was just my first try at converting a dxf file.
   
  Fred


----------



## arnaud

I may be missing something but I don't see how a fin wire mesh could yield a proper electrode once mounted on a cart. 

In particular, I think you need a minimum of rigidity for the stators (at least some orders of magnitude stiffer / heavier than the film you're driving) so as not to cause distortion from stators vibration.

I believe it's a reason why some this stuff remains a bit of an art because all the design parameters compete with each other. You want an acoustically transparent stator but you need it rigid as well (that was a driver for the redesign if the electrode for the sr009). You want a fin diaphragm to more easily damp it and increase bandwidth but it hits back at you with additional resonances to deal with or fall at frequencies where they're least welcome.


----------



## spritzer

The SR-X Mk1 and the SR-Omega (maybe SR-2 but it has never been confirmed as if officially doesn't exist) used very tightly wound copper mesh for the stators.


----------



## chinsettawong

Quote: 





arnaud said:


> I may be missing something but I don't see how a fin wire mesh could yield a proper electrode once mounted on a cart.
> 
> In particular, I think you need a minimum of rigidity for the stators (at least some orders of magnitude stiffer / heavier than the film you're driving) so as not to cause distortion from stators vibration.
> 
> I believe it's a reason why some this stuff remains a bit of an art because all the design parameters compete with each other. You want an acoustically transparent stator but you need it rigid as well (that was a driver for the redesign if the electrode for the sr009). You want a fin diaphragm to more easily damp it and increase bandwidth but it hits back at you with additional resonances to deal with or fall at frequencies where they're least welcome.


 
   
  That's why you need a very study support for this kind of stator.  But how to properly stretch the wire mesh and glue it to its support would be a real challenge.


----------



## wakibaki

Quote: 





arnaud said:


> I may be missing something but I don't see how a fin wire mesh could yield a proper electrode once mounted on a cart.


 
   
  Perhaps you _are_ missing something. An experimental spirit?
   
  It's true that we all need to use our discretion to avoid indulging in useless experimentation.
   
  It seems, however, that your threshold for dismissing an experiment as useless is set at a different level from mine.
   
  When you theorize, what you are doing is guessing. You wouldn't need to do that If you had a comprehensive grasp of the inner physics of an electrostatic transducer. We are all groping here in the absence of good information.
   
   When I finish experimenting, I will not need to guess.

   
  Perhaps I should keep my ideas to myself for the sake of your peace of mind?
   
  w


----------



## chinsettawong

Quote: 





wakibaki said:


> Perhaps you _are_ missing something. An experimental spirit?
> 
> It's true that we all need to use our discretion to avoid indulging in useless experimentation.
> 
> ...


 
   
  Just do it, Fred!  It would be fun to see how it turns out.


----------



## arnaud

wakibaki said:


> Perhaps you _are_ missing something. An experimental spirit?
> 
> 
> It's true that we all need to use our discretion to avoid indulging in useless experimentation.
> ...




No need to get all worked up, and by all means share your findings! The point I brought comes from Stax interviews. 

On the physics side, besides working in the field of acoustics & vibration for 15 years and doing that stuff daily, yes, absolutely, I am still learning everyday about that stuff and experimentations of wachara and others greatly help...

So by all means, don't take it the wrong way and keep it on!

Cheers, arnaud.


----------



## chinsettawong

My friends and I have been trying to make the proper headband for these JF clone.  At the end, we come back to the one similar to what JF is having. 
   

   
  These phones sound really nice.  No kidding!  
	

	
	
		
		

		
		
	


	



   
  Wachara C.


----------



## spritzer

I think yours looks better than the new QA version.  
	

	
	
		
		

		
		
	


	



   
  Are you running at standard Pro bias for these?  Any issues with them being inefficient?


----------



## wakibaki

Hey, that is _cool_. I've been trying to come up with a headband design ever since I decided to make my own earcups. That looks simple to make but comfortable.
   
  Fred


----------



## chinsettawong

Quote: 





spritzer said:


> I think yours looks better than the new QA version.
> 
> 
> 
> ...


 

 Thanks Birgir.
   
  Yes, I run them using the standard Pro bias.  As far as the efficiency, I think they're as efficient as my other headphones.  KGSSHV 450V version is able drive them with ease.


----------



## chinsettawong

Quote: 





wakibaki said:


> Hey, that is _cool_. I've been trying to come up with a headband design ever since I decided to make my own earcups. That looks simple to make but comfortable.
> 
> Fred


 
   
  Hi Fred,
   
  I didn't want to copy the way Quad did, but I simply couldn't find a better and easier way to make the headband.  I am lucky that I use the double sided PCB for the back cover.  I simply solder the wires onto the back cover.  I think I'll sand the whole thing and give it a black paint to finish it off. 
   
  We'll have a DIY meeting this coming weekend.  Let's see how my other friends like these headphones.  
	

	
	
		
		

		
		
	


	



   
  Wachara C.


----------



## spritzer

Quote: 





chinsettawong said:


> Thanks Birgir.
> 
> Yes, I run them using the standard Pro bias.  As far as the efficiency, I think they're as efficient as my other headphones.  KGSSHV 450V version is able drive them with ease.


 
   
  That's what I thought would happen which makes the QA choice of double the Stax bias even more bizarre.  It also meant they didn't have to design anything but if it was Stax compatible they could actually make a dent in the market.


----------



## chinsettawong

I'm sure QA uses much thicker spacers and so they have to go with much higher bias voltage.
   
  Here are some detail information about my newest headphones.
   
  1.  Diaphragm active area:  76 mm x 120 mm
   
  2.  Spacer material and thickness:  0.5 mm single sided PCB
   
  3.  Stator material and thickness:  1 mm single sided PCB
   
  4.  Diaphragm:  3.5 microns Mylar
   
  5.  Diaphragm elongation (tension):  about 0.4-0.5%
   
  6.  Bias voltage: 580VDC
   
  Wachara C.


----------



## chinsettawong

I'm trying out the headphones with my Stax SRM-252A right now, and to my surprise, the amp has no problem driving these headphones.


----------



## spritzer

The QA has higher bias (1200V) but also much higher drive voltages.  That in it self is fine but I really don't see the need for it and I can just see it being a bad thing.  The real problem with the Floats is that they started life using OEM drivers from the US and when they switched to making them, they just copied the design part for part.  Sorta the same as with the current Quad speakers.  Nobody there has even an inkling on how to improve on the ESL63 aside from useless cosmetic details and addons that don't do anything.


----------



## thune

*If* I'm getting this right, an unsealed configuration (no pads, free air) for an electrostatic driver will show a nearfield acoustic resonance peak and rolloff in the bass. I apologize if this has already been explained: but how is this avoided/controlled in QA/Float style headphones, just with proper tension or with damping or something else?


----------



## chinsettawong

Hi Thune,
   
  It is true that the bass rolls off with the unseal configuration, but you compensate that with bigger diaphragm area.  The music sounds more natural this way too. 
   
  Wachara C.


----------



## thune

Is there any bass resonance or peak, or does the response seem flat until it rolls off?


----------



## arnaud

From my experience with Stax headphones, you should see quite a bit of an overshoot at the free air resonance. It's mostly controlled by the material I think so wachara's set must be doing the same thing. 

Now, if the free air resonance is low enough, that may not be objectionable, or even enhancing the experience as wachara puts it. 

I would have though you need some kind of low pass filter to compensate for the front back cancellation though but it seems wachara experienced that if the area is large enough you can get by (this is very nearfield after all so you may indeed limit the cancellation effect by keeping the radiation surface large).


----------



## chinsettawong

One of these days I should learn to make some measurements as I can't really tell anything about the resonance.


----------



## arnaud

Am happy to measure these for you if you send a pair my way wachara


----------



## chinsettawong

Which ones do you like?


----------



## arnaud

I am quite curious about your open baffle transducer and your sr-omega replica (the one you prefer over the 009)! Both can be driven by pro-bias amp right?

I have returned my in-ear mics because I had matching and snr issues but this would motivate me to restart working on this test rig! I can measure on a flat baffle of coarse but it'd be nice to have a calibrated response instead...


----------



## chinsettawong

No problem.  I can probably send them over to you maybe at the end of next month.  Let me show them to my Thai friends here first.
   
  Here is how they look today.  With the additional elastic bands at the front and back, the phones now can be sit on the head more securely.  I'm now very happy with them.
   

   

   
   
   
  Wachara C.


----------



## arnaud

Awesome wachara, that will give me time to prepare too


----------



## AnakChan

arnaud said:


> Awesome wachara, that will give me time to prepare too


May I put up my hand to have a demo of it when you receive it please? With Wachara's permission, naturally.

Happy to bring the Invicta over to hook up to your amp, & bring lunch with a bottle of wine over to your place, let the kids play & the wives talk.

I'd _love_ to give this DIY a listen .


----------



## chinsettawong

Quote: 





anakchan said:


> May I put up my hand to have a demo of it when you receive it please? With Wachara's permission, naturally.
> 
> Happy to bring the Invicta over to hook up to your amp, & bring lunch with a bottle of wine over to your place, let the kids play & the wives talk.
> 
> ...


 
   
  Hi Anakchan,
   
  I'll be so glad if you could try them and let me know your impression.  
	

	
	
		
		

		
		
	


	



   
  Wachara C.


----------



## arnaud

anakchan said:


> May I put up my hand to have a demo of it when you receive it please? With Wachara's permission, naturally.
> 
> Happy to bring the Invicta over to hook up to your amp, & bring lunch with a bottle of wine over to your place, let the kids play & the wives talk.
> 
> I'd _love_ to give this DIY a listen .




Sounds like a plan . Let's give some time to wachara to get the shipment ready and for me to get the measuring rig to the next level...


----------



## chinsettawong

How do you like them in black and white.


----------



## spritzer

Now that does look good.


----------



## hifi2all

Wachara, do you prefer the sound of the last speakers to your previous projects?


----------



## chinsettawong

I did a comparison listening test yesterday between my previous oval shape and the new headphones.  What I heard were very different sounds between the two.  The new phones sound very relax and laid back while the oval shape one had more details and aggressiveness.  
   
  About the efficiency, the oval shape was about 10-15% more efficient.  To get the same listening level, I had to turn up and down when changing the phones.  
   
  I think the main thing that makes them sound so differently is the fact that one is seal while the other is open.  This also affects greatly on their efficiencies.
  It's very difficult to say which ones sound better because they are very different.  I like them both very much though.  
	

	
	
		
		

		
		
	


	



   
  Wachara C.


----------



## chinsettawong

Before going to the annual Thai DIY Audio meeting, I had to cover up the back side of the phones so that people would not stick their fingers inside and get a shock.  I looked around the house and finally decided to use my wife's stocking.  
	

	
	
		
		

		
			





  I actually heard a few people really like to use the stocking as a damping cloth on their ESL. 
   

   
  I took with me the new phones, the oval shape ones, and KGSSHV to the meeting.  Many people had never heard of electrostatic headphones before and were very interested to come and try my phones. 
   

   
   

   

   

   
  Guess what?  About eight out of ten people who tried the phones like the sound of the new ones better.  However, they all complained that they looked very ugly.  I had to show them how JF looked and they all laughed.
   
  Let me show you how crazy Thai DIYers can be.  We have a WE212 SE amp at the meeting.  The tubes are huge.  
	

	
	
		
		

		
		
	


	



   

   

   

   
  The 845 tubes in front of WE212 look so small in comparison. 
   
  Wachara C.


----------



## arnaud

That's commitment! The person who brought the speaker rig with the huge tubes amp deserve a couple of beers from all the attendees...

Glad to hear your latest creation was well received wachara, makes me even more curious. I think it will be difficult to get you to part with it for a while .

I made some progress here and received microphones that have good potential. Probably in a few weeks time I will be ready to measure your cans. The open baffle seems to be quite close to the ears from the pics above (like resting on the ear). Is that right? That may cause additional challenge to measure these...


----------



## spritzer

The Floats are open baffle so measuring them will be rather difficult. 
   
  Those WE212's are nuts.  Love the pic with the amp on one side and tinkering with it turned on.  Only one hand though...


----------



## arnaud

Quote: 





spritzer said:


> The Floats are open baffle so measuring them will be rather difficult.


 
   
  For a while, I had some really tiny mics that fit right inside the concha. They would have been perfect for this expect the SNR and matching was plain terrible so I returned them. The current ones might indeed present some challenge.


----------



## wakibaki

I found some 5mm green perspex in my scrap bin, so I started thinking I could build up some cups out of hoops. Now it's a bit late to run the CNC because of the noise, so the last few are going to have to wait until tomorrow.
  

  
 Anyway, to keep from getting bored I did some CAD... these are 5 stacked rings.
  

  
 I figure I can make a stretcher for the wire mesh out of 2 concentric hoops, just like embroidery rings.
  
 I'm having a lot of difficulty turning gerber files into isolation milling gcode. Does anybody know of a free program that does gerber2gcode reliably? There are a few out there, but I'm getting tired of trying them out only to discover they don't really work.
  
 w


----------



## Congo5

LineGrinder is free but seems picky about the gerbers and settings. only free one I could get to work so far.
 also the Gcode is not optimized and caused a lot of stops and starts...(slow)
 which can be fixed with Opti   http://pcbgcode.org/read.php?6,5
  
  
 cambam works well for me..  the trial is limited to 40 starts, which if left running....
 Plenty to see if you want to spend $150 on..


----------



## wakibaki

I figured out what the problem with engraving the PCBs is, my demo version of Mach3 is refusing >500 lines. I thought the license I was given was good. Time to move to LinuxCNC, I think.
  
 Making some progress with the cups. Need to trim the bolts...
  

  
 Looking at it now, I'm a bit concerned that the 'ears' might break, it occurred to me that I can make this in 3 main parts, the centre piece from aluminium, the outer rings wood, say mahogany.
  
 I've ordered up some alu sheet.
  
 w


----------



## chinsettawong

That's a nice looking cup. 

I'm glad you've found the real problem with your g-code. I only use Linux-CNC, and it's perfect for me. You should try it.


----------



## wakibaki

I downloaded LinuxCNC. Now I need a second hard disk.
  
 A trial fit of stators:-
  

  
 Aluminium plate came today, but I blew up my PWM controller for the CNC spindle, so waiting for IRF740 FET.
  
 w


----------



## chinsettawong

That looks nice. 
	

	
	
		
		

		
		
	


	




 
  
 By the way, what hole diameter are you using on your stators?  The holes seem pretty big.
  
 Wachara C.


----------



## wakibaki

Those are 3.175mm, 1/8 inch, the size of my general milling bits. The overall outside diameter of the cups is 100 mm, the ring thickness is 7mm, with an additional 7mm for the inner mounting ring. That makes the stators 82mm dia. with 2mm clearance to the cups. I think overall the cups could be a bit bigger, but I had to start somewhere, 100mm is the number I picked...
  
 Got LinuxCNC loaded onto a disk, it was hell's own job to get it to see my network storage disk, but eventually I got it to work with FTP.
  
 w


----------



## dude_500

The shop I work in got a big nice CNC mill, so I figured I'd take DIY stators to a new level. Just finished the first stator for my upcoming Orpheus009 headphones. Takes more than 4 hours to make a stator, but they are beautiful! Made of stainless that is 1.2mm thick pocketed to 0.4mm. Overall transparency is approximately 50%.


----------



## chinsettawong

Hi Dude_500,
 The stator looks really nice.  
	

	
	
		
		

		
		
	


	



  
 What is the dimension of your stator?  How will you insulate it?
  
 Keep us posted of your progress.  
	

	
	
		
		

		
		
	


	



  
 Wachara C.


----------



## dude_500

The active area is 84mm x 122mm. Much larger than any other headphones I've made. 
  
 The stators are insulated and held with FR4 frames, and then just join the typical sandwich. This also helps eliminate unnecessary capacitance. I'm using 0.8mm diaphragm spacers instead of 0.5mm since the diaphragm is so big.


----------



## chinsettawong

That's a nice and big active area.  I still don't understand how you will insulate your stator.  Will you powder coat it or will you spray paint it with some plastic paints?
  
 The spacer thickness of 0.8 mm is too much, IMO.  If  I were you, I would try 0.6 mm or 0.7 mm.  You'll also need to increase your bias voltage higher. 
  
 Let us know how it goes.
  
 Good luck.
  
 Wachara C.


----------



## dude_500

chinsettawong said:


> That's a nice and big active area.  I still don't understand how you will insulate your stator.  Will you powder coat it or will you spray paint it with some plastic paints?
> 
> The spacer thickness of 0.8 mm is too much, IMO.  If  I were you, I would try 0.6 mm or 0.7 mm.  You'll also need to increase your bias voltage higher.


 
  
 For the metal itself, I was just going to leave it as is. I've not had a problem with exposed metal on the stators in my previous builds. If I have any issues, I suppose I'll spray paint the inner-face as I've done on some PCB stators. I don't anticipate any safety issues with sweat/dust screens and meshes on both sides of the driver. 
  
 I'll start out with 0.8 as I've already cut the parts, but if it's not efficient enough I'll keep those numbers in mind!


----------



## chinsettawong

I have to confess that stretching Mylar to the right tension is extremey difficult.  When I give it too much tension, the bass is gone.  With too little tension, the diaphragm loses its stability.  Using the inner tire stretcher, even though its very easy to work with, it's rather difficult to make it just right, since you need to stretch the mylar so little and it's very difficult to measure the exact elongation.  Using the clip and weight method, you'll need a helping hand, otherwise the diaphragm can break easily.
  
 I've redone the diaphragms on my new open buffle headphones so many times that I have lost count.  I decide that I would go with a little less tension to get the bass and increase the spacer thickness just a little to make the diaphragms stable.  I find it very easy to add the extra thin spacer in between the stator and spacer.  I cut a thin plastic sheet which measures around 0.1 mm and put it in between the stator and spacer.  So the new spacer thickness now becomes 0.6 mm.  The phones are a little less efficient now, but the bass is good, so I'll leave it like this.
  
 Wachara C.


----------



## wakibaki

Nice looking stators, Dude. Have you thought about perhaps making the segments equal areas? Although of course, this might just make the system have more pronounced resonances. It's a bit of a problem not having access to a body of research on these subjects
	

	
	
		
		

		
			





.
  
 I'm having trouble ATM trying to figure out how to make diaphragm spacers/supports. 0.5mm PCB is virtually unobtainable here, and shipping from the US is prohibitive. Maybe I can mill the 1.6mm stuff down to thickness. I still have to face the mylar stretching problem.
  
 On a brighter note, I got LinuxCNC (EMC2) up and running, it's head-and-shoulders above Mach3 IMO, and free too. If anybody's contemplating trying CNC, turn over a hard disk to a Linux install, forget Mach3.
  
 w


----------



## n3rdling

What do you like more about LinuxCNC?  From what I gather the UI is like a normal computer program whereas mach3's UI is made to mimic a DRO on a machine.  I'm getting used to mach but I'll admit it's not the most intuitive program to use. 
  
 Those stators are pretty cool, but in the interest of consistency I'd make the areas equal and I'd use plastic bracing so that the electrostatic field isn't altered by the spokes.
  
 I never got around to posting when it was being discussed, but the main advantage of wire stators is immunization to corona discharge.


----------



## dude_500

I hadn't even considered the implications of that geometry. There's no way I could make the pockets the same shape since it's an oval, but I suppose I could do same area. I can't imagine the difference being perceptible, but who knows.
  
  
 Anyways, I tested the flatness of the stator I machined and it's not really going to cut it. Turns out the pocketing milling forces caused the bottom to punch out since the surface was pulled up into the end mill while cutting. I may be able to solve that with a straight-flute end mill, or alternatively I'm also considering getting it done on EDM.
  
 I'm going to turn the stainless stators into a long term project. So that I can get my mind off these headphones and back to studying, I just cut some FR4 stators and built the headphones this weekend (besides, I'd want a direct comparison anyways after putting all this work into the stainless). They sound beautiful compared to my 007 clones. The sound stage is huge in comparison, and they really fill in the treble response which my 007's were a bit weak in. Also the bass is incredibly dynamic and punchy, unlike anything I've heard in any other headphones. I'd guess almost surely just due to their size.
  
 I'll have to end up increasing tension because as predicted with the 0.8mm spacers, they're not all that efficient. I'm only at 280V bias right now though so it should be fine with more voltage on that and a bit more tension to keep it stable (since I'm not exactly worried about losing some bass).


----------



## chinsettawong

Hi Dude_500,
  
 As you have noticed, the size of the drivers does make a difference.  
	

	
	
		
		

		
		
	


	




  You definitely get a bigger sound stage and more dynamic. 
  
 Are you biasing at 280V for your 0.8 spacer thickness?  That's way too low.  You won't have enough juice to feed the phones even with your KGSSHV.  At least you should try 580V, IMO.
  
 By the way, your headphones look great.
  
 Wachara C.


----------



## wakibaki

I was very grateful for the evaluation version of Mach3 initially. It allowed me to get some results quickly and I didn't have the enormous hassle of making a Linux machine see my Network Attached Storage disk, so I could just send CAD-originated gcode from anywhere.
  
 With EMC2 I had to cope with the fact that my Linux is very rusty, but once installed and networked I found it more intuitive. It's possibly true that it's a computer user's program, rather than a shop-floor miller's program, because I found everything I needed just by looking in the menus. CNC has moved, anyway, from being a blue-collar machine-driver's game to being a creative outlet for designers.
  
 Mach3 crashed the bit into the table, twice blew a fuse and a FET because it sometimes corrupts the axis positions when you load a new program going from metric to imperial (or the other way, I'm not sure), I found I had to check for that before every machine start.
  
 EMC2 has several toolpath display options in 2D and 3D, showing table limits. Smooth graphics. The display in Mach3 is primitive, difficult to manipulate with keypresses + mouse to zoom and pan, and Mach3 frequently loads programs out of scale.
  
 Mach3 hits you with a zillion on-screen functions many of which are really irrelevant and only run the risk of swamping the user with options. CNC is really all about gcode and writing gcode or creating it by exporting from a CAD program, not being able to override the current settings, such as feed rate, from the control panel. That's what we call '**** on a bull'. Most of the buttons on an industrial DRO stay clean. They're just there to baffle the apprentices.
  
 EMC2 has very few on-screen controls. You can set the jog spacing to a variety of steps from 0.005 mm to 5 mm to continuous. Brilliant when you want to get an axis back to 0. That's about the only on-screen control, the jog, apart from homing the axes, start, emergency stop. I had to write a program to zero an axis for Mach3.
  
 EMC2 has a much more _reliable_ feel, more worked-out, more polished. Night-and-day is an overworked metaphor in audio, but that's what I thought when I changed over. I have a lot of complaints about Linux, and the guys who wrote it not having any consideration for users, but I really feel that EMC2 is function-focussed and built by guys who really knew what they were doing in terms of creating a useable, useful interface.
  
 And then it runs 500+ lines of code for free, if you have a hard disk spare, which I had. I'd already run into the 500 line barrier when trying to rout PCBs. That's $150 to spend on bits or materials.
  
 w


----------



## chinsettawong

n3rdling said:


> What do you like more about LinuxCNC?  From what I gather the UI is like a normal computer program whereas mach3's UI is made to mimic a DRO on a machine.  I'm getting used to mach but I'll admit it's not the most intuitive program to use.
> 
> Those stators are pretty cool, but in the interest of consistency I'd make the areas equal and I'd use plastic bracing so that the electrostatic field isn't altered by the spokes.
> 
> I never got around to posting when it was being discussed, but the main advantage of wire stators is immunization to corona discharge.


 
  
 There are a few UI on LinuxCNC that you can choose to use.  The program running under Linux is very reliable and free.  I can't ask for anythng more.  
	

	
	
		
		

		
		
	


	



  
 When you say that wire stators are immune to corona discharge, do you mean that because the wire is round and the there is no sharp adge so that there is no corona discharge? 
  
 Wachara C.


----------



## n3rdling

waki thanks for that write up.  My Mach3 is licensed, but I might check out EMC2 since the toolpath views look way better.  I don't know much about Linux though, so I will probably run into problems there.  What kind of speeds and feeds are you guys achieving on your PCB/MDF cuts?
  
 Quote:


chinsettawong said:


> There are a few UI on LinuxCNC that you can choose to use.  The program running under Linux is very reliable and free.  I can't ask for anythng more.
> 
> 
> 
> ...


 
 Yes precisely


----------



## chinsettawong

Hi n3rdling,
  
 Try EMC2 and you'll love it.  
  
 My max feed rate is around 4800 mm/min.  When drilling holes on my stator I run the feed rate at around 3600 mm/min.  But when routing and cutting, I slow it down to around 1800 - 2400 mm/min.
  
 My CNC mill has ball screws.  The pitch is 5 mm.  I use unipolar stepper drivers running at half step.  I've got the Gecko G540 driver but haven't had time to hook it up.  I'm sure that by using Gecko G540, biploar drivers, I can run a little faster.
  
 Wachara C.


----------



## dude_500

chinsettawong said:


> My max feed rate is around 4800 mm/min.  When drilling holes on my stator I run the feed rate at around 3600 mm/min.  But when routing and cutting, I slow it down to around 1800 - 2400 mm/min.


 
  
 You cut FR4 at 1800-2400mm/min? I'm confused, I cut it at 100-200mm/min. Do you do tons of extremely shallow passes?


----------



## chinsettawong

dude_500 said:


> You cut FR4 at 1800-2400mm/min? I'm confused, I cut it at 100-200mm/min. Do you do tons of extremely shallow passes?


 
  
 With 1 mm FR4, it takes just 1 pass at that speed.  And I thought I was cutting too slow.


----------



## wakibaki

wakibaki said:


> So you apply the antistatic fluid to one side of the diaphragm only? I would have thought you could double the force on the diaphragm if there is twice as much charge distributed on it...
> 
> w


 
  


bidoux said:


> The equation that rules the way the diaphragm moves only considers the difference in voltage thus it is not necessary to double coat the diaphragm.


 
  
 If you take a look at the section "DISTORTION IN ELECTROSTATIC LOUDSPEAKERS: Feb 1956" on this http://douglas-self.com/ampins/wwarchive/wwarchive.htm#diel page of Douglas Self's site (The Wireless World Archive), you will see why it is absolutely necessary to consider the charge on both sides of the diaphragm.
  
 w


----------



## n3rdling

I don't think it's really necessary.  The displacement is miniscule at the diaphragm thicknesses we're using: 1-3 um.  If you wanted a perfect match of fields I guess you could coat both sides, but this has two disadvantages: a near doubling of the membrane weight and loss of the greatly improved environmental immunization of the uncoated side.


----------



## wakibaki

What I'm talking about is *understanding* the forces inside the driver. As long as you persist in the view held by bidoux, you'll never understand what's going on.
  
*You* may not think it necessary to consider the charges on both sides of the diaphragm, but perfectionists will never be satisfied as long as a potential source of distortion is ignored.
  
 2 other things, I don't know where you got them. Doubling of the membrane weight. This would mean that the coating vastly outweigh the mylar. I don't know what numbers you have to justify this, but you should post them in the same post where you make the assertion, not just throw it in with no substantiation. 'Loss of the greatly improved environmental immunization of the uncoated side'. I don't understand what you mean by this, and I don't know which 'immunization' mechanisms you refer to.
  
 w


----------



## n3rdling

Umm..OK.  I hope I didn't hurt your feelings as it seems you took offense for some odd reason.  I think I made it clear what I considered the pros and cons of each method.
  
 What do you want to know about the forces?  Constant charge, charge migration, and displacement are nothing new and have been discussed on HF in the past (I can't recall the threads but I'm sure this thread has information on those already). 
  
 I agree that there will be people that want to get rid of any potential distortion and that's a good thing.  I was just pointing out that the displacement is so small that the added distortion is going to be very small as well.  Here's the thing though: displacement will still exist to some degree depending on how evenly you coat the sides.  I think it would be really hard to get the exact same amount of coating on each side of the membrane by hand.  In fact, you could theoretically end up with *more *displacement than if you had just coated one side from the start.
  
 I'd wager that the coating outweighs the membrane pretty significantly.  Of course this will depend on which coating you decide on as well as how much you apply.  If you can provide me with exactly how much coating you are using on a single side I can provide you with numbers. 
  
 Regarding my last statement, I'm simply talking about the uncoated side of the membrane (in conjunction with the stator on that side) being much more immune to things like dust and humidity since the membrane is essentially insulated on that side.  wachara can correct me if I'm wrong but I think this is why he chooses to coat one side. 
  
 I'm not trying to discourage you from coating both sides.  This thread is all about experimentation.  I think you should try both methods and report your findings.


----------



## wakibaki

n3rdling said:


> Umm..OK.  I hope I didn't hurt your feelings as it seems you took offense for some odd reason.


 
  
 No offence taken. I simply had a technical disagreement with bidoux. I asked the question about coating both sides. He replied with a totally spurious answer regarding voltages and spewed up a load of irrelevant equations in justification of his answer. I came across a simple discussion of the issues with a mathematical description of the situation that I could show easily with a link. Then you jumped in with an attempt to dismiss the issue, which I thought ill-considered and unsubstantiated. I'm not interested in what you're prepared to bet on, sight unseen. If the weight of the coating is significant, then perhaps we need to think about the nature of the coating.
  
  
 If these issues have been discussed previously no-one went to the trouble to provide links to where they were discussed or to simply sum up the conclusions.
  
 w


----------



## n3rdling

As long as you don't put gobs of coating (depending on which type of course) on both sides it shouldn't make much audible difference - the 3 dB roll off point will still be supersonic.  As you said though, "perfectionists will never be satisfied".


----------



## dude_500

This is very interesting. I'm doing a rigorous physics analysis to see exactly how important this single-sided coating distortion is, and to find out if it is irrelevant or not compared to driving forces.
  
 I've been working the math here and taking it a bit further in analysis for a few hours and as best I can tell the paper is spot on, and putting a coating on both sides will remove a source of distortion (it is crucially important that both have their own bias resistors, though, or all benefits are gone... I wonder if any retail headphones have ever done this?).
  
 Does anyone know what the typical diaphragm displacements are at a reasonable listening level? I don't have even a ballpark estimate, and it is of great importance to the analysis of this source of distortion as the distortion is highly non-linear with displacement
  
  
 One thing this brings out is that lower bias and more drive voltage has to have less distortion, because you increase the drive force to distortion force ratio. Of course this would increase amplifier distortion, so it's hard to say what the sweet spot would be without enormous analysis, and it would be specific to every amplifier topology.


----------



## wakibaki

As n3rdling has pointed out, there are some difficulties in getting the coatings on both sides identical. Then there's the problem that the membrane itself should be an insulator (although I imagine Mylar _is_), and the question of feeding through 2 resistors.
  
 The diaphragm supports (spacers) will need to be polished free of the slightest trace of swarf, as a tiny piece of copper could penetrate the membrane and produce a short. Perhaps it would, in fact, be easiest to simply coat one side...
  
 There's a suggestion in the papers I linked that the membrane should be untreated and that reliance should be on the surface resistivity of the diaphragm being high, but not as high as the bulk resistivity of the diaphragm material.
  
 As regards the diaphragm displacements, they're less than +/- 0.5 mm, certainly in the case of Wachara's, he mentions that occasionally the diaphragm contacts the stators when things go wrong.
  
 I'm just trying to glue up my first membrane, I'm using the water-based carbon glue that's advertised as 'wire glue'. I don't even know if it will dry when it's covered with Mylar.
  
 w


----------



## arnaud

I'd have to look at the simulations I ran again but my recollection was that you could get in the +/- .3mm rms displacement at high SPL around the first resonance (50Hz or so) for the sr009. So much so I once thought the hole in the center of the stator had some to do with this...


----------



## chinsettawong

Hi W,
  
 Are you going to use the carbon glue so that both sides of the diaphragm can be energized?  Since the diaphragm will be very highly stretch, I doubt if this water base glue is going to do the job.  The best glue I would recommend is the contact cement or the yellow rubber glue. 
  
 I've never tried coating on both sides of the diaphragm, but it certainly will be fun to find out if it will be beneficial.
  
 Wachara C.


----------



## chinsettawong

Regarding the spacer thickness, it all depends on your driver's dimension.  You can go as thin as you want, but then you need to stretch your diaphragm so much that it'll not collapse to one side of the stators.  When you do that, you lose the bass.  To my experience, for the diaphragm width of 78 - 80 mm, 0.5 mm is probably the thinnest you can use.   With Stax Lambda type of driver which has the diaphragm width of only 50 mm, the spacer thickness can go much thinner.  And that's why Stax Lambda series are more efficent than the Omega series.
  
 Wachara C.


----------



## dude_500

wakibaki said:


> There's a suggestion in the papers I linked that the membrane should be untreated and that reliance should be on the surface resistivity of the diaphragm being high, but not as high as the bulk resistivity of the diaphragm material.


 
  
 It's a great suggestion, but unfortunately it just doesn't work, the surface resistivity is simply too high at least for mylar. I've tried uncoated diaphragms, it never charges to make any sound at all.


----------



## schorsch

I





chinsettawong said:


> Stax Sigma sounded very interesting.  To clone it would be fun.



Dear Wachara 
I aufgestellt this teo Times )
In The next Weeks I'll try

Regards Geoeg


----------



## arnaud

I have received two of Wachara's creations here and color me impressed!
  
 Only little time spent so far, with the Omega clone, and I like what I hear. It's sort of a mix of Omega 2 mk1 and SR009 through my amplifier.
  
 I'll start with the cons, which all seem to point to a lack of juice on the amplification. It seems like a tough cookie to drive, I don't get much extension at both ends of the frequency range, the imaging is quite Left/Right/Center, and it overall sounds quite sleepy on my stock 727 amp.
  
 Now for the pluses. I absolutely love the natural voicing and non-agressive nature of the phone. It reminds me very much of the 007mk1 in that regard. When listening to the 009 just after, I do hear much more detail but the tonality does seem off with some voices in the sibilance region (as if I could hear the same dreaded nasal coloration of some more recent generations of Lambda headphones). I have to spend more time to get a handle on this but, so far, the Omega clone is very gentle in the way it presents treble, very different from the 009. Even though I cannot get a proper seal, the bass is not bloated like it gets with an 007mk2. Overall the tonal balance is quite good, very pleasing and non-agressive, good presence and body, very far away from the stereotypical ethereal attribute of stat phones actually. 
  
 I suspect the observations above on the Omega clone would change drastically with some beefier amplification but that's all I got with me for now (it might change soon).
  
 I haven't even started to play with the open baffle can, looks like some busy schedule ahead .
  
 MANY THANKS to Wachara, the man has got talent and great ears too, I could not dream of being to make and tune that stuff all by ear myself!
  
 Arnaud


----------



## arnaud

Just started to listen to the open baffle phones, oh my... Wachara, you're a genius at this! This time the imaging is fantastic as well as the treble extension. The bass rolls off but the mid-bass quantity is plenty to make it sound quite balanced overall.
  
 Also, on the Omega clone, I get totally different response by pressing the cups a little so as to ensure the seal. In particular, it then goes down right to the sub-bass region. I think I will be making a few different measurements later on (the open baffle might be tricky though, as suspected).
  
 Arnaud


----------



## chinsettawong

Hi Arnaud,

I need to point out to you that the phones you were hearing weren't Omega clone. They're more or less my own version of the Orpheus. The phones are of Oval shape. I actually prefer the sound from these than the Omega clone.

When you compared them to Stax SR009, you'd noticed that the SR009 was more efficient. My phones are more like SR007 and should need a beefier amplifier, unfortunately. 

The open baffle phones would need even more power to drive. Have you got any other more muscular amplifier? 

Wachara C.


----------



## arnaud

Wachara, 
  
 Thanks for the clarification, I keep mixing things up. Ok, Orpheus clone makes more sense given the shape & size .
  
 Quote:


chinsettawong said:


> Have you got any other more muscular amplifier?


 
  
 Working on this . Honestly speaking, I can feel the potential and it's pretty darn awesome already!


----------



## dude_500

Tonight's project was a bias knob on my PSU. A knob that everyone making electrostatic headphones should add to their power supplies immediately! It is extremely fascinating to be able to scan the bias from zero to high without having to re-wire anything.
  
 The following data was collected at a variety of biases. One channel was tested, and the test fixture was completely untouched between all data collections, so this data is not contaminated by experimental error. The earpad was sealed to the text microphone panel. The results really surprised me, especially the THD!
  
 It seems that as bias is lowered, treble gain increases at the 500hz crossover point (whatever that crossover is, seems to be in all electrostatic headphones, DIY or not). In fact that is exactly what I first noticed in listening. As bias increased, treble harshness decreased and relative bass amplitude increased.
  

  
  
 I'm now loving my new headphones even more at 780V bias. A noticeable and significant improvement over 400V!


----------



## chinsettawong

With your thick spacer, you should try them at 900-1.2 KV. You might find them even more interesting. 

Wachara C.


----------



## wakibaki

Here is a very nice stretcher:-http://www.ebay.co.uk/itm/24x24-Screen-Stretcher-Mesh-Stretching-Tension-Too-3-yards-Silk-Fabric-as-gift-/160965481632?pt=LH_DefaultDomain_2&hash=item257a4a54a0, but very expensive. I'm thinking I could maybe make something like this, maybe with a couple of vices screwed to a piece of board, or maybe even just some threaded rod and make some pieces with the milling machine...


----------



## chinsettawong

Hi Wakibaki,
  
 That kind of stretcher is too good for our application.  It's too big too.  I spent less than US$10 into making my inner tire stretcher.  I went to a bicycle shop and asked for the smallest inner tire that they had available.  It costed me only around US$3.  I then searched around my house and found some scrap woods.  I cut, glued, and put everything together.  Even with this cheap stretcher, I still think that it's too good.  The problem is that I don't really need to stretch the diaphragm that much.  If you can find a helping hand, I think the stretcher using clips and weights is better.  It's easier to repeat the process too.
  
 Wachara C.


----------



## wakibaki

Yes, of course that stretcher is overkill, but it shows a technique and a machine design that can be copied. I want to try making a stator with that fine stainless steel mesh I found, I want to be able to apply some force to pretension it because I think that it'll be possible to make a more rigid structure that way, in the same way that aircraft have stressed skins. This is how I was hoping to avoid the problems with stator flexing that were brought up.

I looked at your inner tube stretcher, but I couldn't tell exactly how it worked from the pictures. Perhaps you could write a short description of how it works to make things clearer for the rest of us, if it's not too much trouble.

After some experimentation with spindle speeds, depth of cut, feed rate, and particularly lubrication, I've succeeded in getting my CNC to cut the 1050 aluminium plate that I bought. It's taken me a long time, but I'm hoping to have a finished headphone in a week or so. Because I'm still recovering from surgery and chemo, I'm tired a lot of the time, so sometimes days go by and I get nothing done, but it means that I've had time to think about the mechanical design and modify it. I'm a bit more confident that the cups will actually hug my ears now.

I ordered a pair of velour covered pads 100 mm diameter, they fit the cups perfectly. Cool. Something I don't have to make from scratch.

I've also done some CAD drawings of the amplifier case. I found a digital voltmeter to display the bias voltage which I've decided to make variable. With the CAD drawings I think I have reasonable hope that everything will fit together, even though it's taking me forever to get it done.

w


----------



## chinsettawong

The inner tube stretcher is very easy and cheap to build.  First off, you need to build a wooden frame.  The frame is just big enough to fit your inner tire. 
  
 To use it, you simply cut the Mylar sheet larger than the size of the frame.  You wrap the Mylar to the back side and tape it down to the frame.
  

  

  
 You then inflate the inner tire and the Mylar should be stretched evenly in all direction. 
  

  
 You apply glue on your spacer and glue it down on the Mylar.
  

  
 Release the air form the tire and cut out the diaphragm and you're done.  Even though this method works well, you tend to stretch the diaphragm a little too much. 
  

  
 It'll take a few trials and errors to know exactly just how much tension you need.  With too much tension, you don't have good bass.  With too little tension, your diaphragm won't be stable.  
	

	
	
		
		

		
			




  
 I hope you get the idea.  I'm sorry that I mix up pictures of the small and big stretcher.  The principle is the same.  I use this big stretcher to make my full range ESL.


----------



## davidsh

^Woah, that's pretty wicked. Nice, indeed


----------



## bbest

Hello!

  
 I have STAX 507. Could someone suggest where I can buy damaged membrane for one drive?


----------



## chinsettawong

Hi bbest,
  
 We really don't have a concrete idea of what material exactly that Stax is using to make the diaphragms for its 507.  If you really want to replace the diaphragm, you might need to replace the diaphragm in both right and left driver.  The diaphragm material that we are using is Mylar.  Any thickness up to 3 microns has been proven to be quite good.  I personally prefer using 3 microns Mylar.  You can find some sellers on Ebay.
  
 Wachara C.


----------



## davidsh

You prefer 3 microns? Any idea why Stax has chosen to settle between 1 and 1.5 microns?


----------



## chinsettawong

I like it better because I have actually tried them all.


----------



## bbest

chinsettawong said:


> Hi bbest,
> 
> We really don't have a concrete idea of what material exactly that Stax is using to make the diaphragms for its 507.  If you really want to replace the diaphragm, you might need to replace the diaphragm in both right and left driver.  The diaphragm material that we are using is Mylar.  Any thickness up to 3 microns has been proven to be quite good.  I personally prefer using 3 microns Mylar.  You can find some sellers on Ebay.
> 
> Wachara C.


 
  
 ok - thanks for sugestion! But another question - how could I clean membrane from dust and hears's fat? With wich liquid can I do this (of cause without damaging membrane)?


----------



## chinsettawong

bbest said:


> ok - thanks for sugestion! But another question - how could I clean membrane from dust and hears's fat? With wich liquid can I do this (of cause without damaging membrane)?


 
  
  
 Are you sure you want to do this?  Blowing the dust off, gentle wiping, or bushing can all be done.  However, I'm not sure if it'll fix your problem.  Can you describe your problem and what you have already done?
  
 For ESL, some people clean them with shower water.  But I really don't recommend it for the earspeakers.


----------



## wakibaki

Thanks, Wachara. That's clear now, and cheap and easy to do.
  
 I ordered the rest of the parts for the amplifier from Farnell last night, so I will be able to check that the layout is correct and order the PCBs in the next few days.
  
 w


----------



## bbest

chinsettawong said:


> Are you sure you want to do this?  Blowing the dust off, gentle wiping, or bushing can all be done.  However, I'm not sure if it'll fix your problem.  Can you describe your problem and what you have already done?
> 
> For ESL, some people clean them with shower water.  But I really don't recommend it for the earspeakers.


 

 I simply take off dust from membrane with cotton pads. It is all ok with sound. 
 In damaged drive, in defending film of stator, was small hole size of match head. This hole I taped with glue. And this drive became airtight.


----------



## chinsettawong

bbest said:


> I simply take off dust from membrane with cotton pads. It is all ok with sound.
> In damaged drive, in defending film of stator, was small hole size of match head. This hole I taped with glue. And this drive became airtight.




Do you mean that the diaphragm has a small hole on it or is it the dust cover that has a hole?  It is very unlikely that the diaphragm has any hole - unless you really crank up the volume so much that the diaphragm is burnt through.  The dust cover on the other hand is very fragile.  I'm not so sure if taping up the hole can really cure the problem.  Try the headphones for a few days and let us know if the problem is really solved.

Wachara C.


----------



## bbest

chinsettawong said:


> Do you mean that the diaphragm has a small hole on it or is it the dust cover that has a hole?  It is very unlikely that the diaphragm has any hole - unless you really crank up the volume so much that the diaphragm is burnt through.  The dust cover on the other hand is very fragile.  I'm not so sure if taping up the hole can really cure the problem.  Try the headphones for a few days and let us know if the problem is really solved.
> 
> Wachara C.


 

 Hello!
  
 Small hole in *defending film of stator*, not in diaphragm. Well, it's still ok in sound of damaged drive. So repaire was good for it.


----------



## chinsettawong

bbest said:


> Hello!
> 
> Small hole in *defending film of stator*, not in diaphragm. Well, it's still ok in sound of damaged drive. So repaire was good for it.




We call that a dust cover diaphragm. It's there to protect the driver against dust and humidity. It's very important that this dust cover is in good shape. Otherwise, a lot of odd things could happen. I'm glad to hear that your fix is good.

Wachara C.


----------



## dude_500

Have any of you had problems with your diaphragms gaining a permanent charge? One channel is very close to unstable with 0V bias! This seems to have happened after I wiped down the coating with a paper towel, presumably statically charging the plastic itself.
  
 It makes horrendously loud stax-fart when I compress the earcup on my ear, and slowly peels off the stator. 
  
 Know a good way to discharge the mylar itself? I guess this would be the same procedure as 'breaking' electret headphones.


----------



## chinsettawong

Hi dude_500,
  
 I don't think that the diaphragm is permanently charged.  If you think that is the case, you can try to confirm it by playing some music through it without any bias voltage to see if you can hear music loudly.
  
 I'm sure that you don't have enough tension on your diaphragm.
  
 Wachara C.


----------



## dude_500

chinsettawong said:


> Hi dude_500,
> 
> I don't think that the diaphragm is permanently charged.  If you think that is the case, you can try to confirm it by playing some music through it without any bias voltage to see if you can hear music loudly.
> 
> ...


 
  
 It made a little sound at zero bias, but not much. So you're right, no significant charge build up there.
  
 Came up with an idea this afternoon, and successfully solved by re-painting my stators with flat paint instead of glossy. Now a nice quiet thud when it hits instead of a deafening scream. This makes sense, since with glossy paint, even if a plastic insulative paint, large surface contact can occur between the diaphragm and stator, making it much harder for it to peel away and also making more noise.
  
 Now very stable at my max bias of 900V with no change to the diaphragms.
  
  
 So moral of the story is use flat paint on stators, not glossy.


----------



## spritzer

There shouldn't ever be contact between the stator and the diaphragm.  If that happens then the distortion shoots up by a huge margin.


----------



## chinsettawong

Findng the right tension is a very difficult task indeed.


----------



## dude_500

spritzer said:


> There shouldn't ever be contact between the stator and the diaphragm.  If that happens then the distortion shoots up by a huge margin.


 
  
 With the whole paint problem, I just mean when you push the headphones into your ear slamming the diaphragm out, not during normal operation. Paint doesn't matter during normal operation, only when the diaphragm is slammed into the side manually which is when I was having my troubles.


----------



## chinsettawong

Hi dude_500,
  
 You'll soon find out that the paint doesn't help with your problem that much.  I still think that you need to put more tension on your diaphragm in order to solve the problem once and for all.  With the right tension, you can also increase your bias voltage.  The phones will sound even livelier and more pleasant.
  
 Wachara C.


----------



## dude_500

chinsettawong said:


> Hi dude_500,
> 
> You'll soon find out that the paint doesn't help with your problem that much.  I still think that you need to put more tension on your diaphragm in order to solve the problem once and for all.  With the right tension, you can also increase your bias voltage.  The phones will sound even livelier and more pleasant.
> 
> Wachara C.


 
  
 At what point will I realize that the paint doesn't help the problem? The paint solved the problem, completely. So far confirmed with about 20 hours of listening and expecting it to remain this way for the foreseeable future!
  
 Diaphragms are about the same tension as all the headphones I've made in the last two years, all worked and do work great minus the revision that had glossy paint, which has now been fixed.
  
  
 If you don't believe the paint texture can matter and care enough to try, spray the stators of an old driver set with glossy paint and give them a listen. Push it towards your ear to slam the diaphragm and listen to the screams! You might want ear protection


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## chinsettawong

I was the one who advised you to always paint your stators, wasn't I? If that totally solved your problem, I'm glad for you. On my headphones, if the diaphragm ever touches the stator, it would just bounce right back. With the riight tension, even if you don't paint your stators (Stax doesn't paint its SR007 stators), the diaphragm would just bounce out after touching the stator. And that creates the famous Stax fart sound.

Comparing your new phones with your prior version, which one sounds louder?

Wachara C.


----------



## dude_500

chinsettawong said:


> I was the one who advised you to always paint your stators, wasn't I? If that totally solved your problem, I'm glad for you. On my headphones, if the diaphragm ever touches the stator, it would just bounce right back. With the riight tension, even if you don't paint your stators (Stax doesn't paint its SR007 stators), the diaphragm would just bounce out after touching the stator. And that creates the famous Stax fart sound.
> 
> Comparing your new phones with your prior version, which one sounds louder?
> 
> Wachara C.


 
  
 Last time I listened to SR007's, they did have a fair bit more noise to the slam than my headphones do with the flat paint I use (which is nearly silent), although nothing like this glossy paint. I could see the surface of typical copper clad being a lot more textured than glossy paint, especially if Stax gives it a sanded finish. Who knows, not really worth debating about. I've had mixed results with exposed copper, great results with flat paint, and disastrous results with glossy paint. Take from it what you will.
  
 Indeed, thanks for the painting idea. If I'd just used the same paint as last time, I wouldn't have had these problems!
  
 The new headphones at 900V bias sound about the same volume as the old headphones at their 580V bias (I don't like to drive them any higher than that, I've heard pops and crackles in the 700V range).Although I only really listen to the new ones since they sound vastly better in basically every regard. 
  
 I would have expected the difference in efficiency to be (0.5/0.8)^2, but it's a little more favorable than that. Likely because of the larger driver area. 
  
  
 Should have everything at the NY meet on Saturday.


----------



## chinsettawong

The larger diaphragm area does indeed make a difference. 

Have fun at the NY meet and let us know how other people like your headphones. 

Wachara C.


----------



## spritzer

chinsettawong said:


> Findng the right tension is a very difficult task indeed.


 
  
 It is indeed and Stax managing to maintain it for hundreds and hundreds of units is just nuts.


----------



## federicopol

Hello everyone,
 my name is Federico and that's my first post here (actually i registered because of this thread 
	

	
	
		
		

		
		
	


	




).
  
 1- Wachara your diy headphones seems fantastic, thank you for sharing your designs.
  
 2- After some research i won an auction for a basic 2050 stax set because this thread urged me to build some diy esl headphones and i needed an amp.... i'll wait for the set, listen to it and in the meantime start designing something buildable 
	

	
	
		
		

		
		
	


	




.
  
 3- i have a little question for the gurus: is there a reason if nobody attempted to clone Stax sigmas using Wachara ideas?
 I was thinking that a 3d printer could replicate the peculiar sigmas case in a cheap and effective manner.
 I'll probably build something easier first like one of Wachara's round designs then move on the "Sigma clone" so i have plenty of time for research and design. 
  
 Thank you everyone for your time and sorry for my bad english.
 Federico


----------



## n3rdling

I've actually been working on a (hopefully improved) version of the Sigmas and some other stuff, but not an exact clone.  You might want to PM jaycalgary to see if he still has the exact dimensions of the Sigma cups as he cloned them in the past.  You can open up your SR-202s and take some measurements of the drivers to clone them and put them in the Sigma cups.


----------



## federicopol

Thank you for the answer, thank you for the tips, i have on my harddrive an image with sigma measurement (found here on headfi, probably is the same image you are referring too).
 My idea is similar to yours: keeping the sigma concept but adapted to the manufacturing capabilities i can use: a 3d printer and a cnn pcb drilling milling machine.
 So i am sure my headphones will be really different from a real sigma but i'd like to thinker about the "concept" the sigma is based on.
 By the way, is the embroidery hoop method to stretch mylar working for someone or is better to use the bike tire method?
 Thank you


----------



## chinsettawong

Hi Federico,

You have a very good idea. I have been thinking of getting a 3D printet for quite a while now too. I'm sure that it's very good for printing the enclosure and headband parts.

As you might have known, I've made many different versions of headphones. I highly recommend my oval shape style to other versions. To me and many friends who have tried them, we like them a lot more than other versions. The next one I would recommend is JF style headphones. The size of driver does really make a big difference. A local friend actually prefers this one to his Stax SR009. 

Anyway, the most important thing is to have fun making them. If you need any assistance, please do not hesitate to ask. We are always here to help. 

Wachara C.


----------



## federicopol

Hello Wachara,
  
 3d printing is fun (but is even funnier to build 3d printers) building one is not difficult and if you have built a diy cnc building a 3d printer is similar.
  
 I have given my prusa i3 (3d printer) to a friend because i prefer building new thing than use them (but i have a lifetime deal with my friend: i give you my printer you print for me when i need it
	

	
	
		
		

		
			





) so i'll start experimenting with enclosures as soon i have some time to draw something on the cad.
  
 Thank you for you designs and assistance, i'm here to learn because i am an esl newbie but i have various projects in mind for diy esl headphones, some are probably bad ideas but some could show potential (i hope).
  
 The first esl i'll try to make is the oval one, then to work on the "PseudoSigma" concept.
  
 I'm sure i will ask a lot of things.. thank you!


----------



## chinsettawong

Hi Federico,

I'm actually very itching to make a 3d printer myself. The X,Y,and Z movement and control is no problem for me, but I do not understand how the extruder works and controlled yet. I'm sure it's a lot of fun making one. Please don't mind me to ask a few questions if I decide to make one in the future. 

As far as diaphragm stretching technic, I actually prefer the inner tyre stretcher. It's very easy to get a repeatable and even tension for your diaphragms. You just need to make sure not to stretch your diaphragm too much. It'll take you a few trials to get it right.

Have fun!

Wachara C.


----------



## dude_500

chinsettawong said:


> I'm actually very itching to make a 3d printer myself. The X,Y,and Z movement and control is no problem for me, but I do not understand how the extruder works and controlled yet. I'm sure it's a lot of fun making one. Please don't mind me to ask a few questions if I decide to make one in the future.


 
  
 Usually when people make their own they build the motion stages and structure, but buy the extruder module from makerbot or an equivalent company.


----------



## federicopol

dude_500 is right, some parts (electronics for motion control, extruders and the software) are usually standards.
 The one i used for my printer are  an arduino connected to a ramps1.4 shield (the shield to control the steppers, a standard extruder from ebay and the firmware for the arduino was Marlin)
 Everything is opensource in the world of diy 3d printer, reprap.org is a good starting point to have an idea about softwares, extruders and the electronics involved.
  
 You can ask every question you want (i'm not an expert, my knowledge is limited) and i'll happily answer what i can.
  
 Ok when the time to strech some mylar will come i'll ask my little cousin his bike for "repairs"


----------



## n3rdling

Back when I was looking at 3D printers, the "resolution" on parts didn't seem that good.  Have things changed considerably since?


----------



## miceblue

Hm, I'll subscribe to this thread. I might try a D.I.Y. electrostatic headphone eventually, when I get the time.

As for 3D printing, how fine are you looking at? I think 3D printers have pretty good resolution nowadays, in the order of micrometers (100 micrometers for the MakerBot Replicator 2 3D printer and 300 micrometers for the Formlabs Form 1, or so they claim), but I don't know how long ago you looked at them and how "low resolution" they were back then.


----------



## chinsettawong

I'll study more about 3D printer.  It seems like fun. 
	

	
	
		
		

		
		
	


	



  
 The resolution of 100 micrometers is good enough for frames, headbands, and etc.  But it's not good enough for making precision parts such as spacers and stators.
  
 Wachara C.


----------



## federicopol

I was trying to insert the jpeg of my project for of the oval shape esl but i discovered that as a head-fi newbie i can't post images.
  
 By the way do someone knows a source for 0,5mm fr4 in europe?
 The only one i found is conrad.de that supplies that product
  
 http://www.conrad.it/ce/it/product/523644/Bungard----Materiale-di-base-per-piastrine----120106Z33----LxPxA-160-x-100-x-05-mm
  
 but that's photosensible (is the term right?) material, and i can't find anything else.
 And what about mylar? I found a supplier on ebay but he sell's big rolls of 20m or more.
  
 Do someone hd fortune finding mylar and pcb material in EU?
  
 Thank you everyone


----------



## dude_500

If you're milling it anyways, photosensitive doesn't matter as it's just a surface coating. You can clean or sand it off anyways if you want.
  
 I think most of us buy strange thicknesses of FR4 from this ebay seller and it looks like shipping to Europe is possible http://www.ebay.com/itm/120802756087?var=420050924079&ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649#shpCntId
  
 Be aware that the seller is exceptionally sketchy and often takes weeks to ship and has very poor communication (if you're lucky, about half the time it'll ship the next day!). But it's about the only place to get it I'm aware of.
  
  
 As for mylar, you should go with the ebay seller in Taiwan. You'll use 20M and probably more if you really get into making headphones, lots of trial and error involved in making these drivers.


----------



## wakibaki

Because of the postage cost and difficulty of obtaining 0.5 mm PCB in Europe, I have been thinking about trying to use a sandwich made of 0.125 mm Lexan http://www.ebay.co.uk/itm/CLEAR-LEXAN-FILM-POLYCARBONATE-PLASTIC-SHEETS-A4-SIZE-0-25MM-0-50MM-0-75MM-/200989753144?pt=LH_DefaultDomain_3&var=&hash=item2ecbec3f38 and 0.005 in (0.127 mm) brass sheet http://www.ebay.co.uk/itm/K-S-Brass-Sheet-005-X4-X10-/281197572078?pt=UK_ToysGames_RadioControlled_JN&hash=item4178ae6fee.
  
 Still working on my phones, I've got the headpiece pretty much finished...
  

  
 ...still a ways to go, I don't get anything done a lot of days, but I'm still digging away at it. This will have a kevlar strap between the cup holders when I get to it. Don't want those threaded rods rubbing away on my bald head.
  
 w


----------



## paomag

Hi Federico
 2micron Mylar, 5 Metres x 300 mm wide  at: http://www.freeflightsupplies.co.uk/
 See Index:  Indoor --> Lighweight covering materials--> Mylar covering material foil.
 Also available 1 (!!!) and 5 micron
 Works fine!
 About 10 £ with P&P from UK to Italy


----------



## Richard Ray

*It looks good, but can look perfect!*


----------



## paomag

*2 microns*: perfect? Mah!!  I do not know but it works well. Not easy to handle but 5 meters are sufficient for many tests.
 Another source for the mylar in small qty is :   http://turnertoys.com/Mylar-Film.html  ( in U.S.)
 I use laundry softener Comfort to coat the diaphragm, it is far better than graphite.


----------



## federicopol

Thank you Paomag, but i have bought the mylar some days ago from the taiwanese seller. Soon i will have a lifetime supply of mylar because he offered me 60 meters of mylar at the same price of 40m plus elvamide so i bought 60m...
  
 In the meantime i received my stax amp and my sr202, i love the esl sound the detail is incredible, but the faux leather earpads are a pain, i have the urge to build some esl headphones because the stax are the best headphones i have ever listened to.
  
 Now that i can post images: here is my stator, is based on Wachara oval shaped design but is still in "beta stage" because i haven't decided how to build the enclosure and the headband. Wakibaki's headband seems nice and really sturdy but i'd like to use a different approach. I hope to keep a low driver weight so i can have a lighter headband, probably using only one strip of flexible steel like grados or sennheiser momentum.
  
 The holes have a diameter of 2mm and the distance between each center is 3mm so i have a distance of1 mm between each row.


----------



## chinsettawong

Your stator design looks nice.


----------



## dude_500

federicopol said:


> The holes have a diameter of 2mm and the distance between each center is 3mm so i have a distance of1 mm between each row.


 
  
 You might consider a 60* staggering pattern for the holes. This is what almost all electrostatic drivers use as you can achieve a much higher transparency.


----------



## Tjj226 Angel

Has anyone tried to make larger rectangular drivers like the jecklin floats yet? Or is everyone avoiding that since it would require a different amp?


----------



## shipsupt

http://www.head-fi.org/t/498292/my-diy-electrostatic-headphones/1035#post_9747894


----------



## Tjj226 Angel

shipsupt said:


> http://www.head-fi.org/t/498292/my-diy-electrostatic-headphones/1035#post_9747894


 
 Cool!
  
 Ok, guys I would like some advice. I am on holiday break, and I would like to finally sit down and build me some headphones. I have already made some electrostatics before, but I used stuff like plastic wrap just to build kind of a dry run headphone. 
  
 I know this is kind of an ambiguous questions, but I am looking to build myself a kind of end all be all electrostatic headphone. Price is not a huge issue, and I am well aware that the sound is not only going to depend on the material and design I use, but also the build quality that I put into the headphone itself. 
 
Assuming that the build quality will be perfect, does anyone know of a really kick but design with a fair amount of bass and a really warm sound signature?


----------



## n3rdling

The SR-007 and SR-003 probably have the warmest sound signatures in the Stax lineup.  It's been hypothesized in the past that the reason for this is because they don't perforate the entire stator.  In other words, there are holes in the middle area of the stators and a thick border of solid material on the outer ring.


----------



## miceblue

I'm still fairly new when it comes to electrostatic headphones.

 Do the diaphragms excite air particles as opposed to moving them like typical diaphragms?
 How does a Jecklin Float sound? The diaphragms aren't angled are they? If not, wouldn't the planar "air wave" be misaligned with one's ear?


----------



## chinsettawong

tjj226 angel said:


> Cool!
> 
> Ok, guys I would like some advice. I am on holiday break, and I would like to finally sit down and build me some headphones. I have already made some electrostatics before, but I used stuff like plastic wrap just to build kind of a dry run headphone.
> 
> ...




if you want a warm sound signature, just pick a design you want and do not etch out the copper in the inactive area on the stators. This leaves the headphones with higher capacitance and warmer sound signature as you like it.

Wachara C.


----------



## Tjj226 Angel

miceblue said:


> I'm still fairly new when it comes to electrostatic headphones.
> Do the diaphragms excite air particles as opposed to moving them like typical diaphragms?
> How does a Jecklin Float sound? The diaphragms aren't angled are they? If not, wouldn't the planar "air wave" be misaligned with one's ear?


 
  
 Jecklin Float headphones are kind of angled. When you put them on, there is some foam that kind of aligns the drivers (so to speak).


----------



## Tjj226 Angel

chinsettawong said:


> if you want a warm sound signature, just pick a design you want and do not etch out the copper in the inactive area on the stators. This leaves the headphones with higher capacitance and warmer sound signature as you like it.
> 
> Wachara C.


 
  
 Huh, that is interesting. 
  
 Do you have a favorite design yet? I see you have a lot more new designs since the last time I was poking around this thread. I am going to have all my parts milled out by a professional and therefore I do not need to do a practice headphone or anything like that, so if you could also recommend me the best quality parts available, I would also be appreciative. 
  
 -----------------
  
 On a separate note, I was looking through this forum, and I see a lot of people who seem to be having difficulty finding/making stax sockets. 
  
 Forgive me if this is a stupid comment, but why is it important to have a stax socket? So long as you do not have other stax headphones, could you not use something like either 2 6.3mm cables or 2 3 pin xlr cables and simply combine the two bias pins inside the amp? 
  
 It just seems like it would be easier than making your own socket.


----------



## chinsettawong

I like my oval shape headphones. They have big soundstage and good dynamic. The JF style headphones aren't bad either.

As far as jack and socket, you certainly don't have to use the Stax type. However, it gives you a good flexibility if you ever want to try to use your headphones with a Stax amp or a pair Stax headphones with your DIY amp.


----------



## AnakChan

chinsettawong said:


> I like my oval shape headphones. They have big soundstage and good dynamic. The JF style headphones aren't bad either.
> 
> 
> As far as jack and socket, you certainly don't have to use the Stax type. However, it gives you a good flexibility if you ever want to try to use your headphones with a Stax amp or a pair Stax headphones with your DIY amp.




Are these the same oval shaped HE90-like that you loaned to arnaud? I must admit I found the JF-styled to have a larger soundstage. Or have you made another oval-shaped headphones?


----------



## chinsettawong

Hi Anakchan,
  
 Yes, what I recommended was what you and Arnaud have tried.  Among all the headphones that I've made so far, these are still my favorite.
  
 As for JF style headphones, with their big size drivers, there's no doubt that the sound stage is big.  If I were to make another pair, I would try to reduce the width of the active diaphragm just a little so that I'll be able use 0.5 mm PCB as spacer.  Otherwise, these headphones do seriously need a powerful amp to drive them properly.  
  
 Happy New Year!
  
 Wachara C.


----------



## davidsh

I really admire your work here in this thread. I hope I can make my own 'stats some day. How do you avoid dust in the driver when making the 'stats? I am to open up my lambda sigs due to dust in the driver, and I have been told my changes of removing the dust without making the issues worse are fairly slim unless I have a dust free environment (which I don't)


----------



## chinsettawong

Yes, the dust can give you a really big headache.  I don't have a clean room either.  I just try to clean my work area before I do any disassembling work.  I use a magnifying glass to look for dust and I like to use adhesive tape to stick up the small dust on the stator and diaphragm.
  
 When you have some dust inside the driver, it's most likely that you have some holes on your dust covers.  Over time, the moisture and dust find their way inside the driver and cause all kinds of problem.  So, please check to see if your dust covers are still in good shape.  You want to fix that too.
  
 Wachara C.


----------



## davidsh

Ohh, forgot I didn't reply. Well, there are small holes in the dust cover. Yet, there are no channel imbalance issues at the moment (there was some time ago). Now it is just buzzing and sizzling, usually after half an hour of use.. Therefore I suspect the dust is outside the stator and not between stator and diaphragm. I can't see any hairs or the like, though..


----------



## dude_500

I don't have any experience with diagnosing real Stax headphones, but I've usually found on my DIY that dust on the stator or between stators causes a periodic popping noise, whereas dust in a stator hole, outside the stator, on the outer edge  of the diaphragm holder, overhanging mylar (wouldn't be a problem in non-DIY headphones), or anything else that is just charged but not touching the stator to cause squealing sounds.
  
 At this point, if it's squealing I don't even check the diaphragm.


----------



## chinsettawong

Hi Davidsh,

The humidity inside the cup can cause a problem, especially when you have some holes on your dust cover. You might want to try to patch up those holes using adhesive tapes and see if they help. If not, you'll need to redo the dust cover. It's very critical that all the dust covers are in good shape.

Happy New Year!

Wachara C.


----------



## davidsh

Happy new year to you two as well. Thank you for your help. I don't quite see how taping the dust cover should help on humidity, but I guess I'll try as soon as I get some thin double adhesive so I can seal the whole thing again when done.


----------



## chinsettawong

You want to have an air tight environment inside the driver.  With a pair of good dust covers on the front and the back, the humidity won't affect the driver.  But if there are holes, especially on the dust cover facing your face, the moisture will eventually get inside the driver and cause problems.  Taping those holes might or might not help.  I'm not sure, but please try since you have nothing to lose.  
 
Wachara C.


----------



## jcx

thin plastic films aren't perfect moisture barriers - most plastics with polar molecular structure can carry ~1% equilibrium water molecules - and they diffuse right on through the film if there's a humidity difference
  
 the diffusion through a sealed film does take some time but eventually the inside will be at the same as the average of the outside humidity


----------



## dude_500

I finally got around to switching from 0.8mm to 0.5mm on spacers of my Orpheus clones (been meaning to since day 1). As expected, volume approximately doubled for same voltage. It also sounds much better with a more open sound stage (this observation should be ignored since it is based entirely on the placebo effect since I can't double-blind without building a second pair of headphones).


----------



## chinsettawong

Hi Dude_500,
  
 Glad to hear that you've finally tried 0.5 mm spacers.  With this thickness, I bet you need to be extra careful with the tensioning of the diaphragm and the dust on the stators.  It takes me a lot of trials and errors just to get the right tension.
  
 By the way, I want to share my thought with you about the stators of the new SR009.  You must have noticed that there is a big hole right in the middle of the stators.  The phones are quite a bit more efficient than SR007.  If my thought is right, they make this hole there so that there isn't a pulling and pushing force in the very middle where it's the weakest point of the diaphragm.  Therefore, you can use even thinner spacers.  I think the spacer thickness of SR009 should be around 0.4 to 0.45mm.  With less copper, the phones also sound more bright.  I might try to build a pair using this concept to see if my thought is right.
  
 Let's have fun building more headphones this year.  
	

	
	
		
		

		
			




  
 Wachara C.


----------



## dude_500

As it turns out, I actually did that about a month ago and never got around to posting about it. It makes it WAY more stable. I never even bothered painting the new stators because they're just so incredibly stable even as bare copper (there is absolutely no way my diaphragms tensioned as they are right now would be stable without that hole).
  
 I'm not going to even pretend to be able to analyze the slight nuances to the sound quality it might make when it takes an hour to swap out stators, nothing dramatic.


----------



## chinsettawong

Oh, that's nice to hear!
  
 Then I guess my thought is right. With that hole there, the diaphragm is more stable, and you can actually use thinner spacers.  I'm sure that it works even better in round shape stators.
  
 Thanks for sharing.
  
 Wachara C.


----------



## n3rdling

That should also help with reducing small stator vibrations.  I wonder if the limitation of diaphragm xmax changes the sound of the bass though.  I would think it'd lead to less impact, any thoughts?
  
 I took full measurements of my HE90 drivers a while back and from what I could tell the spacers seemed to be between 0.6 and 0.7mm in thickness.  Keep in mind this was by eye though, so it was very hard to see.  I remember thinking "there's no way that's less than 0.5mm" though.


----------



## chinsettawong

I don't think that it would help with stator vibrations though.  However, It might limit the max diaphragm vibation a bit, but you can also lower the diaphragm tension a little to help boost up the bass, IMO.
  
 The spacer of HE90 is difinitely 0.5 or less.  I've listen to them many times and they're as efficient as SR007.  So, the thickness can't be more than SR007.
  
 I also have made some measurements on HE90.  But my measurements are taken from the outside of the frame looking inside.  Do you happen to have the measurements of the exact dimension of the staor?  Could you kindly share them with me?  It would be interesting to try the exact dimensions and see if I can make them to sound exactly like the real thing.
  
 Wachara C.


----------



## n3rdling

I was surprised at the spacer thickness myself.  They could have increased efficiency depending on the % of open area on the stator.
  
 I have all the dimensions in a drawing I did when I had the drivers out in front of me.  I'll sketch something up in CAD and message you tomorrow.


----------



## chinsettawong

Unfortunately, open area on the stator doesn't affect it's efficiency. 

Thanks in advance for sharing the dimension info with me. 

Wachara C.


----------



## davidsh

I am wondering, what warrants the high prices on headphones like the orpheus and sr-009 if you look at material costs?


----------



## chinsettawong

It's more of a market niche and peace of mind, IMO.


----------



## davidsh

I thought so. Thank you for clarifying.


----------



## jcx

you might try asking some of the builders what hours they've sunk into their projects - and how far from finished, commercial quality they are
  
 how many $k if they billed at competitive rates for their labor - including the failures, blind alleys, just redoing as skills improved
  
 capitalisim really does work - special knowledge, skills as well as tooling, even distribution channels are worth premiums over raw parts cost - how much does the raw metal and plastic for a modern automobile cost?
  
  
 and sales volume has a big impact all fixed costs, overhead are burdening the fewer sales - ES headphones and amps would cost a lot less if the market were millions of units instead of thousands a year


----------



## wink

Well said.......


----------



## wakibaki

jcx said:


> capitalisim really does work




Hmm. I understand the point as you intend to make it jcx, but I wouldn't be entirely happy about making such a bald statement when we've all (all of us ordinary wage slaves and hobbyists) taken such a financial beating at the hands of those with the greatest responsibility for working the controls of the capitalist system...

Then there's the fact that many would judge audio electronics to be possibly the most dysfunctional industry imaginable.

I don't entirely disagree with what you're saying, I just think we all need to take a bit more critical view of the capitalist system than giving it the wholehearted endorsement of saying 'it works' without some qualification.

I don't want to see one of the most interesting threads here dragged off into an argument though, I really wish you'd found a less potentially contentious route to make your point.

w


----------



## nikongod

wakibaki said:


> Hmm. I understand the point as you intend to make it jcx, but I wouldn't be entirely happy about making such a bald statement when we've all (all of us ordinary wage slaves and hobbyists) taken such a financial beating at the hands of those with the greatest responsibility for working the controls of the capitalist system...


 
  
 While I agree that the traditional definitons of "capitalism" no longer describe our global financial climate, I dont think that really applies to audio companies. 
  
 Work the numbers back, I think you will see his justifications line up - following traditional definitions & guidelines of "capitalism."


----------



## dude_500

Another thing I tried while bored in the shop a few weeks back was making huge holes just to see what would happen. I ended up going with kind of what planar magnetics are structured like.
  
 They sounded absolutely terrible. Severe bass roll off, basically they ended up being tweeters. Unfortunately I don't seem to have the frequency response anymore, but it was pretty horrendous in the bass department. 
  
 I didn't know what to expect, but certainly didn't expect them to be as bad as they were. Why would the roll off be so extreme? My best guess is the higher frequency modes propagate across the entire diaphragm while the bass frequencies are unable to and end up being only locally driven where the electrodes exist.


----------



## schorsch

One of the Most interesting threads I ever read !!!!

A long time subscriber

Regards Georg


----------



## chinsettawong

dude_500 said:


> Another thing I tried while bored in the shop a few weeks back was making huge holes just to see what would happen. I ended up going with kind of what planar magnetics are structured like.
> 
> They sounded absolutely terrible. Severe bass roll off, basically they ended up being tweeters. Unfortunately I don't seem to have the frequency response anymore, but it was pretty horrendous in the bass department.
> 
> I didn't know what to expect, but certainly didn't expect them to be as bad as they were. Why would the roll off be so extreme? My best guess is the higher frequency modes propagate across the entire diaphragm while the bass frequencies are unable to and end up being only locally driven where the electrodes exist.




That's interesting. I can't think of any good reason for such a bad roll off in bass. Thanks for sharing though.

Wachara C.


----------



## davidsh

I am thinking above design might creat constructive and/or destructive interference on the diaphragm as it isn't a uniform electrostatic field with that configurations. Not that I think it has anything to do with the bass but it might lead to resonances?


----------



## denoclock1

Hi,   I'm a novice with regards to using this forum - what I'd like to do is correspond with you DIRECTLY about my Stax NEW SR-3 headphone problem.   How?     Den.


----------



## dude_500

denoclock1 said:


> Hi,   I'm a novice with regards to using this forum - what I'd like to do is correspond with you DIRECTLY about my Stax NEW SR-3 headphone problem.   How?     Den.


 
  
 Hover over someone's name and click Send PM. Some forums require a certain number of posts before you can PM, not sure if this is one of those.


----------



## chinsettawong

Hi Den,
  
 You can also post your problems here and we'll try to help you.
  
 Wachara C.


----------



## denoclock1

Thank You DUDE_500 for assisting me - very good of you to take the trouble.   My quest is very important and I need all the help I can get.   Thanks again.    Den.


----------



## dude_500

Does anyone else have any doubts as to whether the 0.9 micron film from indoorspecialties.com is actually mylar? It doesn't heat tension, at all. You can blast it for minutes with a hot air gun and as long as you don't melt it, it'll return right to its original state. Any thoughts on what else it might be?


----------



## chinsettawong

I don't think it's Mylar either. 
  
 I've tried it so many times.  It sounded really good for a short while and then started to elongate and failed. 
  
 Nowadays, I only use 3 microns Myar.  It's the best one for me so far.


----------



## Congo5

20 months ago I started this project, It took time to build some CNC machines and learn enough CAD/CAM.
 Then started learning to build amps, Now back to headphones:
  
   Thanks to all the information in this thread I can report that they work really well.
 These are a ruff unfinished prototype, but sound so good that I may never take them apart-
 until they break.
  
   I'm using a DIY Firstwatt F5 to drive transformers while waiting to finish a KGSSHV.
  

  
 80mm active area, .5mm spacing, 2um Mylar, 673 1.8mm holes in stator, officemax screen cleaner spray for coating.
  
 using bias at about 500v, don't know cause I haven't built or bought a way to measure it yet.
  
 when I get the housing design nailed down I will try to make something nice looking.
  
 A Big Thanks to Wachara and notable others.....


----------



## chinsettawong

Wow! Those look really nice! Welcome to the club. Please do post more info and pictures. Congratulations on your successful build.


Sent from my iPhone using Tapatalk


----------



## Congo5

The working ones are on the top of next photo.
 to me they sound much better than anything here. the next best is some Lambda Spirit's.
 These are more efficient and much lighter, more forward, much bigger sound.
 will have to take some measurements, but will have to take them off to do it.
 That might take a while.
  
   For the oval's I will have to build custom pads.. but have one driver working.


----------



## chinsettawong

It seems like you have been playing with them all by yourself. 

Those are really nice looking drivers. When you're done with these, please try the float clone version too. I really like them.


Sent from my iPhone using Tapatalk


----------



## complin

I would really have loved to have the opportunity to come along and hear this stuff. Yeh dedication indeed.
 If your creations sound anything like the original floats (one of my favorite headphones together with Stax). Do you find the sonic presentation completely different and unique to any other headphone past or present?
 I have the Stax Sigmas but they still sound a little closed in compared to the Float.
 I guess the nearest thing would be the Senn HD800 but still does not have quite the freedom and airiness of the Floats.
  
 The original Floats do roll off somewhat at the bottom end, but the new Float QA's with the revised energiser transformer have supposedly improved the bottom octaves. I believe there are several sets of the QA's among headfiers over there. Have you had chance to listen as your design looks as though it borrows a lot from the QA's 
	

	
	
		
		

		
			





     
  
 Quote:


chinsettawong said:


> Before going to the annual Thai DIY Audio meeting, I had to cover up the back side of the phones so that people would not stick their fingers inside and get a shock.  I looked around the house and finally decided to use my wife's stocking.
> 
> 
> 
> ...


----------



## chinsettawong

Hi complin,
  
 Thank you very much for your interest.  If you have a chance to come by Bangkok, you are most welcome to try all my headphones.  We have quite an active group of Headfiers here.  Many of us own electrostatic headphones.  Yes, I have tried the new QA float for a brief session.  I did like them.  However, It's too bad that they don't make them compatible with Stax ampliers. 
  
 My float style headphones sound more relaxing than my other phones.  Yes, the bottom bass does roll off a little.  But they sound just like my electrostatic loudspeakers.  However, the phones are a little less efficient, and they need a powerful amp to shine.  KGSSHV and especially DIY T2 make them sing so amazingly.  
  
 I'm thinking of making another pair of float style headphones.  This time I'll make them more efficient so that all Stax amps will be able to drive them easily.
  
 Wachara C.


----------



## complin

Yes I have been an electrostatic headphone user since the mid 1960's so you realise I like them a lot
  
 Phones like the floats have such large drivers its going to be difficult to make them that efficient I believe. The later Jecklins and the QA's use 1200 volt bias voltage.
 Having heard the new Float QA's what are your feelings regarding the bottom octaves? How do they compare to the Stax 007/009. I believe they need a meaty amplifier to make them sing 30/40 watts.
  
 I have been in conversation with Manfred Stein the owner of Quad in Germany about his new amplifiers for the Float QA. I assumed that they would have a native bias supply driven directly from the integrated amplifier. However he says that in his opinion the Float QA still needs the step up transformers to perform correctly. So his new amplifiers just drive the original step up transformers but are integrated into a single box!
  
 Andreas Rauenbuehler in Germany http://www.high-amp.de/html/frame.html has designed a dedicated amplifier which will drive both stax and the Jecklin Float. Below is a copy of the schematic for his 1200/100 volt bias supply
  
*©Copyright Andreas Rauenbuehler​*




  
 Quote:


chinsettawong said:


> Hi complin,
> 
> Thank you very much for your interest.  If you have a chance to come by Bangkok, you are most welcome to try all my headphones.  We have quite an active group of Headfiers here.  Many of us own electrostatic headphones.  Yes, I have tried the new QA float for a brief session.  I did like them.  However, It's too bad that they don't make them compatible with Stax ampliers.
> 
> ...


----------



## chinsettawong

Hi complin,
  
 Unfortunately for me, I had only tried the QA float for only about 5 minutes.  I only remembered that they sounded really nice.  I didn't do a direct comparison between them and other headphones.  But, I guess, since there's no seal, the very bottom bass wouldn't be so clear as headphones with sealed earpads. 
  
 I think QA float drivers have thicker spacers than mine.  There is nothing wrong with using high bias voltage except that you can't use them with a lot of dedicated electrostatic headphones amplifiers.  And I realy feel that's a pity.
  
 I might reduce the width of the driver by a few millimeters and increase the length a little.  With narrower width, I can reduce the spacer thickness down to 0.5 mm, and that'll make the phones more efficient.  I'm sure they'll sound really nice too.  
  
 Wachara C.


----------



## complin

I think that the driver design is exactly the same as the original Float PS2 which is 1200 volt. Perhaps more modern materials have been used.
 I believe where the changes have been made in how the drivers have been mounted, the headband and the step-up transformer.
 Personally I prefer the original style of the float, for me a timeless and futuristic design that will never date. The new style looks rather DIY 
	

	
	
		
		

		
		
	


	




 for a commercial product. Its a pity they did not up date the original by using say carbon fibre, 3D printing etc.
 I know that kiertijai has a set of the QA's and he has been very impressed with them
  
 Quote:


chinsettawong said:


> Hi complin,
> 
> Unfortunately for me, I had only tried the QA float for only about 5 minutes.  I only remembered that they sounded really nice.  I didn't do a direct comparison between them and other headphones.  But, I guess, since there's no seal, the very bottom bass wouldn't be so clear as headphones with sealed earpads.
> 
> ...


----------



## chinsettawong

There are at least 3 pairs of QA float around here that I know of.  Do you mean that you prefer the boxing helmet style headband?
  
 I actually like how K1000 places its drivers on the headband.  I think I might do something similar for my next ones.  
	

	
	
		
		

		
		
	


	



  
 By the way, do you prefer QA float over other electrostatic headphones?
  
 Wachara C.


----------



## dude_500

It was pointed out to me that stators that are double-sided copper will be vastly more temperature stable and remain way flatter compared to single sided in the long term. I haven't tried this yet, but maybe I'll make one side double sided and see if I can hear a difference. Even if there's no apparent difference, it certainly can't hurt and is the technically better way to build them. I believe the sr-007 is double sided.


----------



## chinsettawong

The stators of SR007 are indeed double sided. They are plate thru holes. The stator thickness is about 0.7 mm. They are thin and strong.

The way I see it is that the extra copper on these stators leaves them with higher capacitance. That's why SR007 sounds not as bright as other Stax models.

It would be interesting to try though.

Wachara C.


----------



## dude_500

Extra copper on the outside face should not increase capacitance at all, since there is no e-field between that copper and the opposing face. The through holes could very, very slightly increase capacitance due to fringing fields, but it would only be in a way that would increase the uniformity of force and make everything better.
  
 The only way to increase capacitance would be to have more surface area on the inner stator faces. It appears the sr-007 might have unnecessary copper there also, but that's an entirely different issue.


----------



## chinsettawong

Please try it then, and do let us know how you like it.


----------



## complin

Well I prefer the Floats for certain types of recording, particularly where it has been made in a great acoustic environment. The soundstage on the Floats I find particularly good.
 However; I could never give up my Stax such as the 007 Mk1's, 009's and Sigmas as they all have unique and different attributes. The Lambda series are not to be ignored either, particularly the LNS
  
  
 Quote:


chinsettawong said:


> There are at least 3 pairs of QA float around here that I know of.  Do you mean that you prefer the boxing helmet style headband?
> 
> I actually like how K1000 places its drivers on the headband.  I think I might do something similar for my next ones.
> 
> ...


----------



## JamieMcC

Wow what a interesting thread, just subscribed and have started reading from the first page.


----------



## davidsh

Indeed very interesting, though I must confess I haven't read the whole thread. It is kind of a dream of mine to make my own 'stats, but I just don't have the tools and I'm not too good at diy either


----------



## Congo5

Has anyone tried to mimic the 007 stator design?
  
 These are 80mm active, 840 1.2mm holes.

  
   also,  any (ebay) ear pads to try?
 or dimensions to try, heigth, hole size, volume?
 or should I learn to sew and try to make the  007 pads?
  
 I thought making ES drivers would be worthwhile but had no Idea they would be this good.
  
 thanks


----------



## chinsettawong

Those stators look really nice. How do you like them as compared to other versions? Do you feel that they have warmer sounding?

By the way, do you use single or double sided PCB?

Wachara C.


----------



## dude_500

congo5 said:


> Has anyone tried to mimic the 007 stator design?
> 
> 
> also,  any (ebay) ear pads to try?
> ...


 
  
 Yes, I have made 007 clone drivers. I actually bought the sr-007 earpads on ebay to use. In my fairly extensive experience with earpads on these DIY headphones, the driver sets 10% of the sound, and the earpad geometry and material sets 90% of the sound. If you want to actually get sr-007 sound, you'd best buy the earpads or at least fabricate nearly exact clones yourself.
  
 I have been told, and agree, that they sound very similar to the actual sr-007.
  

  
 Incidentally I don't really like the sr-007, and as a result rarely listen to them compared to my Orpheus clones.


----------



## complin

I assume they are not true Orpheus clones as they have stators built from glass, and the driver itself is coated with gold particles?
  
 Quote:


dude_500 said:


> Yes, I have made 007 clone drivers. I actually bought the sr-007 earpads on ebay to use. In my fairly extensive experience with earpads on these DIY headphones, the driver sets 10% of the sound, and the earpad geometry and material sets 90% of the sound. If you want to actually get sr-007 sound, you'd best buy the earpads or at least fabricate nearly exact clones yourself.
> 
> I have been told, and agree, that they sound very similar to the actual sr-007.
> 
> ...


----------



## dude_500

Correct, I just used FR4. I do have access to gold sputtering and will make gold glass stators some day just for the sake of actually cloning them, but it's not very high on my priority list at the moment as I don't believe the sound will be any different.


----------



## Congo5

chinsettawong said:


> Those stators look really nice. How do you like them as compared to other versions? Do you feel that they have warmer sounding?
> 
> By the way, do you use single or double sided PCB?
> 
> Wachara C.


 

  Single sided, could not think of a reason for DS,  Will report when I try these, it may be a bit because
 I have many projects going at once.
  
 Quote:


dude_500 said:


> Yes, I have made 007 clone drivers. I actually bought the sr-007 earpads on ebay to use. In my fairly extensive experience with earpads on these DIY headphones, the driver sets 10% of the sound, and the earpad geometry and material sets 90% of the sound. If you want to actually get sr-007 sound, you'd best buy the earpads or at least fabricate nearly exact clones yourself.
> 
> I have been told, and agree, that they sound very similar to the actual sr-007.
> 
> Incidentally I don't really like the sr-007, and as a result rarely listen to them compared to my Orpheus clones.


 

 Thanks for that Pic!  yours look exactly like the 007, Great Job.
 I was just moving in that direction, from the ones I did that work well.
  
   I don't know what a SR-007 sounds like, just looking for ideas here.
  
 did you make or buy the Orpheus pads?
  
 Thanks


----------



## dude_500

congo5 said:


> did you make or buy the Orpheus pads?
> 
> Thanks


 
  
 I just couldn't justify the ~$1000 for Orpheus earpads, so I did make my own. Nothing about it is exact since it's hard to get dimensions of the Orpheus. My drivers are actually probably a bit larger.


----------



## Congo5

dude_500 said:


> Incidentally I don't really like the sr-007, and as a result rarely listen to them compared to my Orpheus clones.


 
 OK would you recommend this?  active is 70x105mm
 just finished drawing it and can scale it or ??


----------



## dude_500

There's no right answer, build them and see if you like them! Obviously a lot of people like sr-007. A lot of people would consider my orpheus clones too bright (which by the way are 84 x 122mm active area), but they're exactly what I want and are quite possibly the best headphones out there for me, but not for a lot of people. The greatest thing of making your own headphones is you get to tune them to what you want, which is difficult to do without experimentation. 
  
 I did once make 56x82mm headphones, and I'd say they were definitely too small. Pretty much impossible to get any bass out of them. 70x105 is certainly an interesting size to try.


----------



## chinsettawong

Yes, just do it!
  
 This is my version:
  

  
 For me, my DIY headphones sound the best.  
	

	
	
		
		

		
		
	


	



  
 Wachara C.


----------



## complin

Where are you trying to source these from? Sennheiser charge nothing like that amount.
 Quote:


dude_500 said:


> I just couldn't justify the ~$1000 for Orpheus earpads, so I did make my own. Nothing about it is exact since it's hard to get dimensions of the Orpheus. My drivers are actually probably a bit larger.


 
  
 The Orpheus is brighter than the SR-007, but I expect the majority of people have not heard the two side by side


dude_500 said:


> There's no right answer, build them and see if you like them! Obviously a lot of people like sr-007. A lot of people would consider my orpheus clones too bright (which by the way are 84 x 122mm active area), but they're exactly what I want and are quite possibly the best headphones out there for me, but not for a lot of people. The greatest thing of making your own headphones is you get to tune them to what you want, which is difficult to do without experimentation.
> 
> I did once make 56x82mm headphones, and I'd say they were definitely too small. Pretty much impossible to get any bass out of them. 70x105 is certainly an interesting size to try.


----------



## dude_500

I made some earpads with a smaller inside opening (new left, old right)
  

  
 Pretty much did as expected. Substantially shrank the sound stage, while improving the sound quality (but not magnitude) of the bass and being a fair bit darker of a sound.
  
 Overall, I substantially like the old earpads better. They offer a much more believable image and are overall way more enjoyable to listen to. The only artist that sounds better on the new ones is 2Pac.


----------



## Congo5

Dude  how thick are your pads? are the new ones thicker?
 they look pretty big in size(OD).
  
   A friend made these with lambskin, modeled after the 007 pad pictures.
 just guessing that it will work well, after all its Stax.
 they are comfy.
 also are some T50rp and SR-3 pads for reference.
  
 have not tried them yet, still using 105mm (OD) ebay ones for now.
  
 .

  
 thanks for the post N pic......


----------



## chinsettawong

dude_500 said:


> I made some earpads with a smaller inside opening (new left, old right)
> 
> 
> 
> ...


 
  
 I also like the bigger opening in the middle.  I share the same experience as yours.
  
 But, the ones without earpads aren't sounding that bad either - the sound stage is huge too.


----------



## chinsettawong

congo5 said:


> Dude  how thick are your pads? are the new ones thicker?
> they look pretty big in size(OD).
> 
> A friend made these with lambskin, modeled after the 007 pad pictures.
> ...


 
  
 Your DIY earpads look really nice!
  
 My Omega clone's earpads are about 35 mm on the thicker side and 20 mm on the thinner side.
  
 Wachara C.


----------



## dude_500

congo5 said:


> Dude  how thick are your pads? are the new ones thicker?
> they look pretty big in size(OD).


 
  
 They are both 1" thick foam mounted on a 0.125" ABS holder which directly contacts the driver, so the face of the earpad is about 1.2" from the driver.
  
 Both are 148mm x 110mm OD. Old ones are 114mm x 76mm ID, new ones are 100mm x 62mm ID (those are the dimensions of the foam, the leather and seam add probably another 3-4mm on each side).
  
 Anyone happen to know what the orpheus ID is?


----------



## chinsettawong

The Orpheus earpads' ID is about 45mm x 90mm.


----------



## the-Toaster

Hello Guys.
  
 I readed the complete thread since yesterday.
 And I have to say:
  
 Great work of everybody.
  
 But I have one question.
  
 The dust and humidity saving foil.
 Is it mounted direktly on the pcb?
 Is it glued on?
 Could be that I had overreaded this information...


----------



## Congo5

on 1mm or so spacer.
  
 has to be able to move in both directions...
  
 and welcome


----------



## the-Toaster

Thanks for welcome.
  
 And now I can sleep better this night...


----------



## dude_500

the-toaster said:


> Hallo Guys.
> 
> I readed the complete thread since yesterday.
> And I have to say:
> ...


 
  
 The dust screens are just like diaphragms, they are mounted on a frame and suspended a distance away from the stator and the outer grill. The only difference is they are lower tension than the diaphragm, and often crumpled up.
  
  
 Unrelatedly, one thing I discovered many months ago is how to avoid squeal. It's actually not dust (at least, not usually... I know in extreme cases, it can be). When making diaphragms, I used to just run my finger around the rim once and call it good. But it is imperative that the inner edge of the diaphragm is securely glued entirely around the inner perimeter. The squealing is the diaphragm oscillating against the holder frame, likely some charge exchange going on if it's not glued on well. Run your finger along where the red line is in this picture immediately after gluing the diahragm (very carefully, obviously watch your finger nails, don't want to scratch the mylar). My headphones used to almost always squeal periodically especially in high humidity. Ever since I started doing this, I've NEVER had squealing headphones and can even wear them with wet hair (seriously guys, that's no more dangerous than wearing them at all).


----------



## the-Toaster

Thanks for the answer.
  
 Exactly that was it I came on by myself. But I didn't find it in the comments. So I was in conflict.
 So thanks for losen my conflict... ;D


----------



## davidsh

It is amazing how little is actually known about 'stats and their weird behaviour. 
  
 Now that we are at it, I want to tape up some holes in a dust protector on my LS (it is squealing, have had problems with imbalance too), and I have been told that I need to use a knife to get into the dust protector because it is glued together.. Anyways, if I try to tape up the dust protector, how should I close the hole thing again, with some thin double adhessive or something?


----------



## the-Toaster

Let us see some pics of your LS and the dust protector.


----------



## davidsh

the-toaster said:


> Let us see some pics of your LS and the dust protector.


 
 Not much to see, just a handful of small holes (Ø 1-2 mm or so) and one bigger hole as I remember. Will try looking a little closer at it later 2day.


----------



## n3rdling

Battle of the adhesives!
  

  
 An assortment of different glues, spray adhesives, cements, and epoxy.  Most are "recommended for plastics".  Only a few are actually decent for Mylar.  Any recommendations I should order and throw into the gauntlet?
  
  
 HE90 clones that I need to re cut (errors).  These are close to exact Sennheiser dimensions, just need smaller holes:


----------



## dude_500

n3rdling said:


> An assortment of different glues, spray adhesives, cements, and epoxy.  Most are "recommended for plastics".  Only a few are actually decent for Mylar.  Any recommendations I should order and throw into the gauntlet?


 
  
 You want to use contact cement, nothing else comes close. Specifically, I think I use DAP Weldwood contact cement (I've used a few brands, and they basically all work great).
  
 Apply it to the frame, let it sit for 3-5 minutes, drop it on the mylar, and it's instantly bonded permanently. Only the most prominent bumps adhere right as it touches the surface, but when you flip it over just run your finger over the bonded area and it all sticks. After it's been squeezed in a headphone driver for a few days, you can't get it off even if you try (sometimes I do try if I want to reuse the frames, and it takes five minutes of scrubbing and peeling with strong solvents).


----------



## chinsettawong

Yes, you want to use contact cement.


----------



## n3rdling

dude_500 said:


> Specifically, I think I use DAP Weldwood contact cement


 
 Yes!  I bought this stuff like 2 years ago when I first started messing with Mylar but couldn't remember the name of it.  I was recently going to build those HE90 clones for a local meet (drew everything up and had all pieces cut the night before) but I misplaced the cement.  I ended up having to use 3M Super 77 which I had laying around, and it totally ruined the project as it bubbled and out gassed too much, making the film lose tension in spots around the rim.  I was so bummed as I had everything ready, just needed assembling.  I just ran to Home Depot and grabbed a small bottle...I like this stuff because it comes with the convenient little brush applicator under the cap.  Thanks


----------



## chinsettawong

Are you not going to etch out the copper around the outer ring of your stator, n3rdling?


Sent from my iPhone using Tapatalk


----------



## n3rdling

I'll make spares so I can etch one set and leave the other set alone


----------



## chinsettawong

Hi Milos,
  
 This is my design of HE90 clone based on the real measurement.
  

  

  
  
 In the mean time, I am making another pair of my Oval shape headphones.  I'm learning to use danish oil to paint my wood.  I really like it.


----------



## arnaud

Wachara, you gotta stop sometime soon or you'll outdo the original... Simply marvelous! 
  
 I was talking about your float inspired open baffle model earlier today to another french head-fief, I realize I absolutely miss your phone! Hopefully, you give me another chance to listen to them / or updated version once I receive my BHSE (I felt both cans were seriously underpowered by my 727 amp)!
  
 Also, I never got a around to processing the measurements I made on these guys, I am truly sorry for letting you down there... I won't promise date anymore but it's certainly not forgotten. You manage great tuning by ear anyway so probably it's not a big deal 
  
 Arnaud


----------



## chinsettawong

arnaud said:


> Wachara, you gotta stop sometime soon or you'll outdo the original... Simply marvelous!
> 
> I was talking about your float inspired open baffle model earlier today to another french head-fief, I realize I absolutely miss your phone! Hopefully, you give me another chance to listen to them / or updated version once I receive my BHSE (I felt both cans were seriously underpowered by my 727 amp)!
> 
> ...


 
  
  
 Hi Arnaud,
  
 I'll be glad to send the headphones to you. 
  
 For these headphones, you'll really need a powerful amp.  I've not tried BHSE, but my DIY T2 and KGSSHV can drive them very well.
  
 Wachara C.


----------



## dude_500

chinsettawong said:


>


 
  
  
 Those frames are beautiful. When I tried to make wood frames that held the drivers with milled out guides and everything, the piece warped severely in all directions by as much as an 1/8th of an inch. Do you do anything specific to keep them flat and in the correct oval dimensions after milling? I was using padauk wood, which for all I  know was simply a bad choice.


----------



## chinsettawong

dude_500 said:


> Those frames are beautiful. When I tried to make wood frames that held the drivers with milled out guides and everything, the piece warped severely in all directions by as much as an 1/8th of an inch. Do you do anything specific to keep them flat and in the correct oval dimensions after milling? I was using padauk wood, which for all I  know was simply a bad choice.


 
 Thanks for your compliment.
  
 No, I didn't do anything specifically to treat the wood.  I guess you need to find wood that's pretreated and you don't have to worry about it.  Given high humidity here, I think my wood does warp a little, but so far I haven't found that to be a problem.
  
 By the way, I have another thing that I really want to share with you guys. 
  
 Sometime last month when I went shopping in a supermarket, I got a bottle of concentrated floor cleaner.  It comes in a small sample bottle.  Guess what?  I put it on a test diaphragm and found the surface resistance to be as good as Staticide 6300 that I've recommended you guys before.  This stuff is super cheap, and it's readily available in a local supermarket here.  I've put it on my headphones for over a month now, and it's been performing very well.
  
 So, if you can get the same stuff in your area, try it.


----------



## n3rdling

Nice work Wachara   I like the look of the cups, shiny without a plastic look.  The stator holes look kinda strange, but I think that could be from taking the picture zoomed out?  If you ever need, I can use a program to automatically fill in the stators with holes at any angle/spacing/diameter/shape you need.  I can even make the holes custom (like hexagons, for example).  It has made designing much more efficient for me. 
  
 Also, why is there a circle within a circle on the perimeter of the stators/spacers?  Do you plan to slightly countersink the stators?
  
 Regarding the cleaner, that looks like a nice cheap option but I'm not sure how long it will last before starting to flake off the diaphragm.  The Licron and certain Staticides are supposed to be permanent ESD coatings. 
  
 Arnaud, what did you think of the floats in comparison to the SR-009s?


----------



## chinsettawong

n3rdling said:


> Nice work Wachara   I like the look of the cups, shiny without a plastic look.  The stator holes look kinda strange, but I think that could be from taking the picture zoomed out?  If you ever need, I can use a program to automatically fill in the stators with holes at any angle/spacing/diameter/shape you need.  I can even make the holes custom (like hexagons, for example).  It has made designing much more efficient for me.
> 
> Also, why is there a circle within a circle on the perimeter of the stators/spacers?  Do you plan to slightly countersink the stators?
> 
> ...


 
  
 What program is it that you use that has this holes filling function?  That would save a lot of work.  
  
 The outer circles are the ones for the stator.  The inner, smaller ones are for my top plate where I screw the whole thing to fix to.  I've forgotten to take them off when taking the picture.  All the holes align perfectly, but when I zoom in and take a snap shot, the holes don't look that good.  I don't know why.  The hole size and dimensions are based on my first measurement and your data.  I think this is as close to the real thing as it can be.
  
 As for the floor cleaner, I like to mention it again that this could be a cheap alternative.  How long will it last?  I don't know.  But since we are doing DIY work, we can recoat the diaphragms anytime we want to.
  
 By the way, the cleaner is very easy to apply.  Wipe it on and it dries in a few minutes.  However, it leaves a haze on the diaphragm.  I buff it off and the diaphragm is totally transparent.  The surface resistance stays at around 80 - 100 M Ohm per square even after a month.
  
 Wachara C.


----------



## n3rdling

I'm using SolidWorks, but it's very expensive and can have a steep learning curve.  I much prefer to use normal CAD programs but none of the ones I own have a function for automating this process. 
  
 I get the same issue with the stators looking weird when scaled down.  I think it's just a resolution problem, but no big deal. 
  
 Do you have a Megger or how are you measuring such a high resistance accurately?
  
 I see you've moved on to using additive instead of subtractive tabs.  I was thinking of doing this but I didn't want to make the walls of the cups too thin in that lower area, especially with the cable already hanging from there.  Have you run into any issues with the protruding tabs?  Seems like they would make life easier.  I actually wanted to make mine 1/4" or 3/16" wide rectangles so that I could just crimp quick disconnects onto the end of my Stax cable and not have to worry about soldering in that tight space.
  
 I was thinking about the float clones and they seem like a fun project.  I know the original design doesn't bother with fully sealing earpads and this probably isn't a big issue since the drivers are so large and close to the ears, but have you tried to use massive sealing earpads?  I think the bass could be incredible.


----------



## chinsettawong

Yes, I have a 4 Giga ohm 1000V resistance meter by Fluke.  I bought it just to check the resistance on the diaphragm.  
	

	
	
		
		

		
		
	


	




 
  
 Actually I design the Orpheus stator and spacer tabs similar to the real one.  I think either additive or subtractive tabs are fine.  It also depends on the way you design your cups too.  One thing that I don't understand about HE90 is that why do they put the taps at the top instead of bottom closer to the cable entry?
  

  
 This is how I would do it.
  

  
  
 Float style headphones certainly is fun.  The headphones sound very much like a pair of loudspeakers.  Though they don't have close ear pads, but the bass can go really deep.  You won't hear as much details as the ones with pads, but they'll certainly put a smile on your face.  No I have not made big ear pads for them, but I'm sure that if I do, the headphones will give a lot of bass.  
  
 Wachara C.


----------



## frank2908

dude_500 said:


> I made some earpads with a smaller inside opening (new left, old right)
> 
> 
> 
> ...



Hi, i've never seen a diy leather pads this neat. Could u pls share a tutorial? This is very beneficial for my other project


----------



## arnaud

Wachara, here are the notes I took when I tested your float and orpheus clones. Sorry for the dirty copy/paste, the comments are much very rough and don't reflect how much I enjoyed them. They were underpowered by the 727 amp though, that is certain.

Orpheus clone: 
> Very easy on the ears (mid/highs quite smooth, treble rolled off), SR009 comes of as in-your-face and much brighter in comparison, SR007 is in between the two. Orpheus clone sounds muffled on SRM727, opens up on LLmk2.
> Bass is quite round / full sounding. 009 is tighter, 007 is similar both go quite a bit lower / or provide much more kick.
> Soundstage has limited depth bit L/R/C. Sounds is bit like in a box, 007mk2 more open, 009 even more.

Float clone: 
> Much brighter / neutral sounding than Orpheus clone. Brighter than (or less bass) 007mk1 but still less bright than SR009. 
> Can feel the vibration of the frame (feels like speaker is next to the ear, left ear rattles with acoustic bass).
> Works best with light music / strings & voices. Bass is nice (tight / well textured) but clearly missing low bass / sub-bass
> Soundstage much more realistic than orpheus clone, open sounding, well in front


----------



## chinsettawong

Hi Arnaud,
  
 Thank you very much for your note.
  
 Let me prepare my Float clone, and I'll send them off to you next week.  I'll let you keep them for a longer period of time.  Please share them with your friends in Japan.
  
 When I got the Orpheus clone back from you last time, I noticed that the phones were not sounding balanced.  I'm not sure if you noticed that when they're with you.  Anyway, they're now with a good friend in the USA.  So, I can't send them to you this time.  I can send my new pair to you after I've finished making them if you're still interested.  But I'm taking my time and they'll probably won't be ready before May.
  
 Wachara C.


----------



## OnyxOcelot

Hello Chinsetta and all DIY ES headphone folks,
  
 Apologies if you had mentioned this earlier in the thread, but I was curious about one aspect in particular of ES headphone construction.
  
 I have just begun reading Sanders' "Electrostatic Loudspeaker Design Cookbook" as one of the steps towards making my own ES headphones, and he mentions that the shape and size of stator-holes would have an impact on the sound.  In writing that, it seems obvious, but I was curious if any of you had experimented with different shapes of stator-holes than the standard round through-hole.  
  
 For example, one might imagine using a v-tip bit, and producing holes which were larger on one end and smaller on the other. These holes could either 'face' in or out, or be alternated back and forth.    I could also imagine drilling the holes at an angle to the stator.  These changes might alter the sound in a positive or negative way, but are worth trying, if only for fun.
  
 Have any of you adventurous DIY'ers tried these alterations?  Feel free to tell me they are stupid ideas.  I will try them anyway!
  
 Best,
 OnyxOcelot


----------



## dude_500

> Have any of you adventurous DIY'ers tried these alterations?  Feel free to tell me they are stupid ideas.  I will try them anyway!


 
  
 I've tried 1mm vs. 2mm holes, but not the different shaped holes. I want to think there's a difference and the 1mm sounds better, but really it's so subtle that it could all be in my head. I only have one pair of headphones so it takes too long to switch out drivers to really be able to tell.


----------



## arnaud

chinsettawong said:


> Hi Arnaud,
> 
> Thank you very much for your note.
> 
> ...


 
  
 Hi Wachara,
  
 This is super generous of you, I feel embarrassed because I haven't done anything in return - I was supposed to help you with your test rig remember?
  
 Of course, I (and several others here actually  ) would be delighted to get to hear it again, but at the very least shipping is on my this time (or something you need from Japan??).
  
 cheers,
 arnaud


----------



## chinsettawong

onyxocelot said:


> Hello Chinsetta and all DIY ES headphone folks,
> 
> Apologies if you had mentioned this earlier in the thread, but I was curious about one aspect in particular of ES headphone construction.
> 
> ...


 
  
 Hi OnyxOcelot,
  
 A few people that I know have actually talked and discussed about the shape and size of the stator-holes and their influence in sound.  Yes, I have done quite a few tests in the past.  And I can't really hear a significant difference in sound when comparing the different hole sizes.  However, I do like it better with the more open area stators.  I feel that the sound stage is wider and the sound is more transparent.  I have no measurement though, and it's just my feeling.
  
 This is a picture of my first version of Oval shape stator:
  

 Later on, I put a lot more holes on it and it becomes:
  

  
 I also played around to see if asymmetrical alignment of holes would make a much difference in sound.  So, I made something like these:
  

  
 You're welcome to try something different.  You might have better ears than us.  
  
 Wachara C.


----------



## chinsettawong

arnaud said:


> Hi Wachara,
> 
> This is super generous of you, I feel embarrassed because I haven't done anything in return - I was supposed to help you with your test rig remember?
> 
> ...


 
  
 Hi Arnaud,
  
 I'm always glad to lend my headphones to friends.  It's no problem at all.  I've got to many of them here anyway.  
	

	
	
		
		

		
			




  
 Please enjoy them and let me know your thought on how I can improve them.
  
 I'll send them to you early next week.  Please let me know when you've received them.
  
 Wachara C.
  
 PS.  I might need your help on some items from Japan in the future.  Please help me when I need your help.


----------



## OnyxOcelot

chinsettawong said:


> You're welcome to try something different.  You might have better ears than us.


 
 Unlikely, Wachara!  
  
 Could you just confirm that by more 'open area' on the stator, you mean fewer holes, and therefore greater stator-area?  Or do you mean more open as in more openings (holes)?  
  
 Thanks, dude_500, for the reply as well.  I think I will start with 1 or 2 mm straight holes and play around with shape / angle later on down the road.
  I will post back any findings if I do end up trying it.


----------



## chinsettawong

onyxocelot said:


> Unlikely, Wachara!
> 
> Could you just confirm that by more 'open area' on the stator, you mean fewer holes, and therefore greater stator-area?  Or do you mean more open as in more openings (holes)?
> 
> ...


 
  
 By more open area, I mean more holes.  Well, actually, it means more area for air to flow through and not just more holes.  
  
 I prefer something like this:
  

  

  
 to this:
  

  
  
 Comparing 2nd picture and 3rd picture, I'm sure that you can tell that the stators in 2nd picture has a lot more open area than the 3rd.  
  
 And that's what I mean.
  
 Wachara C.


----------



## n3rdling

I don't think shaping the holes as cones would really make much difference for our application.  Usually you only see that kind of thing being done as a way to prevent corona discharge on the stators (sharp edges + high voltage).  This is why people will make sure to orient their perforated sheets so that the rounded over side of the sheet faces inwards.  Note though that we're operating at much lower voltages than speaker applications here., so it shouldn't be an issue.
  
 I do wonder though if there'd be any measurable increase in efficiency if you were able to cut the holes so that they'd be shaped like miniature horns.  I think the open area percentage would probably be too small.


----------



## dude_500

Has anyone tried this 0.5 micron OS film? http://hobbyspecialties.com/product_info.php?cPath=28&products_id=44
  
 I can't find much information, but google seems to be under the belief that OS film is genuine mylar


----------



## n3rdling

I was going to get that a few months ago but it's not Mylar.  It's not even polyester...it's polypropylene.


----------



## PretentiousFood

Hoping to join the leagues of DIY stats soon, just need to finish up my CNC.  Why is it that Mylar's the polymer of choice here? Easier to tension?


----------



## chinsettawong

Hi PretentiousFood,
  
 Hope to see your headphones soon.  If you have any questions, please don't hesitate to ask.
  
 Mylar or Hostaphan film is usually the choice of diaphragm material.  They are very strong and do not elongate much after tensioning or heat treating.
  
  


dude_500 said:


> Has anyone tried this 0.5 micron OS film? http://hobbyspecialties.com/product_info.php?cPath=28&products_id=44
> 
> I can't find much information, but google seems to be under the belief that OS film is genuine mylar


 
  
 I can't find anywhere on the site mentioning that it's 0.5 micron.  
  
 Wachara C.


----------



## dude_500

chinsettawong said:


> I can't find anywhere on the site mentioning that it's 0.5 micron.


 
  
 The owner of indoorspecialties told me it is the place to get 0.5 micron. This page has a bit more information: http://www.micronwings.com/Products/OSfilm0.5Micron/
  
 As far as I know, that is OS film and they're all going to be the same.
  
 This page (not much credibility) indicates that OS film is mylar: http://www.homefly.com/reference/Covering%20Weights%20Product.htm


----------



## n3rdling

I think it's one of these two:
 http://www.innoviafilms.com/Our-Products/Packaging/Propafilm-OS.aspx
 http://www.cryovac.com/na/en/food-packaging-products/oxygen-scavenging-headspace.aspx
  
 I've looked on the Dupont website for films before and never saw any mention of "OS film".


----------



## OnyxOcelot

n3rdling said:


> I think it's one of these two:
> http://www.innoviafilms.com/Our-Products/Packaging/Propafilm-OS.aspx
> http://www.cryovac.com/na/en/food-packaging-products/oxygen-scavenging-headspace.aspx
> 
> I've looked on the Dupont website for films before and never saw any mention of "OS film".


 
 The first website mentions OS film being "Biaxially Oriented Polypropylene (BOPP)" as opposed to mylar's "Biaxially Oriented Polyethylene Terephthalate (BoPET)" (http://en.wikipedia.org/wiki/BoPET)  Not sure what that means in terms of performance, but it does seem to mean that OS film is not mylar.  Then again, perhaps mylar is copywritten and this is a way around that copyright.  I'm really just guessing there...
  
  
According to http://en.wikipedia.org/wiki/BOPP#Biaxially_oriented_polypropylene_.28BOPP.29 on BOPP:
"When polypropylene film is extruded and stretched in both the machine direction and across machine direction it is called _biaxially oriented polypropylene_. Biaxial orientation increases strength and clarity. BOPP is widely used as a packaging material for packaging products such as snack foods, fresh produce and confectionery. It is easy to coat, print and laminate to give the required appearance and properties for use as a packaging material. This process is normally called converting. It is normally produced in large rolls which are slit on slitting machines into smaller rolls for use on packaging machines."
  
 I'd never think that much engineering goes into plastic wrap... 
	

	
	
		
		

		
			




  
  
 Now, I'm about to ask some very silly questions -- questions that will no doubt reveal the very depths of my ignorance of the fundamental electricity principles of an ES headphone driver.  I'm confused about the wiring of an ES driver:
  
 1. The normal bias stax plug has two separate bias connectors.  Is there one for each driver, or should each bias connection attach to each driver?
  
 2. Each channel has a positive and negative connection.  I'm assuming the positive connection goes to one stator and the negative to the other (and it is important that that the two channels are in phase.  Is this correct?
  
 3. More generally, how does an ES driver work?  I understand the basic idea, but I keep getting stuck on the notion that a signal is passed through the stators when there is only one wire connected to each stator.  Is there a weakness in my 10th grade electricity rule that for a circuit to be complete, it must connect the negative and positive terminals?  Any analogies to water, hoses, crimping would be appreciated.
  
 Thanks,
 OnyxOcelot


----------



## n3rdling

Mylar is DuPont's brand of BoPET film.  There are others such as Hostaphan, etc.  BOPP is different altogether.  Another alternative is PEN but I haven't found any as thin as what's typically used here. 
  
 Each driver should have a direct connection to the bias line of the cable and gets connected to the diaphragm.  In 6 pin Stax used 2 lines for bias along the entire length of the cable, in 5 pin they just split the bias line at the Y-splitter. 
  
 Yes, one goes to the inner stator and one goes to the outer stator.  AFAIK absolute polarity isn't audible, but they need to be in phase with each other (ie. you can't have one channel with the + on the inside and the other channel with - on the inside).  I've read in the past that almost all Stax are wired out of absolute phase, and I think that even showed up in Tyll's measurements. 
  
 There are websites that can explain this better and more in depth, but basically you have a thin, electrically charged film suspended between two conductive plates.  The audio signal is amplified to a high voltage and as it runs through the plates, the stator with opposite polarity to the film pulls the film towards it while the stator with the same polarity as the film pushes it away (opposites attract, think of magnets).  The plates have holes in them so that when the film vibrates it can push air through the holes and out of the driver, making sound.  The amount of force applied to the film by a stator is a function of the distance between the two, and the closer they are together the stronger the force (think gravity/magnetism).  Since two stators are used, we are able to keep a linear force on the diaphragm at all times under normal operating conditions.


----------



## DingoSmuggler

onyxocelot said:


> More generally, how does an ES driver work?  I understand the basic idea, but I keep getting stuck on the notion that a signal is passed through the stators when there is only one wire connected to each stator.


 
 An ES driver is a capacitor. There is a transfer of charge through an electric field, not through electrical conduction.
 If you look up some explanations of capacitors and get a vague idea of how they work, then that will flow into your understanding of ES drivers.
  
 Interestingly, the converse is also true. Capacitors are also ES transducers, just terribly inefficient.
 Once I had a class B power amp driving a dummy load, and I was overloading it severely. Aside from the fact the mains transformer was trying to vibrate the chassis apart, the main power supply caps were actually outputting audio, quite soft and heavily distorted, but audible none the less. Probably a bit more useful than using caps as speakers, I've seen people use poly caps as microphones too. Get an interesting colored vocal from them. Don't have any links off the top of my head, but i'm sure google might find something.


----------



## chinsettawong

Have you guys ever tried food wrap plastic as diahragms yet? If not, try it. You'll be surprised how good it can sound.


----------



## AManAnd88Keys

chinsettawong said:


> Have you guys ever tried food wrap plastic as diahragms yet? If not, try it. You'll be surprised how good it can sound.


 

 The first Jecklin Float prototype used that material


----------



## arnaud

I was wondering about the food wrap , it can work? I want to try making a diy stat someday, maybe after the kids grow up a bit and I get some time again .


----------



## davidsh

chinsettawong said:


> Have you guys ever tried food wrap plastic as diahragms yet? If not, try it. You'll be surprised how good it can sound.


 
 I can imagine, also the dust protectors on most e-stat drivers are pretty much food wrap plastic, right?


----------



## OnyxOcelot

dingosmuggler said:


> An ES driver is a capacitor. There is a transfer of charge through an electric field, not through electrical conduction.
> If you look up some explanations of capacitors and get a vague idea of how they work, then that will flow into your understanding of ES drivers.


 
 Thanks.  This analogy definitely helps.
  
 And thanks n3rdling for the explanation of the wiring / polarity / principle.
  
 It seems most of your DIY ES headphones use a bias closer to Stax's "Pro Bias" of 580v.  Is there a reason that using a higher bias is easier for DIY construction?  I imagine the thickness of stators, spacers, and diaphragm coating should change proportionally with bias voltage for an equal volume output (if my understanding of n3rdlings explanation is correct).  If I'm going ahead using a 230v bias, what thickness dimensions would you recommend?  Apologies if this was hashed out earlier in the thread -- I don't recall anyone using the lower voltage bias...


----------



## chinsettawong

davidsh said:


> I can imagine, also the dust protectors on most e-stat drivers are pretty much food wrap plastic, right?


 

 No, I don't think so.  The stuff used by Stax is definitely not similar to food wrap.
  
 I think I have posted this video before, but anyway, here it is possibly the easiest DIY electrostatic headphones ever built using food wrap as diaphragms.  I think they sound pretty good.
  

  
 Wachara C.


----------



## chinsettawong

onyxocelot said:


> Thanks.  This analogy definitely helps.
> 
> And thanks n3rdling for the explanation of the wiring / polarity / principle.
> 
> It seems most of your DIY ES headphones use a bias closer to Stax's "Pro Bias" of 580v.  Is there a reason that using a higher bias is easier for DIY construction?  I imagine the thickness of stators, spacers, and diaphragm coating should change proportionally with bias voltage for an equal volume output (if my understanding of n3rdlings explanation is correct).  If I'm going ahead using a 230v bias, what thickness dimensions would you recommend?  Apologies if this was hashed out earlier in the thread -- I don't recall anyone using the lower voltage bias...


 
  
 Well, actually, you'll want to use higher bias voltage possible, because it gives you good efficiency.  However, as you increase your bias voltage, you have to make sure that you've done everything right.  And that's quite difficult.
  
 I go with 580V bias voltage simply because it's a Stax standard for all of their new headphones.  And I can just plug my headphones in any of Stax amp.  It makes my lives easier.
  
 Why are you aiming at 230V bias voltage?  I don't know what spacer thickness you should use, but if I'll do it,  I'll probably go for 0.35 - 0.4 mm. 
  
 Wachara C.


----------



## OnyxOcelot

Wachara,
  
 I'm only aiming at a 230v bias because I recently purchased an SRD-7 (sb) Stax Energizer to power my as-yet-unfinished 'stats.  This is probably not ideal.  It does, however, allow me to play around with DIY 'stats without a serious investment.  I will post back with results once I've completed them.  
  
 Eventually, I would like to build a DIY 'stat amp, but have only limited experience populating PCB's, and thought it best to avoid starting with such a high voltage system (insert smiley being zapped here).
  
 OO


----------



## dude_500

There's nothing wrong with making them for 230v. Also there's nothing wrong with running 580v headphones at 230v, you just need more drive amplitude. 
  
 At the NY meet on Saturday I blind tested Lambda standard bias (230v) against Lambda pro bias (580v), and aside from the different in sensitivity, I was unable to determine any difference between the two. The sound was absolutely identical.


----------



## spritzer

Those two are very different irrespective of the bias voltage.


----------



## davidsh

dude_500 said:


> There's nothing wrong with making them for 230v. Also there's nothing wrong with running 580v headphones at 230v, you just need more drive amplitude.
> 
> At the NY meet on Saturday I blind tested Lambda standard bias (230v) against Lambda pro bias (580v), and aside from the different in sensitivity, I was unable to determine any difference between the two. The sound was absolutely identical.


 
 Interestsing, I have always found the normal bias to have a generally 'softer' presentation, but that might just be placebo. I wouldn't be surprised. Using NB for pro bias earspeakers would be a good test for driving the amp to it's limit if they sound identical 
  
 Anyway, to my understanding pro bias and normal bias 'stats are just as efficient if you decrease/increase the stator spacing accordingly?


----------



## ayaflo

chinsettawong said:


> Have you guys ever tried food wrap plastic as diahragms yet? If not, try it. You'll be surprised how good it can sound.


 
  
 I am still stuck at that(at least dreaming of it
	

	
	
		
		

		
		
	


	




) .. aluminium mosquito mesh for the stators and food wrap with dish soap( replacing graphite powder). As for the components, planning to use a voltage multiplier circuit for BIAS supply to diaphragm and an AF transformer from a source.. just that I can't find the supply and transformer anywhere near my residence!!
 tried contacting one or 2 wholesale suppliers who in turn requested I purchase it from the central market ( which is 56km one way)...only hope is to travel to my hometown and talk to some audio repair shops and pull these stuff together!! but then caught at work!!
 fYuX..


----------



## chinsettawong

ayaflo said:


> I am still stuck at that(at least dreaming of it
> 
> 
> 
> ...


 

 Aluminum mosquito mesh and food wrap sound like a good combination.  However, I wouldn't recommend dish soap though.  Try floor cleaner or computer screen cleaner spray or gel instead.


----------



## chinsettawong

davidsh said:


> Anyway, to my understanding pro bias and normal bias 'stats are just as efficient if you decrease/increase the stator spacing accordingly?


 
  
 That's true.


----------



## dude_500

davidsh said:


> Anyway, to my understanding pro bias and normal bias 'stats are just as efficient if you decrease/increase the stator spacing accordingly?


 
  
 While true, it's not generally what is done. Normal bias stax are substantially less efficient than the equivalent pro bias models. I'm not sure why, perhaps it's harder to get half thickness stable at half voltage. From my experience with thicknesses and listening to lambda pro and standard side by side, I would say the spacer thicknesses are either the same, or extremely close to each other.


----------



## davidsh

chinsettawong said:


> ayaflo said:
> 
> 
> > I am still stuck at that(at least dreaming of it
> ...


 
 Now we just need a very simple and DIY-ish way to make some connectors that fits in a Stax amp. Would be a good starter project


----------



## complin

The Jecklin Float is 1200v Bias but they have much larger drivers than most electrostatic headphones. The earliest version was 1500v.


----------



## ayaflo

Remembering my experience with Wachara's Orpheus clone.. It was exemplary if anything.
  
 My reference headphones back then were Sony MDR-SA5k and SRH-940 out of an audinst HUD MX-II(?) .... When I auditioned his Omega Clones, I couldn't get the fit right besides it being not very comfortable.....Nor was the volume going high enough but the bass quality was beautiful. It was power hungry and apart from the near zero distortion and a wholesome sound, it was nothing special at least at that particular volume.
  
 But when he asked me to try the Orpheus clones and I did,  I just stopped evaluating the sound and the headphone all of a sudden! It was just temptuous beautiful music oozing out... I realized if a headphone is like the Orpheus clones and the file quality good enough .. people will like any kind of music!! I remember Mr. Wachara asking me to sit back and listen to some more of the music but then it was poisonous and I had a flight to catch!
  
 I spend a lot of money on minor upgrades in sound which is just absolutely worthless when you can make ESLs and Electrostatic headphones on your kitchen table!


----------



## n3rdling

I do most of my DIY work on a pool table 
	

	
	
		
		

		
		
	


	



  
 It's cool that the DIY estats are making an impression at meets.  I saw positive feedback for dude_500's DIY phones recently as well.


----------



## complin

_*So we have Stats-2-DIY-for*_


----------



## jgazal




----------



## ayaflo

Very many joyous Birthday wishes to you Mr. Wachara! 
  
 Have a memorable celebration!


----------



## chinsettawong

ayaflo said:


> Very many joyous Birthday wishes to you Mr. Wachara!
> 
> Have a memorable celebration!




Thanks Azaan. I did have a wonderful birthday with my family.


----------



## OnyxOcelot

Just completed my first pair of ES drivers.  
  
 Do they make noise?  Yes, they make noise which definitely resembles music.  In fact, they sound quite OK, considering everything that went wrong in the process:
  
 --Most of my problems were due to slop and mis-calibration in my DIY CNC router.  I tried routing the copper clad board to the correct thickness for the spacers and discovered that my bed was not level (or rather, the gantry wasn't even with the bed), which meant the spacers were pretty mangled.  They were different thicknesses at different spots and had an uneven finish.  This was so bad that they somehow didn't properly insulate the diaphragm from the stators.  I decided to just put electrical tape around the edge of the spacer / diaphragm unit and call it a day.  
  
 --The diaphragm was not sufficiently stretched, or maybe not sufficiently glued, so it pulled back in to the center and creased in spots. I used 3M 77 spray adhesive.  I have contact cement, but am loathe to use such a nasty chemical when I can avoid it.  Guess I shouldn't avoid it next time.
  
 --I used a microphone cable for each driver (2 twisted pairs and a shield) -- put the bias through two of the wires (one from each twisted pair) and used the remaining wires for the signal.  Thoughts on this type of wire?  Use of shield?
  
 --I used anti-static spray that expired in 2001 for the diaphragm coating.  
  
 --I made a connector with 3-pin XLR cable pins and a piece of wood to make the connector.  Seems to have worked alright, but obviously not ideal.
  
  
 Anyway, I have the thinner spacer material on order.  For now, I am just glad (and surprised) that they work at all.  Thanks for the help, all, and will post back when I've made prettier drivers and housings.
  
 Oh, and could anyone give me a quick comparison of rectangular ES drivers vs. round / oval drivers?  I would love to make some rectangular ones, simply because slop / backlash on my CNC would be much less of an issue.  How does the sound differ?


----------



## davidsh

^That's nice 
	

	
	
		
		

		
		
	


	



  
 Twisted wires are probably okay but might not be ideal as it will increase capacitance from what I hear. Reason why most 'stats use straight type of wire.


----------



## chinsettawong

onyxocelot said:


> Just completed my first pair of ES drivers.
> 
> Do they make noise?  Yes, they make noise which definitely resembles music.  In fact, they sound quite OK, considering everything that went wrong in the process:
> 
> ...




Congratulations on your good start. Looking at your pictures, I smile to myself thinking about the very first day I fire up my first pair of DIY headphones. They're pretty much in a lot worse case than yours. I didn't have any idea of what I was doing. My bias voltage was over 1000V and yet they didn't make any sound. 

About the shape of headphones, IMO, the shape doesn't matter. You want the largest diaphragm area you can make. The area does make a huge difference.

If you want to make them rectangular shape, go ahead. I don't see any disadvantage of that at all. In fact my Float clone is rectangular and it sounds fantastic. 

Good luck.

Wachara C.


----------



## n3rdling

3M Super 77 was one of the adhesives I tested.  Poor results.  Like you said, it bubbles up and makes the diaphragm lose tension.  3M 90 did better but it comes out in a thick stream so it's not easy to apply.  Contact cement blows them away though.  Any pics of your CNC?


----------



## chinsettawong

I have mentioned it many times that contact cement is the only way to glue your diaphragms.


----------



## davidsh

I can't help marvel over the simplicity of e-stat drivers. What seperates flagship material from something like a humble, basic lambda in your opinion?


----------



## arnaud

Looks can be deceiving, maybe it's possible to get something working, but there are so many variables in the design (and it's far from just the electrode) that it's a feat to make something great sounding and in a consistent manner.


----------



## chinsettawong

davidsh said:


> I can't help marvel over the simplicity of e-stat drivers. What seperates flagship material from something like a humble, basic lambda in your opinion?


 

 In my opinion, Lambda series are very good headphones.  Even the entry level SR202 or SR207 are very good already.
  
 In terms of sound quality, it's very difficult to say if the flagships are that much better.  I think it's up to a personal preference, if you don't consider about the cost factor.
  
 Wachara C.


----------



## chinsettawong

I've almost forgotten that I made this pair of HE-6 to electrostatic conversion.  I'm listening to them right now.  
  

  
 If anybody has a pair of broken HE-5 or HE-6 laying around, I highly recommend that you try this conversion.  
	

	
	
		
		

		
			




  
 Wachara C.


----------



## musicinmymind

chinsettawong said:


> I've almost forgotten that I made this pair of HE-6 to electrostatic conversion.  I'm listening to them right now.
> 
> 
> 
> ...


 
  
 I have and HE-400, which am not using much as I have HE-6 now. Not able to sell them as prices has come down a lot, I paid $400 and if I sell now may be lucky to get 250$.
  
 Can you please suggest how to attempt this conversion, look interesting, willing to try for fun part of it.


----------



## chinsettawong

Hi musicinmymind,
  
 A friend of mine sent me this pair of broken HE-6 that he didn't want it anymore.  I took out all the parts inside, made the inside measurements, drew all the parts, and made the parts using my CNC machine.  If you have access to a CNC router, you can do it.
  
 If your HE-400 aren't broken, don't do it.  My biggest headache when making headphones is to make a decent and good looking headband.  I basically just use the HE-6's cups and headband for my DIY headphones.
  

  
 By the way, the diaphragm diameter of these headphones is as big as Stax SR-007.  
  
  
 Wachara C.


----------



## OnyxOcelot

n3rdling said:


> Any pics of your CNC?


 
 Sure. It is large, but I only tend to use the first third to half of the table. Still fraught with issues -- mostly stemming from a mediocre stepper driver system, somewhat under powered steppers, and the use of threaded rod rather than proper acme screws.  Nevertheless, it does seem to make parts with a fairly high degree of repeatability and accuracy.  Certainly better than I could do by hand!


----------



## DouglasQuaid

I have a supply of 3m 8001 static cleaner at the lab.  Is 1x10^11 too high of a resistivity for a diaphragm coating?  I see most of the solvents used in this thread are closer to 10^6-10^9.  If it's too high, I'll just buy something more effective.


----------



## chinsettawong

Yes, the resistance looks to be too high.


----------



## wakibaki

Still trying to put a pair of phones together. I just have to spray the stators with insulation, stretch and glue the diaphragms, dismantle and rebuild everything with moisture membranes and the cable in place.
  
 I went with this very simple adjustable headpiece, it's a bit heavy, needs some bits slimmed down, but it's at least functional for a first experiment. The headband is velcro, the earpads velour from ebay.
  
 Of course I still need to build some kind of amp.
  
 w


----------



## n3rdling

Those look cool.  Can you link to those earpads?  Also, I thought you were going to make those with wire stators instead of plate stators.


----------



## chinsettawong

wakibaki said:


> Still trying to put a pair of phones together. I just have to spray the stators with insulation, stretch and glue the diaphragms, dismantle and rebuild everything with moisture membranes and the cable in place.
> 
> I went with this very simple adjustable headpiece, it's a bit heavy, needs some bits slimmed down, but it's at least functional for a first experiment. The headband is velcro, the earpads velour from ebay.
> 
> ...


 
  
 Nice to see your progress.  The headband looks unique but seems a bit heavy though. 
  
 Wachara C.


----------



## complin

Could this be electrostats in the style of Abyss AB-1266? 
	

	
	
		
		

		
			




  
 Quote:


wakibaki said:


>


----------



## wakibaki

The earpads. I couldn't find them in my purchase history. I think these are identical:-http://www.ebay.co.uk/myb/SavedSellers?ssPageName=STRK:ME:LNLK:MEFSX&_trksid=p3984.m2034.l3390 They look like what I remember, lots of detail in the advert, which is why I went with them. Pleather might give a better seal, but that's just a detail.

I do have some stainless steel wire gauze, but I've got the PCB stators cut already, I don't want to get sidetracked into experimenting until I've got working diaphragms with very similar sounds.

Yes, the whole thing is heavier than it need be. There is a lot of room for circular holes in the parts, but in my haste I pressed ahead with the simplest design that I felt would take the punishment and be adjustable. The arrangement of stacked rings means that installing moisture shields will be straightforward. 

When I thought of using the nylon studding, I found a choice of colours, and I realised that I was in the throes of creating a design with a certain steampunk flavour, plus I have succeeded in reducing the headphone to a flat pack kit.

w


----------



## chinsettawong

I've been thinking of doing something like this for a while, and now I'm seriously thinking of going ahead.  
  

  
 The purpose of having this bigger hole in the center of the stator, IMO, is to reduce the push and pull force in the center of the diaphragm so that one can lower the diaphragm tension and / or lower the spacer thickness to get higher efficiency.  In ESL speakers, we often put a silicone spacer there for the same purpose.  
  
 The hole, silicone dot, cover up that middle circle when applying coating material on the diaphragm so that the diaphragm in that area is non conductive, or etch out the copper in the middle region of the stator, IMO, would yield the same result?
  
 Dude_500 is the only person I know who have made such a design on his test stators.  Can you share your view or experience on this?
  
 Wachara C.


----------



## n3rdling

The membrane would move differently in the two scenarios:
  
 With the silicon dot you're essentially putting a spacer in the middle, so the membrane moves like a vibrating donut.  The good thing about the dot is that you get more stability on the diaphragm but no sound radiating from that point.
 With the empty hole in the stator you have a non conductive area but the membrane can still move there from the momentum generated.  The good thing about this method is that you still get sound coming through that hole, but you don't gain as much physical stability and there may also be additional distortion if the field is too weak there (hole too large). 
  
 I think it will sound very similar in the grand scheme of things, though.  I would probably make the hole longer/skinnier to reflect the shape of the stator (distance from hole edge to stator edge).


----------



## dude_500

chinsettawong said:


> Dude_500 is the only person I know who have made such a design on his test stators.  Can you share your view or experience on this?
> 
> Wachara C.


 
  
 It doesn't seem to change sound quality. I haven't really tested stability. Instinct tells me it helped stability, but it could be entirely in my head without a direct test. There is no scientific reason it should help with stability other than the decreased surface area which is minuscule. I'm not sure it really matters, as according to actual measurements I did recently increasing tension does not decrease bass. Within certain bounds, I think that is all in our heads and fueled by placebo.
  
 The only thing I know for sure that's really nice about it is that you can glance at it and instantly know visually whether it's gone unstable which is actually pretty hard to do in a traditional stator.
  
 I finally got a decent way to measure my headphones with in-ear mics and I do plan to do some comprehensive experimental stator analysis at some point, but I'm moving out into the real world in a few weeks and won't have access to CNC equipment probably until I buy/build my own stuff so it might be a while.


----------



## davidsh

Can't help thinking the best solution to get most stability + efficiency would be a curved stator which in turn would allow the stators to get closer to the diaphragm and make the movement of the diaphragm more uniform with lesser excusion in the middle and more around the edges relative to using 'flat' stators.
 Also, increasing surface area of the stator will mean more force applied to the diaphragm, right? So I guess it's a compromise between surface area and acoustic transparency, eg. efficiency and transparency, when making 'stats assuming the dimension of the stators/diaphragm is known?


----------



## dude_500

Long term stability does seem to be a problem here. My headphones aren't doing so well with spring weather. It's hot and humid today (more so than any day yet this year), and I'm practically down to standard bias to keep headphones stable that have been stable at pro-bias for a year and a half up to this spring (literally have been sealed up for a year and a half, only aging has affected it). These are all on 2um mylar from ebay. Glad I put adjustable bias on my amp! I wonder what the solution to this problem is...
  
  
 Update: Upon further thought, I think the problem is the coating reacting with the temperature/humidity. Usually when I slam bias down to zero it takes a second or two for the sound to go away. Today, it instantaneously goes away implying the resistance dramatically dropped today, possibly to the point of causing instability. I can only imagine that all anti-static cleaner liquids would have similar properties, I've been using http://www.elexp.biz/chemical/1733.jpg


----------



## chinsettawong

About stability, once it fails, it's very difficult to fix.  I've tried many, many times and there's no help.  Even shrinking the diaphragm with hot air doesn't help.
  
 The humidity can cause a problem.  But, I'm not sure if it's related to the diaphragm instability.  I have witnessed a lot of the noise problem during high humidity season, but not the instability issues.


----------



## n3rdling

Do you think there was creep in the contact cement?


----------



## chinsettawong

n3rdling said:


> Do you think there was creep in the contact cement?


 
  
 In my case, no.


----------



## complin

Anyone read this ?
  
  http://www.quadesl.org/index.php/hard-core/panel-coatings/original-quad-coating
  
http://www.ebay.co.uk/itm/Electrostatic-Speaker-Conductive-Coating-Elvamide-120g-/280534535726?pt=Vintage_Electronics_R2&hash=item4151294e2e


----------



## dude_500

n3rdling said:


> Do you think there was creep in the contact cement?


 
  
 Not this problem. I took one pair apart last night and the tension remains about the same as it was before. However, I switched the coating out to a very thin layer that takes 5-10 minutes to charge in winter, and it took about 3 seconds to charge. Today is a bit less humid and it's at about 10 seconds. So it's definitely the extreme atmospheric sensitivity of the coating that's causing my problem.


----------



## chinsettawong

complin said:


> Anyone read this ?
> 
> http://www.quadesl.org/index.php/hard-core/panel-coatings/original-quad-coating
> 
> http://www.ebay.co.uk/itm/Electrostatic-Speaker-Conductive-Coating-Elvamide-120g-/280534535726?pt=Vintage_Electronics_R2&hash=item4151294e2e




Trust me. You don't want to use Elvamide.


----------



## chinsettawong

dude_500 said:


> Not this problem. I took one pair apart last night and the tension remains about the same as it was before. However, I switched the coating out to a very thin layer that takes 5-10 minutes to charge in winter, and it took about 3 seconds to charge. Today is a bit less humid and it's at about 10 seconds. So it's definitely the extreme atmospheric sensitivity of the coating that's causing my problem.




Have you ever measured the resistivity on the diaphragm? My headphones and all Stax headphones that I've tried can charge up instantaneously.


----------



## dude_500

chinsettawong said:


> Have you ever measured the resistivity on the diaphragm? My headphones and all Stax headphones that I've tried can charge up instantaneously.


 
  
 I've tried, never gotten anything to read less than max value on a meter. The ones that take a few minutes to charge in winter I tried to measure by putting 400V across the diaphragm and measuring current with a triple-darlington, which came up with something like 3*10^14 ohm/sq +- a lot. 
  
 That's on the extreme high-end of what I'd ever do. But if I use my coating material sufficiently for instant-charging (basically put a bunch on and don't think about it), it's always going to be unstable even for unacceptably high tensions in this weather. Seemed to last through last summer although I was in a different climate.


----------



## chinsettawong

Wow, that's an extremely high resistivity.  I doubt if your diaphragms can really be fully charged.
  
 If I were you, I would go for a bit thicker spacers, and put on a less resistive coating. 
  
 For my Float clone, I couldn't get the right tension and stability when using 0.5 mm spacers.  In the end, I cut a piece of 0.1 mm thick plastic sheet as extra spacers.  It's amazing to see how the extra 0.1 mm can help stabilize the diaphragms.
  
 Wachara C.


----------



## OnyxOcelot

So, I built a set of rectangular drivers today, sized around 75x90 mm.  I'm using .5 mm spacers with Stax normal (230V) bias, and a static-guard spray as coating.
  
 The most obvious negative characteristic is that low-end distortion begins at higher volumes (a high, but not untoward listening volume).  The high end does not seem to distort, or is masked by the more prominent low-end rumble.  The distortion is unnoticeable at lower volumes, or with more mid-range heavy music.
  
 What might be causing this distortion at relatively low volumes?  
 Any suggestions for how I might overcome it?  
  
 I'm finding the headphones fairly inefficient to begin with, so I may give a second coating of static-guard to begin experimenting.  
  
 Thanks in advance for any tips!
 OO


----------



## chinsettawong

onyxocelot said:


> So, I built a set of rectangular drivers today, sized around 75x90 mm.  I'm using .5 mm spacers with Stax normal (230V) bias, and a static-guard spray as coating.
> 
> The most obvious negative characteristic is that low-end distortion begins at higher volumes (a high, but not untoward listening volume).  The high end does not seem to distort, or is masked by the more prominent low-end rumble.  The distortion is unnoticeable at lower volumes, or with more mid-range heavy music.
> 
> ...


 
  
 Can you show us some pictures of your phones?
  
 With 0.5 mm spacers, you can already use Stax pro bias voltage of 580V.  Your headphones will be much more efficient too.
  
 I'm not sure what is causing the distortion, but I'm guessing that your current bias voltage is too low and you have to crank up your volume too much that your amp is running out of juice.
  
 By the way, how do you drive your headphones?  Do you use step up transformers or do you use an electrostatic headphones amp?
  
 Wachara C.


----------



## OnyxOcelot

chinsettawong said:


> Can you show us some pictures of your phones?
> 
> With 0.5 mm spacers, you can already use Stax pro bias voltage of 580V.  Your headphones will be much more efficient too.
> 
> ...


 
 Sure.  I will attach a photo of their current test set-up (attached by rubber band to an old pair of earpads).  As with my previous pair, they are plagued with some build-quality issues that have more to do with my CNC than the design.  Fortunately, I think all build-quality issues on this pair are purely cosmetic.  
  
 I am driving my headphones with a stax energizer with only normal bias.  Eventually, I would like to build a dedicated amp, but for the moment, this will have to do.   Perhaps the distortion is coming from the amp driving the energizer, but I did not have this issue on the previous pair, so I think it might be some unique quality of this shape of diaphragm...
  
 In any case, I'll try to increase efficiency with another coating of static-guard and see what happens.


----------



## dude_500

That is very odd if there is audible distortion at low amplitudes only. Are you testing this on a pure sine tone and distinctly hear a distorted tone with harmonics? Or do you just "hear distortion" listening to music?
  
 The only thing I can think of would be crossover distortion in a crappy power amp. There aren't a lot of forms of distortion that would become less audible at higher amplitudes, but that one could.


----------



## chinsettawong

Maybe your diaphragms are unstable and are stuck to one of the stators.




Sent from my iPhone using Tapatalk


----------



## OnyxOcelot

dude_500 said:


> That is very odd if there is audible distortion at low amplitudes only. Are you testing this on a pure sine tone and distinctly hear a distorted tone with harmonics? Or do you just "hear distortion" listening to music?
> 
> The only thing I can think of would be crossover distortion in a crappy power amp. There aren't a lot of forms of distortion that would become less audible at higher amplitudes, but that one could.


 
 Sorry, I guess I wasn't clear.
  
 I only hear distortion in the bass at higher volumes.  I *am* using a very crappy integrated power amp, but did not experience this problem on my first set of round drivers.  I added a pre-amp to try and take some strain of the power amp, which seems to have only somewhat reduced the problem.  I am listening to music rather than a sine wave or sweep, but the distortion is patently obvious.  Audiophile headphones, these ain't, unfortunately.
  
 Wachara is probably right that .5mm is too thick a spacer for the normal 230V bias.  Perhaps my first round drivers were small enough that it didn't matter.  
  
 I will try ordering some thinner spacer material and keep on building.
  
 Thanks!


----------



## dude_500

onyxocelot said:


> Sorry, I guess I wasn't clear.
> 
> I only hear distortion in the bass at higher volumes.  I *am* using a very crappy integrated power amp, but did not experience this problem on my first set of round drivers.  I added a pre-amp to try and take some strain of the power amp, which seems to have only somewhat reduced the problem.  I am listening to music rather than a sine wave or sweep, but the distortion is patently obvious.  Audiophile headphones, these ain't, unfortunately.
> 
> ...


 
  
 If it's bass at higher volumes, that definitely points to clipping. Indeed your efficiency is probably very low with 0.5mm at 230v, causing the power amp to clip to get enough volume out. 
  
 That said I took apart the drivers of my standard bias SR-X mk3 for a repair, and the diaphragm spacers appear to be approximately 0.5mm (unfortunately I didn't have any calipers with me). They could be a little smaller, but certainly not by much.


----------



## n3rdling

When I get that problem (low efficiency and lots of bass distortion) on Stax I've had, usually the problem is that the driver stack is loose and there's a little gap as a result.  Usually at an angle.


----------



## jgazal

I am not certain if this is the right place to ask.
  
 Are there eddy currents (foucalt currents) inside the aluminum earcup of a SR-009 or SR-Ω? Can I assume that the more mass in the earcup the more induced eddy current inside the earcup? 
  
 Is there a dope or an specific aluminum alloy that reduce free electrons in the earcup?


----------



## nikongod

jgazal said:


> I am not certain if this is the right place to ask.
> 
> Are there eddy currents (foucalt currents) inside the aluminum earcup of a SR-009 or SR-Ω?


  
 Anywhere current flows, there are eddy currents.


jgazal said:


> Can I assume that the more mass in the earcup the more induced eddy current inside the earcup?


 
  
 No, you can assume that the lower the electrical current the smaller the induced eddy current. Since electrostatic headphones operate at current levels small enough to be imaginary, you can estimate the eddy currents to also be imaginary.
  


jgazal said:


> Is there a dope or an specific aluminum alloy that reduce free electrons in the earcup?


 
  
 You made this up. I'm declaring shenanigans.
 Lets just say for a second that you did not make this up. Why do you think it would be worth trying? Do you have any indication that "reducing free electrons in the earcup" would have any positive effect? Do you have any indication that it would have any effect at all?


----------



## jgazal

nikongod said:


>


 
  
 No, I have no indication that "reducing free electrons in the ear cup" would have any positive effect.
  
 Just think about a naive student that have no deep knowledge of electronics and is just learning how transformers work. He has just read what eddy current is and asks if this happens in metallic ear cups.
  
 I understand that to a have little knowledge is worse than having no knowledge at all. Sometimes I assume things that are not correct simple because I have no deep understanding of electronics. On the other hand, I admire your knowledge.
  
 I would never claim it has a negative effect.  It was really a naive question. I should not have mentioned any models specifically. I concur with you that it probably does not have any effect.


----------



## wakibaki

If you mean 'reducing the free movement of electrons in the material of the cup itself', you could use a dielectric instead of a conductor for the cup, but of course there will be displacement currents.

w


----------



## jgazal

Warning: long post.
  
  


Spoiler: Warning: Spoiler!



Thank you for the responses. I was not only thinking in headphones. I just want to better understand ferromagnetic, paramagnetic, diamagnetic and dielectric materials down atom level. This doubt follows me since my younger ears, but unfortunately I have chosen a profession that is far away from this field of knowledge.
  
 Particularly in the metallic ear cups I have doubts like:
  
 1) When the material creates a magnetic field and when it creates an electrostatic field. Now I see that aluminum is diamagnetic so it may actually increase a magnetic field. And thanks to nikongod now I know eddy currents in the ear cup are on smaller order of magnitude than I was imagining. So any magnetization of the aluminum is a faint force and coincides with the stator generated force, so it is an irrelevant doubt.
  
 2) How the electrostatic field of the stator interact with the metallic ear cup. The thick anodizing skin isolates the ear cup. Suppose I earth the ear cup so the internal lattice can suck and loose electrons from and to the ground. Would that increase the electrostatic field over the diaphragm? Will it be a relevant force, since the ear cup is more distant than the stator itself? Probably it would be a faint force so it is an irrelevant doubt.
  
 3) What is the magnitude of the magnetic field created with the paramagnetic stator? Is the Mylar diaphragm driven by two fields of force (electrostatic and paramagnetic)? Is there any difference between a paramagnetic field and the electrostatic field? Is one related to spin alignment and the other related to the simple accumulation of charges? What are their orders of magnitudes?
  
 I was recommend to buy a book of solid state physics, but there are a quite a bit of authors and they seem to be expensive books. And chances are I am not going to have the mathematical skills to understand the subject.
  
 Probably no one is interested in theory. The headphone is just built and it works and measure well so there is no real evidence that magnetic field play a significant role. It is just that I am curious about the subject.


----------



## dude_500

jgazal said:


> Spoiler: Warning: Spoiler!
> 
> 
> 
> ...


 
 1) Yup, eddy currents don't do anything of relevance for milliamps at audio frequencies
 2) The field between the stators is fixed regardless of what's in the surroundings outside the inter-stator gap. The stators set fixed voltage potentials, so the field between them is just voltage/distance. You can potentially change the fields outside the gap, possibly substantially, using metal. But this region does not affect the diaphragm which is in an isolated world due to the fixed potential stators.
 3) I have not run the math, but I would be absolutely shocked if the magnetic effects are anything more than many orders of magnitude lower in force than the electrostatic forces. If they were on the same order, then electrostatic headphones should make a good bit of sound with no diaphragm charge voltage.


----------



## jgazal

Thanks nikongod, wakibaki and dude_500 for taking the time to explain. You are great!


----------



## wakibaki

I was just pulling your leg.

w


----------



## jgazal

wakibaki said:


> I was just pulling your leg.
> 
> w


 
  
 I admit the idea of making a dielectric aluminum alloy is stupid. 
 If one were so concerned about paramagnetism, would just use wood or plastic... 
 Anyway, "quamquam ridentem dicere verum quid vetat?"


----------



## wakibaki

τὸν κρατοῦντα μαλθακῶς θεὸς πρόσωθεν εὐμενῶς προσδέρκεται.

w


----------



## wink

Quote:jgazal 





> Anyway, "quamquam ridentem dicere verum quid vetat?"


 
 "What prevents me from speaking the truth, though laughing?"
  
 Quote:wakibaki 





> τὸν κρατοῦντα μαλθακῶς θεὸς πρόσωθεν εὐμενῶς προσδέρκεται.


 
 "God from afar looks graciously upon a gentle master"
  
 Quote:jgazal 





> I admit the idea of making a dielectric aluminum alloy is stupid.  If one were so concerned about paramagnetism, would just use wood or plastic...


 
 The non-ubiquitous unobtanium would serve very well here.


----------



## chinsettawong

I'm so glad to see wakibaki still active with his DIY.


----------



## wakibaki

Thanks.

Yes, I was a bit depressed for few weeks, but then you realise that you are still alive, and you still have to fill the remainder of your life, which is all any of us are doing anyway. What _used_ to give meaning to my life _still_ gives meaning to it, and although I build things to use, building is fun in itself.

I have built one side of the electrostatic headphones complete down to the cable and connector. The other side is just a little hand-fettling away.

Now I need an amplifier. I have completed the design work for the I solid state amplifier I talked about previously, with some small exceptions. I have designed a case to make on the cnc mill, it uses perspex and aluminium sheet. I ordered the wrong transformers, so I have not ordered the boards, because I always check the layout against the parts, because dimensions in data sheets can be hard to interpret. Building something like this is always quite stressful, because of the cost implications of a mistake, so I have a quick fix in mind.

I have bought a 15W (TPA20202024) amplifier and Meanwell 12V supply. I intend to build an EHT supply after the style of the one on Rod Elliott's site:- http://sound.westhost.com/project105.htm, and wire it up with a pair of centre-tapped transformers. I wonder if anybody would care to recommend some transformers for this service? I don't want to spend a lot, I just need something to prove the phones.

edit:

This is what I am thinking about:- 

http://uk.farnell.com/multicomp/vtx-146-015-106/transformer-15va-2x-6v/dp/1675043

Fred


----------



## wink

Just get a good NAD, Yamaha, Sansui, or Pioneer amp and a Stax SRD7/SB and you're good to go.
 Or, you could build a KGSS, KGSSHV, BHSE or DIYT2.
  
 Or, even buy a Stax SRM-252s or SRM-323s.


----------



## wakibaki

Doh! I picked a tx with a CT secondary, when what is required is a CT primary. I must be a bit distracted.
  
 Here is the latest iteration of the depletion MOSFET design. I have carefully made these stacking boards 100mm square, this is the best value/size on sites such as seeedstudio.com and iteadstudio.com. 10 ea. of these cost ~U$75.
  

  
 The bottom layer, the amplifier, has a largely unbroken copper plane on the upper surface, the upper 2 layers have largely unbroken copper planes on their undersides. The power is supplied via vertical descenders as required locally by the amplifier. That's the theory anyway.
  

  
 The schematic shows DN2540, but IXYS IXTP01N100D should be substituted for UK mains operation with ~650V bias available. I have all the parts excluding the transformers and boards. I have part-drawn an enclosure in 3D inAutocad:-
  

  
 Dimensions are 5*5*4 interior. 2, 3 and 5mm acrylic and alu sheet.
 This will enable me to figure the placement for the fasteners and controls. The back will be alu. plate to heatsink the active devices, the front smoked acrylic, to permit the digital bias voltage readout to be visible on the top shelf of the PCB stack. Top and bottom will have cooling slots. This has been designed to permit low-effort production on my CNC mill.
  
 w


----------



## wink

The centre-tapped primary is not a problem as long as the secondary is centre-tapped too.


----------



## chinsettawong

I'm sure that Wakibaki knows what he's doing.


----------



## wakibaki

I found these:- http://www.ebay.co.uk/itm/Toroidal-230V-Mains-Transformer-15VA-0-6V-0-6V-/300976618233?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item46139abaf9
  
 In this case the primary and secondary swap roles, but this is dual both sides.
  
 This is the bias supply:-
  

  

  
 w


----------



## chinsettawong

Guys!  Any progress on your headphones and amplifiers? 
  
 I bought a roll of 2 microns Mylar from Ebay and put it on my Omega clone.  I like it.  The trick is to not stretch the Mylar too much - just enough to get rid of wrinkles.
  

  
 Wachara C.


----------



## Congo5

does this count?
 12ax7 / 5965 like post# 7
 thanks for the update on the 2 microns Mylar....
 its all I have to work with...good to know.


----------



## davidsh

All the single sided planars got me thinking.. Has anyone experimented with single sided electrostats or perhaps making the sides facing your ears more acoustically transparent (smaller stator surface area)?


----------



## wakibaki

I went to Malta for a week. I used to live there when I was 8~12 YO.

Some things arrived by the time I got back:-



These are the parts for the transformer-style amplifier I decided to take a flyer with. It's only ~8W into 8ohms, which is 8vrms, with a transformer ratio of 40, but I still think it should drive the phones.

w


----------



## dude_500

chinsettawong said:


> Guys!  Any progress on your headphones and amplifiers?
> 
> I bought a roll of 2 microns Mylar from Ebay and put it on my Omega clone.  I like it.  The trick is to not stretch the Mylar too much - just enough to get rid of wrinkles.


 
  
 Interesting, I have my 2-micron mylar extremely tight - I think I hung about 12 pounds of weights on it for my last diaphragms, and it's not really enough. Works fine, and tighter didn't reduce bass (based on double blind testing... it certainly did reduce it by placebo effect). 
  
  


davidsh said:


> All the single sided planars got me thinking.. Has anyone experimented with single sided electrostats or perhaps making the sides facing your ears more acoustically transparent (smaller stator surface area)?


 
  
 I believe this leads to charge migration in electrostatic drivers. Works fine in magnetic because there is no magnetic charge involved.


----------



## chinsettawong

dude_500 said:


> Interesting, I have my 2-micron mylar extremely tight - I think I hung about 12 pounds of weights on it for my last diaphragms, and it's not really enough. Works fine, and tighter didn't reduce bass (based on double blind testing... it certainly did reduce it by placebo effect).


 
  
 Well, you just say it yourself that it's not really enough.  Then I don't think your Mylar is extremely tight already.  With inner tube stretcher, it's easier to get the diaphragm too tight.  When you do that, you get something like these:
  

  
 When you say you use 12 pounds of weight on it, I assume you mean you put a total of 12 pounds of weight all together, right?  If that's the case, that might not be enough.
  
 When I used water bottles as weight the last time, it's not really enough too.
  

  
 I can't believe that you don't hear a sonic difference between very tight diaphragms and the ones that aren't too tight. 
  
 I hear a lot better bass from the diaphragms below than the ones I posted above anytime.
  

  
 Wachara C.


----------



## dude_500

chinsettawong said:


> Well, you just say it yourself that it's not really enough.  Then I don't think your Mylar is extremely tight already.  With inner tube stretcher, it's easier to get the diaphragm too tight.  When you do that, you get something like these:


 
  
 Ok, in that case I think we just have different definitions of really tight. I've never even tried anything this tight, mine all look like your last picture for the most part. My bass comparisons would all be done at differences of 10-20% weighting. I imagine I'd have to nearly double to get up to the tightness you have pictured.
  
 And yes, that is 12 pounds total distributed among 16 weights. At some point I will up that to probably at least 16 pounds since on a hot humid day I have to drop bias to about 500v right now.


----------



## chinsettawong

dude_500 said:


> Ok, in that case I think we just have different definitions of really tight. I've never even tried anything this tight, mine all look like your last picture for the most part. My bass comparisons would all be done at differences of 10-20% weighting. I imagine I'd have to nearly double to get up to the tightness you have pictured.
> 
> And yes, that is 12 pounds total distributed among 16 weights. At some point I will up that to probably at least 16 pounds since on a hot humid day I have to drop bias to about 500v right now.


 
  






  I'm glad that we now understand each other better.  I just don't want others to get confused reading our posts. 
  
 So, are you making any more amps or headphones?  As for me, I've been lazy these past few months and haven't done anything new.  
	

	
	
		
		

		
		
	


	



  
 Wachara C.


----------



## dude_500

chinsettawong said:


> I'm glad that we now understand each other better.  I just don't want others to get confused reading our posts.
> 
> So, are you making any more amps or headphones?  As for me, I've been lazy these past few months and haven't done anything new.
> 
> ...


 
  
 No... I just graduated from college so it'll be some time until I get my life in order and have the tools to do much work on these things. I'm sure I'll get back to it at some point though!


----------



## ondesx

Hello,
  
 Can you tell me if the Topical antistat from Reztore will be a good candidate for Mylar coating ? Same product than Licron Crystal ?
  
 http://www.charleswater.co.uk/CharleswaterCatalogue/FloorCareMaintenanceProducts/ReztoreCleaningProducts/TopicalAntistat/71035/#.U4O1n1h_sWs
  
 Thank you for your answers,
  
 OndesX


----------



## dude_500

ondesx said:


> Hello,
> 
> Can you tell me if the Topical antistat from Reztore will be a good candidate for Mylar coating ? Same product than Licron Crystal ?
> 
> ...


 
  
 I doubt there's any way to identify which is better than another from what the label says. And I imagine any spray will work reasonably well. The only variability I can think of would be long term stability of the coating.
  
 Also I really hope you have a cheaper source of that stuff. $195 for 12L is probably not a logical purchase.


----------



## ondesx

Ooops ! I don't payed for the sample !...


----------



## ondesx

Otherwise are such products of any help (on the PCB) of the Cells ?
  
 http://www.aclstaticide.com/acrylic_conformal_coating.html


----------



## dude_500

ondesx said:


> Otherwise are such products of any help (on the PCB) of the Cells ?
> 
> http://www.aclstaticide.com/acrylic_conformal_coating.html


 
  
  
 It might be, I don't know what finish that has but I assume glossy... I tried a spray paint with a glossy finish and it was very bad, loud squealing when hit by the diaphragm and actually decreased stability. I theorize that the glossy surface increases surface area of contact when hit by the diaphragm making it a bad situation. It could have been some other property of the paint I used, though. Now I only use matte finishes.


----------



## chinsettawong

I haven't noticed a problem with all the paints that I've used - glossy or matt.
  
 It could be a problem with the certain brand of paint that you used though.


----------



## ondesx

Thanks Guys !...
  
 Short questions perhaps already debated here or elsewhere :
  
 - what is better for the diaphragm, too much tensioned or not. Obviously, the resonance frequency rises with the tension, but what about the sound quality ? Some of you have a quantified value in mind (in Newtons) ?

 - as far as the coating of the diaphragm, one side or both must be prepared ? Will this have any incidence on audio quality ? 

 - for the "track" on the internal face of the spacers for the polarization of the diaphragm, I suppose that smaller is the width of this track, better it is, since the capacity will be lowered this way ? If the diaphragm is coated both sides, a track on each spacer is perhaps advised...
  
 Again thank you all for your help.


----------



## dude_500

ondesx said:


> Thanks Guys !...
> 
> Short questions perhaps already debated here or elsewhere :
> 
> ...


 
 -Well, too little tension is worthless because it goes unstable. So I guess too much is better than too little. But just right is better than too much, because too much will hurt bass.
 -I think we mostly do one-side on the DIY ones. Hard to know what retailers do. If you run the math, coating both sides versus one is the same situation. What mathematically would greatly reduce distortion, at least in theory, is having both sides coated but insulated, and both having a few meg-ohm resistance to the bias supply. It'd be very difficult to implement this, I don't know if anyone ever has. I can't find the paper that talks about this at the moment, it's somewhere in this thread.
 -I don't think the track size really affects anything. You're worried about capacitance between the stators because it affects the amp. The capacitance on the bias supply is basically irrelevant, it's DC.


----------



## jcx

one sided coating, the thickness of the diaphragm hardly matters to the E field, the force, balance since it is a small fraction of the spacing and the e_r of the Mylar even reduces the small effect of the thickness of the diaphragm more  - do you really get the spacing/centering/flatness within few microns?


----------



## dude_500

jcx said:


> one sided coating, the thickness of the diaphragm hardly matters to the E field, the force, balance since it is a small fraction of the spacing and the e_r of the Mylar even reduces the small effect of the thickness of the diaphragm more  - do you really get the spacing/centering/flatness within few microns?


 
  
 Here is the paper that outlines the concept of isolated coatings on each side: http://douglas-self.com/ampins/wwarchive/wwarchive.htm#diel
  
 I went through the math a while back and it seems to be a correct assessment. Intuitively it seems absurd though, so possibly some math trick going on I fell for.


----------



## ondesx

dude_500 said:


> But just right is better than too much


 
 Do you have an idea of this tension in Newtons/unit of surface ?


----------



## dude_500

ondesx said:


> Do you have an idea of this tension in Newtons/unit of surface ?


 
  
 If that's just how much weight do I hang from a unit area circle of mylar, it'd be about 1.1kN/m^2 (approximately 13 pounds divided amongst 16 weights hung from a 10" diameter circle).


----------



## ondesx

dude_500 said:


> -I think we mostly do one-side on the DIY ones. Hard to know what retailers do. If you run the math, coating both sides versus one is the same situation. What mathematically would greatly reduce distortion, at least in theory, is having both sides coated but insulated, and both having a few meg-ohm resistance to the bias supply. It'd be very difficult to implement this, I don't know if anyone ever has. I can't find the paper that talks about this at the moment, it's somewhere in this thread.


 
  
 I probably missed something here, because it doesn't appear very difficult to coat each side of the diaphragm, since after coating one side, the spacer with the copper track for polarization and the corresponding stator are glued on this side. Then the diaphragm and this ensemble (i. e. spacer/stator) are flipped and the coating of the other side is easily done. Afterwards, the spacer with the copper track facing the diaphragm and the second stator are glued on this side. 
  
 Thus, each spacer have a track connected to a small "ear" with a hole, where the wires for the polarization are attached. I suppose that the same polarization wire can be connected to both "spacer tracks"...
  
 Of course, all the holes and the soldering/connections must be done before gluing all these pieces all together, in order to preserve the diaphragm. 
  
 The only unknown is the electrical quality of the glue : will be good enough the contact of the "spacer track" and the membrane, through all glues ?


----------



## jgazal

Did Stax normal bias have both sides of the diaphragm coted?


----------



## dude_500

ondesx said:


> I probably missed something here, because it doesn't appear very difficult to coat each side of the diaphragm, since after coating one side, the spacer with the copper track for polarization and the corresponding stator are glued on this side. Then the diaphragm and this ensemble (i. e. spacer/stator) are flipped and the coating of the other side is easily done. Afterwards, the spacer with the copper track facing the diaphragm and the second stator are glued on this side.
> 
> Thus, each spacer have a track connected to a small "ear" with a hole, where the wires for the polarization are attached. I suppose that the same polarization wire can be connected to both "spacer tracks"...
> 
> ...


 
  
 I doubt contact cement will conduct at all. Also, if going for the full effect of isolating the two sides with high resistance connection to bias, it would be necessary to keep the coating away from the edges or charge current could flow across the two sides that way. I think that would be the hardest thing.
  
  


jgazal said:


> Did Stax normal bias have both sides of the diaphragm coted?


 
  
 I recently repaired some SR-X MK3 and they appeared to be coated on both sides but it was hard to be sure. I didn't want to touch them with anything to try to measure them.


----------



## jgazal

dude_500 said:


> I doubt contact cement will conduct at all. Also, if going for the full effect of isolating the two sides with high resistance connection to bias, it would be necessary to keep the coating away from the edges or charge current could flow across the two sides that way. I think that would be the hardest thing.
> 
> 
> 
> I recently repaired some SR-X MK3 and they appeared to be coated on both sides but it was hard to be sure. I didn't want to touch them with anything to try to measure them.


 
  
 So although both sides of the diaphragm may be coated, there are no two bias input pins for each channel, right?
  
 Did normal bias amplifiers have two separate bias regulators?


----------



## dude_500

jgazal said:


> So although both sides of the diaphragm may be coated, there are no two bias input pins for each channel, right?
> 
> Did normal bias amplifiers have two separate bias regulators?


 
  
 Even doing what I described (which I don't think any retail headphones ever have, and probably no DIY either), you'd only need one bias supply and one bias wire from the amp to each side. You could take one wire into the headphones and have two high value resistors inside each side to break the wire out to each side of the diaphragm.
  
 The headphones coated on both sides just connect the same bias line to each side, so they also only need one line/supply.


----------



## wakibaki

I'm used to using heat to shrink plastic film, the kinds used for covering airframes and wings of model aircraft.

I used the heat gun a long way away from the mylar film to keep the temperature low and controllable. At first the film sagged, then tightened as I moved the heat closer VERY slowly. As soon as the wrinkles disappeared I removed the heat. I haven't been able to test the result yet tho.

w


----------



## davidsh

I don't see why coating both sides should make any difference, it's just a static charge after all.


----------



## wakibaki

I wondered about the effect of coating both sides of the diaphragm, however I put this aside as I attempted the practicality of assembling my first pair of phones.
  
 It's not easy perhaps to visualize the exact arrangements inside the electrostatic headphone capsule until on starts to construct one from scratch.
  
 I discovered that, for me, the contact to the film sorts itself out like this:-
  
 1. You take one spacer, coat the copper area carefully with an even film of contact adhesive, set it aside to dry. Start to tension the mylar with the bicycle pump. When the mylar looks good, drop the spacer onto it, adhesive side down. Press with the fingers all round the edges to ensure adhesion, before removing the ring from the surrounding mylar with a scalpel, carefully removing any rags. The copper on this spacer plays no role in connecting to the diaphragm, it's just there for symmetry.
  
 2. Now the antistatic can be applied to the film, on the opposite side from the spacer.
  
 This means that when the diaphragm is assembled with the second spacer, the copper on this spacer butts up against the coated side of the diaphragm, and is available to provide a consistent, low-ohmic connection to the periphery of the high-resistivity diaphragm. Usually protruding tabs are formed at the edge of PCB of both spacer and stators to allow connection.
  
 w


----------



## ToddTheMetalGod

I wish that I was good at DIY. I think it would be so cool to build a pair of electrostatic headphones. What a life experience . Some of you guys/girls should go into engineering!


----------



## chinsettawong

A heat gun can't shrink the diaphragm enough to make it stable, in my experience.

Sent from my SM-N9005 using Tapatalk


----------



## n3rdling

Heat shrink of most PET film is about 2% in x/y direction and 1.4% in z according to all the datasheets I've looked at.  The only one I've seen with a much different spec is the special heat shrinkable Hostaphan which is something like 20%, but way thicker than what we use (12 micron minimum).  Probably best to use mechanical tensioning and then heatshrink after if needed.


----------



## ToddTheMetalGod

Could someone please give me some details about how the Stax Pro Bias headphones are constructed? I think I might try my hand at building an electrostatic and I plan on using the SRM-252S as the amp. I know from reading this thread that the spacers should be 0.5mm in thickness (for Pro Bias), but how thick should the stators be? Also if I want to make a rectangular driver (long side vertical, like Stax), what driver dimensions should I be using? I would appreciate any help I can get .


----------



## davidsh

^Stator thickness doesn't really matter much.

Is there no reason not to coat/paint the stators for insulation, you should do that, right? Don't see that mentioned often.


----------



## ToddTheMetalGod

davidsh said:


> ^Stator thickness doesn't really matter much.
> 
> Is there no reason not to coat/paint the stators for insulation, you should do that, right? Don't see that mentioned often.


I'm going to paint mine, just to be safe.


----------



## poecillia

I made a electrostatic headphone by own design. I used wire instead of perforated plates. You can find a description on http://esl.hifi.nl/project09.htm
 Tekst is in dutch but google translate is your friend


----------



## ondesx

dude_500 said:


> I doubt contact cement will conduct at all. Also, if going for the full effect of isolating the two sides with high resistance connection to bias, it would be necessary to keep the coating away from the edges or charge current could flow across the two sides that way. I think that would be the hardest thing.


 
  
 Well, here is my proposition... 
  
 The copper track on the spacers occupies only half internal of their surfaces. 
  
 Remember, each spacer and the copper on the stators are separated by a small gap (say 2 mm).
  
 The half external part of the spacers is used for gluing them to the diaphragm. Both spacers have a small "ear" on the central and lower part of each, where the copper track finishes. This will provide a very secure and safe connection both to the polarization and to the membrane. 
  
 Any comment welcome.


----------



## ToddTheMetalGod

If I don't have access to a CNC machine to cut PCB, what would you guys suggest that I do for spacer material? I'm thinking plastic would work well because it's an insulator, but I don't know how I would get it in the shape/size I need.


----------



## wakibaki

chinsettawong said:


> A heat gun can't shrink the diaphragm enough to make it stable, in my experience.


 
  
 Ah, OK. I was resigned to rebuilding them a few times. I'm trying to finish the HT supply.
  
 I went to the library today, to use the laser printer. My UV lightbox is playing up, I haven't figured out how to mill PCBs but I know I can do toner transfer with the regular paper in the library if I keep the tracks wide. Anyway I forgot to take a vernier. When I got home the printout was undersize. Grrr.
  
 w


----------



## dude_500

toddthemetalgod said:


> If I don't have access to a CNC machine to cut PCB, what would you guys suggest that I do for spacer material? I'm thinking plastic would work well because it's an insulator, but I don't know how I would get it in the shape/size I need.


 
  
 Oval/circular shape might be hard, but you can make some nice rectangular drivers without any CNC tools. Here are a few pictures of my early drivers before I got CNC access. These parts are all made with nothing but a dremel and a tiny drill press.


----------



## jcx

dude_500 said:


> jcx said:
> 
> 
> > one sided coating, the thickness of the diaphragm hardly matters to the E field, the force, balance since it is a small fraction of the spacing and the e_r of the Mylar even reduces the small effect of the thickness of the diaphragm more  - do you really get the spacing/centering/flatness within few microns?
> ...


 
 the “trick” with the WW analysis is that the 2 conductive coatings on the micron thin Mylar membrane is a huge capacitance and therefore the front and back coatings are AC short circuited regardless of an R between front and back
  
 the principle that the charges can move in the conductive coating is fine though and the E field force is proportional to the density of charges – they just totally miss the real geometry effect
  
 the problem with conductive membranes is that the charges can move around within the conductor under the influence of the E field which varies as the distance between the conducting, polarized surfaces move
 so even if no new charge comes in from the polarizing supply because of the big resistor, if the membrane coating is low resistance the charges can move over the surface of the diaphragm in the low resistance coating to be closer to the oppositely polarized stator
  
 I ran up these sims in the toy student version of QuickField, the 256 node limit on the mesh doesn't get you far so the dimensions aren't to scale
  
 the model geometry is axisymmetric about the bottom x axis,
  
 right, left vertical lines are the radial sections of circular planes, our “stators” +1000 V left, -1000 V right
  
 curved line in the middle is a radial section of a displaced diaphragm
  
 in the 1st conductive membrane sim the diaphragm is a uniform potential over the whole surface: +1000 V polarizing V
  
 in the second the curve is given a constant surface charge density to approximate a high resistance coating
  
 (“diaphragm” curve is random hand entered – not from anywhere in particular)
  
 it turns out that the E field energy density (plotted in color) difference across the diaphragm is proportional to the surface force on the membrane (expand the units and you get n/m^2)
  
 the 1st pic's conductive membrane is being pulled harder in the middle where the charges in the conducting coating have been free to run to the center – this piling on of the force in the middle over deflects it as the membrane gets closer to the stator giving distortion
  
 I think you can see that the 2nd, “constant charge” situation shows much more uniform force on the diaphragm
  
  

  
  
 I believe the ideal “constant charge” ESL implementation would be to “glue” some charges uniformly distributed over the surface of the membrane without having any surface conductor at all
 but electrits don't seem to be good mechanically so we use high resistance coatings on the mechanically good Mylar – we want the resistance so high that the charges we trickle in with the polarizing V supply don't want to move across the surface because the RC time constant is much longer than any audio signal
 this high surface resistance is not just to prevent the charges from moving on/off the membrane through the polarizing supply resistor but also the time constant should be too long for the charges to even move from one part of the diaphragm surface to another
  
  
 coating both surfaces really doesn't matter - its the deflection/E field concentration/charge movement that causes the force to be nonlinear with applied V when the membrane is highly conductive


----------



## poecillia

toddthemetalgod said:


> If I don't have access to a CNC machine to cut PCB, what would you guys suggest that I do for spacer material? I'm thinking plastic would work well because it's an insulator, but I don't know how I would get it in the shape/size I need.


 

 You can find spacer material everywhere in your home. For instance insertable TAB index deviders for office binders are available in the right thickness and can be shaped with scissors or a Stanley knive. This material offen is polypropylene, which is difficult to glue, but good sanding will help.
  
 You can use massive cardboard as well. For low resistance (coated) diaphragma's fine, but if you use a high resistance diaphragma its better to paint the cardboard to avoid the risk of leak of charge as carbonboard has a very low conductivity..


----------



## ToddTheMetalGod

poecillia said:


> You can find spacer material everywhere in your home. For instance insertable TAB index deviders for office binders are available in the right thickness and can be shaped with scissors or a Stanley knive. This material offen is polypropylene, which is difficult to glue, but good sanding will help.
> 
> You can use massive cardboard as well. For low resistance (coated) diaphragma's fine, but if you use a high resistance diaphragma its better to paint the cardboard to avoid the risk of leak of charge as carbonboard has a very low conductivity..


All right, thanks .


----------



## ondesx

After some research and estimations, it seems that the distorsion remains very low because the film is very thin !... 
  
 Thus, we don't have to worry about the coating : only one side, will do the job.


----------



## davidsh

Yet you don't want the charge to move when excursion of the diaphragm happens, I suppose? That'll introduce distortion as jcx lines out?


----------



## jgazal

jcx said:


> the “trick” with the WW analysis is that the 2 conductive coatings on the micron thin Mylar membrane is a huge capacitance and therefore the front and back coatings are AC short circuited regardless of an R between front and back
> 
> the principle that the charges can move in the conductive coating is fine though and the E field force is proportional to the density of charges – they just totally miss the real geometry effect
> 
> ...


 
  


davidsh said:


> Yet you don't want the charge to move when excursion of the diaphragm happens, I suppose? That'll introduce distortion as jcx lines out?


 
  
 What is the minimum coating resistance that allows "constant charge" to avoid migration within the diaphragm surface and what is the minimum coating conductance to charge the diaphragm?
  
 How long it takes to achieve full surface charge of the diaphragm with such "high resistance coating"?
  
 With uncoated membranes, what is the sensitivity? If I push them hard, can the stators achive the air voltage breakdown? 
  
 Suppose one could laser or photo etch shields with several patterns* and spray gun the coating chemical solution at a certain pressure and during certain time so that the coating is made at certain regions at certain thickness according to a given precision (variables: shield accuracy, proportion accuracy of elements in the solution, pressure in the spray gun, time spraying…).
  

  
 When the animation starts, in diaphragm to the right, green color regions are coated surfaces of the diaphragm and blue color then represents uncoated Mylar. There are traces that connect the concentric coated regions. Which length and coating thickness the traces that connect the concentric coated regions must have in order to its resistance reduce charge migration from circle to circle?
  
 Suppose 24 hours or more (48 hours, i.e.) to fully space charge all the concentric circles at the rated voltage bias. Since the traces seem to add serial resistance, what is the charge gradient or voltage gradient from the inner circles to the outer circles and how they scale up from hour one to hour 48?
  
 Urghh, this seems very hard to achieve, so now a different perspective.
  
 Now the diaphragm depicted to the left. The outer coating in the front side of such diaphragm (green) could be connected to 580V pro bias and the inner coating in the back side (yellow) could be connected to +230V normal bias**. Blue color represents uncoated Mylar at each side of such “double bias” and “double side” coated diaphragm. Would that increase linearity?
  
 I have drawn the pattern according to low frequency vibration modes that arnaud described. I presume low frequencies cause more diaphragm displacement and charge displacement than midrange. But vibrations modes also change as we go up in frequency (arnaud simulated the stators, is the same vibration mode for diaphragms?):
  


arnaud said:


> (...)
> Examples below with the first 2 stator resonances at about 750Hz and 1400Hz, left is the old stator, right is the new one with smaller perforated area. In both cases I ignored the copper trace / etching so this is assuming 1mm FR4 (also I used isotropic average properties for the material even though its mechanical properties are actually somewhat direction dependent):
> Mode 1 (730Hz for both stators):
> 
> ...


 
  
 Maybe segregating the pattern in east and west portion with 230v bias within the surfaces in the peak of the 1400Hz vibration mode?
  

 Yellow (front 580V pro bias); green (back 230V bias); blue (uncoated Mylar).
  
 Urghh, this also seems very hard to achieve. Perhaps there is no optimum diaphragm coating pattern for all vibrations modes of the diaphragm in the audio spectrum.
  
 I do not know much about the physics behind this transducers, but this is certainly the coolest thread***.
  
 --------------------------------
 * Shields only used in production process.
  
 ** Or a -230V negative normal bias or -80V unstandardized negative bias, changing the coating pattern, I honestly do not know…
  
 *** if I had a lab, I would build all crazy or stupid configurations just to test if they work… Maybe with theory background to simulate their behavior, I would probably build considerably less “prototypes”. Knowledgeable people in ee please do not shoot me if I said something stupid.


----------



## wakibaki

You should probably use 1.6mm for the PCB thickness, this is the most commonly encountered.

I have thought about how to make all these parts, including spacers, from regular PCB thicknesses, because thin PCB is not easy to obtain in the UK. If concentric stepped rings are used in the supporting structure, this is comparatively easy to achieve with a CNC mill, even if skimming the PCB proves too difficult.

w


----------



## dude_500

wakibaki said:


> You should probably use 1.6mm for the PCB thickness, this is the most commonly encountered.
> 
> I have thought about how to make all these parts, including spacers, from regular PCB thicknesses, because thin PCB is not easy to obtain in the UK. If concentric stepped rings are used in the supporting structure, this is comparatively easy to achieve with a CNC mill, even if skimming the PCB proves too difficult.
> 
> w


 
  
 I feel like getting sufficient repeatability for channel matching by either making stepped rings or skimming a PCB would require vacuum holddown on a machine specifically designed for highly repeatable z-axis mounting, and it still might change day to day (but that might be irrelevant for DIY). The relevant distances we're talking about for channel matching are tremendously small to easily repeat over a wide x-y area.
  
 I did recently see a video of someone's PCB mill that scanned the x-y area electrically detecting the copper surface while dropping z every half inch or so to create a mapping of the z non-perfections and then adjusted the g-code in realtime to correct for a flat surface. By doing this they were able to mill circuit boards taking off effectively no more than the copper whereas you have to go fairly deep if you don't have some elaborate mounting scheme or a z-axis mapping system.


----------



## n3rdling

If you don't have access to a vacuum hold down table, you can level the spoilboard and use double sided carpet tape to hold down the PCB pretty flat.  A more expensive option is to use a floating head.
  
 There are two programs I know of to do what you describe:
 http://www.pcbgcode.org/
 http://www.autoleveller.co.uk/


----------



## jgazal

Okay, no feedback, I must have said something nonsense. More down to earth, how much reduction in efficiency (at 30Hz, 300Hz, 1kHz and 10Khz) one would expect adopting a semi-coated, single-side, diaphragms like these:
  

  
 I know you can say “go and build one yourself to test it”, but right now I do not have the practice you guys have…


----------



## dude_500

jgazal said:


> Okay, no feedback, I must have said something nonsense. More down to earth, how much reduction in efficiency (at 30Hz, 300Hz, 1kHz and 10Khz) one would expect adopting a semi-coated, single-side, diaphragms like these:
> 
> 
> 
> I know you can say “go and build one yourself to test it”, but right now I do not have the practice you guys have…




  
 Rather than "go build one", I'm going to say go simulate one for yourself. It would be tremendously difficult to conceptually analyze what any of those patterns would do. There are so many dynamics at play here.


----------



## jgazal

You are right. The patterns may alter the vibrations modes itself. Perhaps a coating pattern that match the exactly the holes in the stators. But then one would have half the coated area and probably a strong decrease in sensitivity. (no constant charge effect...). Thank you for your response!


----------



## chinsettawong

I received a few pieces of these car speaker grills from a friend.  So, I put them to good use.


----------



## wink

Your artisan streak shows up again.  Well done.


----------



## OnyxOcelot

jgazal, do you have a plan for how to coat a diaphram as such?  Perhaps a stencil held on top of diaphragm with your coating material sprayed or brushed on through?
  
 A hopefully quick question with a long explanation:
 I put together another set of rectangular drivers yesterday.  These have very thin spacers(.015 in or .381 mm), which unfortunately are double sided copper plated board.  I say unfortunately because I have been having trouble isolating one side from another.  Inevitably, with the number of screw holes around the outside, and the very little isolating material between the two copper plates, there are some very small burrs or strings of copper connecting one side to another, even after a considerable effort at their removal.  After my very best attempt at removing any and all burrs, I measured a resistance of ~250 mega-ohms between the top and bottom of the spacer.* 
  
 Assuming that perhaps this level of resistance between stator and diaphragm (once the unit was put together) might not affect the unit's performance, I put the unit together and tried it.
  
*Question 1: will this very high resistance connection between stator and diaphragm cause a detriment to performance in the unit?  Should a stator and diaphragm be completely isolated?*
  
 Once I put the unit together, it seemed to work.  However, when I put the driver down and increased the volume, it began sparking along the sides (where the copper of the spacer and the copper of the stators are exposed and close to one another).  I don't know if this is because the gap is so much smaller than my previous set (both because the spacer is thinner *and* double sided) or because the edge is not covered in tape (as were my previous sets, which didn't use screws).
  
*Question 2: do your drivers spark along the edges and is there a way that you avoid this (electrical tape, hot glue, etc.)?  I suppose this all could be due to my double sided copper board, so if anyone knows where to source thin copper plated board that is single sided in the USA, let me know.*
  

 Thanks for the advice,
 OnyxOcelot
  
  
  
  
 *I should specify that my multi-meter would jump back and forth between a very high resistance and Open Loop.


----------



## chinsettawong

I think you still have some copper dust sticking to the side of your spacer.  I always use a sand paper to sand the edge of the spacer.  Sanding at an angle also helps remove some copper near the edge.  If all else fail, you can still etch out the copper on one side of the PCB using chemical.
  
 About the PCB supplier in the USA, there is one that I've bought PCB from:    http://www.ebay.com/itm/FR4-Copper-Clad-Laminate-PCB-Printed-Circuit-Board-Material-FREE-SHIPPING-USA-/120802756087
  
 The material is pretty good.
  
 Please show us your drivers.
  
 Wachara C.


----------



## OnyxOcelot

Also, I would like to solicit criticism for this stator design.  It has slots rather than holes, and I made it simply to cut down on machining time.  On my CNC, it took over 20 mins to cut each stator with holes.  With this design, it took less than 10 mins.  How might it affect the sound produced?
  

  
 Thanks,
 OO


----------



## chinsettawong

onyxocelot said:


> Also, I would like to solicit criticism for this stator design.  It has slots rather than holes, and I made it simply to cut down on machining time.  On my CNC, it took over 20 mins to cut each stator with holes.  With this design, it took less than 10 mins.  How might it affect the sound produced?
> 
> 
> 
> ...


 
  
 Slots are fine.  I don't see any problem with that at all.
  
 If I were you, I would paint the stators.  You want them to be well insulated.  That way you won't get spark so easily.
  
 What is the measurement on your stator?
  
 Wachara C.


----------



## jgazal

onyxocelot said:


> jgazal, do you have a plan for how to coat a diaphram as such?  Perhaps a stencil held on top of diaphragm with your coating material sprayed or brushed on through?


 
  
 I have never built an electrostatic headphone. It is just a theoretical exercise, because I overthink things a bit. I just want to better understand how the transducers work. Please follow Wachara and dude_500 advices. They have built fully operational units.


----------



## OnyxOcelot

chinsettawong said:


> Slots are fine.  I don't see any problem with that at all.
> 
> If I were you, I would paint the stators.  You want them to be well insulated.  That way you won't get spark so easily.
> 
> ...


 
 I figured as much.  The slotted stators should have an equal amount of open and conductive area as one with holes.
  
 What type of paint do you use?  And do you cover them entirely or just the edges where they touch the spacer?
  
 The stators are ~ 88 x 76 mm.  I would like to make larger ones for the next attempt.


----------



## chinsettawong

onyxocelot said:


> I figured as much.  The slotted stators should have an equal amount of open and conductive area as one with holes.
> 
> What type of paint do you use?  And do you cover them entirely or just the edges where they touch the spacer?
> 
> The stators are ~ 88 x 76 mm.  I would like to make larger ones for the next attempt.


 
  
 Since you don't try to etch away any copper, I would paint the whole stator.  Acrylic paint is what I always use.


----------



## davidsh

It is ofc quite important to leave an area unpainted so you can solder wires etc.
How do you connect a wire to the diaphragm without making a gap between the stators and diaphragm?


----------



## n3rdling

The wire doesn't connect directly to the diaphragm.  It connects to the inner side of one of the spacers (which is why single sided PCB is used here) which then presses up against the coated side of the diaphragm, acting as a "charge ring".  By using tabs on the spacers there is no extra gap at the connection point.


----------



## davidsh

Ohh I get it now, thanks


----------



## dude_500

onyxocelot said:


> Also, I would like to solicit criticism for this stator design.  It has slots rather than holes, and I made it simply to cut down on machining time.  On my CNC, it took over 20 mins to cut each stator with holes.  With this design, it took less than 10 mins.  How might it affect the sound produced?
> 
> 
> 
> ...


 
  
 Slots don't work well for me. I did roughly the same for stators, and it was abysmally terrible. It takes "no bass" to a whole new level. I have no idea why. My test was done by replacing stators and nothing else, even used the old diaphragm so the test was controlled and nothing else was going on.
  
 Here is what mine looked like


----------



## chinsettawong

dude_500 said:


> Slots don't work well for me. I did roughly the same for stators, and it was abysmally terrible. It takes "no bass" to a whole new level. I have no idea why. My test was done by replacing stators and nothing else, even used the old diaphragm so the test was controlled and nothing else was going on.
> 
> Here is what mine looked like


 
  
 I can't really see what's wrong.  But I guess the open area might be too much.
  
 If I were to do it, I would make the slots much smaller than the bars.
  
 Wachara C.


----------



## MDR30

chinsettawong said:


> Hi,
> 
> I've made the amp for about a year now.
> 
> ...


 
  
 Hello,
  
 This amp may have been dicussed later in the thread, but I wonder if there are boards and transformer available from somewhere. Or maybe an even better, simple DIY amp design?


----------



## davidsh

And I wonder how it stacks up against the good ol' T1


----------



## AManAnd88Keys

davidsh said:


> And I wonder how it stacks up against the good ol' T1e



Speaking of the good ol' T1... I currently have one on sale, an it's been modified.


----------



## chinsettawong

mdr30 said:


> Hello,
> 
> This amp may have been dicussed later in the thread, but I wonder if there are boards and transformer available from somewhere. Or maybe an even better, simple DIY amp design?


 
  
 The amp is already as easy as it can be built.  I hard wired the amp in just about one afternoon.
  
 If you want other, better designs, you can go with Dr. Gilmore's.  His KGSSHV, for example,  is an excellent amp, and it's pretty easy to build too.
  
  


davidsh said:


> And I wonder how it stacks up against the good ol' T1


 
  
 Unfortunately, I don't have a T1 to compare it with.  But I would say it's a good amp for the little money you spend to build it.


----------



## Tyll Hertsens

Simply an outstanding effort, Chinsettawong!
  
 Thank you for sending your marvelous headphones in for measurement. I wouldn't have believed it had I not done the measurements myself.
  
 Very, very nice!!!
  
 http://www.innerfidelity.com/content/extraordinary-diy-electrostatic-headphones-chinsettawong


----------



## purk

tyll hertsens said:


> Simply an outstanding effort, Chinsettawong!
> 
> Thank you for sending your marvelous headphones in for measurement. I wouldn't have believed it had I not done the measurements myself.
> 
> ...


 
 Yay!!  Congrats Mr. Chinsettawong!!


----------



## arnaud

Now, that is a well deserved compliment, congratulations Wachara!


----------



## chinsettawong

Thank yoy Tyll for your kind comments and measurements. 

Sent from my SM-N9005 using Tapatalk


----------



## Tyll Hertsens

You are most welcome, Wachara, really a stunning achievement. 
  
 We'll take it to email from here...I've got to figure out how to get them back to you properly.
  
 But I've got 'til Monday to take care of that, so I'll be enjoying a bit of your creation at my leisure over the weekend.
  
 Thank you so very much for the opportunity to experience your headphones.
  
 Outstanding job!


----------



## n3rdling

Great stuff! 
	

	
	
		
		

		
		
	


	



  
 Tyll, will you be attending the upcoming LA meet?


----------



## Francisk

I truly admire your fantastic work Chinsettawong....keep it up.


----------



## chinsettawong

tyll hertsens said:


> You are most welcome, Wachara, really a stunning achievement.
> 
> We'll take it to email from here...I've got to figure out how to get them back to you properly.
> 
> ...


 
  
 Hi Tyll,
  
 If you like them, please enjoy them for a longer time.  I have no rush to have them back.  
	

	
	
		
		

		
		
	


	



  
 Thanks again for your kind review.
  
 Wachara C.


----------



## chinsettawong

arnaud said:


> Now, that is a well deserved compliment, congratulations Wachara!


 
  
   


purk said:


> Yay!!  Congrats Mr. Chinsettawong!!


 

   


francisk said:


> I truly admire your fantastic work Chinsettawong....keep it up.


 

  


n3rdling said:


> Great stuff!


 
  
 Thanks a lot guys!
  
 Wachara C.


----------



## davidsh

Seems the treble rolls a slight bit more on the orpheus clone compared to 009. Is that so, do they have slightly less treble energy? From the measurements, it seems the upper mids on the orpheus clone is slightly more prominent too (1-2kHz).


----------



## MattTCG

I was able to hear these yesterday. I was simply awestruck at what the OP and creator was able to accomplish. I was able to compare the 009 and Orpheus and will be sharing impressions later...


----------



## chinsettawong

matttcg said:


> I was able to hear these yesterday. I was simply awestruck at what the OP and creator was able to accomplish. I was able to compare the 009 and Orpheus and will be sharing impressions later...


 
  
 Did you listen to the pair that was with Purk?


----------



## MattTCG

^^ Yes, that was the pair.


----------



## purk

chinsettawong said:


> Did you listen to the pair that was with Purk?


 
 Yes, Matt dropped by yesterday and we had a great time listening & chatting about gears.  He was super surprised & delighted at the same to hear your headphones out of the DIY T2 & BHSE.  Thanks again P Wachara, your Orpheus clone is truly an amazing headphones.


----------



## Hun7er

Congratulation for these headphone !
  
 Did you commercialise them on future ?


----------



## Francisk

I hope one day I'll get to listen to Wachara's phones


----------



## chinsettawong

hun7er said:


> Congratulation for these headphone !
> 
> Did you commercialise them on future ?


 
  
 Thanks Hun7er.
  
 I have been making headphones purely for fun.  I do not have any plan to sell them at all.  I encourage you to try to build them by yourself.  They can actually be built by a lot of stuffs around you very cheaply too.


----------



## chinsettawong

francisk said:


> I hope one day I'll get to listen to Wachara's phones


 
  
 You're welcome to try them anytime you come to Bangkok.


----------



## Francisk

I definitely will plan a trip to Bangkok just to listen to your headphones Wachara. I'll PM you once I manage to get some time off work, probably towards the end of the year


----------



## davidsh

Some wire, metal mesh, a strip of thin copper, cardboard or plastic for spacer material, some Mylar, some coating for the mylar and suitable glue would in principle be enough to make an electrostatic driver.


----------



## Francisk

You sure make it sound really simple Davidsh....boy am I tempted now


----------



## chinsettawong

Just to make it even simpler to build, you can try food wrap plastic from your kitchen and liquid soap as coating material.  
	

	
	
		
		

		
		
	


	




  Food wrap does sound very good too.  
	

	
	
		
		

		
		
	


	



  
 I now use a floor cleaner to coat my diaphragm, and it works very, very well.


----------



## chinsettawong

I have posted this video clip before, but let me do it again so that you can hear how good a simple built headphone can sound.  
	

	
	
		
		

		
		
	


	



  

  
 This guy from Thailand took my advice and built his own headphones from something simple to find.  I give him two thumps up.
  
 And of course, the food wrap plastic is used here as the diaphragms.
  
 Wachara C.


----------



## gikigill

Ghetto STAX FTW!


----------



## Francisk

Both Wachara's headphones measurement by Tyll Hertsen sure don't look ghetto to me.


----------



## Hutnicks

chinsettawong said:


> I have posted this video clip before, but let me do it again so that you can hear how good a simple built headphone can sound.
> 
> 
> 
> ...





 OR
  
http://www.esldiy.com/esldiy/forum/index.php?topic=12.msg35#msg35


----------



## Francisk

Thanks for the videos Wachara & Hutnicks


----------



## wakibaki

What a great finding. This shows that it is possible to DIY systems with superb quality without enormous cost, although it is obvious that Wachara could have bought many off-the-shelf systems for his investment in money and time.

A standard electrostatic capsule would be seized on by many people, I think. The idea of organising production of one is so compelling that I will be forced to investigate it if nobody else appears to be doing so.

Fred


----------



## chinsettawong

wakibaki said:


> What a great finding. This shows that it is possible to DIY systems with superb quality without enormous cost, although it is obvious that Wachara could have bought many off-the-shelf systems for his investment in money and time.
> 
> A standard electrostatic capsule would be seized on by many people, I think. The idea of organising production of one is so compelling that I will be forced to investigate it if nobody else appears to be doing so.
> 
> Fred


 
  
 Hi Fred,
  
 If you need any design from me, just let me know.  I'm more than willing to share.
  
 Wachara C.


----------



## chinsettawong

Ok, I'll try something different this time.  Let's see if there will be any improvement.
  
 I've made some little modifications to my Float style headphones design.  I'm going to have a 6 mm hole right in the middle of the stators similar to what Stax is doing with their SR009.  At the same time, I'll shrink the spacer width by 2 mm.  I'm shooting for more diaphragm stability and hopefully I can use 0.5 mm spacer without any issue this time.


----------



## vr1

Great job Mr. Chinsettawong !


----------



## chinsettawong

I've got some free time this afternoon.  So, I went out to cut some stators.


----------



## davidsh

It looks great.
 Damn, I wish I had access to a CNC mill!


----------



## jgazal

davidsh said:


> Damn, I wish I had access to a CNC mill!


 
  
 Try this: http://fablabdanmark.dk/
  
 Other world locations: http://www.fabfoundation.org/fab-labs/


----------



## davidsh

Cool, thanks!


----------



## ayaflo

chinsettawong said:


> I've got some free time this afternoon.  So, I went out to cut some stators.


 
  
 Looks great. What plan do you have in mind for these ? Perhaps the original Stax SR Sigma layout. with the driver angled at the ears from back to front, projected outwards. They tend to increase the sound-stage and improve imaging from the numerous user posts here in Head-fi.


----------



## davidsh

ayaflo said:


> Looks great. What plan do you have in mind for these ? Perhaps the original Stax SR Sigma layout. with the driver angled at the ears from back to front, projected outwards. They tend to increase the sound-stage and improve imaging from the numerous user posts here in Head-fi.


 
 Seems very likely, though it is hard to get deep and low distortion bass from such a setup. My Sigmas definitely has more depth to the sound than my hd800.


----------



## chinsettawong

I had a chance to listen to a pair of SR Sigma before, but frankly, I thought the sound was quite colored.  The new Jacklin Float QA, however, sounded wonderful to my ears.  That's why I have chosen to build the Float style headphones.  The last pair that I built had some problems, and so I'll try something different this time.   
	

	
	
		
		

		
		
	


	



  
 Wachara C.


----------



## chinsettawong

Ok, all the parts are cut and all the needed holes are tapped. Next, I need to etch away the unwanted copper.


----------



## wakibaki

This is a 100mm diameter stator and diaphragm pair.
  

  
  
 It took me a while to figure out how to make the PCB software generate gerbers and drill files to do this job since it is not really what the software is intended to do. I can get the diaphragm supports (spacers) in 0.6mm. The stator can be 1.6mm, this is cheapest. The stator can be covered with solder resist, except where there are pads. The mounting pad holes are M2, intended to accommodate Nylon bolts, the custom pads are just slightly larger than the holes which are M3.   Total cost for 20 (5 sets) would be ~$110 delivered. $22 per set before postage. I still need to figure out some connection points on the edge.
  
 These are not large capsules, but they fit into board dimensions which are available under the very best deal from China. I could go for 100*150mm rectangular or oval. This would increase the cost to $190 or $38 dollars a set.
  

  
  
 This would relieve constructors of the need for a CNC mill, and access to different thicknesses of PCB, plus the stators could be resist-coated, one less process.
  
 Fred


----------



## chinsettawong

Hi Fred,

Your designs look really nice.  I think the prices you got were quite reasonable too.  

Can they do 0.5 mm PCB as spacers?

For your information, the SR007's stators are 0.8 mm double sided PCBs.

Wachara C.


----------



## davidsh

That does indeed look great!


----------



## wakibaki

I can get 0.6, 0.8, 1.0, 1.2, 1.6, 2.0 mm thicknesses. 0.6 & 2.0 cost extra. It's unfortunate that 0.5 is not available, but I hope that the 0.6 will still prove acceptable

I thought that for the stator the stiffest one at no extra cost was the one to go for, but 0.8 is the same price. Do you think there is an advantage to the thinner one? In sound quality?

I have kept the capacitance as low as I could conveniently, I can maybe improve it slightly.

The prices are absolutely rock-bottom, but I know from experience that the quality will be acceptable.

Fred.


----------



## davidsh

I might be interested in a kit if that proves possible


----------



## Hutnicks

davidsh said:


> I might be interested in a kit if that proves possible


 

 Now that is one heck of an idea.


----------



## davidsh

hutnicks said:


> davidsh said:
> 
> 
> > I might be interested in a kit if that proves possible
> ...


 
 Isn't that the idea? Seems we talked about just that earlier in the thread. A kit, also with a bit of mylar in the package, that would be perfect. Only a housing, some wires, suitable coating and some stretching is needed then.


----------



## wakibaki

OK, what do you mean by a kit? A set of 4 PCBs or an assembled capsule with a pretensioned diaphragm? That is a much bigger ask.

Edit: Cross post - I see what you mean by a kit.

I can visualise building a stretcher to apply a constant tension from diaphragm to diaphragm, but that would be a time consuming task to calibrate, and would probably force me to take on MOT status, which I am reluctant to do, whereas I could supply PCBs at cost+, which I do already for other items.

There is also the question of which of the 2 designs to go with.

Our wonderful health service are spending tens of thousands of pounds on my treatment, no-one has suggested that I have less than six months left. At the same time I don't have so much to leave my wife and pets that I would want to burden them with the expense of unsold boards, so I'd need some assurance that they wouldn't be sitting on my hands.

I am happy to make the Gerbers available if anyone wants to pursue getting their own PCBs made.

Fred


----------



## chinsettawong

Hi Fred,
  
 0.6 mm spacer is definitely OK.  You'll just need to turn up your volume a little more when listening.
  
 I've been using 1 mm PCB as stators.  I think it's good enough.  Stax's SR007 has 0.8 mm stators, but they're double sided PCB.  I'm not sure if the extra copper on the other side adds up to its capacitance though.
  
 About the two headphone designs, if I were to choose for you, I would go with the round one.  For one thing, the ear pads are a lot easier to buy - if you choose not to make them yourself.  With good diaphragm tensioning, I'm very sure they can sound as good as the Original Omega.
  
 If I can do anything to help, please let me know.  
	

	
	
		
		

		
		
	


	



  
 Wachara C.


----------



## chinsettawong

After getting the headphones back from Tyll, I sanded and repainted my wood cups with Danish oil, and they look so much better than with polyurethane.  
	

	
	
		
		

		
		
	


	



  
  
  
 The phones sound very nice even with a cheap Stax SRM-252A.


----------



## arnaud

Heineken! You deserve a better beer for such a good repainting job!


----------



## CosPhi

Hello to all...
  
 ...and congratulations to your remarkable results. Even though I have known about ESLs I have only started documenting seriously for a few days and the amount of enthusiasm from all the DIYers who got to finish making headphones or speakers got to me, too. Unfortunately, for now all I have are ideas and plans, for the lack of means behind them, but that may change in the future as I plan to actually build (at least) a pair of headphones, even if it's just to satisfy my curiosity.
  
 Still, I have a few questions that, after reading all(!) the 98 pages, seem to be unanswered and I couldn't find information in other links, even though I can make some guesses. In the end, what I value most is a practical answer to a theoretical one, so here it goes:
  
 1) For a direct drive amplifier -- considering an average one -- what would be the peak voltage at maximum swing? For example, I have seen examples of tube amplifiers supplied at +/-350V, so the peak voltage must be at ~20V~30V, but I have also seen a solid-state amplifier supplied at 300V, which would imply at least half peak voltage (150V), so I am confused.
  
 2) Since the capacitance of a headphone speaker is very small, by my calculations less than 100pF (for example a 100x100mm square with +/-1mm spacing would have, in theory, 44.25pF, not counting dielectrics&co), will a series resistance with high values (kOhms up) influence the response or can it be left there to prevent accidents (wire breaks, touches your face). I know the biasing supply is no danger due to the ~tens~hundreds of MOhms series resistance, but the signal wires are a different matter. For example, for a 50pF headphone and a 100kOhm series resistance, the -3dB frequency would be ~32kHz, no worries for the spectrum, but also harmless for a high-voltage swing in case any accident happens.
  
 There may be more questions about minor details like these but, for now, it's these two, only.
  
  
 Anticipated thanks,
 Vlad


----------



## chinsettawong

arnaud said:


> Heineken! You deserve a better beer for such a good repainting job!


 
  





  Unfortunately, we don't have that many selections around here.


----------



## chinsettawong

Hi Vlad,
  
 Welcome to the DIY world.  
	

	
	
		
		

		
		
	


	



  
 1.  For typical tube amps, the amps are coupled with output transformers, and therefore the output voltage swing isn't all that high.  However, the amps for electrostatic headphones are connected directly to the headphones.  The voltage swing is as much as the power supply.
  
 2.  Voltage swing from an amp can indeed be lethal.  So, we have to make sure that the headphones are safe enough to wear.  We normally use single sided PCB as stators.  The insulated side is safe enough for headphones.  The dust cover also acts as an extra protection.
  
 Wachara C.


----------



## CosPhi

Hello Wachara
  
 And thank you for the welcome. If the voltage swing, for a direct drive amplifier, is as high as the supply, then it goes into saturation (clipping). Normally the output stage has to stay within the linear region so as to have as little distortion as possible. While they can go rail-to-rail in theory, in practice it would be lower.
  
 Still, by pure luck, I found with Google an article from TI, snaa046, which gives an example of solid-state amplifier and some numbers: for a 400V supply (class A), output has ~200Vpp and its supposed to be able to drive Stax type 1 headphones (whichever those may be, I have never had any in my hands). At any rate, that was the info I needed.
  
 On the other hand, I see no series resistor to the output, so, even if the plates and stator are isolated inside the earcup, the wires might still present a problem if they somehow break (I have seen, many times, people feeling a sudden urge to get up, forgetting the headphones they were wearing, and this is just one example...  ). The resistor cannot carry high current since the impedance for a 50pF at 20kHz is ~63.7kOhms, so with the 200Vpp (from TI's appnote) there would be ~1.11mA RMS (thus ~78mW dissipated power). In theory, a 10kOhm resistor could be placed in series and the gains would be: no sacrificed bandwidth and protection against high-voltage signal (not to mention it would be the cheapest protection of output stage at shortcircuit).
  
 Well, thank you for the answers and, if I'll have more questions, you'll know... 
  
  
 Vlad


----------



## Francisk

The headphone with Danish oil sure looks lovely Wachara. How I wish I'm listening to your headphone and chilling out with a beer to two


----------



## Q Mass

arnaud said:


> Heineken! You deserve a better beer for such a good repainting job!



Perhaps Chinsettawong should consider employing his unique cloning skills to brew some better beer? 

A brewer friend of mine once told me that the live yeasts used in some of the worlds best beer can be 'harvested' from a nearly finished bottle and used to produce very high quality home-brew 'copies'.

Best beer brand EVER ( imvho.....)
http://www.beeradvocate.com/beer/profile/207/645/

On topic too! ( diy/cloning, intoxication as a hi-fi tweak! )


----------



## chinsettawong

q mass said:


> Perhaps Chinsettawong should consider employing his unique cloning skills to brew some better beer?
> 
> A brewer friend of mine once told me that the live yeasts used in some of the worlds best beer can be 'harvested' from a nearly finished bottle and used to produce very high quality home-brew 'copies'.
> 
> ...


 
  






 That sounds like a fun DIY project.


----------



## chinsettawong

At last, they are singing now.  
	

	
	
		
		

		
		
	


	



  

  
 I use just enough tension to get rid of the wrinkles on the diaphragm this time, and so far I think the phones have been pretty stable.  However, things might change when I put a headband on them.
  
 Wachara C.


----------



## davidsh

Aren't you afraid of getting dust between the stator and diaphragm?


----------



## chinsettawong

davidsh said:


> Aren't you afraid of getting dust between the stator and diaphragm?


 
  
 You probably can't see from the pictures, but I've put a dust cover on already.
  
 By the way, about the noise from dust problem, the easiest way to help solve it is to paint your stators.  I always do that on all my stators.
  

  
 I cover the stators with spacers and pray paint them.  I use permanent ink to cover the area where the paint misses out.  Then I chemically etch away the copper on the uncovered area.   If the paint is still in good shape after the etching process, I'll just keep it as is.  Otherwise, I might repaint the stators again.
  
 If you do a good job, the copper on your stators is well insulated.  And you'll have less chance of noisy drivers.
  
 Wachara C.


----------



## chinsettawong

The Float number 2 is now singing.  
	

	
	
		
		

		
		
	


	



  

  
 The stability is quite a bit better than the previous pair when using 0.5 mm spacers.   But I'm not sure if it's the hole in the middle or the shorter width of the spacer that helps. 
  
 Anyway, the phones now have pretty good dynamic and very wide sound stage.  The low bass still rolls off a bit when compares it with my Orpheus clone.  But, it's not bad at all.
  
 Wachara C.


----------



## Dark_wizzie

Any chance this will turn commercial?


----------



## chinsettawong

dark_wizzie said:


> Any chance this will turn commercial?


 
  
 Maybe when I'm old and retired.  
	

	
	
		
		

		
		
	


	



  
 However, I highly encourage you to try to make them by yourself.  I'm sure that you'll have a lot of fun.  
	

	
	
		
		

		
		
	


	



  
 Wachara C.


----------



## gikigill

I'm interested in making them myself but need help and advice.


----------



## chinsettawong

gikigill said:


> I'm interested in making them myself but need help and advice.


 
  
 We're always here to help.


----------



## Francisk

The Float v2 looks super awesome. I hope I'll get to listen to it some day. Keep up the good work Wachara


----------



## Dark_wizzie

chinsettawong said:


> Maybe when I'm old and retired.
> 
> 
> 
> ...


 
 You might be capable of doing something like this, but I know nothing about how to build of stuff like this. I was looking at the directions on how to assemble an Odac and I turned around and ran the other direction.


----------



## gikigill

Currently on vacation but will start something when I'm back. Might have to get a few workshops to help with the parts as I have no tools or machinery.


----------



## chinsettawong

After spending more than 10 hours with the phones, I'm glad to say that the phones are stable with 0.5 mm spacers.  And they certainly sound very good with my KGSSHV.
  

  
 Here are the details of my build.
  
 1.  The active area is 120 mm x 76 mm. 
 2.  The perforated holes are 2 mm with the exception of the large 6 mm holes in the middle
 3.  The spacer thickness is 0.5 mm.
 4.  The diaphragm is 3 micron.
  
  
 Wachara C.


----------



## Francisk

I can literally call the Float v2 ear-speakers because it looks like 2 mini speakers on the ears


----------



## chinsettawong

Let me show you a technic I use to clean small dust on my stators.  
	

	
	
		
		

		
		
	


	



  

  
 As you peel out the adhesive tape,  the dust go off with it.  
  
 Wachara C.


----------



## bluemonkeyflyer

chinsettawong said:


> Let me show you a technic I use to clean small dust on my stators.
> 
> 
> 
> ...


 
  
 I'm late to the party but look forward to reading all 100 pages in this thread.
  
 Truly amazing work and such generosity to share with everyone!  
  
 Perhaps this has already been discussed, but I wonder if anyone has found sources for the materials needed to make the 'phones and a good CNC service.
  
 Many thanks to Wachara C and all who have posted tips and techniques,
  
 BMF


----------



## davidsh

Damn, it would be a big favor to everyone having this thread indexed.


----------



## kevin gilmore

Wachara is graciously sending me a present which I will examine and turn
 into some machine code and then some full NC made stator panels and as many
 of the rest of the parts as I can make.
  
 This was the result of a great idea by wachara.
http://gilmore.chem.northwestern.edu/dsc_0783.jpg
  
 So when I said that I would never ever build electrostatic headphones...
 I lied.
  
 And the equipment I have is capable of making stators out of glass and
 I have a vacuum system capable of coating them, so this should be a
 whole bunch of fun.
  
 When you go to sleep and dream in G code, you know you are in trouble.


----------



## davidsh

kevin gilmore said:


> Spoiler: Warning: Spoiler!
> 
> 
> 
> ...


 
 I like the sound of that! Why would one make stators out of glass, though?
  
 Anyway will stay tuned


----------



## kevin gilmore

the sennheiser he90 (orpheus) had glass stators

ross walker gave me a lot of info years ago on how
quad did their tensioning. And i have some other
confidential info on diaphram manufacture that
should help


----------



## bluemonkeyflyer

kevin gilmore said:


> the sennheiser he90 (orpheus) had glass stators
> 
> ross walker gave me a lot of info years ago on how
> quad did their tensioning. And i have some other
> ...


 
  
 Good Stuff!


----------



## MattTCG

You just have to wonder if some magic will happen here...


----------



## bluemonkeyflyer

matttcg said:


> You just have to wonder if some magic will happen here...


 
 ...Abra Cadabra...Done!


----------



## Kerry




----------



## chinsettawong

I tested the Float style headphones for a few hours yesterday, and everything is fine.  They are my gift to Kevin for his kind generosity and contribution to the DIY community.
  
 Please don't laugh at my headphones though.  
	

	
	
		
		

		
		
	


	




  They sound good, but they look kind of ..... 
	

	
	
		
		

		
		
	


	



  
 Wachara C.


----------



## n3rdling

Let me know if you need help drawing stuff up.  I've done a number of different stator designs and accompanying housings.  Probably best to decide which pad you want to build around first.


----------



## chinsettawong

I feel that the Float style headphones are really good and easy to DIY.  For me, the most difficult parts to make are the ear pads and headband.  If you follow how I make the Float style headphones, you'll see that I use welding rods to make the arc of the headband, a piece of leather for the head pad, and foam covers with cloth as ear pads.  
  
 I will post a detail drawing soon (I'm still learning to use CAD).  
  
 Wachara C.


----------



## gikigill

Is anyone willing to build these or sell parts as a kit for others to assemble? 

I would be first in line to pickup a fully working kit and put it together.


----------



## bluemonkeyflyer

gikigill said:


> Is anyone willing to build these or sell parts as a kit for others to assemble?
> 
> I would be first in line to pickup a fully working kit and put it together.


 
  
 Same, here.


----------



## wakibaki

You will see a few pages back that I have drawn up some PCB designs for stators and spacers. These are untested, but the likelihood of there being problems are small.

While I have made parts myself at home on my CNC mill, I know from the time and effort involved that no-one here is likely to take on producing these parts in numbers for customers here without it being a labour of love (i.e. ultimately a drain on the producer), or priced at a level which would to a degree obviate the putative advantages of DIY.

So I think the solution is to get these manufactured by a mass-production process.

Unfortunately, as some of you may be aware, I am having chemo for terminal lung cancer. I am far from dead, but I am very tired much of the time. Progress, consequently, is intermittent.

It will cost about U$110 to produce 5 sets of stators and spacers. Before post and handling the cost will be ~ U$22 per set. I can afford to front the cost, but I would prefer to have sufficient expressions of interest to cover the surplus items.

In the circumstances perhaps it would be better if someone else handled the transactions, I am happy to pass on the design files if anyone volunteers.

Some discussion about the design, particularly the mounting details, might be required, as requirements might vary.

Note that following Wachara's recommendation, I am focussing on the 100mm circular design, since suitable pads (at least to get you started) are available off-the-shelf from eBay.

From what I understand, food-grade Mylar and a range of household antistatics can produce good results, so a set of PCBs are the one really difficult item to obtain to get you going.

Fred


----------



## dude_500

Unless tensioning jigs, coating materials, adhesives, and known mylar is included in the kit, people need to realize that it takes a LOT of trial and error and experience to get diaphragms tensioned and coated in a way that will last a long time and stay stable at a desired bias voltage. It is basically an art form, and would not at all be a traditional electronics kit that you put together in a weekend and be done.
  
 Only getting stator PCB's, it could still take months to years to get to the point of having really nice headphones. Just making sure everyone knows what they'd be getting into!


----------



## wakibaki

dude_500 said:


> Only getting stator PCB's, it could still take months to years to get to the point of having really nice headphones. Just making sure everyone knows what they'd be getting into!




What, you mean, I shouldn't bother trying because the cancer will probably take me first? Thanks.


----------



## dude_500

wakibaki said:


> What, you mean, I shouldn't bother trying because the cancer will probably take me first? Thanks.


 
  
  
 That is not even remotely what I meant. I'm simply letting people know that stator PCB's do not make it an "easy kit". There could be a lot of misunderstanding.


----------



## jgazal

wakibaki in black humor mode?


----------



## wakibaki

I don't mean any harm by it. Probably a bit of frustration speaking there, but it's hard to pass an opportunity like that by. Once in a lifetime, you might say...

Here's the amplifier, txfrmrs, LT and EHT supplies. Still haven't turned it all on.


----------



## bluemonkeyflyer

wakibaki said:


> You will see a few pages back that I have drawn up some PCB designs for stators and spacers. These are untested, but the likelihood of there being problems are small.
> 
> While I have made parts myself at home on my CNC mill, I know from the time and effort involved that no-one here is likely to take on producing these parts in numbers for customers here without it being a labour of love (i.e. ultimately a drain on the producer), or priced at a level which would to a degree obviate the putative advantages of DIY.
> 
> ...


 
  
  
 Fred,
  
 You're a mensch. 
  
 I'm interested. Count me in for a set if you decide to proceed.
  
 When/If ready, PM your Paypal ID to me and I will send payment + shipping, immediately.
  
 Best,
  
 Keith


----------



## Hutnicks

wakibaki said:


> What, you mean, I shouldn't bother trying because the cancer will probably take me first? Thanks.


 

 Hey. I think we all appreciate your efforts to an amazing extent.
  
 If it's of any inspiration to you at all. Your countryman, Reginald Mitchell designed the Spitfire under the same circumstances.


----------



## Q Mass

Just because something's an art form, doesn't mean that us ordinary folk shouldn't have a stab at it too!
 Count me in Waki.
 In the event you have trouble gathering enough interested parties, I'll take two sets.
  
 My amateur daubing's will almost certainly take an aeon, and may inspire nothing more than nausea upon completion, but I'd appreciate the opportunity to accidentally produce a masterpiece, so I'd like to salute your efforts Fred.
  
 I'm sorry to hear about the cancer, I wish you well dude.
  
 Your post inspired me to take a look at your website.
 Much of the electronics goes over my head, but having read through your polemics and drugs pages I have found that I strongly agree with everything that you wrote 
	

	
	
		
		

		
		
	


	



 I plan to check that I also agree with the rest of your site, if I do I may even do you the honour of bookmarking it


----------



## bluemonkeyflyer

q mass said:


> In the event you have trouble gathering enough interested parties, I'll take two sets.


 
 Same, here x 2 or 3...just don't want to Bogart.


----------



## bluemonkeyflyer

P.S.
  
 Super Cool web site!
  
 It'll be fun to explore it all.
  
 K


----------



## chinsettawong

I'm sorry that I can't help with arranging the GB.  However, if you need any of my designs, I'm more than willing to share them.  Just let me know.
  
 Here are the detail measurements of my latest Float style headphones.
  

  
  

  
 While getting the parts is only half of the process, please don't be discourage to try and explore the different techniques of tensioning and coating the diaphragms.  It will take sometime to master it, but I can assure you that it will be a very fun learning experience.  
	

	
	
		
		

		
		
	


	



  
 Wachara C.


----------



## ralphfcooke

Hi, I've been a longtime lurker on this thread, and believe I have most of the skills needed to build a pair of electrostatic
 headphones; I've also been recently buying a few older, lower cost units from e**y, mostly electret units.
   If a group buy for the stators/any other parts were made available I would definitely be interested in a couple of sets ( my skills may not be quite as good as I would like and a spare is always useful. 
   Going back to the electret sets I have ( Sony ECR500, Stax SR40, Maruni EH805) I am using them with a STAX SRD4, or SRD-7sb adapter, but find there is some imbalance with all the phones. I have checked with a scope that the imbalance is in the phones, not the energisers, so, I am wondering whether it is feasible to dismantle any of the capsules and replace the electret diaphragm with a 'proper' electrostatic one.
   I appreciate that I will have to rewire the phones, but is this a worthwhile exercise, or should I simply build new capsules?
  
 Many thanks
  
 Ralph


----------



## chinsettawong

I bought a 3D printer last month, and have been learning to draw 3D models.  So, here is my first version of a 3D printed Omega Clone cup.  If it turns out any good, I'll share the file with you.


----------



## n3rdling

Very cool Wachara!  Which model did you get?  If you don't mind, can you post close up shots of the final plastic pieces so we can see the resolution capabilities of the printer?  I figure I'll wait a good 2 years until I get one since that area should be much improved in that time.
  
 Really I just want one for things that would require more than a 3 axis CNC, like the hinge mounting holes you have on the sides of the cups.  Don't forget to draw a slit for the cable to fit through.   I think it'll also come in very handy for making a piece that connects the hinge to the headband.  Good luck!


----------



## chinsettawong

I have a Prusa i3.  The working area is only 180 mm x 180 mm.  My intention is to use it to make parts like the arc and headband.  I'm still learning to draw and having a hard time puting holes in their precise locations. 
  
 Unfortunately, I don't have a good camera with me now.  Following pictures are the best that I could take.  I still need to learn a lot about this 3d printing.  I think it has a good potential.


----------



## chinsettawong

What a fun machine a 3D printer is!  I think it has a very good potential.


----------



## Kerry

Great looking work Wachara.

looks to me like you're getting the hang of this pretty quickly 

Can't wait to see what else you come up with.


----------



## chinsettawong

kerry said:


> Great looking work Wachara.
> 
> looks to me like you're getting the hang of this pretty quickly
> 
> Can't wait to see what else you come up with.


 
  
 Thanks.  I've been having a lot of fun learning to use the printer.  I think I have learned quite a few things so far.  
	

	
	
		
		

		
		
	


	



  

  

  
  
 The ABS plastic is quite good.  It's melting point is high, and so I try to use it to make a male jack for the headphones.  Looks like it might just work.


----------



## MuZo2

Great work


----------



## pickyear7

Brilliant! Very creative and dedicated work. I wonder, do you think a person without much technical knowledge could manage to build a pair?


----------



## arnaud

There you go, Wachara is leading the revolution again!! A bit flashy color for me but impressive nonetheless!
Arnaud


----------



## ToddTheMetalGod

Wachara if you keep improving your designs like this you should apply for a loan, perhaps you could make your own headphone manufacturing company... or develop models for another company at a cost .


----------



## chinsettawong

arnaud said:


> There you go, Wachara is leading the revolution again!! A bit flashy color for me but impressive nonetheless!
> Arnaud


 
  
 Hi Arnaud,
 I do feel that the color is too flashy too.  However, it's just a preliminary prototype to prove that it works.  I have a plan to print it out using black ABS plastic.  
	

	
	
		
		

		
		
	


	




 
  
  


toddthemetalgod said:


> Wachara if you keep improving your designs like this you should apply for a loan, perhaps you could make your own headphone manufacturing company... or develop models for another company at a cost
> 
> 
> 
> ...


 
  
  





  When I'm old and retired, I might consider just that.  For now, everything is just for fun.


----------



## TomAus

Looks great - well done!


----------



## davidsh

Lol, I wonder what your headphones would go for if auctioned..


----------



## chinsettawong

Ok, here is an update of my Stax plug.
  

  
  

  
 I've put up the file at here
  
 You need to sacrifice the pins from 2 sets of XLR male plug to make a piece of this.  The holes are design to be a tight fit for the pins.  Depending on the accuracy of the 3d printer you use, you might need to enlarge the holes a little before you can squeeze the pins in.  Well, you might need a hammer to knock the pins in.  
  
 Wachara C.


----------



## kevin gilmore

a very small precision hand vise works much better and forcing the pins in.


----------



## Dark_wizzie

How long does it take for you to personally make one? And how much does it cost you? I'm not capable of making one and I won't try, but still, I'm curious.


----------



## miceblue

I'll subscribe to this thread for future reference.


----------



## chinsettawong

kevin gilmore said:


> a very small precision hand vise works much better and forcing the pins in.


 

 Thanks Kevin.  Will try that.
  
 Wachara C.


----------



## chinsettawong

dark_wizzie said:


> How long does it take for you to personally make one? And how much does it cost you? I'm not capable of making one and I won't try, but still, I'm curious.


 
  
 I make the headphones on my own pace.  They'll take me at least 1-2 weeks to make a pair.
  
 The cost of material isn't that much at all.


----------



## Dark_wizzie

chinsettawong said:


> I make the headphones on my own pace.  They'll take me at least 1-2 weeks to make a pair.
> 
> The cost of material isn't that much at all.


 
 Well, knowledge is power, and it shows!


----------



## bluemonkeyflyer

Chinsettawong,
  
 I'm looking forward to seeing the finished headphones and hearing your impressions.
  
 Thanks for sharing your processes.
  
 I may have over-looked it...what make/model 3D printer are you using? ...and, what software?


----------



## chinsettawong

Well, they are finished. I put the drivers from my prior pairs into the 3d printed cups today. 
	

	
	
		
		

		
		
	


	




My 3d printer is Prusa i3.


----------



## bluemonkeyflyer

^ 
 Nice!
  
 How do they sound, and compared to others?


----------



## chinsettawong

bluemonkeyflyer said:


> ^
> Nice!
> 
> How do they sound, and compared to others?




To my ears, they are same, same. However, I very much prefer the look of wood cups to plastic ones.

Wachara C.


----------



## schorsch

Me too)

Regards Georg


----------



## frank2908

chinsettawong said:


> To my ears, they are same, same. However, I very much prefer the look of wood cups to plastic ones.
> 
> Wachara C.



Then you HAVE to try the wood filament from laywoo d3 or colorfabb.if you print at the same temperature throughout your print, it will look like cardboard color, but there is a tutorial from the net to immitate wood grain. Wood is my favourite 3d printing material now, and I also planning to print headphones part from it.


----------



## chinsettawong

frank2908 said:


> Then you HAVE to try the wood filament from laywoo d3 or colorfabb.if you print at the same temperature throughout your print, it will look like cardboard color, but there is a tutorial from the net to immitate wood grain. Wood is my favourite 3d printing material now, and I also planning to print headphones part from it.


 
  
 I just bought a roll of that stuff last Saturday, and I'll try it sometime.  
  
 Wachara C.


----------



## chinsettawong

A local friend came to see my last weekend.  He brought with him a pair of his version of Omega style headphones.  We put them up with 3 microns diaphragms.  They sounded very lovely.
  

  

  

  
 He is already into making another pair.  I'm sure they'll look and sound even better.  
	

	
	
		
		

		
		
	


	



  
 Wachara C.


----------



## bootdsc

chinsettawong said:


> Well, they are finished. I put the drivers from my prior pairs into the 3d printed cups today.
> 
> 
> 
> ...


 
  
 Looks sharp, how much finishing work did you have to do? My solidoodle tends to make a mess of my prints and have to spend some time with a file for a good fit.


----------



## chinsettawong

Hi Bootdsc,
  
 I didn't have to do anything.  I print all these parts out and they fit together nicely.
  
 Well, at the beginning, all the prints were a big mess.  But now, I think I know what I'm doing and everything comes out OK.
  
 Wachara C.


----------



## purk

Leading the way again K P Wachara!!  Man...you really outdone yourself again this time.


----------



## jgazal

I have been reading the SR-009 imbalance thread and I think it is better to post my questions here.
  
 Humidity, diaphragm tension and diaphragm coating resistivity were already mentioned in this thread. But humidity is usually mentioned as a factor when using the drivers and I have not found any mentions of the relationship between humidity and the coating process.
  
 This article describes the effects of humidity in very sensitive production processes: 
  


> By far, the most pressing need for humidity control in a semiconductor cleanroom comes from photoresist sensitivities. It's photoresist that demands the tightest (most expensive) control limits because its properties are so sensitive to relative humidity.
> 
> Actually, both relative humidity and temperature are critical for resist stability and precise dimensional control. Even at constant temperature, photoresist viscosity decreases rapidly with increasing relative humidity. Changing viscosity, of course, changes the thickness of a resist film spun-on by a fixed coating recipe. Reference 2 cites an experimental demonstration in which a three percent variation in relative humidity produced a thickness variation of 59.2 A (sic) in resist thickness.
> 
> ...


 
  
 Do you feel from your experience that coating the diaphragm in very humid days derives more drivers with imbalance? 
  
 I see that DIY drivers use a FR4 ring to hold the diaphragm. What material the SR-009's ring is made of? Is it metal like the stators?
  
 I wonder if, contrary to the use of a FR4 ring to hold the diaphragm, a metal ring worsens the dimensional control of the ring/diaphragm structure.
  
 Anyway, if it is such a precise process, a 95% reject rate is not bad at all. And congratulations to all DIYers of this thread that achieve such stability!


----------



## n3rdling

I don't think humidity while coating will matter much for arcing, but it might have a slight effect on the resistance of the coating.  Humidity plays a factor in arcing because the voltage breakdown of air gets decreased with more humidity thus an arc in the small gap between stator and vibrating diaphragm.  Think of it like making the gap smaller.  Humidity while coating wouldn't really make the coating thicker (ie lessening the gap).  If it lowers the resistance this can lead to more current on the film and possibly more damaging arcs but it's probably not a big issue.  I believe Wachara lives in a very humid climate so maybe he's noticed a difference in summer/winter.
  
 Whatever material Stax uses for spacers, it isn't something as conductive as metal.  That would assure constant arcing.  The reason FR4 is used is to isolate the voltage on the diaphragm from the voltages on the stators since FR4 has a high resistance.  There was one member here who had ants in his SR-009 a while back and he ended up making a thread with a bunch of detailed pictures of the drivers.  That's the only place I can think of that might show the spacers used.


----------



## dude_500

Humidity affects the coating material while in use, not while coating (at least as far as I've experienced and can conceive of). It also seems to accelerate the wear on DIY coatings. The pros have it figured out well enough that the coating isn't going to just go bad... at least not for most, maybe the SR-009 does.
  
 I'd say it's not so much about arcing as it is about stability. Well designed headphones will simply never arc. But diaphragm stability is much much harder to design for. 
  
 In my building experience, it is very possible to make a diaphragm in November that will last the entire winter, and the first humid hot spring day it's shot forever, eternally unstable.


----------



## chinsettawong

I too don't think humudity during the coating process has any bad effect on the coating material - my coating material is actually water base.
  
 From time to time, my headphones do have some imbalance issue.  Most of the times when that happens, I find some small arc spots on the diaphragm.  The arc isn't severe, it just leaves spot marks on the diaphragm.  Recoating usually fixes it.
  
 Wachara C.


----------



## chinsettawong

jgazal said:


> I see that DIY drivers use a FR4 ring to hold the diaphragm. What material the SR-009's ring is made of? Is it metal like the stators?
> 
> I wonder if, contrary to the use of a FR4 ring to hold the diaphragm, a metal ring worsens the dimensional control of the ring/diaphragm structure.


 
  
 Do you know that Stax also uses PCB as stators and spacers is their SR007?
  
 In Stax Lambda series, the spacers are made of brass rings.


----------



## jgazal

Thanks n3rdling, dude_500 and chinsettwong. 

  
 I knew spacers need to insulate stators and diaphragm, but I did not know the Lamda series had brass rings. So do they use electrical insulating coating at the rings or stators?
  
 I have been a fool trying to figure out what is happening, because there are too many variables…


----------



## chinsettawong

jgazal said:


> Thanks n3rdling, dude_500 and chinsettwong.
> 
> 
> I knew spacers need to insulate stators and diaphragm, but I did not know the Lamda series had brass rings. So do they use electrical insulating coating at the rings or stators?
> ...


 
  
 It's easier to just show you the pictures than to try to explain it.
  

  

  
 The stator is glued to a piece of plastic.  The stator is perhaps powder coated.  So, it's insulated.
  
 When put together, the different thicknesses of spacer and stator makes the air gap of around 0.4 mm.  There is about 1 mm of spacing between the outer diameter of the stator and inner diameter of the spacer.


----------



## urlgr-A

Dear Chinsettawong. Yet another headfier  you have inspired. I have been reading and re-reading this magnificent thread for some weeks ( and I am still not finished) and decided to join the forum because I think it is time to contribute and say thanks to you and many others that have so kindly shared your experiences. I have been thinking a lot about making my own set of electrostatic headphones for some years and it was only when I was poorly with a bad stomach some weeks back that I came across this thread that seems to contain exactly the accumulation of info that I think I need to start having a go myself. So... post number 1 here goes...
 I have taken on a big project, as I have to build myself an amp as well. I am looking at the exstata possibly. Yours or anyone else's advice here would be appreciated.  I don't have a CNC router but I can design using CAD and frequently use a 3D printing house for making parts for my other little projects. 
 I want to concentrate on the design of the driver parts and experiment a bit and this thread has that well covered. 
 So please tell me what you think if you can.
 1) I am considering using the perforated metal sheet found in microwave oven doors as my stator material (scrapped doors I mean!). It is already beautifully flat (usually) and free from burrs and sharp edges. The holes are round and on some ovens are about 1 mm diameter, spaced 'very close' (not sure how close as it varies from door to door). I think the doors are made of steel sheet and insulated with some special paint. I can cut the shapes of the stators out of this I thought.
 2) Is there a way you can specify the tension you use on your diaphragms that can be easily reproduced by me? For example, the size of the masses used to stretch the film, or perhaps you can specify the natural resonant frequency of the stretched film (such as what one might hear if it is gently tapped with a finger).
 3) Have you considered stretching the film in one direction only? I mean rather than trying to stretch it in two or more directions. Don't some ESLs use film only unidirectionally tensioned?
 4) Do you think it would be useful to have a mechanism built-in to the driver in which the film tension can be adjusted in-situ so that it would be possible to tune a driver to find its 'sweet spot' so-to-speak?
 Thanks in advance!


----------



## n3rdling

1.  That sounds like a good material to use on the cheap, but it'll depend a lot on the open area %.  40-50% is preferable.  You can get a sheet of perf metal for pretty cheap online, might not be worth a trip to the scrap yard.  Be careful when cutting out the shape of your stator so you don't bend the metal at the cut line (metal snips will do this).
 2.  chinsettawong has some pictures in this thread showing his stretching rig.  IIRC he uses something like 6 water bottles suspended off a small table.  I'm not sure how large the piece of Mylar is though.
 3.  If you stretch only one way you might get some long wrinkles in the film which wouldn't be good.  I don't really see a reason to do this, especially with the tight tolerances for a HP driver.
 4.  That's a pretty interesting idea but I think it would be really hard to implement.  The film is glued down to a spacer so really you're trying to have an adjustable spacer.  One way this might be able to be done is to use some kind of elastic spacer that is compressed between the stators.  You then try to figure out a way to cut a notch into that spacer and a notch into one of the stators, both all the way around.  Align them face to face and as you tighten the bolts holding everything together, the notches will 'slide' the elastic outward.  This is hard to describe but it doesn't seem like fun to try.  An easier thing to do is to adjust the tension by heat shrinking the film.  It wouldn't be reversible, but you could at least see what tension (measure the resonant frequency) gives you the best sound.  Normal PET film has about 1.7% shrinkage under heat, but there is heat shrinkable kind that has something like 25% shrinkage...only problem with that stuff is that it's pretty thick (~25 um I think).


----------



## khbaur330162

I like the idea of point #4. I agree, it seems complicated. Best I could come up with is you have oversized, overly thick spacers on a diaphragm set at the lowest "desired" tension within the range. The stators would be threaded inside the inner diameter of the oversized spacers (variable stator spacing). Attached to the stators, however, would be "secondary" spacers. These secondary spacers would actually determine your diaphragm's active area and stator spacing. As you screw the first stator into place its secondary spacer applies the desired tension to the diaphragm by pushing on the diaphragm creating a "plateau" shape in it. Then the second stator is tightened to clamp the diaphragm down. I'd imagine the threads would have to be pretty fine in order to achieve high adjustment resolution and I think it would be better if the secondary spacers were more like washers (not attached to the stators) so that they would move in/out freely and apply less rotational force to the diaphragm when the second stator is tightened.


----------



## arnaud

khbaur330162 said:


> I like the idea of point #4. I agree, it seems complicated. Best I could come up with is you have oversized, overly thick spacers on a diaphragm set at the lowest "desired" tension within the range. The stators would be threaded inside the inner diameter of the oversized spacers (variable stator spacing). Attached to the stators, however, would be "secondary" spacers. These secondary spacers would actually determine your diaphragm's active area and stator spacing. As you screw the first stator into place its secondary spacer applies the desired tension to the diaphragm by pushing on the diaphragm creating a "plateau" shape in it. Then the second stator is tightened to clamp the diaphragm down. I'd imagine the threads would have to be pretty fine in order to achieve high adjustment resolution and I think it would be better if the secondary spacers were more like washers (not attached to the stators) so that they would move in/out freely and apply less rotational force to the diaphragm when the second stator is tightened.


 
  
 Or you could use a hair-dryer and heat shrink until both diaphragms resonate at the same frequency . Wachara does this by ear, any cheap microphone hold close to the electrode could easily measure the open air resonance. BTW, it's variable with stax phones but I recall in the 120-150Hz range for my omega 2 and SR009 phones.


----------



## urlgr-A

*Hello khbaur330162*
 Thanks for you comments and ideas about adustable diaphragms. What you described is very similar to what I had in mind, if I understood you correctly. Anyways my thinking was as follows:
 The diaphragm is held at a 'lower' tension in a large stiff outer frame (the frame  is a sandwich of two 'hoops') and the stators are inserted into each side of the frame with spacers already attached to them. Regarding the adusting screws, I was thinking about them being inserted radially in the large outer frame. The stators would  have their own frames with slots to accept the ends of the adusting screws. The end of each screw is conically bevelled at say, 45 dergrees. As the screw is turned clockwise, its conical end engages the slots on the stator frames such that it works like a wedge pushing the stator assembly up and stretching the diaphragm on a "plateau" as you said. One would have to adjust each screw in turn a little at a time.
 I think your idea is better here with threaded stator halves, although this would mean the drivers would have to circular. I don't mind... Fine thread pitches yes indeed.
 I have been sketching out ideas for these parts to be 3D printed in Shapeways black (nylon?) plastic.
  
 Hmm... does look a bit of a challenge... still there's always that old hair drier


----------



## chinsettawong

You can also do it my way.  I always cut more spacers than I need.  I glue a few more diaphragms to play with different tensions.
  
 If you want to do the adjustable diaphragm, please do not forget that you're playing with lethally dangerous high voltage too.  Be very careful.
  
 Wachara C.


----------



## chinsettawong

By the way, if you tension your diaphragms using a tensioner, the diaphragms are already very tight.  The hot air from a hot air gun can't help to tension the diaphragm that much anymore.
  
 Wachara C.


----------



## urlgr-A

Thanks arnoud
 So Stax does its tensioning to get 120Hz to 150Hz. Pretty tomtom drum tight then. That's a useful nugget to note down.
 When I was thinking about this, it was really from the point of view of what a drag it might be to disassemble each driver to perform tensioning.
 Far better I thought to not give dust a chance to enter - not disturb anything and just turn a little screw or adjuster somewhere.
 A lot easier said than done. 
 Patience is what I need.
  
 btw I am just down the road from you in Kyoto.


----------



## urlgr-A

Thanks chinsettawong


> You can also do it my way.  I always cut more spacers than I need.  I glue a few more diaphragms to play with different tensions.
> 
> If you want to do the adjustable diaphragm, please do not forget that you're playing with lethally dangerous high voltage too.  Be very careful.


 
 Yes the high voltage had not escaped my notice. As I am sitting here just theorising, for me, as a beginner in this I will probably do as you say
 and just make a number of diaphragms at different tensions. Are you still using 3 micron mylar?
  
 Another question for you. Long ago in this thread you found you could control the brightness of the sound by removing excess copper from the stators.
 I am considering making stators from microwave oven doors (so they are all metal - no FR4). This means I am starting with a stator that is all holes and
 no blank areas. The sound might be bright- I have no idea but, do you think it would be possible to adjust the high frequencies by covering a few of the stator
 holes on the *back* of the stator with conductive copper tape? Obviously this adjustment would be made without any high voltages present 
	

	
	
		
		

		
			




  
 With all this thinking about the headphones I have yet to consider what amp to build for it. I won't be able to test anything until I get that part done will I?


----------



## arnaud

urlgr-a said:


> Thanks arnoud
> So Stax does its tensioning to get 120Hz to 150Hz. Pretty tomtom drum tight then. That's a useful nugget to note down.
> When I was thinking about this, it was really from the point of view of what a drag it might be to disassemble each driver to perform tensioning.
> Far better I thought to not give dust a chance to enter - not disturb anything and just turn a little screw or adjuster somewhere.
> ...




No worries, should lookup measurements I made before to confirm.

We must meet some day, there are another couple of stat nuts in tokyo, we organize meets sometime. 
We have one of chinsettawong diy with us at the moment, you could see how it works!
Still waiting for my bhse to drive them properly though as some of his units need a lot of juice...
Cheerrs,
Arnaud


----------



## Q Mass

How about adjusting the tension of the diaphragm via a mechanism similar to an adjustable drum head.
  
 I can think of a way to proto' a threaded headphone shell using a large plastic jar lid with a large hole cut out of the centre so that when you tighten the lid down on the top of the jar ( also plastic ) it traps the diaphragm ( already stretched on the usual ring, like a drum head ) dragging the ring over the lip of the jar thereby adjusting the tension according to how tightly the lid is screwed down.
 Most of the plastic jar could be cut away leaving just the threaded 'neck'.
 I don't have any good ideas re' how the stators would be integrated, maybe just the usual arrangement of spacers,stators and diaphragm stacked up, but in this case between the jar lid, and the jar neck.


----------



## urlgr-A

Hello n3rdling and thank you for your detailed reply.
 Regarding the possibility of using microwave oven doors as stator material, well, I have already got my doors from a scrapyard! I checked the holes and spacings. All the holes are circular.There are two sizes among the five doors I managed to obtain.
 1.2 mm holes, with 1.5 mm centres. 1.3 mm holes, with 2 mm centres. The pattern of hole centres in both cases is based on equilateral triangles and not a parallel grid. Imagine a honeycomb but with circular holes instead of hexagonal holes. ( I know there must be a proper name for this pattern). These measurements are just from visual checks from pictures I took. Actually I want to upload the pictures but I can't seem to do this._ I don't have permission_ the message tells me...
  
You mentioned that the diaphragm is glued to the spacers. The idea I have doesn't have them glued to the spacers at all but if sealing at the spacer diaphragm boundary is needed them I was thinking of a thin bead of silicone sealant to do this. 
The mechanism is difficult to describe without pictures so I need to sort out how to do that. But as Q Mass succinctly put it, it works like the adjustment of the tension on a drum head.
  
I am also wondering about tailoring high frequency response (i.e. trying to fly before I can crawl 





) using copper conducting tape to cover some of the holes on the backs of the stators. Chinsettawong describes removing copper where the holes are absent from his pcb stators and it affecting the response so I surmised that I might be achieving a similar effect by doing it this way (isn't what I am proposing a feature of the SR-007 mk2 stators? ) . What do you think?


----------



## urlgr-A

Hi Q Mass and thanks for your comments. 
 The mechanism you describe is indeed something like what I have in mind. I want to upload some diagrams but I don't have permission. Probably because I am a newbie here... I guess. I need to take a proper look at the forum rules.


----------



## urlgr-A

Hello arnoud....
  
 Sorry I didn't get back to you sooner.   Do you still have one of chinsettawong's headphones with you now?  Oh wow. I would really love to see them!  Which ones are they? 
 As far as meeting up sometime, yes I would love to do that.  You say you are waiting for a BHSE, so that means you are waiting for a chunk of cash to woft your way, or have you really bought one? (Sorry, I am relatively poor, so all this talk of Blue Hawaii and SR-009 vs SR-007 is way beyond my means at present.)
  
 I have a few of questions. First about the Stax SR-009. (I am looking around on this thread and in other places but not a satisfactory answer found as yet)
  
 What is the purpose of the large hole in the centre of the stator? It is somewhat trumpet shaped/tapered in profile yes?
  
 What is the extent of the conductive coating pattern on the diaphragm? What I mean by this is, is the center uncoated (and therefore undriven I suppose). I read that some unidentified Stax engineer said it was to do with temperature. Hmm.... do they ever get that warm? Is it a way to contour the frequency response somehow?
  
 I can now upload images so attached is my proposed stator material. There are two sizes as you can see. What do you think? I am thinking about ratios of open hole area here as well as hole sizes. 
  

  
 Do you think either size is suitable? The material appears to be painted steel. The entire door is pressed and finished off in one piece i.e. the mesh is integral to the door.
  
 Another question, would the eXStatA be a good amp to drive my home grown stats? Or is there anything else you can recommend? I am currently on the verge of ordering components you see. 
  
 Regards.


----------



## chinsettawong

Hi urlgr-A,
  
 Your perforated metal sheet looks good.  I'm sure either one will work just fine.  Please be sure that the metal sheet still has very good insulation.
  
 What would you use for your spacers?
  
 The headphones with Arnaud now are my version 1, Jacklin Float style headphones.  The spacer is 0.6 mm, and yes, they require a bit more powerful amp than Stax headphones.
  
 If you want to build your own amp, I highly recommend you build a KGSSHV.  It's relatively easy to build.  I also have an eXStatA, but I prefer KGSSHV.
  
 Wachara C.


----------



## n3rdling

If you're on a tight budget try to look around for a used vintage SRM-1 Pro or SRD-7 transformer box.


----------



## urlgr-A

Thanks Chinsettawong.
 What would I use for spacers?
 Well, I have some 0.5 mm styrene sheet (from Tamiya) as used by plastic modellers. I also have some 0.3 mm as well, so I can double it up to make 0.6 mm if need be. This plastic sheet is very smooth and of uniform thickness but not as stiff as very thin FR4 I guess.
 If it is going to be clamped in a "stator sandwich" the will lack of stiffness matter?
  
 Another possibilty for spacer material is Formica, a thermoset plastic laminate. 
  
 I am thinking about using 2 or 3 micron mylar for the diaphragm material and contact glue to attach it to the spacers. Here in Japan there is one you can find in just about any DIY store called G17, a contact glue very similar to Dunlop Thixofix. I will stretch the mylar as per your method with 800g pet bottles.
  
 Another knowledgeable Head-fier in this thread mentioned something about stabilizing the mylar once it is stretched. Do you advise doing this? If so, how do you do it?


----------



## chinsettawong

The stiffness from styrene foam by itself won't be able to hold the diaphragm tension. You'll need to glue it to the stator then glue the diaphragm on. But I'm not sure how stiff your stator is. The stiffness does matter, because the air gap is only 0.5 mm. Any warping can cause unevenness and your driver won't be stable.

I'm not sure how you can stabilize the diaphragm. Do you mean to use heat to further shrink the diaphragm? In my experience, if you use weight or inner tire tension method to tension your diaphragm, further heat shrinking doesn't help much at all. 

Either 2 or 3 microns diaphragm sounds very good.

Wachara C.


----------



## urlgr-A

chinsettawong said:


> The stuffness from stylene foam by itself won't be able to hold the diaphragm tension. You'll need to glue it to the stator then glue the diaphragm on. But I'm not sure how stiff your stator is. The stiffness does matter, because the air gap is only 0.5 mm. Any warpping can cause unevenness and your driver won't be stable.
> 
> I'm not sure how you can stabilize the diaphragm. Do you mean to use heat to further shrink the diaphragm? In my experience, if you use weight or inner tire tension method to tension your diaphragm, further heat shrinking doesn't help much at all.
> 
> ...


 

 The styrene sheet is not expanded foam like packaging material, it is actually a hard plastic sheet, not quite as stiff as FR4. As for the stator stiffness, I understand what you mean. I will see when I cut them out 
	

	
	
		
		

		
		
	


	




 and therein could be a problem, so I was thinking that if they are not stiff enough, though I expect them to be good enough, then I will put a stiffening frame on the back of them similar to that used on the SR-009.  (Obviously I might lose some stator holes when doing this.)


----------



## dude_500

urlgr-a said:


> The styrene sheet is not expanded foam like packaging material, it is actually a hard plastic sheet, not quite as stiff as FR4. As for the stator stiffness, I understand what you mean. I will see when I cut them out
> 
> 
> 
> ...


 
  
 I used 0.5mm styrene sheet to hold diaphragms in my early days of electrostatic headphones, it is not strong enough. Perhaps if you were to use a really thick rim it could, I was using about 7mm as the widest. It works alright if you never disassemble anything (the pressure of the driver screwed tight keeps everything in place). But if you then open it up in a week, the diaphragm will lose all its tension because the styrene no longer has the same strength and shape it did before.
  
 It works great for all the other spacers you need though! Works great to hold dust covers where tension doesn't need to be so high. It's cheap and easy to cut compared to FR4.


----------



## urlgr-A

n3rdling
 I have taken your advice. Thank you.
 I have found a used SRM-1 pro Mk2 PP version C.
 This was the last of this model maybe... Perhaps you can correct me here.
  
  
 Now for a question. Would it be fairly straightforward to make the bias voltage adjustable?
 What would be a good way to achieve this? A separate box perhaps, a separate supply I mean.
 I say this because it seems to be something that accomplished DIYers in this thread are doing when testing their creations.


----------



## dude_500

urlgr-a said:


> Now for a question. Would it be fairly straightforward to make the bias voltage adjustable?
> What would be a good way to achieve this? A separate box perhaps, a separate supply I mean.
> I say this because it seems to be something that accomplished DIYers in this thread are doing when testing their creations.


 
  
 It is for all practical methods impossible to make the output of an amplifier become adjustable bias by adding an external box. This is because the output impedance is very high, so you cannot simply add an adjustment potentiometer.
  
 It is easy to make your own adjustable bias supply, though. Take whatever voltage supply you want, and put a very high value potentiometer across it. Then the output voltage is simply the wiper. Make sure to add ANOTHER very high value fixed resistor to this brush before going to the output. Otherwise at full voltage, you could get killed by the bias because the wiper would connect straight to the high voltage supply. Be cautious of safety, pots aren't really rated for bias voltage levels. Make sure the chassis is well grounded, and watch for arcs on first power up. I picked a random pot off the shelf, I think 10Mohm, and it worked with no problems.


----------



## n3rdling

urlgr-a said:


> n3rdling
> I have taken your advice. Thank you.
> I have found a used SRM-1 pro Mk2 PP version C.
> This was the last of this model maybe... Perhaps you can correct me here.
> ...


 
 Yes that's the last version of that amp.
  
 Another option for variable bias supply is to get one of the proportional high voltage DC-to-DC supplies from a place like EMCO.  They can output a voltage high enough for speaker ESLs.  Read the spec sheet to check the input voltage, but I think it's something like 0-15V.


----------



## Tachikoma

Hi everyone, I've been trying to re-coat a pair of old Gamma Pro drivers using antistatic cleaning liquid, and I've run into a strange problem. The volume of one of the drivers always drops when music isn't playing (despite being charged by the bias), then starts to rise and it eventually becomes louder than the other driver. Is this to do with the coating, or perhaps I've overstressed the wire that connects the bias to the stator?


----------



## n3rdling

Did you recoat both drivers?  If so, one side or both sides of the diaphragm?  This isn't being driven from one of the self bias transformer boxes right?


----------



## Tachikoma

Yes, I recoated both drivers, but the answer is that I've broken the foil that connects the bias to the stator. The reason it still works at all is because I added a second wire to "buff up" that connection previously.
  
 Anyway, how do you guys make sure that you've applied the same amount of coating on both drivers?
  
 I coated both sides of the diaphragm, because I noticed that the diaphragm was always getting stuck on the uncoated side, and it would stop sticking after I coated it (to an extent). I'm using an SRM-T1S.


----------



## urlgr-A

Hi Tachikoma
 I am quite new to this scene but a couple of things occurred to me from your description. 
  
 First,  I believe there shouldn't be an electrical connection between the bias signal and the stators. You said you broke the foil that makes this connection. That puzzled me. The bias connects to the plastic film diaphragm only and the modulated (audio) signal connects to the stators. The foil could be the bias connection to the diaphragm?
 As far as I know,
  
 the inner stator connection,    (next to your ear)  
 the bias connection,        
 and the outer stator connection,  
  
must be kept separate.
  
 Second, your antistatic coating must not contaminate the spacers between the diaphragm and the two stators. I imagine that weird behaviour might result if this happened (But I don't know as I haven't experienced this myself this yet). Since you are re-coating your diaphragm it remains connected to the spacers yes? The diaphragm must be kept connected to a spacer in order to maintain its tension. I can picture myself in your situation, covering the spacers with thin strips of masking tape first, before spraying.  
  
  
 Just my thoughts. (I have probably stated the blindingly obvious! If so I am sorry) Perhaps someone else more experienced than I can add something to this?


----------



## Tachikoma

If you look closely at http://wiki.faust3d.com/wiki/images/8/8d/Stax_SR-XMk3_driver.jpg and http://qix.it/site_media/headfi/sr3n/2.jpg, you'll see a tiny strip of foil connected to the bias terminal on the driver. The strip of foil terminates at the stator on the opposite side. I'm not really sure how biasing works in electrostatics tbh, maybe the bias conducts to the diaphragm via the stator? I always thought the bias was applied across the stators to create a potential across the driver.
  
 The spacers in these Stax drivers are separate from the diaphragm, so there's no contamination issue to worry about.


----------



## urlgr-A

Hi again Tachikoma.
 I am studying the pictures now...
 I can see there are just the three connections. These would seem to be the inner and outer stator connections and the diaphragm connection. 
 As to how this all works, there isn't a potential 'across' the diaphragm as such. This is a static charge placed on the diaphragm. This means it only needs one connection and this connection 'leaks' charge out onto the diaphragm surface where it stays for a while, so long as it can't find a way to leak away.
  
 The usual way that I have seen this done from pics and explanations on this thread is by attaching a flat foil or a thin metal (such as copper) conductor that surrounds and contacts the entire circumference of the diaphragm on its coated side. Within this circumference the static charge is maintained by the bias voltage. Interestingly the DIYers here are usually coating only one side of their diaphragms (someone correct me here if I am wrong).
  
 This thin conductor ring or  "charge ring" must not make any electrical contact with any stator.
 Conversely, unlike the diaphragm, to operate properly, the stators must not hold any charge. They are receiving the audio signal at a high voltage and they must change their voltage as the audio signal changes. 
 The stators receive their respective voltages 180 degrees out of phase so that when one stator is 'pulling' on the diaphragm, the other is 'pushing'.
  
 I hope this makes sense. 
  
 On the SRX mk3 picture it looks to me as though the centre black lead is the bias for the diaphragm and the yellow lead is the connection for the inner (ear side) stator while the greenish lead at the top of the picture is for the outer stator. 
  
 btw there is an article that explains very well how all this works: "Notes on DIY Electrostatic Headphones" by Chu Moi
  
 Cheers


----------



## urlgr-A

Hello arnoud.
 I wonder, do you have those measurements for the Stax diaphragm tension? 
 I am running through the options of what diaphragm size and shape to make, spacing and how to seal against my head (circumaural) with shaped
 ear cushions, and then there is the idea of angling the drivers and what the distance should be from driver to ear... the list goes on!
  
 Trying to find out what the reasoning was for making the Lambda drivers an elongated circle shape as opposed to circular, or oval shapes. 
  
 I got myself an SRM-1 mk2 PP amp, hoping that it will be able to drive whatever I end up creating. This is the first electrostatic amp I have ever acquired.
  
  I hope it will be a good amp.


----------



## OnyxOcelot

Hello again all,
  
 I am glad as always that this thread continues to be as active and inspirational as it does.  My own headphone making studio has been somewhat dormant as other interests and jobs took over my time.  Fortunately, I've got some time now to reboot the machinery and see if I can't crank out a few sets of drivers.  Before I start ordering bits, I thought I would poll you about a couple of issues:
  
 1. Do you suppose the size of the stator holes affects sound?  In which way?  I was thinking that generally having more, smaller holes would ensure that the signal reached the diaphragm in a more uniform fashion, but I don't know that that is supported by fact...
  
 2.  I understand that some of you etch out the extra copper on the stator.  How does this affect the thickness of the stator?  I would be worried about creating a stator with a thicker center than rim -- being unable to keep the air gap between the diaphragm and stator constant.  How have you dealt with this?
  
 3.  Regarding cables and connectors, do you have recommendations for cable types and connector housings?  For those of you located in the US, do you have a reliable source for these parts?  I was thinking of using an XLR connector with the guts ripped out and a custom delrin insert holding 6 of the larger pin sizes (which seem to fit the Stax jack nicely), but didn't know if there was another connector housing which normally has the pin-base (the part that the pins sit in, not sure the proper term) sitting flush with the front, rather than inset.
  
  
 I hope to someday be a part of the question-answering community here on head-fi DIY, but for the moment, I will do my best not to repeat questions!
  
 Best,
  
 OnyxOcelot


----------



## chinsettawong

Hi OnyxOcelot,

Most of us here are DIYers. We make the headphones base on trials and errors. I encourage you to do the same as I don't believe that you'll only make one pair. 

1. I am not sure that smaller holes are better. I have been drilling 2 mm holes on all my stators, and I like all of them.

2. I use chemical etching method for etching out the unneeded copper. I think it etches out copper very evenly.

3. As for cable, try to get an extension cable of Koss ESP950. It's good and cheap.

Have fun!


----------



## OnyxOcelot

Thanks ChinsettaWong!  You're definitely right that I just need to start and make a few mistakes!
 OO


----------



## urlgr-A

You are right Onyxocelot,
 Time to build and mess up a few times in order to find the right path. Me too here!
  
 Now then, the Sennheiser HD800 is a great set of headphones, its large sound stage being particularly good (so I hear - pun intended) and this set me thinking. It uses a 56 mm driver with a hole in the centre. I am considering using the same (as far as I can make it) ear cup shape with angled driver to fit a slightly bigger _electrostatic_ driver located in approximately the same place. I am thinking around 60 mm  to 65 mm diameter might be possible while preserving the carefully designed enclosure shape. Of course this new driver won't have a hole in its centre. I want to duplicate the shape and volume of the HD 800 ear cup and experiment with the micro-mesh walls of the ear cup enclosure. I assume the mesh restricts the movement of air in and out of the enclosed space. 
Is that right?
 Since Sennheiser have also been extolling the virtues of a planar wavefronts with their ring driver it occurred to me that an electrostatic driver can do a better job making planar wavefronts than any ring driver anyway.
 I am wondering if anyone has any views on whether this idea might be workable and what problems I might encounter when attempting this. For instance, can a slightly larger electrostatic diaphragm produce a bottom end coming anywhere close to the smaller area ring driver in the HD800? I mean, can its extra area make up for its presumably lower excursion?
  
 cheers all
  
 urlgr-A


----------



## n3rdling

The volume of the cup is pretty large on the HD800.  You may need to use thicker spacers and run at a higher bias to get the bass you're looking for.  Lining the interior walls with the right material will be important to get rid of unwanted reflections.  Sounds like a very interesting project though


----------



## NoPants

I like the idea of the project from an aesthetic point of view, but I imagine a fair amount of difficulty achieving the desired fidelity. Are you hoping to get the benefits of the SR-Sigma in an HD800 package?


----------



## dude_500

n3rdling said:


> The volume of the cup is pretty large on the HD800.  You may need to use thicker spacers and run at a higher bias to get the bass you're looking for.  Lining the interior walls with the right material will be important to get rid of unwanted reflections.  Sounds like a very interesting project though


 
  
 I have never experienced any evidence that higher bias affects the sound in any way. It simply increases the volume with a lower signal voltage on the stators.


----------



## n3rdling

The suggestion should have read to run thicker spacers (more excursion for bass slam) and thus higher bias (keeping bias at 580 might not be sufficient depending on how thick he makes the spacers, decreasing volume and increasing distortion potentially).


----------



## davidsh

Sure, having thicker spacers increases the possible excursion, but that's about it. I have a feeling the actual limiting factor will be the diaphragm tension. If there isn't enough space for excursion I guess the diaphragm will hit against the stators which must sound rather ugly. And perhaps cause arcing.


----------



## n3rdling

Hitting the stators is a guaranteed arc.  You have to take the voltage breakdown of air (say V/mm for ease) and determine what the max excursion you're willing to allow, keeping in mind humidity (lowers voltage breakdown of air).


----------



## chinsettawong

If you insulate your stators well, then there won't be arcing even if the diaphragm hits the stator. For headphones, you really want to use the thinnest spacers you can. In my early days, I used 1 mm spacers and biased them upto 1200V. Nowadays I only use 0.5 mm spacer and bias them at 580V. The thin spacers help a lot with the efficiency. 

I can play my music as loud as I can take and still the diaphragms are not hitting the stators.


----------



## urlgr-A

Hello all.
 A few days of pondering and sketching in my note book and looking around for bits and pieces in local hardware stores leads me to some more message reading and more research questions.
  
 Quote:


n3rdling said:


> The volume of the cup is pretty large on the HD800.  You may need to use thicker spacers and run at a higher bias to get the bass you're looking for.  Lining the interior walls with the right material will be important to get rid of unwanted reflections.  Sounds like a very interesting project though


 
  
 Yes the volume is quite large I agree, however it looks to me as though the Stax SR Sigma also has fairly large boxes for ear cups. I don't know of the Sigma boxes are sealed against the ears but the diaphragm area is about the same as I am thinking for my drivers (The Stax uses 44 mm X 89 mm with 22 mm radius ends - by my measurements anyway - and I propose to use 65 or 66 mm circular).
 In the case of the HD800 ear cups i noticed on close scrutiny that the paneled sections of the walls of the ear cups are actually not sealed but full of tiny holes (like a very fine stainless steel mesh I thought). I am wondering whether I would need to do something similar with mine. What do you think?
  
 As for the spacer issue, I don't know. I intend to start with 0.5 mm spacers and 580 volts bias from my Stax SRM1 Mk2 amp. The bias is fixed for the moment at least. I propose to use 2 micron Dupont Mylar C but the coating I am not certain of yet.
  
  
 Will graphite rubbed into the surface prove more long-lived than anti-static spray or dish soap or fabric conditioner?


nopants said:


> I like the idea of the project from an aesthetic point of view, but I imagine a fair amount of difficulty achieving the desired fidelity. Are you hoping to get the benefits of the SR-Sigma in an HD800 package?


 
 Yes, I suppose you are right - I am! The SR Sigma sound stage though, by all accounts, is uniquely huge and up front. I don't suppose I will be getting near that but I will try for a sound stage wider and more forward than I currently get with my Audio Technica woodies and my Senn 565s. My woodies actually have a very good wide sound stage (maybe because they also use slightly angled drivers), so I will be trying to better them really.
  
 What sort of difficulties do you anticipate I will come across?
  
 I am asking knowing very well there will be plenty of challenges. What I am hoping for is that by attempting to make my driver similar in shape and size to the HD800 I might have something that already sounds pretty good. Do you follow my thinking?
  
  
 Since I don't have my own set of HD800s, I am trying to locate some drawings or get some dimensions of these headphones. There are plenty of photographs to be studied of course and I have amassed quite a few of those and measured off them as best I can. 
  
 Does anyone have any such measurements? or drawings? (a strangely unique question I guess!)
  
 I have estimated from pictures that the drivers are tilted at an angle of 8.6 to 8.7 degrees from, shall we say, 'flat', that is, parallel to the side of one's head.
 The ear cups look to be about 110 mm outside vertically from apex to apex (corner to corner? ) of the otherwise round ear cup shape. 
  
 So many questions I seem to be generating...
 I have to say that this is a marvelous place to come to and explore and I really do appreciate everyone's helpful comments. None of this would be remotely possible for me to attempt without it.
  
 Cheers all anyway. Time for me to get some shut-eye now...
  
 urlgr-A


----------



## Tachikoma

> Will graphite rubbed into the surface prove more long-lived than anti-static spray or dish soap or fabric conditioner?


  
 Can't answer the rest, but from what I've read, graphite has a tendency to fall off, so it will have a shorter lifetime than the sprays if anything.


----------



## urlgr-A

As for diaphragm coatings, what about polymer sealant coating used on car paint?  (some use it on their cars instead of wax). Has anyone tried this?


----------



## chinsettawong

Hi urlgr-A,

How about you try it out and let us know if it works?


----------



## urlgr-A

HI Chinsettawong. OK, then I will try it. I have a couple of bottles of it already. It says it is anti-static and it must be a durable coating.  I hope it sticks to mylar.
  
 Well, if nothing else my diaphragms will be nice and shiny 
	

	
	
		
		

		
			




  
 btw Do you measure the resistance of your coatings before using them? 
  
 cheers
  
 urlgr-A


----------



## davidsh

You could try and measure I suppose, but most multimeters are probably not very accurate in that kind of setting.
Correct me if I'm wrong.


----------



## n3rdling

Megger


----------



## ondesx

Hello Wachara,
  
 Do you think that a solution of an antistat (like Licron) with graphite particles will do a good job as a coating for the Mylar ?
 The two major issues from my point of view are first the small arcing on the graphite particles remaining on the film and the time to last of the coating... It seems that some antistat will last 3 more times than other... Any advice are welcome !...
  
 I wonder what is the "thinnest" trace necessary to carry the high tension of an headphone cell ?
  
 Do you think that insulating the stator with some plastic films will accumulate charges, thus reducing the sensitivity of the cell ? Is it better if we use epoxy coating ?
  
 Thank you for your help,
  
 My Very Best,


----------



## urlgr-A

Hi All.
 An update with some pics. Just to re-cap, I have been working on the idea of making electrostatic drivers that are fitted into angled large volume ear cups, using the Sennheiser HD800 angled design as a starting point.
 I found an ideal item that could be made into an ear cup. It is a PVC pipe reducer. Supposed to be for reducing 100 mm pipe to 65 mm. The moulding is very clean, and extremely rigid,  so this is what I went with. I cut some rings to make stator holders from PVC pipe as well. The main difficulty was cutting them dead square and the next task will be polishing the cut ends flat and smooth.
  
 The actual driver that will produce sound will be 70 mm in diameter. I still haven't decided whether or not to vent the ear cups with a porous stainless steel foil on the sides (marked with a pencil in the third and fourth pictures below) which is what the Sennheiser uses. The foil is rather like that used in electric razors. It has 1000's of tiny sub-millimetre holes . Any ideas or constructive comments/ suggestions would be appreciated.
 Progress has been and will be slow as I only have a little spare time to work on this. 

 Here is the PVC reducer as purchased:


 and here is the first prototype cut from it:


 and an inside view, marked with where I might cut vent holes and then cover with the micro foil...

 Here is another one cut to what I believe is the right depth and angle, matching that of the HD 800 but as you can see the driver hole is much larger:


 ...and a side view:

 I have yet to get some Mylar. I am looking for a local supplier here in Japan. Haven't found one yet.
  
 Cheers all


----------



## NoPants

might want to try setting the driver in before cutting the vent holes


----------



## n3rdling

That's very creative!  Has anybody measured the angle the HD800 drivers sit at?


----------



## urlgr-A

n3rdling said:


> That's very creative!  Has anybody measured the angle the HD800 drivers sit at?


 
 Yes, I tried to. From separate images and a video frame capture I got an angle of just under 9 degrees. The taper angle of the cone shape of the ear cup was hard to measure though. Also on the HD800, the cone shape to the ear cup is truncated at the part behind the ears (giving the cup its distinctive shape) because otherwise the ear cup would run out of skull to press against I guess! I realised why that was done and have tried to do the same with mine.
 I have to fashion a lip around the edge of the ear cup to take a slender ear cushion which you can see I have started to do in the pics - the white edge is the lip. I think it needs to be widened slightly.


----------



## NoPants

Have you considered gutting an HD800 to prototype? Seems like a reversible endeavor should you not get the results you want.


----------



## chinsettawong

ondesx said:


> Hello Wachara,
> 
> Do you think that a solution of an antistat (like Licron) with graphite particles will do a good job as a coating for the Mylar ?
> The two major issues from my point of view are first the small arcing on the graphite particles remaining on the film and the time to last of the coating... It seems that some antistat will last 3 more times than other... Any advice are welcome !...
> ...


 
  
 Hi,
  
 If you can get Licron antistatic spary, you can use it just as it is.  Don't mix it with anymore graphite.  While you want the coating to be conductive, you want a very high resistivity too.  Mixing graphite will not make it better.  In fact, you might get lower resistivity and it's no good.
  
 Licron antistatic spray has proven by many DIYers to be very stable and long lasting. 
  
 You can insulate your stators whatever way you like.  If you can do a good job with epoxy coating, I think it's very good too.
  
 Wachara C.


----------



## chinsettawong

urlgr-a said:


> Hi All.
> An update with some pics. Just to re-cap, I have been working on the idea of making electrostatic drivers that are fitted into angled large volume ear cups, using the Sennheiser HD800 angled design as a starting point.
> I found an ideal item that could be made into an ear cup. It is a PVC pipe reducer. Supposed to be for reducing 100 mm pipe to 65 mm. The moulding is very clean, and extremely rigid,  so this is what I went with. I cut some rings to make stator holders from PVC pipe as well. The main difficulty was cutting them dead square and the next task will be polishing the cut ends flat and smooth.
> 
> ...


 
  
 That's an interesting idea.  Looking forward to seeing what they'll turn out to be.  
  
 Wachara C.


----------



## ondesx

Thank you for your precise answers Wachara. I believed that the use of some PET films, as insulators, weren't an option, since they might accumulate charges in between them and the conductor, thus progressively lowering the sensitivity of the cell...
  
 Do you have an answer for the other question, about the thickness of the conductor traces ? (what might be the lowest thickness possible for a given polarization tension ?)
  
 Do you explained elsewhere the composition of the coating that you use ?
  
 Thanks a lot for your help.


----------



## chinsettawong

ondesx said:


> Thank you for your precise answers Wachara. I believed that the use of some PET films, as insulators, weren't an option, since they might accumulate charges in between them and the conductor, thus progressively lowering the sensitivity of the cell...
> 
> Do you have an answer for the other question, about the thickness of the conductor traces ? (what might be the lowest thickness possible for a given polarization tension ?)
> 
> ...


 
  
 I'm not sure what the thinnest thickness of the conductor traces can be.  For me that doesn't concern me at all.  All I want is the total thickness of spacer to be around 0.5 mm and stator of around 1 mm.
  
 I do not make my own coating material anymore.  I've been using computer screen cleaner gel or floor cleaner liquid as a coating material for many years already.
  
 Wachara C.


----------



## ondesx

Thank you again, here are my stators (2 mm for the holes about 1 mm for the thickness) and the external rings made of PMMA.
  
 Do you have any last suggestion for gluing (type of glue, precautions, etc.) :

 - the stators and the spacers/conductive rings (FR4 0.5 mm)
 - the spacers/conductive rings and Mylar.
  
 The issues are to maintain both a good conduction between the spacers and the Mylar even with the glue and to use the thinnest possible layer of glue... 
  

  
 OndesX


----------



## chinsettawong

I use contact cement or rubber glue.  It's the only glue I've found that would stick to Mylar well. 
  
 Are you not using FR4 as your spacers?
  
 Wachara C.


----------



## ondesx

chinsettawong said:


> Are you not using FR4 as your spacers?
> 
> Wachara C.


 
 Thank you Wachara.
  
 Yes as stated above (0.5 mm thickness). I'll send a picture asap...
  
 Is the contact cement also an option between FR4 surfaces ?
  
 Do you have a reference ? Will 3M Super 77 and/or Hi-Strength 90 do the job ?


----------



## urlgr-A

Hello ondesx
 That is nice looking work. Very nicely made parts there. The spacers are acrylic plastic yes? They will be stiffer than my first attempts using styrene sheet. Did you use a CNC router to make the stators?
 I don't have such a machine myself so I have made my stators from microwave oven doors. The challenge here  is getting them flat enough. I am working on that problem now.
 Here is a pic of my stators.


----------



## chinsettawong

ondesx said:


> Is the contact cement (do you have a reference ?) also an option between FR4 surfaces ?


 
  
 Contact cement sticks to any surface very well.  We call it rubber glue here.  It's yellow in color.  You apply it on the spacer ring and let the glue dry for about 3-5 minutes; then you apply force to glue the ring to the diaphragm.  It should stick instantly and the bonding should be very high.
  
 Wachara C.


----------



## ondesx

urlgr-a said:


> That is nice looking work. Very nicely made parts there. The spacers are acrylic plastic yes? They will be stiffer than my first attempts using styrene sheet. Did you use a CNC router to make the stators?


 
 Hello,
  
 Yes the external spacers are made of PMMA. They are LASER cut. Their goal is to rigidify the FR4 of the stators.
  
 These stators are PCBs in fact. It is much cheaper to order PCB, than CNC circuits, at least for me. It's a perfectly adapted and already insulated material for this purpose. Most PCB manufacturers can provide such circuits in different flavors... (i. e. thicknesses, mask color, peelable mask, copper thickness, etc.).
  
 With a thin PCB, we can avoid to build up Helmholtz resonators.


----------



## n3rdling

ondesx said:


> Thank you Wachara.
> 
> Yes as stated above (0.5 mm thickness). I'll send a picture asap...
> 
> ...


 
 I think I did a writeup in the thread earlier, but those were both in my test and neither worked well.  They're super messy and create bubbles in the gap as they off gas.  The contact cement is best.
  
 Those are pretty stators, what's the green mask?  Paint?  Also, did you forget to put the mounting holes on the perimeter of the stators?


----------



## ondesx

It seems that the tension of the Mylar must be the same for both cellls (i. e. left and right), otherwise this mismatch will result in an alteration of the soundstage and the stereo.

How do you can keep a constant tension for all cells ?


----------



## ondesx

n3rdling said:


> Those are pretty stators, what's the green mask?  Paint?  Also, did you forget to put the mounting holes on the perimeter of the stators?




Hello,

The green coating is very classical in PCBs. It's often called color mask and can be of different colors. Green is the most often chosen one.

The holes will be made after the gluing of spacers. It's much easier since all the cell, but the Mylar, is in place and the holes of the external rings are easily aligned. 

The spacers and the stators are firmly tighten and it is easier to drill holes through them.

Doing like that, the holes for all layers of the cells are perfectly aligned.


----------



## ondesx

Is cement glue the same as cyanoacrylate glue ?


----------



## n3rdling

ondesx said:


> It seems that the tension of the Mylar must be the same for both cellls (i. e. left and right), otherwise this mismatch will result in an alteration of the soundstage and the stereo.
> 
> How do you can keep a constant tension for all cells ?


 
 chinsettawong has a few pictures here that show how to get around this problem for a single pair of drivers.  Simply stretch your Mylar, put cement on the 2 spacers that will hold the diaphragm (1 per channel), and drop them both onto the stretched Mylar.  This will ensure both resulting diaphragms have the same amount of tension.


----------



## ondesx

Additional question : how much is enough for the tension of the diaphragm and how to perform this perfect tension ?


----------



## chinsettawong

Trials and errors, my friend.


----------



## ondesx

chinsettawong said:


> Trials and errors, my friend.


 
 And what about the method ?


----------



## AManAnd88Keys

ondesx said:


> And what about the method ?



The method is all about trial and error... Please take some time to read the thread from the beginning, it might help a lot. Maybe you will even get answers to questions that you don't have now, but will arise later on.


----------



## ondesx

amanand88keys said:


> Please take some time to read the thread from the beginning, it might help a lot. Maybe you will even get answers to questions that you don't have now, but will arise later on.


 
 I already read the 100+ pages, but I don't remember that anyone gave a quantified method for the diaphragm tension. I mean considering the polarizing high voltage, the distance D/S, the thickness of the Mylar, the quality of the coating, etc.
  
 Another important question seems not be answered until now. To protect the diaphragm from dust and dirt, some authors use a Mylar (not tensioned this time) at the outside of the stators.
  
 Does someone think that this film may impair the audio quality of the cell ? If not, is it possible to install this "protection" at the inside face of the stators instead?
  
 Thanks.


----------



## ayaflo

Hi there ondesx... do check out the thread again. I remember the answers to your questions already present in this thread.


----------



## ayaflo

Creative thing with the pipes.. mr urlgr-A


----------



## jgazal

chinsettawong said:


> I just want to show you guys just how much weight you have to pull on the diaphragm.  When I tried to glue my diaphragm last week, this was what I did.
> 
> 
> 
> ...


----------



## chinsettawong

ondesx said:


> I already read the 100+ pages, but I don't remember that anyone gave a quantified method for the diaphragm tension. I mean considering the polarizing high voltage, the distance D/S, the thickness of the Mylar, the quality of the coating, etc.
> 
> Another important question seems not be answered until now. To protect the diaphragm from dust and dirt, some authors use a Mylar (not tensioned this time) at the outside of the stators.
> 
> ...


 

 Hi ondesx,
  
 I think you should try to understand the basic principle of all the components that make up an electrostatic headphone driver.  The dust cover is just there to protect the driver against dust and sweat.  If you don't want to put it on, it fine too.  To my ears, if the dust covers are not stretch tight, they don't affect the sound.
  
 Frankly, I've done all my works based on trials and errors.  I don't have any quantified method.  Perhaps it woud help if you can do your own experiment and share your findings with us.
  
 Wachara C.


----------



## ondesx

> Originally Posted by *chinsettawong* /img/forum/go_quote.gif
> 
> The dust cover is just there to protect the driver against dust and sweat.  If you don't want to put it on, it fine too.  To my ears, if the dust covers are not stretch tight, they don't affect the sound.
> 
> Wachara C.


 
 Hello Wachara,
  
 Thank you for the input.
  
 For the tension jig, I made some trials with a 12" cycle inner tube on a cardboard cylinder similar to the one shown on your picture (see the enclosed picture). The issue is that the pressure used isn't always the same and also depends on several parameters.
 I should try with some fishing sinkers instead of the tube, since they have a more precise value and are more easier to link to the pliers attached to the Mylar.
  
 I'll report the result of this try asap.
  
 As far as the dust cover, do you think that using it at the inside face of the stators should be an issue ? Or it's better to place it on the outside face ?
 One additional advantage if that cover is in between the diaphragm and the stator, is that it will act as an electrical insulator (i. e. no arcing even the stator isn't insulated itself ).
 The only unknown for me in this case, is the possible interaction between this dust cover and the diaphragm...
  
 Thank you again for your very invaluable help.


----------



## chinsettawong

ondesx said:


> Hello Wachara,
> 
> Thank you for the input.
> 
> ...


 
  
 I've posted it somewhere in the thread that using the inner tyre tensioner, you would easily put too much pressure on the diaphragm.  You just have to try and see how tight the diaphragm is good for you. 
  
 As for dust cover, like I've told you, it's there to protect dust.  I'm sure you can put it anywhere you like as long as it serves its purpose.  I encourage you to try different configurations and let us know how you like best.
  
 Since you have everything already, just do it.  You'll see everything more clearly once you've got your hands on the real thing.
  
 Wachara C.


----------



## ondesx

chinsettawong said:


> Since you have everything already, just do it.  You'll see everything more clearly once you've got your hands on the real thing.
> 
> Wachara C.




Yes I'm very close to assemble all the pieces of the puzzle...

It remains a few details on the methodology, since I want to be able to disassemble the cell if something went wrong... 

I need a couple of jigs to do this assembling in a reversible way... At least for the diaphragm with the spacers on one hand and the stators with their outer rings on the other.

I'll report soon here the result.

Thanks.


----------



## ondesx

Hi there,
  
 Mylar tensioned with the inner tube jig : incredible tension !...
  
 I think the use of weights will be more precise.


----------



## chinsettawong

That's way too much tension!


----------



## ondesx

Just a few pics to show the evolution of the project ! We can see the drilling of the stators with the outer rings in place. This method allows perfect alignment of the 4 pieces. Then, the gluing of each half-cell.
  

  

  

  
 Stay tuned !


----------



## chinsettawong

Looking good!


----------



## ondesx

Thank you Wachara !
  
 I already did some "calibrated" masses in order to determine the best tension for Mylar and be able then to reproduce it.
  
 Here is a pic...


----------



## chinsettawong

ondesx said:


> Thank you Wachara !
> 
> I already did some "calibrated" masses in order to determine the best tension for Mylar and be able then to reproduce it.
> 
> Here is a pic...


 
  
 So, you're going to use weight to tension your diaphragms?  How much weight is it for each of them?
  
 Please let us know how you like this method.
  
 Wachara C.


----------



## ondesx

chinsettawong said:


> So, you're going to use weight to tension your diaphragms?  How much weight is it for each of them?
> 
> Please let us know how you like this method.
> 
> Wachara C.


 
 Oh yes ! Definitely...
 The whites are about 600 g and the blues about 400 g (more or less, I don't think that the needed precision is so high...).
  
 The first try had shown that it's not so easy indeed... The more thin the PET the more difficult the procedure. Two main issues, first the pinch of the plastic is not tight enough, thus the film easily escapes, secondly the round form of the jig induces a lot of wrinkles even after attaching a high weight.
  
 Afterwards, it isn't easy to coat the diaphragm without a support under it and, of course, to glue the spacers on each side of it...

  My first tries were made using a 12 µ Mylar, I wonder what will happen with a more thinner film (like 1 to 3µ...).
  
 OndesX


----------



## Congo5

still here and still trying things...
  
   I use an innertube stretcher but have an digital HVAC pressure gauge,(reads in 1/10th LBS)
 Still its easy to over do it.
 But also easy to build extras and slide them in to try. Yes I tend to make them too tight.
  
  One of the problems I have is with coatings, of all the antistatic screen cleaners I have ( none are gel),
 they sound great but only last for hours. Want to try the floor cleaners next.
  
 also have some Staticide 6300 and it has to be baked or dry for 24 hrs at 70F.
 Yesterday I cleaned and applied it and let it dry then sorta baked it on top of a tube amp  (125F).
  
 one side came up fine but the other had really low volume.  What fixed it was cleaning it with alchohol and rubbing
 with dry cotton????
  
  I found a better paint for the stators at Grangers called Sprayon EL609 insulating varnish. 2,850 volts/ml.
 It solved some problems I was having with bias migration/noises.
  
  Using double sided 1mm staters, .5mm spacers, 2um mylar, yellow contact cement.
 been listening for two hours and there is not volume loss or imbalance ........yet...
 getting closer inch by inch. after they are proven stable I will try to make better looking ones.
 for now here is the state of my prototypethose are the largest earpads I have) 

  
 Thanks Wachara!!!


----------



## ondesx

congo5 said:


> One of the problems I have is with coatings, of all the antistatic screen cleaners I have ( none are gel),
> they sound great but only last for hours. Want to try the floor cleaners next.
> 
> also have some Staticide 6300 and it has to be baked or dry for 24 hrs at 70F.


 
  
 From ACL I have "Reztore Staticide" and will try it, but I'm afraid it'll last, like your own attempts, only few minutes or a couple of hours... 
  
 Unfortunately, it seems that graphite also escapes from the diaphragm in a few hours, even after hard rub !
  
 My other concern with all the sprays is the weight added to the membrane...
  
 I don't see a robust method for coating the Mylar for ages at the correct resistivity !
  
 Yet QUAD used a coating that was known to last more than 25 years !...
  
 Any other advice welcome...


----------



## ayaflo

I remember anti-static spray/gel helps ...the ones you get in PC stores. Also floor cleaners do help.
  
 Go through the gallery here and you will be able to find a pic of 2 white bottles.
  
 Regards,


----------



## ondesx

Sorry for this perhaps trivial question, but how did you guys use these static sprays ?
  
 Either you spray it on the film and you wait it dry, or you rub it on the diaphragm with a microfiber cloth ? Intuitively, the rubbing might improve the adherence of the coating...
  
 But, simultaneously some of the coating will be removed. 
  
 Thank you for your opinions.
  
 OndesX


----------



## chinsettawong

It could be my luck, but the antistatic gel and floor cleaner that I use seem to work very well.  I have at least two pairs of headphones here that have been performing well using either one.
  
 For applying, I put just a little drop of gel or cleaner on a piece of microfiber cloth and wipe it on the diaphragm.  The coating is extremely thin that you can't really see the trace of coating.
  
 Wachara C.


----------



## ondesx

Thanks Wachara,
  
 What are the floor cleaner and the static gel ?
  
 I read that you also use these products :
  
 http://www.head-fi.org/g/i/1025405/default/sort/display_order/
  
 And you also gave a recipe with 2 parts of PVA, 5 parts of water, and ink or 1/10 part of graphite...
  
 What is the best approach for you ?...
  
 OndesX


----------



## chinsettawong

I've certainly posted about this product here before. 
  

  
 Please don't use my PVA formula.  It's not so good in high humidity weather.
  
 Wachara C.


----------



## chinsettawong

congo5 said:


> still here and still trying things...
> 
> I use an innertube stretcher but have an digital HVAC pressure gauge,(reads in 1/10th LBS)
> Still its easy to over do it.
> ...


 
  
  
 Nice work!  How do you like your Megatron?
  
 Yes, using the inner tube stretcher, you can easily over stretch your diaphragm.  You have to be extremely patient and gentle when applying the air into the tire.  
  
 Wachara C.


----------



## ondesx

Thanks again Wachara,
  
 I discover that you had some exchanges with Calvin on DIY Audio. He provided this formula :
  
 my recipe for 100mL of coating is:
 1 volume part glue (Tesa brand)
 4 volume parts destilled, deionized water
 2 tiny drops of black writing ink
  
 I think I'll do a first try with my Reztore Staticide sample...


----------



## Congo5

chinsettawong said:


> Nice work!  How do you like your Megatron?
> 
> Yes, using the inner tube stretcher, you can easily over stretch your diaphragm.  You have to be extremely patient and gentle when applying the air into the tire.
> 
> Wachara C.


 

     The Megatron is well worth building,  Its different than the KGSSHV.  I do not use it  in the summer due to heat,
 or when I just want to listen/test for a few minutes. It's hard to describe the sound but I like it very much. its very pleasing.
  
   And since you can wind the transformers.....  highly recommended!


----------



## chinsettawong

congo5 said:


> The Megatron is well worth building,  Its different than the KGSSHV.  I do not use it  in the summer due to heat,
> or when I just want to listen/test for a few minutes. It's hard to describe the sound but I like it very much. its very pleasing.
> 
> And since you can wind the transformers.....  highly recommended!


 
  
 Megatron is certainly on my "to do" list, but I think it'll be a while.  It's nice to know that you like it though.
  
 I did try winding my own transformers before, but it's too much work for me.  Buying them is a lot easier. 
  
 Wachara C.


----------



## NoPants

The Megatron is nice, I recommend a 400V build based on the heat from running at 450


----------



## Congo5

chinsettawong said:


> Megatron is certainly on my "to do" list, but I think it'll be a while.  It's nice to know that you like it though.
> 
> I did try winding my own transformers before, but it's too much work for me.  Buying them is a lot easier.
> 
> Wachara C.


 

 Yea I would not want to wind 7 6.3v filaments, 2 420v and a 16-0-16v. could it be done all in one?
  
   Tonight every thing seems to be working...


 oh I started using the pps transistor washers from the KGSSHV so that I can use metal screws...
  
 all these work,  wish I knew why  
  
 Thanks


----------



## Congo5

nopants said:


> The Megatron is nice, I recommend a 400V build based on the heat from running at 450


 
 yes that is what Spritzer said > so that is what mine is..
  
 still wonder what more would be like.


----------



## NoPants

I'm running at 450 which is why I'm recommending the downgrade. Having built the 350V KGST, 500V KGSSHV, 450 Megatron, and comparing them to the BHSE (400V?) I can safely say it's not that big a difference.
  
 If you want "more" maybe you can build the fancier power supply at 400V, compared to the Blue Hawaii PSU
  
 Other ideas include
 DC filament supply on the input supply, separate 300V supply
 nicer coupling caps like Mundorf supremes, one guy put solens in his iirc
  
 I would explore these before simply rasing the voltages, but that's just me


----------



## chinsettawong

congo5 said:


> Yea I would not want to wind 7 6.3v filaments, 2 420v and a 16-0-16v. could it be done all in one?
> 
> Tonight every thing seems to be working...
> 
> ...


 
  
 Wow!  You are catching up really fast.   
	

	
	
		
		

		
			




  
 How do you like the sound of each design?
  
 Wachara C.


----------



## Congo5

chinsettawong said:


> Wow!  You are catching up really fast.
> 
> 
> 
> ...


 
 yup only 2yrs 3mo preparing 
	

	
	
		
		

		
		
	


	



  
 well just holding them up to my ears they sound very similar. And all Good>>>>
  
 when you account for diaphragm tension as some are tighter and  have less bass.
  
 If I had to pick right now I would say the best is the lower middle black one with less open area / smaller holes.
  
 to my surprise the design and hole size doesn't seem to make much difference. 
  
 based on advice in this thread All are = or >80mm active area.
  
 what does matter is the coating and Pads! lots to get right with Pads.
  
 Thanks


----------



## chinsettawong

congo5 said:


> If I had to pick right now I would say the best is the lower middle black one with less open area / smaller holes.


 
  
  
 Really?  I very much prefer the ones with bigger open area.  If you have good ear pads, you can tell very clearly that the ones with more holes (open area) have a bigger sound stage.  That's how I like my headphones, anyway.
  
 Really nice work!
  
 Wachara C.


----------



## urlgr-A

Hi ondesx
  
*QUOTE *
*Originally posted by ondesx*
  
*"I don't see a robust method for coating the Mylar for ages at the correct resistivity !*
  
*Yet QUAD used a coating that was known to last more than 25 years !...*
  
*Any other advice welcome..."*
  
  
 How about trying polymer sealant? It is normally used instead of wax after washing your car. 
 As it is designed to stick very well to paint finishes and is 'anti-static', it might also stick well to diaphragm materials.  It's waterproof, so I guess unaffected by humidity. Lasts for months in direct sunlight too. I suppose you just wipe it on and let it dry but that part might need some experiments. You are further ahead than me as I still haven't got my Mylar yet but that is what I am going to try first.
  
 urlgr-A


----------



## Congo5

chinsettawong said:


> Really?  I very much prefer the ones with bigger open area.  If you have good ear pads, you can tell very clearly that the ones with more holes (open area) have a bigger sound stage.  That's how I like my headphones, anyway.
> 
> Really nice work!
> 
> Wachara C.


 
 Well I could be completely wrong at this point,
 more soundstage is what I was expecting, 
 so not hearing that I chose the easy to source pad version.
 also mental bias towards what stax has done?
  


urlgr-a said:


> Hi ondesx
> 
> *QUOTE *
> *Originally posted by ondesx*
> ...


 
 I can not find the exact products Wachara uses and am going to try some of what is here.
 Also want to try some of the car products.
 RainX and one of my TireBlack gels says polymer, vinyl protectant, ect.
  
 if plain floor cleaner works ,,,,,  so does other things.
  
 Also its a good Idea to make your design easy to change the film for coatings and cleanings.


----------



## ondesx

Hi All,
  
 After extensive "bibliography" on this topic, I went to the conclusion that NONE product seems to do the trick !... Some for their too low surface resistance (SR), some others because they don't last enough, most of them because the "homogeneity" of the coating is far from perfect !... 
  
 All these issues have the same consequence : the increase of distortion immediately or with the time !
  
 Then I have a short question : why not use an aluminized Mylar ? There are several. They are "perfectly" coated and homogeneous. Since their SR is much lower than the clear Mylar coated with various experimental solutions (10^9-10^11 ohms/square), perhaps a much lower polarization resistance will do the job ? 
  
 If I correctly understood, the issue with aluminized films, most often, is the firing of the diaphragm if the stators are insufficiently insulated, but it seems this insulation is more easier to perform with small surfaces of headphones, isn't ?
  
 Thanks for any feedback.
  
 OndesX


----------



## urlgr-A

Hi ondesx
 Please tell me, what were your findings for polymer sealant? I ask because I have not found such information.
  
 You talk of homogeneity of your coating. Whilst I understand it is desirable to have a lasting coating that is as uniform as possible, other people's efforts have produced outstanding results without recourse to attaining homogenous coatings. Please look at the restoration of Quad electrostatic speakers using a nylon based coating.
  
 http://www.quadesl.org/index.php/hard-core/panel-coatings/original-quad-coating
  
 This is done at home with a small piece of cloth dipped in the solution and spread onto the membrane, manually! After drying the coating is visibly non-uniform but is the equal of the coating it replaces and will last perhaps 20 years, or so it says. I realise this is for speakers yes but the principles are the same are they not? One can adjust the SR of the coating too.
  
 Another point is that if using aluminised film, there are serious problems to be overcome:
  
  A quote from Sanders The Electrostatic Loudspeaker Design Cookbook in this university project thesis mentions exactly what you are considering:
  
 https://courses.physics.illinois.edu/phys406/Student_Projects/Spring13/Nicholas_Jarosz_P406_Final_Project_Report_Sp13.pdf
  
So there are still plenty of things to actually try. btw Wachara's coatings are not giving up just yet as far as I know!  



 
  
Cheers!


----------



## ondesx

urlgr-a said:


> Hi ondesx
> Please tell me, what were your findings for polymer sealant? I ask because I have not found such information.


 
 Hi urlgr-A,
  
 After extensive study, I think that I'll give a try to conductive epoxy... It seems this is the best way to perform long lasting bonds between PCB and several other materials like PMMA and Mylar for example (i. e. for my personal needs...).
  
 As far as the coating of the diaphragm, presently I only have several thicknesses of clear Mylar, then I'll give a try to an anti-static solution like the Reztore from ACL (I already have a sample). Since that are my first cells I have to go to one direction or another...
  
 I thank you very much for the link of this thesis. I began the reading and I noticed several interesting answers to some of my questions. Particularly, about the thickness of the films for example... Interesting too, the point about the aluminized Mylar !
  
 OndesX


----------



## chinsettawong

For your first pair, I would suggest that you stick with what I suggested.  You might not have known, but it took me a very long and frustrating time to actually find something that's cheap and works.  As for me, I have stopped trying to find other coating materials.  I like what I use and I'll stick to them.  I wasted too much time in the past without anybody giving me good guidances.  I just hope you guys listen to me and just make your headphones. 
  
 If you want to do experiments, I propose that you try different driver designs, different diaphragm materials and thicknesses, different ways to stretch your diaphragm and etc. 
  
 About glue, the best glue that I've tried is still rubber glue (contact cement).  Try and you'll see why.
  
 By the way, aluminized Mylar is known to be a "no, no" for diaphragm.
  
 Good luck.
  
 Wachara C.


----------



## ondesx

chinsettawong said:


> About glue, the best glue that I've tried is still rubber glue (contact cement).  Try and you'll see why.
> 
> Wachara C.


 
  
 Thanks again Wachara for your continuous help !
  
 My present issue is that I don't know what is rubber glue (contact cement)...
 Unfortunately.  
  
 Which of the following will be close to your own glue ?
  
 http://www.pattex.fr/fr/produits-pattex/colle-contact.html
  
 Last but not least, none of the glues I've found, is conductive... My PCB rings with their copper trace have to be bond to the coated Mylar, but keeping the electrical contact... The only solution is to use a conductive glue, isn't ?
  
 OndesX


----------



## customcoco

ondesx said:


> Thanks again Wachara for your continuous help !
> 
> My present issue is that I don't know what is rubber glue (contact cement)...
> Unfortunately.
> ...


 
 I'm curious too, based from the pics I've gathered on the interweb, it seems to be mostly used to glue wood on wood...
  
 BTW, Where are you based in France (feel free to reply by PM or not at all if you feel like doing so) ? I'd love to hear your cans once they're done


----------



## chinsettawong

ondesx said:


> Thanks again Wachara for your continuous help !
> 
> My present issue is that I don't know what is rubber glue (contact cement)...
> Unfortunately.
> ...


 
  
 You've got it all wrong.  I glue the Mylar to only one spacer.  The other spacer uses its copper to charge up the diaphragm.  I don't glue this one to the diaphragm.  My drivers are pressed together using non conductive screws.  
  
 By the way, I want to show you my coated diaphragm:
  

  
 I coated the diaphragm with the floor cleaner.  When it's dried, it actually left a haze on the diaphragm.  I then rubbed it off with a piece of cloth, and the diaphragm was very transparent.
  
  
 Wachara C.


----------



## ondesx

chinsettawong said:


> You've got it all wrong.  I glue the Mylar to only one spacer.  The other spacer uses its copper to charge up the diaphragm.  I don't glue this one to the diaphragm.  My drivers are pressed together using non conductive screws.
> 
> 
> Wachara C.


 
 Thank you for this beautiful pic and your explanations.
  
 These are the drawbacks here : I initially thought to this option in my theoretical approach, but of course there is an asymmetry between the two sides of the diaphragm, since obviously one side is free of bond whereas the other has an additional thickness due to the glue. Secondly, with 0.5 thickness of spacers another issue seems to be the rigidity of the ring compared to the force imposed by the tensioned Mylar... 
  
 Incidentally, aside of these two issues, I will use nylon screws (2 mm for the diameter) and I'm not sure these screws might press correctly all the parts, keeping a good flatness for each and a perfect homogeneity all around of the space between the stators and the membrane !
  
 The only cure to these two drawbacks, are first, use a very thin layer of glue, while keeping a solid bond, secondly use a reasonable tension for the Mylar in order to avoid any folding of the spacer ring.
  
 For the second point, I have  perhaps an idea to circumvent this eventuality : use the stator and the outer ring, as a support to keep both structures as flat as possible before cutting the Mylar. The thickness of the glue remains an unknown for me : I don't know how the difference in the distance D/S might impact the "balanced" operation of the cell. Do you have an idea ?
  
 The pressing force will be a surprise when all the 8 screws will be installed in the final step !...
  
 OndesX


----------



## chinsettawong

ondesx said:


> Thank you for this beautiful pic and your explanations.
> 
> These are the drawbacks here : I initially thought to this option in my theoretical approach, but of course there is an asymmetry between the two sides of the diaphragm, since obviously one side is free of bond whereas the other has an additional thickness due to the glue. Secondly, with 0.5 thickness of spacers another issue seems to be the rigidity of the ring compared to the force imposed by the tensioned Mylar...
> 
> ...


 
  
 Hi OndesX,
  
 Don't think too much.  Just make them.  
	

	
	
		
		

		
		
	


	



  
 Wachara C.


----------



## ondesx

OK Wachara
  
 Let's go !... 
	

	
	
		
		

		
		
	


	




 
  
 OndesX


----------



## Congo5

chinsettawong said:


> For your first pair, I would suggest that you stick with what I suggested.  You might not have known, but it took me a very long and frustrating time to actually find something that's cheap and works.  As for me, I have stopped trying to find other coating materials.  I like what I use and I'll stick to them.  I wasted too much time in the past without anybody giving me good guidances.  I just hope you guys listen to me and just make your headphones.


 
   Yesterday / Today I looked for the floor cleaner.  As far as I can tell from the picture the ingredients are:
Linear Alkyl benzene Sulphonate (LAS) and Sodium Lauryl Ether Sulfate
  
  Which here in the USA manufacturers do not have to list the ingredients on the bottle.
  
 Also there are many names a chemical can be named as. (20+)
  
 From what I could find on google they all seem to have very complicated formulas here.
  
 so gave up on that, again.  And just bought some.
  
 and it works, we'll see how long.
  
 If it fails I will try another.
  
 one side is ACL Staticide 6300 and the other is Pledge
	

	
	
		
		

		
		
	


	



  
 listening to these with a KGST tonight
	

	
	
		
		

		
		
	


	




 Ingredients are:

Fragrance(s)/perfume(s)000000-00-1 Isopropanol000067-63-0 Diethylene glycol ethyl ether000111-90-01.0-5.0Ethylene glycol n-hexyl ether000112-25-4 Monoethanolamine (MEA)000141-43-5 Propylene glycol butyl ether005131-66-8 Water007732-18-5 Sodium dodecylbenzenesulfonate025155-30-0 Cocamidopropyl betaine086438-79-1 D-Glucopyranose, oligomeric, C9-11-alkyl glycosides132778-08-6 Liquitint Bright Yellow Dye888888-03-7 Liquitint Sky Blue Dye888888-03-8
  
 Yea I only know what two of those are
  
 Tomorrow I might mount those pads............
  
 Thanks all


----------



## chinsettawong

Hi Congo5,
  
 Nice find!  See?  We don't really need to know what the stuff is made of.  If it works, it works.  
	

	
	
		
		

		
		
	


	



  
 I haven't tried window glass cleaner such as Windex, but I think it'll work too.
  
 Wachara C.


----------



## ondesx

chinsettawong said:


> We don't really need to know what the stuff is made of.  If it works, it works.
> 
> 
> 
> ...


 
  
 Of course, I agree... The only issue is that we never be able to use the same product, since it is not accessible everywhere !...
  
 This is why we need to know the "magic" formula of yours.
  
 Perhaps there is only one of the products of interest, but no one knows if it's not all the elements and why not their precise proportions !
  
 The customer service might help in giving the formula of your miracle product, don't you think so ?
  
 OndesX


----------



## n3rdling

You guys should put your location in your profiles.  If you're not overseas I can give you specific product names to look for.


----------



## urlgr-A

Tis done. Location added.


----------



## chinsettawong

Come on guys! I've been trying to show you that there are a lot of commonly available stuffs that you can use to make a good coating material on the diaphragm. Of course, it's rather difficult to find the exact same product in every country. But I'm sure you can find something useful if you really look around. I would suggest that you go to a computer store and pick up a bottle of computer screen cleaner. The one that says to contain electrostatic discharge should all be OK.

Wachara C.


----------



## davidsh

chinsettawong said:


> Come on guys! I've been trying to show you that there are a lot of commonly available stuffs that you can use to make a good coating material on the diaphragm. Of course, it's rather difficult to find the exact same product in every country. But I'm sure you can find something useful if you really look around. I would suggest that you go to a computer store and pick up a bottle of computer screen cleaner. The one that says to contain electrostatic discharge should all be OK.
> 
> Wachara C.


 
 I can imagine it won't leave much ressidue either as it is likely to be ethanol based.


----------



## chinsettawong

Merry Christmas to everybody!
  
 During the past few weeks, I've been trying to design and make Stax female sockets.  Here is what I've come up with using my 3D printer.
  

  

  

  
 There are still some flaws but I think it's usable.  My printer is printing at 0.4 mm per layer.  If it can print at 0.2 mm, I think it'll turn out a lot nicer.
  
 If anyone wants to try it, here is the link: https://tinkercad.com/things/7pGkeN939L6


----------



## Kerry

That's really cool.

Nice job.


----------



## urlgr-A

Nice work there!  Strangely enough, I am right now working on a DIY Stax plug, which should fit your socket yes? 
 I will post some pics shortly.
  
 urlgr-A


----------



## kevin gilmore

you should still put in the hole for the center pin just in case you want to
 run old headphones.


----------



## chinsettawong

urlgr-a said:


> Nice work there!  Strangely enough, I am right now working on a DIY Stax plug, which should fit your socket yes?
> I will post some pics shortly.
> 
> urlgr-A


 

 Of course the Stax plug fits my socket perfectly.  
	

	
	
		
		

		
			




  

  
  
  


kevin gilmore said:


> you should still put in the hole for the center pin just in case you want to
> run old headphones.


 
  
 Yes, sir!  I'll remember to do that next time.


----------



## Congo5

chinsettawong said:


> Merry Christmas to everybody!


 
  
  
 Those look Nice! 
  
    Today I tried UDPE and it does not machine nicely for me, very stringy
 or I am using the wrong bit.
 Want to try Delrin.

 also have been listening to the JFloat's and just can not seem to want to wear them 
 although except for low bass the do sound good.

 this is made with an XLR connector and castable urethane


----------



## kevin gilmore

you mean hdpe?
  
 delrin works ok.
  
 ptfe works much much better, use carbide bit and 3000 rpm


----------



## Congo5

kevin gilmore said:


> you mean hdpe?
> 
> delrin works ok.
> 
> ptfe works much much better, use carbide bit and 3000 rpm


 
*UHMW ?*
  
*was sold to me as ultra high density polyethyline*
  
*Ok --thanks on the teflon recomendation*


----------



## n3rdling

You might also want to try a single flute bit.  Works cleaner with plastics at least.


----------



## kevin gilmore

polyethylene melts at a very low temperature, so doing that correctly
 requires careful selection of bits, speeds, and more importantly water
 cooling.
  
 Teflon is bunches easier and also more expensive
  
 Delrin also works easier


----------



## lamode

Respect for such an ambitious project! It's great that you are driving the cans direct from the tube. Would be very interesting to hear these!


----------



## Oktyabr

Delrin, in my experience, has a very quick "flash point".  One second it's hard and tooling nicely, the next second, just a degree or two warmer, and it runs like candle wax.  YMMV.


----------



## jgazal

It seems that stators are well addressed with PCB’s, but I have seen an antique electrostatic project which stators are made of hardened steel wire.

 Then I was reading an interesting article in Scientific American about the first human propelled helicopter, which was coupled with a liquid crystal polymer belt, called Vectran. While I was searching the physical specifications of such fiber, I found some metal clad fiber made of similar polymers. For instance: Not-So-Heavy Metal: Electrical Conductivity in Textiles.
  
 Is it possible to use such metal clad fiber to build stators?
  
 I was thinking a perforated frame to braid a continuous spool of such metal clad fiber while keeping enough gaps to stay acoustically transparent.
  
 What tension would be needed to make a reasonable rigid stator with such fabric?


----------



## chinsettawong

Hi jgazal,
  
 You can of course use any conductive material to make a stator.  However, the more important things are the flatness and rigidity.  If you are sure that you can do a good job with the fabric wires, I would say that it'll certainly work.
  
 For ESL, many people like to build thier speakers using electrical wires.  You need to build a jig to hold the wires and stretch them.  It's not an easy job.  Also you'll have to consider the thickness of the insulator of the wires as it will affect the spacing between diaphragm and stator.
  
 Anyway, if you like to give it a try, go ahead.  Please report back what you've found out.  
	

	
	
		
		

		
		
	


	



  
 Happy New Year!
  
 Wachara C.


----------



## n3rdling

Wire stators are a legit alternative to metal plate/PCB.  Acoustat used tensioned wires in their ESL speakers back in the day.  Stax used a copper mesh for the SR-Omega stators.  For a given spacer thickness, wires are a little less efficient, but they are much better at preventing arcing since the wire has a round edge facing the diaphragm.  A cool DIY project would be a stator made from magnet wire - cheap and already insulated for you.


----------



## jgazal

Thank you both! 
  
 I believe the mentioned metal clad fiber (mcf) is not available for consumers, unless someone orders a very large batch. 
  
 What I find interesting is that the manufacturer can add insulation and tailor the clad conductivity. 
  
 I had in mind a stator like this, with “wire docks”:
  
  

  
 Then just “sew” the stator.
  
 I drew extruded edges in each tunnel, to evenly spread the tension along the wire and to avoid damage in the insulation when pulling both ends.
  
 I just do not know how hold/clamp the mcf at both ends to keep it tensioned.


----------



## urlgr-A

Hi jgazal.
 Happy New Year to you.
 That is a great idea. 
 Are you proposing just a parallel set of conductors or a mesh pattern? I do not know what a single set of parallel conductors would do to the sound but you might have issues with modal resonances unless the conductor wires are very tight - but you already mentioned that didn't you?
  
 How about threading a circular or oval stator design in the same way that a tennis racquet is strung? 
One could use flattened wire conductors instead of round section to increase the stator 'non-hole' area  without increasing stress on the stator frame.
  
 I don't know whether the mesh stators used in the Stax SR-Ω are under tension  but they are reinforced with a star-shaped support made of resin or aluminium.  Your design may remove the need of any support  
	

	
	
		
		

		
		
	


	




. 
  
 http://wiki.faust3d.com/wiki/index.php?title=SR-%CE%A9


----------



## jgazal

Happy new year to you too.
  
 The tennis racquet analogy is better than my expression “wire docks”. 
	

	
	
		
		

		
			




  
 Well, this was my first drawing:
  

  
 I just do not know what is better. The way to find out is to prototype both and to assess their performance.

 A mesh seems more rigid, but it is also more complex to sew and to apply tension. I speculate that it would interfere with the optimal stator/diaphragm gap, produce different acoustical reflections etc. The hardened steel wire project I have read had only the vertical axis.
  
 I think the idea is compatible to square, rectangular, oval or circular stators. I just do not know what the performances of each one of those formats are.
  
 And, chinsettawong, please forgive me for disturbing the thread. I know you are always encouraging people to build the transducers with readily available materials, but I just wanted share my thoughts about this exotic fiber…


----------



## chinsettawong

Hi jgazel,
  
 I think you have a wonderful idea.  Just try it and let us know how it goes.  
	

	
	
		
		

		
		
	


	



  
 Happy New Year!
  
 Wachara C.


----------



## jgazal

urlgr-a said:


> How about threading a circular or oval stator design in the same way that a tennis racquet is strung?


 
  

  
 Not exactly a mesh. 
 The vertical axis, which is more distant, applies lower force to the diaphragm. 
 Space between conductors is decreased in the edges of the stator. The edge conductors could also be closer to the diaphragm if the guiding holes are perforated accordingly.


----------



## n3rdling

The mesh has to be very fine...since you have wires going in both directions, they overlap a little and so parts of the wire mesh are closer to the diaphragm and have more influence on the total force.  That's why wire stators are usually only in one direction, so there's no overlapping and all parts of the wire are an equal distance to the diaphragm.


----------



## chinsettawong

There is no point in leaving a hole in the middle of the stator, IMO.


----------



## urlgr-A

Hi all. Time for an update and question on my glacial-paced project. This is part of the first stator. 
  
 Each stator  consists of a perforated sheet (cut from a microwave oven door), supported and held flat by a PVC ring and a star frame made from 2 mm square brass tube.
  
 My question is, does it matter if the star is electrically connected to the perforated sheet? Or is it better to isolate them from one another? They need to be joined in some way because the brass star and outer ring serve to keep the stator material as flat as possible.
  
 cheers


----------



## chinsettawong

That stator certainly looks nice.  The brass star is OK to be electrically connected to the perforated sheet.  No problem!
  
 Wachara C.


----------



## marsupialx

Only slightly off topic, "How possible do you think it would be to scale up the design, (pcb substrates and accompanying techniques and materials), to successfully create desk-top speakers that kick butt? I've read the entire thread and it seems like, esp. since weight is no longer an issue, one could use double sided stators with the rear copper used to solder on stiffening, such as brass tubing. Having never heard them, I don't know how far the "floats" are from being able to do unamplified singing voice type spl levels (not rocking the house) and adequate bass for a subwoofer transition (120hz to 200hz) in the near field, say two feet away. Any thoughts? By the way, absolutely blown away by what you guys are doing / have done. One more question. How successful would you expect a larger version of the "floats" would be positioned more away from the head, say 3/4 of an inch? Thank you very much. -Jeffrey Hill (marsupialx)


----------



## Q Mass

I think I've heard of small , near field 'stats before.
 I'm betting it could sound great.
  
 Why bother with double sided pcb's and brass tubes?, simply glue something to the non copper side of the stators to provide stiffening.
 I don't imagine it needs to be conductive.
  
 (dodgy advice from cluless n00b btw)


----------



## davidsh

I'm considering making a near-field-ish set of 'stats and a step-up transformer as my physics project. Could be interesting but the materials might just be perforated metal sheets and food film depending on budget.


----------



## n3rdling

I would definitely go the perf metal route for that david.  McMaster has aluminum and steel sheets that aren't that expensive and a single sheet should be good for more than the 4 stators required.  For film, there's Mylar on ebay that isn't too expensive and will also be enough for your project.  Since the spacers will be thicker that makes things a bit easier regarding tolerances and also opens up new possibilities for materials.  I know a double sided foam tape from 3M is popular for use as a simple spacer on diyaudio.  Construction of the pair of speakers will probably be $100-150.  The most expensive part will likely be the audio transformers, probably $100-250 for the pair.


----------



## davidsh

I will have to find out about budget. I considered making the transformers myself from wires and iron cores available in the physics class. Performance will probably be horrible. Alternatively, I might consider using my srd-6 box. 
 If budget is really strict I might just use food film.
 Still not sure what I'll do regarding bias.
 Good idea about the double sided adhessive, makes it quite a lot easier though I'm not sure the mylar/food film will stick properly to that?


----------



## chinsettawong

No worry about using the double sided tape. It's proven to work very well by many DIYers. Well, even Martin Logan is using it for making their ESL.

You can also use cheap transfomers to make step up transformers if you are aiming to make hybrid ESLs. 

Wachara C.


----------



## chinsettawong

For those who are interested in building ESL, I recommend you to check out this page.
  
 Wachara C.


----------



## OnyxOcelot

chinsettawong said:


> For those who are interested in building ESL, I recommend you to check out this page.
> 
> Wachara C.


 
 There is also this book by Roger Sanders called the Electrostatic Loudspeaker Design Cookbook which seems quite expensive, but is probably floating around somewhere in a library or could be found cheaper than Amazon.


----------



## OnyxOcelot

Hey Folks,
  
 Just thought I'd check back in with my latest ES headphone driver build.  No grand new ideas here, but I was able to get access to a CNC machine capable of cutting rather accurately, so am pleased with the build quality.  I am still having some difficulty finding the best way of stretching the Mylar, but was able to get a taught set of diaphragms on the third or forth attempt.  My general impression is that they sound rather good: not very bass-heavy, compared to my last pair -- probably because the diaphragm is stretched tighter -- with clarity throughout the midrange.  
  
 I still have yet to build a case, and am listening to them strapped on the front of the hollowed plastic shells of some cans from the 1970s.  An open backed case would give me a better sense of how they should sound, I believe.
  
  
 I would like to understand more fully how each of the variables we can alter in making these headphones affects the output level and quality.  See below the variables I know and do not know for this current build.  IT is quite likely that some of these variables do not affect sound quality (stator thickness and hole shape seem unlikely to make much difference), but I would eventually like to know exactly which variables affect sound in what ways.  If anyone can suggest reading on the subject, or has thoughts, please let me know.
  
 For the time being, I'll keep chugging away on these designs if you all keep chugging away on your designs.
  
 Happy Building,
 OnyxOcelot
   
  
  
*SPECS:*
  
*KNOWN VARIABLES:*
 DIAPHRAGM AREA.......................................................3.5in x 2.5in
 DIAPHRAGM MATERIAL...................................1.4 Micron Mylar film
 DIAPHRAGM COATING.........................Static Guard anti-static spray
 DIAPHRAGM-STATOR SPACING..........................................0.021in
 DIAPHRAGM SHAPE................................................................Oval
  
 STATOR THICKNESS..........................................................0.021 in
 STATOR HOLE SHAPE.................................................vertical slots
  
 POWER SUPPLY...........................Stax SRD-7 (Self-Biasing) Adaptor
  
*UNKNOWN VARIABLES:*
 STATOR OPEN AREA


----------



## n3rdling

You might want to use thicker PCB for your stators on your next attempt and also change the long slots to holes.  With such thin stators and those long slots, I imagine you're getting some stator resonating while music plays, which increases the distortion.  I think I remember somebody trying the slots before and saying they weren't getting much bass also. 
  
 Output level depends mainly on spacer thickness/bias voltage/driving voltage, with some smaller influence from open area % of the stator design.


----------



## chinsettawong

Nice looking stators.
  
 How do you stretch your Mylar now?  To get good bass, you need to tension your diaphragm just right - good stability and not too tight or loose.  It's not easy.
  
 For me, stretching the Mylar to the exact right tension is still a problem.  I have to do and redo it many times until I'm satisfied.  Maybe it's time that we focus on experimenting the best diaphragm stretching method.  If you guys have any thoughts, please share them.  
  
  
 Wachara C.


----------



## chinsettawong

I made this design a long time ago, but never tried to make it.
  

  
 However, my CNC machine works better with drilling than routing.  So, I stick with drilling holes on the stators.
  
 Wachara C.


----------



## marsupialx

Perhaps a non-workable idea, but the way a screen is tensioned on a screen door or a screen is tensioned on a silk screen, if the stator (or perhaps one of the spacers) had a groove around its perimeter, with an o-ring (rubber or metal) placed over the mylar (over the groove), when the assembly is bolted together, it would pull the mylar tight. Experimentaion would be required. Just a thought.


----------



## OnyxOcelot

n3rdling said:


> You might want to use thicker PCB for your stators on your next attempt and also change the long slots to holes.  With such thin stators and those long slots, I imagine you're getting some stator resonating while music plays, which increases the distortion.  I think I remember somebody trying the slots before and saying they weren't getting much bass also.


 
 Yes, I made slots instead of drilling to reduce machining time (I am working on borrowed machine time), but there have been some issues of stator stability -- no resonance yet, but a certain amount of bending as they are fit into the (makeshift) case.  
  
 Wachara, on this pair of drivers, I tried a couple methods of stretching the diaphragm:
  
                   1. I built a rectangular frame with a bicycle inner tube stretched around the outside.  I would use gaffer's tape to attach the mylar around this frame, then inflate the inner tube.  I never quite achieved a high enough tension before the Mylar ripped using this method.
  
                   2. My most successful stretching methods have been the simplest.  I stretched the Mylar using many pieces of gaffer's tape on a flat, clean table.  This allowed me to progressively stretch the diaphragm by moving each piece of tape outward a bit at a time.  This method is in no way repeatable, but without a proper stretching jig, this has been quite successful.
  
 I have noticed that I occasionally get a very high pitched whine in one or both drivers.  It does not sound like a noise issue in the signal, but something else: perhaps a repeated partial discharging of the diaphragm's static charge to the stator.  Perhaps something else.  It may or may not be humidity dependent.  Do any of you have any experience with this particular issue?
  
 Best,
 OO


----------



## davidsh

I have read that a whine might come from corona discharge. Especially forms at sharp edges on the stator


----------



## chinsettawong

Hi OO,

I'm not sure why you can't get enough tension on your diaphragm using inner tire method. As for me, I really have a hard time not to put too much tension on the diaphragm. It's so easy to pump too much air into the tire and that the diaphragm is too tight.

About the noise in the drivers, it's very common. Most of the time it's dust in the driver. You have to clean your stators and diaphragm very well before you put everything together. It takes a lot of patience to clean. Even a very tiny piece of dust can cause this annoying noise.

Wachara C.


----------



## davidsh

I plan to use dishwashing liquid for coating. How much is needed, give or take?


----------



## Tachikoma

With the antistatic fluid I have, I just splatter it on, and rub it till its even-ish.
  
 I have another question about the coating, using the method I mentioned above, my pro bias drivers are now unstable at 580V bias, but its very hard to use less coating, keep it stable at 580V bias and still achieve perfect channel balance. Any ideas on how I might do that?


----------



## chinsettawong

If your diaphragm is unstable, it's because that you haven't put enough tension on your diaphragm.  It's indeed very difficult to tension your diaphragm just right.  Lowering bias voltage certainly helps the stability, but you lose some efficiency.
  
 Wachara C.


----------



## davidsh

I'll be using 10 or 13 um food film for my physics speaker project. Sorrily, mylar was too expensive. Hopefully the film isn't too weak, but it's low density polyethylene. 
  
 I'll try using rinse aid for dishwashers, couldn't find any dishwashing liquid. I'll probably just dissolve it in ordinary tap water.
  
 Wish me luck... Or something. And feel free to shoot me down, but my options are limited.


----------



## chinsettawong

Food film can sound very nice.  Go for it.
  
 However, the liquid soap, in my experience, is not very good.  If you really can't find the computer screen cleanser, you might want to try some easy to find glass window cleansers. I think some of them might just work.  
  
 Wachara C.


----------



## davidsh

I just thought to myself that rinse aid is supposed to be anti static and it seems to spread out nicely on the film. I even succeeded in measuring a 20 Mohm resistance after applying it a bit excessively (2 copper plates separated by a couple of millimetre)
I'll see what I come up with, might find some screen cleansing gel.


----------



## chinsettawong

That sounds like a winner.  Go for it.


----------



## Ali-Pacha

Tried this to get rid of imbalance on my SR-5/NB :

  
 Didn't work, don't use it for your DIY projects 
	

	
	
		
		

		
			





 
  
 Ali


----------



## chinsettawong

Hi Ali,
  
 Can you describe what you have done so far to fix the imbalance issue?  After you've applied the iClean, is the sound louder, quieter or same, same?  How do you apply it? 
  
 Can you post some pictures of your SR-5?
  
 Wachara C.


----------



## analogsurviver

I did not go trough the entire thread, so please forgive me if this was mentioned before. Material suitable for the graphite coating on plastic films is colloidal graphite in water,  commercial name Aquadag, what it used to be the company called Acheson, being somewhere along the way acquired by Henkel :
  http://www.henkelna.com/about-henkel/product-search-1554.htm?nodeid=8798046388225
 For the ESL diaphragm coating, it can and has to be dilluted VERY MUCH - and you can control the resistance by either leaving it as it dries (higher resistance ) or buffing it GENTLY (lower resistance) - gently enough not to remove it altogether.
  
 It was used in DIY project for ES headphones by Pollock in Wireless World - not only for the coating on the diaphragm, but in an almost undilluted state for stators as well; as graphite coating on acrylic perforated plate. The design allows for minimum stray capacitance, as the stator has conductive surface only over the actual diaphragm area and does not extend over the spacer area, which does not contribute to the output and its additional capacitance ( as in most metal stator designs ) detracts from the performance ultimately achievable, particularly in the high frequency response.


----------



## Ali-Pacha

chinsettawong said:


> Hi Ali,
> 
> Can you describe what you have done so far to fix the imbalance issue?  After you've applied the iClean, is the sound louder, quieter or same, same?  How do you apply it?
> 
> ...


 
 Hi Wachara,
  
 it's my first attempt to fix the imbalance. I've learnt two days ago how to open the driver, I've trained myself on my junk SR-X/mk3. I've to say I'm impressed by the smart engineering of these things : everything is small, but incredibly solid, well-adjusted and easy to service.
  
 To apply the iClean, I've sprayed it on the microfiber, then extremely gently rubbing the driver against it, on both sides. I've been a bit generous, so it takes around one minute to dry, but I've waited 10 minutes before re-assembling the driver. The sound is exactly the same.
 I've tried the same on the crackling drivers (no holes though, but 2-3 very small black points...arcing ?) of my SR-X, and the result is the same : no improvement, no worsening.
  
 I plan to test another "real" antistatic product (or rinse aid...davidsh ?), and use some very light paintbrush for coating...but I'll listen to any of your experienced advice at first 
	

	
	
		
		

		
		
	


	




 
  
 I don't have pictures of my opened SR-5, but here it is :

  
 The overall condition is very (very) good, so I really do want to fix them 
	

	
	
		
		

		
		
	


	



  
 Ali


----------



## chinsettawong

That looks to be a very good condition pair of headphones. 
  
 It'll be a pity if you can't fix it.  I would really like to see the inside of the phones.  If I can see it, I can probably help you to fix it.
  
 I'm sure there are 2 dust covers, 2 stators, 2 spacers and a diaphragm on each driver.  Can you tell me if the 2 spacers firmly glued to the diaphragm?  I just hope that the diaphragm is only glued to one of the spacer ring as it'll be a very difficult fix if the two spacers are permanently glued to both sides of the diaphragm.
  
 Wachara C.


----------



## Ali-Pacha

There is no "free" spacer in the driver, both ones are making a sandwich with the diaphragm :

 As you can see, there is a kind of rainbow haze on which the iClean had zero effect.
 This new unmounting / re-mounting session hasn't change anything, no improvement (fair enough), no worsening (breathe...).
 I'm pretty sure it has something to do with the coating I've used since it had also zero effect on my SR-X drivers.

 Ali


----------



## chinsettawong

ali-pacha said:


> There is no "free" spacer in the driver, both ones are making a sandwich with the diaphragm :
> 
> As you can see, there is a kind of rainbow haze on which the iClean had zero effect.
> This new unmounting / re-mounting session hasn't change anything, no improvement (fair enough), no worsening (breathe...).
> ...


 
  
 That's the kind of design I don't like.  By the way, are those spacer rings metal?  Or are they made of PCB?
  
 The problem could come from the coating deteriorates over time especially around the corner where it's suppose to contact with the charge ring.  If the rings are made from metal you might want to put more coating around the inner circle edge to help getting the bias voltage from the ring to the diaphragm.
  
 By the way, I think your coating spray works just fine.  Otherwise, the sound should be softer as you have already cleaned out the old coating.
  
 Wachara C.


----------



## dude_500

I also have some SR-X mk3 with an imbalance. When they arrived one of the diaphragms was stuck to a stator (a failure mode I see in a lot of old electrostats). I took it apart and very carefully peeled it off causing only one spot of minuscule damage to the diaphragm, not a tear. The balance was way, way off so I took them apart again and cleaned the diaphragms and put anti-static coating on just as I do in all my DIY drivers. They got a lot better, but the balance is still way off. Let me know if you figure it out! Since the diaphragm is permanently sandwiched between the two spacers, I don't know if it's possible to really get a good repeatable electrical contact to the coating.


----------



## phauszzie

This is Awesome!!!  I have to ask a few questions though, what CNC mill do you have (bed size, tolerances, etc.), and how do you like it (would you get a different one if you had the chance)?  Does it have some sort of cooling system? I am looking to get one (maybe once I have a real job) for all my DIY needs.


----------



## chinsettawong

phauszzie said:


> This is Awesome!!!  I have to ask a few questions though, what CNC mill do you have (bed size, tolerances, etc.), and how do you like it (would you get a different one if you had the chance)?  Does it have some sort of cooling system? I am looking to get one (maybe once I have a real job) for all my DIY needs.


 
  
 My CNC router table is about 1200 mm x 800 mm which is way too big for making headphones.  If I were to make a new one, I would probably make it 800 mm x 600 mm.
  
 At the beginning I just use a simple wood router for the cutter.  But I have now upgraded it to be a variable speed spindle motor.
  
 Wachara C.


----------



## Pirx

analogsurviver said:


> I did not go trough the entire thread, so please forgive me if this was mentioned before. Material suitable for the graphite coating on plastic films is colloidal graphite in water,  commercial name Aquadag, what it used to be the company called Acheson, being somewhere along the way acquired by Henkel :
> http://www.henkelna.com/about-henkel/product-search-1554.htm?nodeid=8798046388225
> For the ESL diaphragm coating, it can and has to be dilluted VERY MUCH - and you can control the resistance by either leaving it as it dries (higher resistance ) or buffing it GENTLY (lower resistance) - gently enough not to remove it altogether.
> 
> It was used in DIY project for ES headphones by Pollock in Wireless World - not only for the coating on the diaphragm, but in an almost undilluted state for stators as well; as graphite coating on acrylic perforated plate. The design allows for minimum stray capacitance, as the stator has conductive surface only over the actual diaphragm area and does not extend over the spacer area, which does not contribute to the output and its additional capacitance ( as in most metal stator designs ) detracts from the performance ultimately achievable, particularly in the high frequency response.


 
 In Material Safety Data Sheet of Aquadag you can find:
  
*"Incompatible materials:   Copper.Zinc.Aluminum."*
 &
*"Conditions to avoid:   Keep away from heat, ignition sources and incompatible materials."*
  
 I am not sure if it is good idea to use it in ESL drivers.


----------



## analogsurviver

pirx said:


> In Material Safety Data Sheet of Aquadag you can find:
> 
> *"Incompatible materials:   Copper.Zinc.Aluminum."*
> &
> ...


 
 I did state the general materials of the ESL driver by Pollock. Aquadag does not come in contact with any of the mentioned materials. Even aluminium stators are either anodized or covered with high voltage resistant paint - there is no such thing as practical bare Al, Cu or Zn stator.
  
 There is no heat in properly dimensioned ESL driver, there are no ignition sources either.  Should the driver arc for any reason, the result is burnt off portion where the arcing occured and not an open fire.


----------



## Pirx

How do you connect coated mylar to BIAS source? I do it with copper on PCB or copper wire. But it is always copper or aluminum.


----------



## analogsurviver

pirx said:


> How do you connect coated mylar to BIAS source? I do it with copper on PCB or copper wire. But it is always copper or aluminum.


 
 Just use a little dot of undiluted (paste) Aquadag between the stator and and coated mylar. It spreads over larger surface and creates less of a dimensional disturbance than any metal type contact would. 
  
 I would have to check for the integrity of the ultimately copper wire/Aquadag contact (drivers in storage for over 15 years by now ) - but during the operation I do not remember any catastrophic contact failures.


----------



## BillG

Hi All,
 Joined up a few hours ago.  I've been following the My DIY ELECTROSTATIC headphones thread for as long as it takes to read end to end and digest some of what I read.  My intention is to build a decent pair of electrostatic head phones. I'm a regular over on the DIY audio forum and have been heavily involved in the passive mechanical linear tracking tone arm development.  Back in the early 1960s I made successful electret microphone capsules using aluminized mylar film and charging the electret in an oven with polarizing potential applied.   Played around with ESL by throwing a window screen on the carpet with a two foot square of aluminized mylar on top of it and tying the conductive side of the mylar to the plate of a 6L6 output tube, and the window screen to ground. Polarizing voltage and audio all on one wire.  The sound was incredible for the time even though it emerged in a pencil thin beam directly over the center of the diaphragm. I fully expect that these crude early experiments will not be repeated and a real fine product will emerge.I am looking forward to participating in this forum. Best regards to Chinsettawong and  all you members whose postings I've been reading for some time now.
 BillG 
  
 I apologize for posting here if inappropriate.  I have been trying to determine exactly how this forum is set up and the correct way to participate..  Not the easiest thing to do. This thread seems to be where I will be and covers what I'm most interested in.  Please inform me if I'm out of line in any respect.
 Thanks
 BillG


----------



## chinsettawong

Hi BillG,
  
 You're very welcome here.  As I see it, you are no beginner and your experience can surely help us here.
  
 I'm very interested to learn about how you make the electret diaphragm.  Can you please teach me?
  
 If you have any questions, please do not hesitate to ask. 
  
 Wachara C.


----------



## Pirx

analogsurviver < Thanks for explanations. It seems worth trying then


----------



## analogsurviver

pirx said:


> analogsurviver < Thanks for explanations. It seems worth trying then


 
 The original article from Wireless World 1979 : http://www.amateuraudio.fr/images/ww5.pdf


----------



## Ali-Pacha

chinsettawong said:


> That's the kind of design I don't like.  By the way, are those spacer rings metal?  Or are they made of PCB?
> 
> The problem could come from the coating deteriorates over time especially around the corner where it's suppose to contact with the charge ring.  If the rings are made from metal you might want to put more coating around the inner circle edge to help getting the bias voltage from the ring to the diaphragm.
> 
> ...


 
 Hi Wachara,
  
 I've made further investigations :
 - spacer rings on my SR-5/NB look like PCB, where those from my SR-X are stainless steel / aluminum
 - I've tried more agressive coating with my SR-X right channel (still crackling) : lots of coating with a very light brush, especially around the inner circle edge, then slightly wiping coating marks / residues with microfiber tissue. Mint looking when finished (no holes, no black points)
 The result : almost no more sound on this unit ! 
  
 My coating is crap indeed, I've to test anything else. Anyone did test rinse aid ?
  
 Ali


----------



## BillG

Thanks for the link to the Wireless World 1979 article.  I've just finished reading it and noticed the fairly close correspondence between what he had done and what we have been doing here in this thread.  One thing that hit me right off was that the author was applying polarizing charge to both sides of the diaphragm (I'm not sure that it matters).  The other point he made was that coated diaphragms were not generally needed unless the charge had bled off and the relative humidity was extremely dry. I think our anti static cleaner/gel takes care of that nicely. I think that today's 3 to 6 micron thick mylar will be a far better performer. 
  
 What was most important to me at this time was the description and schematics for the solid state amplifier and power supplies.  Working on a retired persons very limited income, this has some very obvious benefits for me.  Has any one of the members used this amplifier or something close to it, and how do the more modern headphones sound when they are powered by it.  Sure I would like to use Wachara's lovely tube amp but I don't want to go whole hog just yet. I'm amazed by the cost of transformers today compared to what we used to buy them for in the "old days".
  Regards,
 BillG


----------



## BillG

Ali,
 Can you swap over the leads from left to right and see if the crackling changes sides?  Just a thought.
 BillG


----------



## analogsurviver

billg said:


> Thanks for the link to the Wireless World 1979 article.  I've just finished reading it and noticed the fairly close correspondence between what he had done and what we have been doing here in this thread.  One thing that hit me right off was that the author was applying polarizing charge to both sides of the diaphragm (I'm not sure that it matters).  The other point he made was that coated diaphragms were not generally needed unless the charge had bled off and the relative humidity was extremely dry. I think our anti static cleaner/gel takes care of that nicely. I think that today's 3 to 6 micron thick mylar will be a far better performer.
> 
> What was most important to me at this time was the description and schematics for the solid state amplifier and power supplies.  Working on a retired persons very limited income, this has some very obvious benefits for me.  Has any one of the members used this amplifier or something close to it, and how do the more modern headphones sound when they are powered by it.  Sure I would like to use Wachara's lovely tube amp but I don't want to go whole hog just yet. I'm amazed by the cost of transformers today compared to what we used to buy them for in the "old days".
> Regards,
> BillG


 
 Regarding amp - good, but nothing to write home about. It is the same "rear end" as say Stax SRA-12S - I actually had to canibalize my Pollock amp to replace one blown output transistor in SRA-12S - which then later went belly up because of the transformer ( that thing is simply too small/too little cooled to be reliable in the long run ).
  
 LM3900 chip is nothing special, today there are many better options. What does still hold true is the absolute necessity to use the best passive components you can possibly find - and afford. That goes particularly for the feedback capacitor - difficult  to procure in required voltage/value to begin with, adding high quality request compounds the problem further. 
  
 Finding output transistors nowadays is getting ever harder. 
  
 Power supply I guess would be pretty similar to that for Wachara's design ( I did not look into it - yet ) ; output transistors or tubes are also more or less the "same" - built with quality parts ( which IS a must if you want your amp to sound better than conventional amp + transformer box/energizer ), one does not save much $ by going with so simple/cheap front end in the overall sense. 
  
 It took me one hell of a better amp to remove even the faintest possibility of an idea that transformer might be better than direct high voltage amp.  But - at $$$$$$$$$. 
  
 I did not want to discourage you, just to make it clear it is not an equivalent of a factory built amp at a fraction of the cost. But it IS listenable.


----------



## Ali-Pacha

billg said:


> Ali,
> Can you swap over the leads from left to right and see if the crackling changes sides?  Just a thought.
> BillG


 
 Some other tests later... 
	

	
	
		
		

		
			




  
 - rinse aid does work !!!!! Finish is ugly, but who cares when no one sees the mylar ?
 - early SR-X/mk3 diaphragms have metal spacers since latest SR-5/NB have PCB spacers
 - metal spacers are probably thinner than PCB ones : when I use a diaphragm from my SR-X in my SR-5/NB, no crackling (see below), but there is a clicking noise as soon as charge bias comes in (barely noticeable on SB boxes, indeed)
 - crackling noise from my SR-X has nothing to do with diaphragms nor cable, but there is probably something with the stators on both sides
  
 All these facts except the first one should rather be on a Stax thread, but I'll sleep a bit less dumber tonight.
  
 Ali


----------



## davidsh

So you tried the rinse aid for repairing your bugged out sr-5? Glad to hear it works! 
I've got a question about the general principles of electrostats. Basically, we are talking a charged film suspended in a varying electric field. Anyway, the charge on the film is one variable that is correlated to the efficiency of the 'stat. The charge depends on the capacitance of the film and the voltage, no?
What determines the capacitance of the film, though? Can you somehow alter it?


----------



## chinsettawong

Hi davidsh,
  
 When you want to change the efficiency of the electrostats, you either change the bias voltage or the spacer thickness.  The capacitance on the film has nothing to do with the efficiency. 
  
 What you want to achieve when coating the diaphragm is that you want it to be conductive and hold the charge for as long as possible.  The coating materials that I recommended in my earlier posts will give the resistance of around 10-100 M ohm per square.  Think of the diaphragm as a capacitor and the coating as a bleeding resistor connecting on it.  The bleeding resistor slowly bleeds away the charge.
  
 Wachara C.


----------



## BillG

chinsettawong said:


> Hi BillG,
> 
> You're very welcome here.  As I see it, you are no beginner and your experience can surely help us here.
> 
> ...


 
 Hi Wachara,
 That really goes a long way back.  There wasn't a lot to it.  I machined an aluminum cup about an inch in diameter outside, and 3/4" inside.  A short distance down from the rim of the cup there was a small flange. Next I made a ring which fit over the cup and was screwed down with nylon screws  to the flange.  The  aluminized mylar film was held over the top of the cup and the ring was bolted down to the flange tensioning it somewhat. with everything properly insulated I connected a 300VDC power supply between the cup and the conducting side of the mylar. The capsule cup and mylar then went into a household baking oven, power was applied, the oven raised to some 350 degrees F.for about an hour.  Then the power supply was turned off and the oven left to cool slowly.  The mylar was charged and the assembly converted for use as a microphone.  It worked as a microphone into a high impedance vacuum tube amplifier (hi gain stage). and was still working more than a year later.  Sorry, but that is all I can tell you about it. 
  
 You might want to try that procedure with one of your Jacklin Float capsules.  I have no idea how much if any volume you could get with it.  Let me know if you have any success at all. Regards,
 BillG.


----------



## davidsh

chinsettawong said:


> Hi davidsh,
> 
> When you want to change the efficiency of the electrostats, you either change the bias voltage or the spacer thickness.  The capacitance on the film has nothing to do with the efficiency.
> 
> ...


 
 What puts me off is that coloumbs law states that the force exerted on a static object in an electric field depends on the charge of the object and the magnitude of the electric field (the electric field depends on spacer thickness and the voltage potential between the stators).
 The charge that the diaphragm will hold is dependent on the capacitance of the diaphragm as well as bias voltage as I see it. In other words the number of electrons that you can stuff onto the diaphragm.
  
 More charge = more electrons = more capacitance and voltage = greater force


----------



## dude_500

davidsh said:


> What puts me off is that coloumbs law states that the force exerted on a static object in an electric field depends on the charge of the object and the magnitude of the electric field (the electric field depends on spacer thickness and the voltage potential between the stators).
> The charge that the diaphragm will hold is dependent on the capacitance of the diaphragm as well as bias voltage as I see it. In other words the number of electrons that you can stuff onto the diaphragm.
> 
> More charge = more electrons = more capacitance and voltage = greater force


 
  
 This is all true, however the only thing affecting capacitance here is surface area of the film/stators, and the distance between the film and the stators. Coating material or thickness does not affect capacitance (of course you have to reach a certain amount of coating in order to actually charge the capacitor, but that is all).
  
 So, to increase the capacitance, you either increase the surface area, or decrease the area between the two stators. C = epsilon A / gap


----------



## chinsettawong

You don't really want to have high capacitance.  That will put more load on the amp and the high frequencies will be tamed down.


----------



## davidsh

Thank you, I am acquinted with what both of you said. I am merely stating that to my logic the force on the diaphragm also depends on the charge of the diaphragm, eg. how many electrons there are on the diaphragm. Any thoughts?


----------



## charlo89

Hi,
 I just stumbled on this wonderful thread. I would like to know what tricks work well.
 For the stator: What materials to use? What coating used?
 For the spacer, what materials to use? What thickness is favorable for a 580V bias ?
 For the diaphragm,How to measure the pressure to apply?
 Thank you


----------



## chinsettawong

billg said:


> Hi Wachara,
> That really goes a long way back.  There wasn't a lot to it.  I machined an aluminum cup about an inch in diameter outside, and 3/4" inside.  A short distance down from the rim of the cup there was a small flange. Next I made a ring which fit over the cup and was screwed down with nylon screws  to the flange.  The  aluminized mylar film was held over the top of the cup and the ring was bolted down to the flange tensioning it somewhat. with everything properly insulated I connected a 300VDC power supply between the cup and the conducting side of the mylar. The capsule cup and mylar then went into a household baking oven, power was applied, the oven raised to some 350 degrees F.for about an hour.  Then the power supply was turned off and the oven left to cool slowly.  The mylar was charged and the assembly converted for use as a microphone.  It worked as a microphone into a high impedance vacuum tube amplifier (hi gain stage). and was still working more than a year later.  Sorry, but that is all I can tell you about it.
> 
> You might want to try that procedure with one of your Jacklin Float capsules.  I have no idea how much if any volume you could get with it.  Let me know if you have any success at all. Regards,
> BillG.


 
  
 Hi BillG,
  
 So you basically just charged the diaphragm while baking it?  It's interesting to hear that you're using aluminized Mylar film.
  
 Thanks for sharing. 
  
 Wachara C.


----------



## chinsettawong

charlo89 said:


> Hi,
> I just stumbled on this wonderful thread. I would like to know what tricks work well.
> For the stator: What materials to use? What coating used?
> For the spacer, what materials to use? What thickness is favorable for a 580V bias ?
> ...


 
  
 Hi Charlo89,
  
 Everything you need to know has already been posted here many times. 
  
 For stators and spacers, I use FR4 copper clad PCB.  The thickness I use is 1 mm for stators and 0.5 mm for spacers.
  
 For tensioning the diaphragm, unfortunately I haven't come up with a good and reliable way to measure its tension.  The tension is done based upon my experience and trials and errors.
  
 Wachara C.


----------



## BillG

chinsettawong said:


> Hi Charlo89,
> 
> Everything you need to know has already been posted here many times.
> 
> ...


 
 Hi Wachara,    
  
 I wonder if you could bounce a laser pointer beam off a tensioned diaphragm onto a wall and then drop a small ball bearing ball onto the diaphragm and observe/measure the deflection.of the beam. the ball would have to drop a specified distance each time it dropped.  So far easy.  now the hard part, how to calibrate the bounce. I don't know!  Rather than dropping a ball, perhaps one could use a calibrated puff of air in the manner the eye doctors do for measuring pressure in the eyeball. If we research that procedure we may learn something more.
 BillG


----------



## chinsettawong

Quote:


billg said:


> Hi Wachara,
> 
> I wonder if you could bounce a laser pointer beam off a tensioned diaphragm onto a wall and then drop a small ball bearing ball onto the diaphragm and observe/measure the deflection.of the beam. the ball would have to drop a specified distance each time it dropped.  So far easy.  now the hard part, how to calibrate the bounce. I don't know!  Rather than dropping a ball, perhaps one could use a calibrated puff of air in the manner the eye doctors do for measuring pressure in the eyeball. If we research that procedure we may learn something more.
> BillG


 

 That sounds too complicated.


----------



## schorsch

Hello, 

Learned some new things in the last Weeks. I have my Stax f81 speakers for repair at a well known German manufacturer. 
He Told me that Stax does no coating.
They produce mylar with the necessary ingredients to make them electrostatic.

All other Makers coat the mylar.

Regards Georg


----------



## n3rdling

One kind of simple way to measure the tension is to run the driver open air with a FR plotting software/mic and check the resonant frequency.
  
 Georg, that's interesting but how is he so sure?  I think Sennheiser used gold vapor deposition to lightly coat their diaphragm.  A sputtering gun can be built for pretty cheap if you have machining capabilities, most expensive part would probably be the lab vacuum.


----------



## phauszzie

Thats when you borrow the local university's lab


----------



## Tachikoma

schorsch said:


> Hello,
> 
> Learned some new things in the last Weeks. I have my Stax f81 speakers for repair at a well known German manufacturer.
> He Told me that Stax does no coating.
> ...


 

 Maybe what they mean is that the F81 uses electret film?


----------



## Tachikoma

ali-pacha said:


> Hi Wachara,
> 
> I've made further investigations :
> - spacer rings on my SR-5/NB look like PCB, where those from my SR-X are stainless steel / aluminum
> ...


 
 The crackling might be caused by tiny fibers left behind by the brush or microfiber. I would use a sponge, or if you are really lazy like me, a finger.
  
 You probably need more coating, don't be shy with it, just spray it all over the diaphragms and rub it till its even. That's how much I needed to get comparable volumes to a fully working drive.


----------



## davidsh

Bump!
 Quote:


davidsh said:


> So you tried the rinse aid for repairing your bugged out sr-5? Glad to hear it works!
> I've got a question about the general principles of electrostats. Basically, we are talking a charged film suspended in a varying electric field. Anyway, the charge on the film is one variable that is correlated to the efficiency of the 'stat. The charge depends on the capacitance of the film and the voltage, no?
> What determines the capacitance of the film, though? Can you somehow alter it?


 
 Does anyone know an analysis on the electrostatic speaker principle perhaps? I have read the cookbook...
  
 Or perhaps another way for me to find out?


----------



## ondesx

Hello,
  
 I somehow redefined the specifications of the tension jig as follows : 
  
 - easy installation of the film, 
 - allow to choose any face of it and, why not, each side, if one wishes to "treat" equally both sides, 
 - the best balanced tension all around the film, 
 - very good retention of the latter to the masses used, even heavy,
 - knowledge of "the tension mass" for a given type of film, 
 - achieve several membranes at once, which in principle should lead to constant membrane tensioning.
  
 As my stators are 10.5 cm of diameter, I achieved a system that takes at least two diameters of the stators, which leads to 4 equally "tensioned" membranes, obtained simultaneously.
  
 I opted for a ring system in MDF, closed with 8 bolts and butterflies, a 6 mm nitrile joint (a silicone one might as well do the job ...). Here are pictures of this "revisited" stretching jig:
  
 External face :
  

  
 Internal face :
  

  
 With the bolts in place - please notice the groove where the nitrile joint will be inserted in order to clamp the Mylar:
  

  
 With the nitrile joint inserted:
  

  
 Mylar in place in between the rings :
  

  
 Jig in action with the masses - Here, near to 14 kg of charge on a 12µ test film !...
  

  
 The central cylinder receiving the whole system ! 
  

  
 This jig can be "reversed" in some sense... Instead of "press" around the ring, it's possible to maintain the rings solidly around a central hole in which the cylinder may be "pushed up", but in this case, again, a surface tensiometer is needed, in order to know the submitted tension !
  
 My jig has several advantages, aside a very good distributed tension of the film and the possibility to flip over easily the rings to access equally to both sides for whatever treatment, one can obtain 4 diaphragms of same tension in one shot, know the value of this tension for a given plastic film, save some Mylar since only a small surface is not used !...
  
 Hope this helps !
  
 OndesX


----------



## charlo89

Thank you for your answer
 I'm currently reading the topic, there are many pages but it is very interesting.
 I wondered if it was possible to design stators with the "fazor" system of audeze, it would require a precise cnc machine to adapt the "fazor" to the tiny holes of an electrostatic stator, but is it worth it?
  
 Edit: I made some research, the problem is the large size of magnet. it's not important on electrostatic structure.


----------



## chinsettawong

ondesx said:


> Hello,
> 
> I somehow redefined the specifications of the tension jig as follows :
> 
> ...


 
  
 Hi OndesX,
  
 Your diaphragm stretcher looks interesting.  Have you tried it with 2 or 3 microns Mylar yet?
  
 Wachara C.


----------



## ondesx

Hello Wachara,
  
 Not yet, but I suppose it'll work in the same way. The unknown for me is the resistance of such a thin film...
  
 A friend of mine told me that it's a delicate material and it'll easily rip. 
  
 What is your opinion ?
  
 OndesX
  
 PS : Though this method has not yet solved the problem of the correct tension value !


----------



## chinsettawong

Hi OndesX,
  
 Yes, the Mylar can be a headache to work with.  The thinner you go, the easier it'll break.
  
 The correct tension value, in your case, will be the amount of weight you put on.  Isn't it?
  
 Before you can get the right value, you'll just have to do a lot of experiments.  Too much tension, there will be less bass.  Too little, the diaphragm will not be stable.   
	

	
	
		
		

		
			




  
 Wachara C.


----------



## ondesx

Hi Wachara,
  
 Yes, but I still have to define a method to determine beforehand the needed tension (i.e. the mass) for a given plastic film...
  
 I suppose that this will be determined through several trial and error, since I haven't any idea about how to build a computer simulation or an analytical study of such a problem...
  
 Any suggestion is welcome, but I suppose you already have thought about this question.
  
 OndesX


----------



## chinsettawong

Trial and error will be your very good friend.


----------



## davidsh

I read on a DIY esl page that as a guideline the Mylar should be stretched 1.5%.
Just passing it on..


----------



## chinsettawong

Stretching the diaphragm that much is way too much, unfortunately.


----------



## n3rdling

That's about the most you can stretch it before it tears.


----------



## ondesx

Hi all,
  
 Here is some maths about the estimation of the tension for the diaphragm.
  
 The resonance frequency of a stretched membrane is a function of the tension and the form of the diaphragm. For a circular membrane, it's known that the tension and the mass have the following relationship :
  
 T=M(f x R^2/0.146)
  
 where :
 T is the tension in dynes/cm
 M is the mass of the membrane in g
 f the resonant frequency
 r the radius of the membrane in cm
  
 It is assumed that a 500 cm^2 - 12µ Mylar membrane has a mass about or less than 1 g and for a 4 µ thin film the value should be 3 times lower i. e. about 0.3 g. A 10 cm stator have a 5 cm radius, thus a surface of 80 cm^2. Then the mass will be about 0.05g. Thus, knowing the diaphragm radius and for an estimated 100 Hz resonant frequency, the tension might be calculated now...
  
 Any comment is welcome...
  
 OndesX


----------



## ondesx

Another formula is given here :
  
 http://hyperphysics.phy-astr.gsu.edu/hbase/music/cirmem.html
  
 For the Mylar the density is 1.3 g/cm^3 and 5.2 g/m^2 if one uses a 4µ Mylar film. For a 10.5 cm of diameter diaphragm, the calculated Tension on this page is about 90 g/m...
  
 Something seems to be wrong.
  
 OndesX


----------



## chinsettawong

I think it's rather difficult to calculate the right tension. Even if you can, how can you make sure that you can get the exact right tension?

I always stretch the diaphragm so that it's free of wrinkles or almost free of. The elongation is probably only around 0.5%. However, since the tension isn't so much. It's rather difficult to get a consistent result. I eventually have to do it a few times before I'm happy with the result.

I suggest that you just try it and you'll see what I mean.


----------



## ondesx

If we must stretch the diaphragm so that it's almost free of wrinkles, the rings alone will do the job in my case. I mean additional weight will be useless.
  
 But, if I correctly remember one picture you posted on this thread (March 2, 2013), you have shown several bottles of water pulling the film... 
  
 http://www.head-fi.org/t/498292/my-diy-electrostatic-headphones/720
  
 You suggested at that time that for a 3µ film, you could use at least 800 to 1000 g for each weight. On the picture, each bottle weighs 650 g and you used a total of 8 bottles, i. e. more than 5 kg  !... I suppose that you might remove the ripples for much less weight isn't ?
  
 Please, can you comment this point ?
  
 OndesX


----------



## arnaud

Assuming you want to match a pair of assembled transducers, how about this:
 - Download a free / cheap SPL analyzer app on your smartphone.
 - Run some white noise through assembled transducer and check the open air resonance frequency using the SPL analyser (1/12 Octave band or some similar setting) by placing the phone nearby either sides of the transducer
 - As expected,  tensioning will directly relate to this frequency and it's fairly easy to visualise as a free transducer has very little self damping so you'll get a nice bump (anywhere between 80Hz and 150Hz I guess).
 - I guess the next job is to build multiple samples and pair them. 
 - Now, unfortunately there is some complication as the free air resonance frequency is quite different from the coupled resonance frequency once the transducer is "acoustically" loaded by the earpad cavity system
 - If it's a non leaky pad, you can expect a severe change in the first coupled resonance, like dropping from 120Hz-150Hz to 40-50Hz in case of Omega / SR009 type frames (see measurement link in my rig, I think I compare free air vs. loaded response of SR009 and SR007 phones)
  
 Just stating the obvious, I probably missed an important point why you are not already doing it this way...
  
 arnaud


----------



## chinsettawong

Quote:


ondesx said:


> If we must stretch the diaphragm so that it's almost free of wrinkles, the rings alone will do the job in my case. I mean additional weight will be useless.
> 
> But, if I correctly remember one picture you posted on this thread (March 2, 2013), you have shown several bottles of water pulling the film...
> 
> ...


 
  
 Using the method I posted certainly works, but I haven't spent enough time doing trials and errors to get the right weights. 
  
 Whatever method you choose to use, you'll just need to try, try, and try until you get it just right.  It's not so easy.
  
 Wachara C.


----------



## chinsettawong

Hi Arnaud,
  
 To make a match pair, I just stretch the Mylar that is just big enough for one pair.  That saves a lot of time and headache.
  
 If I need to find whether they're really match, I simply knock them against the edge of a table and compare the sounds.  The match pair should sound very similar.
  
 Wachara C.


----------



## arnaud

That's right, I always forget about all the tricks you apply Wachara. Somehow they're always so much more reasonable ideas than what an engineer can come up with


----------



## ondesx

chinsettawong said:


> Quote:
> 
> Using the method I posted certainly works, but I haven't spent enough time doing trials and errors to get the right weights.
> 
> ...


 
  
 Yes I understand that I have to try and fail several times... But, my question was about the intensity : removing simply the ripples doesn't need 5 kg around the diaphragm... 
  
 Thus, with your more recent stretched membranes in which range are you ? around one kg or more than 5 kg for à 3 µ Mylar ?
  
 OndesX


----------



## chinsettawong

I don't use weights to stretch Mylar anymore. I use my inner tire stretcher instead.

I stretch it so that the wrinkles are almost all gone. The elongation is just around 0.5% or less.

It's rather difficult to describe. I encourage you to really try it and you'll understand.


----------



## ondesx

chinsettawong said:


> I don't use weights to stretch Mylar anymore. I use my inner tire stretcher instead.
> 
> I stretch it so that the wrinkles are almost all gone. The elongation is just around 0.5% or less.
> 
> It's rather difficult to describe. I encourage you to really try it and you'll understand.


 
  
 OK but do you remember your advice to somebody in this thread :
  
 "If you can find a helping hand, I think the stretcher using clips and weights is better.  It's easier to repeat the process too."
  
 Thus, I'll give a try to a 3µ Mylar with my jig since it's possible, this way, to "quantify" the weight used for stretching it.


----------



## chinsettawong

I agree that using weights, once you get it right, you can have good repetitions. 

Your jig looks good. Go for it!


----------



## BillG

chinsettawong said:


> I don't use weights to stretch Mylar anymore. I use my inner tire stretcher instead.
> 
> I stretch it so that the wrinkles are almost all gone. The elongation is just around 0.5% or less.
> 
> It's rather difficult to describe. I encourage you to really try it and you'll understand.


 
 Hi Wachara et al,
 I'm following this discussion with great interest. Some day soon I'll be ready to do some stretching too.  I raise some issues and ideas which apply to the topic and hope they help in getting the diaphragms we need.
  
 Once the film is stretched to a desired tension, adhesive is applied to the spacer ring and the ring is placed on the tensioned mylar. We hope that the adhesion is great enough so that tension is maintained after the adhesive sets and the covered spacer is removed from the larger mylar sheet.    In making a matching pair of diaphragms for a pair of phones, some adjustment with the hot air gun on the diaphragm with the lower vibrating pitch is possible.  So far so good.  My concern is that the mylar is stretched, on whatever jig is being used, to some arbitrary tightness and simply held there for further adjustment followed by  the glueing. No heat shrinking has taken place yet.  Does that leave the diaphragm in an unstable state? Perhaps pre-shrinking of the mylar should be done to stabilize it.  Preshrinking may not be needed, I don't know yet.
  
 The next parameter to consider is how tight to make it initially.  I'll explore that in the next posting. Gottago now, back later.
  
 BillG


----------



## BillG

Hi All,
 This reply/post is really a continuance of my #1789.  Something I was just getting to was whether or not the mylar film shrinkage or even "coeficient of stretch" is the same for direction of applied tensioning force.  I think I saw something indicating it may stretch more in one direction than the other.  If this is true, what is the result?  Does it even matter?  How to compensate for this is a question.  Maybe prestretching could  be helpful?  
  
 In selecting the desired tightness of the finished diaphragm it seems to be the general opinion that resonant frequency of the diaphragm in free air is the parameter easiest to observe and control.  To those of you all that have built ESPhones what RFs have you found to make the best sounding phone(s)?   Has there been any attempt to find how much changing this RF one way or the other, say up or down, by 10 or 20 Hz makes any real difference in the overall sound quality? 
  
 I suspect that  parameters  other than diaphragm tension  may make as much or more difference in the final sound output.  Tension seems to be the one which is least able to be defined or controlled. This is why I've chosen to begin my  thinking here.
 Regards to all,
 BillG


----------



## chinsettawong

There are really two ways to tension the Mylar.  You either stretch it or heat shrink it.  However, mechanical stretching gives far higher tension than heat shrinking.  I've tried many, many times to use just a hot air gun to heat shrink the diaphragm, but it just doesn't yeild enough tension.
  
 Once the Mylar is mechanically stretched and glued to the spacer ring, if the glue is good, the tension stays stable for a long, long time.  So, please don't worry too much.
  
 As for me, I make the headphones just for myself.  I don't worry too much about the theory, and I just do it.  The test results of my headphones aren't that bad too:   http://www.innerfidelity.com/content/extraordinary-diy-electrostatic-headphones-chinsettawong
  
 Wachara C.


----------



## ondesx

billg said:


> Something I was just getting to was whether or not the mylar film shrinkage or even "coeficient of stretch" is the same for direction of applied tensioning force.  I think I saw something indicating it may stretch more in one direction than the other.  If this is true, what is the result?  Does it even matter?  How to compensate for this is a question.  Maybe prestretching could  be helpful?
> In selecting the desired tightness of the finished diaphragm it seems to be the general opinion that resonant frequency of the diaphragm in free air is the parameter easiest to observe and control.  To those of you all that have built ESPhones what RFs have you found to make the best sounding phone(s)?   Has there been any attempt to find how much changing this RF one way or the other, say up or down, by 10 or 20 Hz makes any real difference in the overall sound quality?
> 
> I suspect that  parameters  other than diaphragm tension  may make as much or more difference in the final sound output.  Tension seems to be the one which is least able to be defined or controlled. This is why I've chosen to begin my  thinking here.
> ...


 
 Hi BillG,
  
 It's true that there are 2 perpendicular stretching directions for PET films, one direction is more difficult to stretch than the other : you might try to stretch manually a small piece of PET to convince yourself.
 But, this isn't a paramount point, as far as you make an homogenous tension around all the film.
  
 The resonance frequency isn't so important, but it must be maintained around 100 Hz more or less. Ten or 20 Hz of variation in this RF isn't an issue.
  
 The physical problem behind the diaphragm tension is that the electrostatic force must overcome this tension on one hand, because if the force can't overcome this tension, no sound will happen ! But, on the other hand, if one uses a too low tension, it results an instability of the diaphragm which collapses on the stators on one side after the other. This is why the value of this tension is so delicate to define : we have to optimize these two contradictory constraints !...
  
 Just to comment a few on the major factors needed to obtain, at least, an usable pair of headphones : I think that the quality of the gluing for the spacers and the diaphragm is paramount, not too thick and as even as possible. The thickness of the spacers and the stators, the insulation of the stators, the efficiency and the lasting of the diaphragm's coating and the rigidity of the whole system are, probably, much more important than the RF.
  
 This is my personal vision of this project, of course.
  
 OndesX


----------



## davidsh

Just want to give an update. I actually finished the esl in my physics project. Very very crude and simple construction. The stretching of the food film was done by hand by twisting metal rods around the 4 sides of the film then stretching, one person per side.


----------



## BillG

chinsettawong said:


> I agree that using weights, once you get it right, you can have good repetitions.
> 
> Your jig looks good. Go for it!


 
 I'm sorry to continue poking at this but it appears that we are not responding to the question that is being asked here.    I too agree that one should be able to get good repetitions using weights.  The problem is that no one seems to be able to recognize what "right" is once you get it.  IMHO those of us who are pushing on theoretical points and definitions etc, are just trying to recognize "right" once we get it.  If we can do that it should be possible to reduce the number of random iterations and zero in on "right" in a reliable manner.
 BillG


----------



## davidsh

But what is right, though? We could start there. What do you think?


----------



## BillG

davidsh said:


> But what is right, though? We could start there. What do you think?


 
 Hi David,
 You read my post correctly and translate it to a small number of words.  In coming up with more knowledge of "right" we could start by establishing a tension that just keeps the diaphragm from touching the stator. This would be a best case for safety.  But would it be the best case for sound?   What other controls could be applied with reasonable effort which would be better than just not touching the stator?  By the way, I'm trying to simplify the process.
 Regards,
 BillG


----------



## davidsh

Well, for the diaphragm not to touch the stator you'd want the restoring force to be great than the electrostatic force at all times. The restoring force depends on the elasticity which depends on the material used and the tension. I think the esl cookbook has something to say about it, though there are no equations as such. I'm not really sure there are any means of calculating this in the first place. Whether the diaphragm will collapse depends on a lot of factors I think. Besides, there are many other types of instability such as crackling or hissing sounds, imbalance and stuff like that. In principle any diaphragm can be made stable if the spacers are big enough but I guess we are assuming that one uses pro bias voltage here.
I am still to figure out how to calculate the forces on the diaphragm, though I'm getting there.


----------



## ondesx

billg said:


> ...read my post correctly and translate it to a small number of words.  In coming up with more knowledge of "right" we could start by establishing a tension that just keeps the diaphragm from touching the stator. This would be a best case for safety.  But would it be the best case for sound?   What other controls could be applied with reasonable effort which would be better than just not touching the stator?  By the way, I'm trying to simplify the process.


 
  
 Unfortunately, there is no easy way to determine, from a theoretical point of view, the "best" tension of the diaphragm for a given polarization voltage.

 First of all, we have to define what we mean by "best". I think that we're looking for the tension of a given film, that allows the loudest audio signal with as much bass as possible... Since the constraints are opposite, none recipe can define _a priori_ this "best" tension. The optimization of this value requires an iterative process between a given tension and several polarization values. Progressively, we might derive this value for a set of parameters (the thickness and the composition of the film, polarization tension and physical data like DS-distance and geometry of the stators).
  
 Anyway, it must be reminded, as mentioned in a previous post, that the quality and durability of the coating of this film, the thickness of the adhesive, the regularity of its deposit, the parallelism and stiffness of all the components are of paramount importance to derive an usable cell !... 
  
 Of course, we state from here that we have already defined the "good stators and spacers", i. e. with the correct number, distribution and alignment of holes, a good thickness of all components without Helmholtz's resonators, and obviously with an homogenous electric field for the whole surface of the film... 
  
 Well, as usual, the more we penetrate in a given technical domain, the more we discover new issues ! 
	

	
	
		
		

		
			




  
 OndesX


----------



## wakibaki

Hi guys.
  
 Sorry I haven't made a contribution for a while. Getting stators and spacers manufactured in bulk has just proved beyond my energy.
  
 Regarding the stretching problem, there are a couple of things that might be done.
  
 A stretching jig might be devised with some kind of repeatability and mechanical graduation.
  
 A way of estimating the tension might be devised.
  
 In reverse order, you could apply a load to the diaphragm, and observe the displacement in the bowing of a reflection of a straight edge or slot source (lamp). You could apply the loading electrically or maybe just with a weight.
  
 As far as a stretching jig is concerned, I was thinking of an arrangement like an embroidery ring to hold the membrane, hand tensioned to remove slack. This would then be inverted (membrane on the bottom) and forced over a considerably smaller inner ring to a graduated depth. I've actually tried this with embroidery rings, but the grip on the membrane was inadequate. PTFE (Teflon) might be good for the surface that bears on the sheet and stretches it. Graphite might be a benign lubricant.


----------



## chinsettawong

billg said:


> I'm sorry to continue poking at this but it appears that we are not responding to the question that is being asked here.    I too agree that one should be able to get good repetitions using weights.  The problem is that no one seems to be able to recognize what "right" is once you get it.  IMHO those of us who are pushing on theoretical points and definitions etc, are just trying to recognize "right" once we get it.  If we can do that it should be possible to reduce the number of random iterations and zero in on "right" in a reliable manner.
> BillG


 
  
 Hi BillG,
  
 As for me, I trust my ears more than anything.  By "just right", I mean it sounds good to my ears.  I really don't know how to quantify the feeling.
  
 Anyway, you can look at the FR of the 2 pairs of headphones that I sent to Tyll for measurement.  If that helps, that's what I meant by just "right".
  
 Wachara C.


----------



## soren_brix

Been lurking at this thread from the beginning almost. 
  
 Want to thank Chinsetta and Tachikoma, and others contributing to this thread.
  
 Have a pair of 404's that in one side didn't sing much.
 The driver has been re-coated. And now sings again 
 As Tachikoma has recommended quite a few times I wasn't shy applying the  coating. Used a micro fiber cloth to rub/polish the mylar as I didn't have a proper sponge.
  
 No squeling, buzzing and I could play rather loud until the 212 sort of gave in.
 I use some tape with mild adhesive to cleanup the stators before assembling. Seems to work fine.
  
 I will glue the driver today and the it takes about 24 hours to harden up.
 So I guess I'll have the final result in a few days.
  
 The most tricky part of this seems to be cracking the driver open without messing up. I use a rather big Stanley knif with fresh blade, and a lot of patients ... but it does take a while to crack it open as for my experience.
  
 Thanks again for all the contribution


----------



## ondesx

For those who are still interested in measurements and quantification, here is a simulation made with the simulator developed by Arend-Jan on his web site :
  
 http://quadesl.nl/sim/
  

  
 Don't worry about the yellow line : it is not meaningful.
  
 You can see that for 500V of polarization and 750 V peak to peak of the modulation, the levels reached for the whole audio band are quite impressive, around 108 dB !...
  
 OndesX


----------



## AManAnd88Keys

soren_brix said:


> *I use a rather big Stanley knif with fresh blade, and a lot of patients ... *


 
 Hannibal, is that you?


----------



## soren_brix

amanand88keys said:


> Hannibal, is that you?


 
 ...that would include a nice bottle of Chianti, Clarice!


----------



## soren_brix

ondesx said:


> For those who are still interested in measurements and quantification, here is a simulation made with the simulator developed by Arend-Jan on his web site :
> 
> http://quadesl.nl/sim/
> 
> ...


 
  


			
				http://quadesl.nl/sim/ said:
			
		

> Like any simulator you can make it do thinks that can not be done in real life.


 ... I guess this simulation doesn't really apply for nearfield, actually you need to be far field for the Walker-equation to be valid AFAIK.
  
 Anyways, I really appreciate your postings/efforts in trying to make the stretching process repeatable. Thanks for the effort/contribution.


----------



## ondesx

> Originally Posted by *soren_brix* /img/forum/go_quote.gif
> 
> I guess this simulation doesn't really apply for nearfield, actually you need to be far field for the Walker-equation to be valid AFAIK.
> 
> Anyways, I really appreciate your postings/efforts in trying to make the stretching process repeatable. Thanks for the effort/contribution.


 
  
 You're probably right, but anyway I guess it'll give an idea of how it'll work and delivers some numbers !
  
 Thank you for your kind words.
  
 OndesX


----------



## arnaud

I had posted numerical simulations in this thread I believe, trying to explain what dude500 observed with various pads depth / size.

Conclusion for me was that you have to think of it as a system. For instance, the free air resonance of driver has nothing to do with the coupled resonance once it is acoustically loaded by the eadpad cavity.

As such, ear pad depth, the amount of leakage through the pads and/or pad-baffle gap all matter. That's why I referred to stax phones earlier in case your design ressembles their dimensions: for omega series, a free air resonance in 120-150hz range translates into a coupled resonance in 40-60hz region which sounds about right target.


----------



## Ali-Pacha

That's why I missed some bass (under 60-80 hz) on my right ear when I used to have middle ear ventilation 
	

	
	
		
		

		
		
	


	



  
 Ali


----------



## soren_brix

soren_brix said:


> Been lurking at this thread from the beginning almost.
> 
> Want to thank Chinsetta and Tachikoma, and others contributing to this thread.
> 
> ...


 
 The glueing went a bit wrong.
 The stators ended up being a tiny bit misaligned - not much, but enough for the eye to witness the displacement when holding up the driver and looking through the driver. When the stators are correctly aligned it is rather hard to tell if there are one or two stators, even if looking at an angle.
 The displacement resultet in an imbalance.
 Dismantled the driver again. Cleaned all glue off the drivers and asssembeled the driver, now being hold together by some strong tape.
 The two drivers apparantly have about the same volume again.

 Still no squeling/buzzing or other strange noises 
 I guess I need a simple jig to keep the stators in place while glueing.


----------



## chinsettawong

Hmm.  A little misalignment shouldn't affect the sound level, IMO.  
  
 Perhaps you should use a clamp or two to hold to whole thing together tightly when you glue it.


----------



## ondesx

Or two wood squares with a serious weight on the upper one, the whole thing on a plane surface, this will do the job perfectly !...


----------



## soren_brix

chinsettawong said:


> Hmm.  A little misalignment shouldn't affect the sound level, IMO.
> 
> Perhaps you should use a clamp or two to hold to whole thing together tightly when you glue it.


 
  


ondesx said:


> Or two wood squares with a serious weight on the upper one, the whole thing on a plane surface, this will do the job perfectly !...


 
  
 Actually did clamp it between two pieces of MDF covered with melamin ... but for some reason it ended up a bit misaligned.
 Having the stators eyeball aligned the driver is as loud as the other one again ;o)
 But thnx anyways ;o)


----------



## davidsh

A little update. We did finish our esl panel (physics project). Tried making our own transformer etc. It did play, though not very loud. Just tried connecting the panel to my srm-T1. It does play music very quietly. I'm at 12-2 o'clock and even then it is not loud at all. The sound is distorted as well, especially playing bass I think. It seems it is because parts or even most of the diaphragm has collapsed on one stator. Either the food film is bad or the tension wasn't high enough. Or both. That is my hypothesis at least.


----------



## dude_500

davidsh said:


> A little update. We did finish our esl panel (physics project). Tried making our own transformer etc. It did play, though not very loud. Just tried connecting the panel to my srm-T1. It does play music very quietly. I'm at 12-2 o'clock and even then it is not loud at all. The sound is distorted as well, especially playing bass I think. It seems it is because parts or even most of the diaphragm has collapsed on one stator. Either the food film is bad or the tension wasn't high enough. Or both. That is my hypothesis at least.


 
  
 Food film generally doesn't work well, it's too stretchy and permanently deforms before it has sufficient tension for use in an electrostatic driver. So yes, I would say you didn't have enough tension and probably couldn't get enough tension with the material you used.


----------



## davidsh

Why can the diaphragm collapse semi-permanently onto one of the stators, which forces enables it to do so?


----------



## dude_500

davidsh said:


> Why can the diaphragm collapse semi-permanently onto one of the stators, which forces enables it to do so?


 
  
 A diaphragm with no tension is inherently unstable. Precisely inbetween the two stators, equal force pulls it in both directions since the distance to the two stators is the same making it quasi-stable in that position. Due to manufacturing tolerances, it will not be precisely in the middle, and even if it were even the slightest deflection would move it closer to one stator. When it is closer to one, it is attracted to it. Even if the stator is neutrally charged, electrostatic induction will cause the electric field between the neutral stator and negatively charged diaphragm to induce a positive charge in the surface of the stator thus creating an attraction to the diaphragm. 
  
 Tension provides an opposite force to the instability so that when the diaphragm is slightly deflected in one direction, the forces of the tension are greater than the electrostatic attraction to the stator and the diaphragm is pulled back to an equilibrium point. So with enough tension, the quasi-stable system turns into a system with a wide region of true stability.


----------



## chinsettawong

davidsh said:


> A little update. We did finish our esl panel (physics project). Tried making our own transformer etc. It did play, though not very loud. Just tried connecting the panel to my srm-T1. It does play music very quietly. I'm at 12-2 o'clock and even then it is not loud at all. The sound is distorted as well, especially playing bass I think. It seems it is because parts or even most of the diaphragm has collapsed on one stator. Either the food film is bad or the tension wasn't high enough. Or both. That is my hypothesis at least.


 
  
 What is the size of your ESL?  What spacer thickness do you use?  What is the bias voltage?  How much is the step up ratio on your transformer?


----------



## davidsh

chinsettawong said:


> davidsh said:
> 
> 
> > A little update. We did finish our esl panel (physics project). Tried making our own transformer etc. It did play, though not very loud. Just tried connecting the panel to my srm-T1. It does play music very quietly. I'm at 12-2 o'clock and even then it is not loud at all. The sound is distorted as well, especially playing bass I think. It seems it is because parts or even most of the diaphragm has collapsed on one stator. Either the food film is bad or the tension wasn't high enough. Or both. That is my hypothesis at least.
> ...


 
 You can have the details, but consider the project a partial failure.
  
 Size: 23x60 cm (approx.)
 Spacer thickness: 1mm (approx.)
 The material used is double adhessive foam tape. The configurations is 2 cm tape around the edges, a strip of 1cm tape in the middle.
 The diaphragm is coated with rinse aid, which seems to work.
 The diaphragm is made of food film ~11um
 Bias voltage: Between 500-1000 volts
 Step-up: 2x1600/1x200 in 3 phase iron core configuration, with small and very poor inductors used for general use in the physics class.
  
 Also tried my SRM-T1 for driving the panel (580 volt pro bias).
  


dude_500 said:


> davidsh said:
> 
> 
> > Why can the diaphragm collapse semi-permanently onto one of the stators, which forces enables it to do so?
> ...


 
 I've got to look into electrostatic induction, somehow I thought the diaphragm wouldn't be subjected to any force when there'd be no potential between the stators as that'd mean no electric field between the stators eg. no forces acting on the charge of the diaphragm.
 This seems to be wrong.
 I find it difficult to understand this concept. Is it much to ask that you break it down (when there's voltage potential between the stators and when there is no potential) or refer me to some litterature?


----------



## analogsurviver

davidsh said:


> You can have the details, but consider the project a partial failure.
> 
> Size: 23x60 cm (approx.)
> Spacer thickness: 1mm (approx.)
> ...


 
 OK - the truth and nothing but the truth.
  
 ES drivers are in principle perhaps the simplest to make - of all the generating priciples.
  
 They are equally the most difficult to make them work right. Because they have to be geometrically exact and have to keep that geopmetrical perfection to work - no matter what.
  
 I will tell you the true anecdote regarding the ES headphones by Neil Pollock, published in Wireless World in late 70s ( I shared the link ). Three students , me included, saw the article the same day. One had his drivers made from phenolic prototype printed circuit board and driven by some transformers in two days - and it fared no better than yours, despite being much smaller in size. The second did a bit better, in about two weeks - also transformers - but to stay on the polite side, let's say he demonstrated ES could potentially work...
  
 I had to get a pro forma invoice, order the Aquadag, wait till it arrived, cleared the customs - before I could do "anything", it was almost two months. Remember, that was in 1980-81, snail mail, Yugoslavia. I did prepare in between the acrylic stators, spacers, etc - but could only proceed after getting Aquadag.
  
 First, I used transformer. It worked - but was not an improvement over Audio Technica ATH-7 electret headphones I owned at the time as I have hoped for.
  
 Enter amplifier. It took me almost 6 or so years, building various amps, before I found something that finally did satisfy me. And better drivers, etc, etc.
  
 If you can, I suggest going to see Quad latest ESL speakers - they differ from their immediate predecessors primarily in how the stators are strenghtened against curving, resonances, etc - and thus achieve even better loudness and better bass, while at the same time having less distortion.
  
 In short, the very first thing an ES driver must NOT be is - a propeller. It should be one precise plane, not twisted and curved. And making this reality is hard - VERY hard. Sennheiser went to untold extremes in their Orpheus - Quartz Glass electrodes (gold plated for conductivity ) that are about the most plan/flat thing on earth, encased in some hard wood from Africa usually used for - propellers in aircraft. Because it resists the deformation better than almost anything else, regardless being hard to machine well. No wonder it was lots of $$$$$.
  
 Regarding literature - http://www.amazon.com/Electrostatic-Loudspeaker-Design-Cookbook-Sanders/dp/1882580001  There was a series of articles on ES drivers in The Audio Amateur, later (reprinted) in The Speaker Builder ( google is your friend - perhaps they are still available as download )  - both by Sanders ( practical guy) and Ronald Wagner (scientific guy) http://www.hificollective.co.uk/books/bk5004.html - and it was more than a mild acrimony between the two. Yet both are very helpful at understanding why and how ES works and what can be made to make practical designs that can be duplicated by a dedicated DIYer.
  
 You can wrap it any way you like - the EXACT method of _*HOW *_ it is made in top commercial designs that were and are successful in the market will most likely be _never _ revealed - it can be one's lifetime work to figure out how to make that driver that was just a bit "off" finally "perfect" - would you spend your entire work life just to be able to give everything away in a forum - for free ? 
  
 This is the primary reason why ES is not more widespread.
  
 And we have not even touched the amps driving these drivers...


----------



## davidsh

Thanks, fine reading, what you say makes sense.
I do not have the time to respond properly but I have read the cookbook by sanders. It was a fine starting point. Don't know the other book, will look into it.

I've now read the wiki page on electrostatic induction. Makes much more sense why the diaphragm can collapse onto a stator.


----------



## chinsettawong

For ESL, we normally keep the spacer thickness to diaphragm width ratio to not more than 1:100. That means if you're using 1 mm spacer, you would want to keep the width of the diaphragm to not more than 100 mm or 10 cm. Your width of 23 cm is way too much and it's rather difficult to make the diaphragm stable. You can try to inject some silicone between stator and diaphragm every 10 cm horizontally. This helps as a spacer on every 10 cm.

For bias voltage, you might want to try at least 1,200V. You also want a high step up ratio transformer to amplify your music signal. You can try using a 110-0-110V primary and 3V secondary transformer. If the transfomer is good enough, it'll make good sound.


----------



## dude_500

davidsh said:


> I've got to look into electrostatic induction, somehow I thought the diaphragm wouldn't be subjected to any force when there'd be no potential between the stators as that'd mean no electric field between the stators eg. no forces acting on the charge of the diaphragm.
> This seems to be wrong.
> I find it difficult to understand this concept. Is it much to ask that you break it down (when there's voltage potential between the stators and when there is no potential) or refer me to some litterature?


 
  
 When the two stators are at the same potential, then there would be no field anywhere in the system if the diaphragm were removed. However, remember that the diaphragm is charged to a high positive potential (accidentally said negative in my previous post). If you have stators at 0V sandwiching a 580V diaphragm then there is electric field between the diaphragm and each stator.
  
 Electrostatic induction allows for a force to exist between a positively charged object and a neutrally charged object by moving charges around inside the net neutrally charged object while keeping its total potential at zero. The stable point is directly in the center between the two stators with no applied potential on the stators, because the electric field on each side of the diaphragm is identical and opposite in sign. 
  
 Now put a potential across the stators, let's say +-20V. Now one side of the diaphragm has a potential drop of 560V, and the other side has a drop of 600V. If the diaphragm is initially in the center between the stators, a force will exist pulling it towards the 600V side. To keep the post free of math, I will leave out the analysis of where the diaphragm finds a new quasi-stable point, but suffice it to say it is not dead center between the stators anymore, thus putting music between the stators makes the diaphragm mechanically reproduce the audio.

 In both cases, zero potential or high potential between the two stators, the same electrostatic induction instability will exist and must be cancelled out by having sufficient tension.


----------



## davidsh

chinsettawong said:


> For ESL, we normally keep the spacer thickness to diaphragm width ratio to not more than 1:100. That means if you're using 1 mm spacer, you would want to keep the width of the diaphragm to not more than 100 mm or 10 cm. Your width of 23 cm is way too much and it's rather difficult to make the diaphragm stable. You can try to inject some silicone between stator and diaphragm every 10 cm horizontally. This helps as a spacer on every 10 cm.
> 
> For bias voltage, you might want to try at least 1,200V. You also want a high step up ratio transformer to amplify your music signal. You can try using a 110-0-110V primary and 3V secondary transformer. If the transfomer is good enough, it'll make good sound.



That's why I put a strip of tape in the centre (to support the diaphragm)
In the right light you can see how the diaphragm doesn't hold tension and is deformed. Barely visible on the images below.


----------



## chinsettawong

Yes, I can see that you don't have enough tension. You can try using a hair dryer to heat shrink the film more. It might help. 

Do you use tape to permanently bond the two stators together?


----------



## chinsettawong

Still you can inject some silicone to further help the stability.


----------



## davidsh

Thanks for the tip


----------



## retaeht

Hi all

I'm planning to build electrostatic headphones.The thing is I would like to make a 2 stage project.First will be the headphones and then later an amplifier.So is there an easy and cheap solution for the amplifier with decent sound.I'm thinking of some sort of cheap output transformers to use with the amps I have for regular speakers,or maybe some cheap amp kit from Ebay etc. to get Me started ?


----------



## analogsurviver

retaeht said:


> Hi all
> 
> I'm planning to build electrostatic headphones.The thing is I would like to make a 2 stage project.First will be the headphones and then later an amplifier.So is there an easy and cheap solution for the amplifier with decent sound.I'm thinking of some sort of cheap output transformers to use with the amps I have for regular speakers,or maybe some cheap amp kit from Ebay etc. to get Me started ?


 
 Don't mean any disrespect, but this is the same as asking: I would like to build a Formula 1 car. First it will be the chassis and then later the motor. So is there....cheap  off Ebay to get me started ?
  
 Eeerrr - no. I DID - surprisingly - find an esl amp kit - by none other than Helmut Becker (Audio Valve ). It ain't cheap, though...
  
 http://www.ebay.com/itm/Audio-Valve-Board-PCB-Electrostatic-Headphone-Kopfhorer-Verstarker-Amplifier-DIY-/261876469298?pt=LH_DefaultDomain_77&hash=item3cf90dce32
  
 You still need a transformer, box, connectors - and KNOWLEDGE to work with high voltages. These things can be lethal if handled improperly.


----------



## retaeht

Thank you for an honest answer.I have some experience with diy amplifiers,tube circuits etc. What I'm after is maybe a "cheap" amp kit (Ebay 15 Euro/Dollar class D amps for example) or a pair of reversed mains transformers, that could handle the load to test the headphones and listen to them for a while,until I have time to make decent more expencive amplifier.If none exist I will have to hold on for a while,save some money and make the amplifier first.


----------



## analogsurviver

retaeht said:


> Thank you for an honest answer.I have some experience with diy amplifiers,tube circuits etc. What I'm after is maybe a "cheap" amp kit (Ebay 15 Euro/Dollar class D amps for example) or a pair of reversed mains transformers, that could handle the load to test the headphones and listen to them for a while,until I have time to make decent more expencive amplifier.If none exist I will have to hold on for a while,save some money and make the amplifier first.


 
 Sorry, no 15$ Class D amps capable of driving ESLs...


----------



## Ali-Pacha

SRD-6/7 from Stax ( normal bias ones are cheap and common) + bias modification ( something like that : http://www.headfonia.com/stax-srm-1mk2-bias-modification/ ) + class d embedded in ?

 Ali


----------



## chinsettawong

I really miss the JF clone that I sent to Kevin, and so I make myself another pair.  I had a hard time tensioning the diaphragm to the right tension.  So I added the thickness to the spacers for another 0.15 mm.  Playing the headphones with my KGST, I really like them.


----------



## Kerry

Nice


----------



## kevin gilmore

they are really nice with the carbon


----------



## chinsettawong

kevin gilmore said:


> they are really nice with the carbon




That's really nice to know. Looking forward to building the amp.


----------



## inuponken

This is my first post here.
  
 I just finished making my 1st DIY ES Headphones.
 Whachara, thank you for sharing your designs!
  
 For the head arm, I gave up bending stainless rod and I am using a coat hunger instead. It is not hard enough to holding cups but...  
  
 Sound is very clear and better soundstage than my SR407.
	

	
	
		
		

		
			




 My next project is JF type..
  
 I will upload images when I got a permission from the site.


----------



## davidsh

Nice, will look forward to that!


----------



## chinsettawong

inuponken said:


> This is my first post here.
> 
> I just finished making my 1st DIY ES Headphones.
> Whachara, thank you for sharing your designs!
> ...


 
  
 Really like to see your photos.


----------



## inuponken

To get a permission for upload images, I need put more posts on the thread
 Sorry for my poor English but let me describe how I made.
  
 I used Reztore Topical Antistatic for the diaphragm coating.
 It is very stable so far. I will keep using it for my future ES projects.
  
 For the 2 um Mylar tensioning, I used water bottle method.
 Started with 360g (included clip = 60g) x 16pcs then stopped at 180g (120+60) x 16pcs that reached satisfied bass sound for me.  
  
 I would like to say thank to everyone on this thread.


----------



## Q Mass

COOL!
I too look forward to your pic's 

How are you powering your 'phones?


----------



## chinsettawong

You can store your pictures somewhere else and post a link here.


----------



## chinsettawong

By the way, what are your spacer thickness and bias voltage, inuponken?


----------



## NoPants

q mass said:


> COOL!
> I too look forward to your pic's
> 
> How are you powering your 'phones?




pretty sure his amps aren't a limiting factor to say the least


----------



## Q Mass

Yeah?
What makes you say that?


----------



## inuponken

I uploaded photos to my album. 
  
 https://picasaweb.google.com/inuponken/ESHP#6178076799726320866


----------



## inuponken

chinsettawong said:


> By the way, what are your spacer thickness and bias voltage, inuponken?


 
  
 Spacer thickness is 0.5mm and bias voltage is 580V.
  
 0.8mm for JF.


----------



## inuponken

nopants said:


> pretty sure his amps aren't a limiting factor to say the least


 
  
 You noticed  HN "inu" (Head Case) = "inuponken" (Head-Fi)


----------



## inuponken

q mass said:


> COOL!
> I too look forward to your pic's
> 
> 
> ...


 
  
 Thanks.
  
 I am using DIY T2 and KGSS.


----------



## inuponken

chinsettawong said:


> You can store your pictures somewhere else and post a link here.


 
  
 I have been uploaded photos to my web album but I couldn't put a link on the thread without permission.
	

	
	
		
		

		
		
	


	




  
 I think I need put more posts.​


----------



## chinsettawong

I see your pictures. Thanks for sharing. The headphones look really nice. I'm sure they sound very nice too.

Congratulations!

Wachara C.


----------



## catfishstevens

Nice headphones, thanks for the pictures!  I'm working on a pair of my own too, also inspired my Wachara; they should be finished soon I hope.  Had to order a real CNC, my mostly 3D printed DIY one wasn't cutting it (no pun intended).


----------



## davidsh

What are the pads?


----------



## NoPants

Please make me a pair I pay you long time


----------



## Q Mass

Nice work Inup!

Which part or parts did you feel the need for CNC machining?
Just the cups?, or did you also use it for spacers etc?


@Davidsh, they look a bit like Audeze leather pads to me....?


----------



## Kerry

Hi Inu,

They look fantastic. I'm going to build mine shortly. I may have some questions for you when I do.


----------



## AManAnd88Keys

q mass said:


> Nice work Inup!
> 
> Which part or parts did you feel the need for CNC machining?
> Just the cups?, or did you also use it for spacers etc?
> ...


 

 Question wasn't directed at me, but as a previous Audez'e LCD-2 owner I'd say that those are very likely genuine Audez'e pads.
  
 Edit: my memory isn't very reliable, but they at least look similar to Audez'e pads.


----------



## inuponken

Thank you to all.
  
 No, these are EP-007. Replacement ear pad (lambskin) for the SR-007.
 8K yen in JPN but $120-160 in US 
	

	
	
		
		

		
		
	


	




 so I asked my friend in JPN to HC them when she visiting to US.
  
 I used CNC for all parts. I build Shapeoko2 kit for this project. 
 I didn’t know anything about CNC and CAD so I started from scratch. 
  
 It is fun to use but noisy…and I pushed emergency stop button for many times.


----------



## derbigpr

inuponken said:


> I have been uploaded photos to my web album but I couldn't put a link on the thread without permission.
> 
> 
> 
> ...


 
  
 Very nicely done headphones, but the question is, how do they sound? 
  
 Did you compare them to any well known headphones? How do they stack up? What is the sound signature like?


----------



## chinsettawong

DIY electrostatic headphones can sound very nice. I often compare mine with Stax  SR007 MKII, and  SR009.


----------



## derbigpr

chinsettawong said:


> DIY electrostatic headphones can sound very nice. I often compare mine with Stax  SR007 MKII, and  SR009.


 
  
  
 I know your measure very well so they must  sound great. How do you determine the tension of the mylar? Was it just trial and error until  you got it right or are there some calculations?


----------



## chinsettawong

derbigpr said:


> I know your measure very well so they must  sound great. How do you determine the tension of the mylar? Was it just trial and error until  you got it right or are there some calculations?


 
  
  
 Yes, I did my trials and errors until I got it right.  I don't know a formula to calculate it.


----------



## ondesx

Hi Inuponken,
  
 Good job indeed !
  
 I saw that you used Reztore : I still have somewhere one bottle for test purposes, but It seems that this product lasts unfortunately not enough in time ... Licron seems to be a much better candidate ! 
  
 What is your opinion ?
  
 OndesX


----------



## inuponken

derbigpr said:


> Very nicely done headphones, but the question is, how do they sound?
> 
> Did you compare them to any well known headphones? How do they stack up? What is the sound signature like?


 
  
 Thanks,
 I only have three SR-X-MK3 and SR-407.  Bass is slightly lower than SR407 but sound is very clear and wide. It is my main rig now.


----------



## inuponken

ondesx said:


> Hi Inuponken,
> 
> Good job indeed !
> 
> ...


 
  
  
 Thank you.
  
 No problem so far but only 3 weeks since I build....  I will use Licron for next if Reztone is not lasts longer.


----------



## ondesx

Please Inuponken can you tell us :
  
 - the thickness and quality of the film you used for the membranes
  
 - the total weight you apply to your jig for the tension of this film
  
 I read the other interesting parameters in one of your posts (spacers and polarization).
  
 Thanks for these precisions.
  
 OndesX


----------



## inuponken

Diaphragm = 2u Mylar film (e-bay)
 Dust filter (front only) = 0.9u Super ultrafilm (http://www.indoorspecialties.com/)
 Frames (cups): 3/4” Red oak board + wood stain + Gross Polyurethane paint (Home depot)
 Stators: t=0.94mm FR4 PCB (e-bay PCB depot) + “KRYLON Digital Photo & Paper Protectant” splay for the coating (office).
 Dust filters: t=0.94mm FR4 PCB (e-bay PCB depot)
 Spacer & Diaphragm: t=0.5mm FR4 PCB (e-bay PCB depot)
 Contact Cement: DAP Weldwood original contact cement (ACE hardware)
 Plastic Rings for the ear pad: Cut out from Compact Disc
 Locking Rings for ear pad: from HE-5 Ear pads (e-bay)
 Top plates: 3/16” black acrylic sheet (e-bay)
 Nylon screws, small wood screws, shrink tubes…
 Punching metal plates: Kenwood Excelon Speaker Grills (e-bay)
 Cable: KOSS ESP950 extension cable (Koss service center)
 Stax connector: from Kevin
 Headband : form my SR-40 (Garage sale) + coat hanger
  
 Tension = 180g (water bottle 120g + Clamp 60g) x 16pcs = Total 2,880g
 2 gallons bucket for tensioning (ACE hardware)
 2in.Spring Clamps for tensioning x 16pcs (Harbor Freight/Home depot)
 Ozakra 16.9-floz empty bottles x 16pcs (from recycle bin in my garage)
 Vinyl coated wire rope = water bottle <> Clamp (from my wife)
 And dxf files from Wachara.


----------



## kevin gilmore

I'm finally getting around to making my own
  
 http://gilmore.chem.northwestern.edu/electrostat1.jpg
  
 hope to make at least a few stators out of the same glass used in the he90


----------



## chinsettawong

Those look really nice. Looking forward to seeing the finished product soon.


----------



## davidsh

How will you coat the quartz glass?


----------



## kevin gilmore

vacuum deposition.


----------



## chinsettawong

I printed out the back covers using my 3D printer.  I think they turn out pretty good.


----------



## Q Mass

I do too!  they look like they mean business!

This is probably like asking someone which of their children is their favourite, but which of your 'phones to you like best?

And which model should I attempt to emulate if I am a bass lover (not a full on bass head) who has a SRD-7 SB?


----------



## chinsettawong

If you like bass, then you want to make the headphones with good seals. My Omega and Orpheus clones both give wonderful bass. The JF clone isn't bass shy though. It's more natural sounding. It's more like you're listening to loudspeakers than headphones. As of now, it's my favorite. 


Sent from my SM-N9005 using Tapatalk


----------



## Q Mass

Thanks man  

One more question if I may?:
I have some of the 0.9u super ultrafilm that inuponkin mentions he's using as a dust cover a few post back .
I had bought it to use as diaphragm film, but maybe it isn't suitable?
Is there any reason that it wouldn't work?

Thanks for any and all guidance!


----------



## chinsettawong

Yes, I really like the sound from that super ultrafilm when it works. The problem is that the film is really sensitive to temperature change. If you use it as the diaphragm, you want to use thick spacers. Otherwise, your diaphragm will be very unstable. Even the heat from your body could change its tension.

Wachara C.


----------



## davidsh

That is pretty extreme. Does that mean the sound will be altered too, especially the bass?


----------



## analogsurviver

chinsettawong said:


> Yes, I really like the sound from that super ultrafilm when it works. The problem is that the film is really sensitive to temperature change. If you use it as the diaphram, you want to use thick spacers. Otherwise, your diaphragm will be very unstable. Even the heat from uour body could change the its tension.
> 
> Wachara C.


 
 That's normal. And is the reason why commercially available options use somewhat thicker films - stability/reliability.


----------



## chinsettawong

analogsurviver said:


> That's normal. And is the reason why commercially available options use somewhat thicker films - stability/reliability.


 
 Mylar isn't like that.


----------



## Q Mass

chinsettawong said:


> Mylar isn't like that.


 

 How so?
  
 (and thanks for all the experience/tips you and other contributers offer here BTW)


----------



## chinsettawong

q mass said:


> How so?
> 
> (and thanks for all the experience/tips you and other contributers offer here BTW)


 

 The Super Ultra film is not Mylar.


----------



## jgazal

chinsettawong said:


> No, in fact I mean just the opposite. The aluminum laminated Mylar has too low resistance.
> 
> Mylar with high resistance coating is much better.
> 
> Wachara C.




Sennheiser claims platinum vaporized diaphragms.
Eight pins connector.
Why? Some kind of negative feedback loop from the transducer to the amplifier?


----------



## chinsettawong

jgazal said:


> Sennheiser claims platinum vaporized diaphragms.
> Eight pins connector.
> Why? Some kind of negative feedback loop from the transducer to the amplifier?


 
  
 I'm not sure about their diaphragm material, but I'm sure that you're wrong about the eight pins connector.  The HE90 connector on my DIY T2 is certainly only 5 pins.


----------



## jgazal

chinsettawong said:


> I'm sure that you're wrong about the eight pins connector.  The HE90 connector on my DIY T2 is certainly only 5 pins.




Forgive me. I should have been explicit. I mean the new transducer.


----------



## chinsettawong

Unless they are doing anything extraordinary, I really can't think of a reason to a have 8 pins connector. 

By the way, has anybody really got a chance to listen to the new headphones yet?


----------



## Dave1951

Hi everyone,
  
 I have been following this forum for a few weeks now and wonder if one of you experts can assist me with some advice.
 I have been using Sennheiser HE60 electrostatic elements in a medical research project.
 However as you all will know these elements are now unavailable and so this led me to discover this forum when trying to find out a little more about these devices
 .
 My opening questions are.
  
 1). What are the HE60 stators coated in to make them conductive?
 As the whole assembly seems to be made of plastic (including the screws) I assumed they were some form of conductive plastic as my Xray of the element only shows up the connecting tags (sorry can't attach the Xray picture as I am too new!)
  
 2). Just how conductive do the stators need to be?
 I notice that constructors on this forum seem to make them out of copper clad fibreglass pcb.
 Do they need to be such a low resistance?
 My project cannot tolerate copper coated pcb as the stator, I have to replicate whatever Sennheiser did. (or some similar 'radiolucent' material)
  
 3). The usual fault with the HE60's is loss of output why is this?
 Reading between the lines it sounds as though it is loss of polarizing voltage on the diaphragm as I don't see any mechanism for the stator going faulty.
  
 4). Are there any constructors out there that can supply CNC machined 'blanks' for the replication of these (or other) elements.
  
 Thanks in anticipation
 Dave


----------



## chinsettawong

Hi Dave,

I have a pair of HE60 as well. When I got it a few years back, it's not sounding very loud. All I did was to recoat the diaphrams with new antistatic cleanser, and the problem was fixed. 

This is a rather typical problem with electrostatic headphones. Overtime the coating on the diaphragm losses its conductivity. Recoating normally fixes it.

Wachara C.


----------



## Francisk

chinsettawong said:


> Hi Dave,
> 
> I have a pair of HE60 as well. When I got it a few years back, it's not sounding very loud. All I did was to recoat the diaphrams with new antistatic cleanser, and the problem was fixed.
> 
> ...


 
 Does this happen to the Audeze LCD-X too?


----------



## chinsettawong

francisk said:


> Does this happen to the Audeze LCD-X too?




No, LCD-X is not electrostatic.


----------



## AManAnd88Keys

francisk said:


> Does this happen to the Audeze LCD-X too?


 

 All Audez'e headphones are based on magnetostatic / orthodynamic drivers. It's a different kind of technology.


----------



## Francisk

Thanks for the confirmation Chinsettawong & AManAnd88Keys. I feel better already and coincidentally this is my 1000th post


----------



## chinsettawong

dave1951 said:


> Hi everyone,
> 
> I have been following this forum for a few weeks now and wonder if one of you experts can assist me with some advice.
> I have been using Sennheiser HE60 electrostatic elements in a medical research project.
> ...


 
  
 1.  The stators of HE60 are made from perforated metal.  I don't think they can ever go bad.  I have a few pictures to show you.  They were taken when I tried to recoat its diaphragms a few years ago.  
  

  

  

  
  
 2.  I use copper clad PCB because it's very flat, cheap, and easy to work with.  You can, of course, use other conductive materials.  But, again I don't think you need to replace those stators on your HE60.
  
 3.  The coating on the diaphragms has too high resistivity.  Recoat your diaphragms fixes the problem.
  
 4.  Very unlikely.  
  
 Wachara C.


----------



## Dave1951

Hi,
 Thanks for your quick reply that was most informative.
  
 However....are you sure that the HE60 stators are made of perforated metal as on the X-Ray image I have of a HE60 element only the solder tags show up as black (ie opaque to X-rays)
 You would see if I was allowed to post the picture!
 The rest of the element shows as a very hazy outline as if the rest of the material is just (see through) plastic or some radio-translucent material.
 If the stators were perforated metal then they would definitely appear solid black with just the perforations showing as transparent!
  
 So it would seem that the Sennheiser HE60's I have,  did not have solid perforated metal stators. Whereas the STAX elements I have in front of me do have solid metal stators but I haven't had these X-rayed yet.
  
 As you say I don't need to replace the Sennheiser stators but was just wondering what they were made of that seemed transparent to X-rays. Looking at the pictures you posted it almost looks like they are gold 'sputtered'. A really thin coating such that they don't interfere with the X-rays?
  
 1).
 Does anyone know just how conductive the stators need to be?
 I know the diaphragm can be Megohms/sqcm but can the stators be made say of plain fibreglass coated with DAG ( carbon colloid) or even carbon fibre.
 So.... a few thousand ohms rather than solid metal (zero Ohms)?
 For this medical application there can be NO (or only tiny amounts) of metal in the electrostatic element.
  
 2).
 So you are saying that the coating on the diaphragm wears out?
 I sent quite a few elements back to Sennheiser in the past but of course this option seems no longer available 
 I have seen that constructors use something like Staticide to coat their diaphragms would this revive the failed HE60's I am using at the moment?
 Do you coat both sides?
  
 3). My main problem is that I need extra elements something like the Sennheiser HE60's which is why I asked if anyone supplied blanks. I don't have CNC capability here but maybe our Medical Physics Department do....
 Are there CAD files available for constructors to cook their own stators/spacers I wonder?
  
  
 This is a great forum BTW I have learned a great deal. I have some novel ideas about repeatably setting and checking diaphragm tension which when I manage to make some successfully I will share with you all.
  
 Thanks in anticipation................
 Dave


----------



## chinsettawong

Hi Dave,
  
 You can post your pictures else where and post a link here.  That's how I do it.
  
 I'm quite sure the stators are metal.  If you absolutely want to confirm it, I can open mine up again to check.  
  
 Anyway, the easy fix for you would be to recoat your diaphragms.  Staticide is a good coating material.  Please try it.  You only need to coat on one side.  When you open your elements up, you'll see that you can only coat on one side anyway. 
  
 It would be difficult for you to make the exact replica of the HE-60 stators and spacers.  
  
 Aren't there any other headphones that you can use in your lab?
  
  
 Wachara C.


----------



## chinsettawong

I'm looking at my HE60 right now.  There are many metal parts in the headphones.  The grills on the back of the headphones, the springs on the headband, the screws, and the cables are all metals.


----------



## Dave1951

Hi,
 Yes there are many metal parts but I would just buy the HE60/HE70 system then strip the HE60's down and throw everything away except the electrostatic element.
 I then built the elements into a totally non metallic headphone for our application.
 As I say the Sennheiser elements didn't seem to have metal stators as they don't show up as metallic on the Xray
 here:-
 https://dl.dropboxusercontent.com/u/81104063/x-ray.jpg
 As you can see only the solder tags show up as metal. There is just the faintest image of the slotted periphery of the stators if you look closely, so the ones I have can't be solid metal!
 The STAX headphone range are the next least expensive headphones to source elements from, but they have LOADS of metal in them which is useless.
 So I need to 'roll my own' hence my plea for help on this forum.
  
 Question.
 When you make your own diaphragm how do you get a connection to it. I see you make a copper clad pair of rings but surely the glue insulates the diaphragm from the copper?
 Do you coat the diaphragm after assemble and bridge the insulating glue with Staticide?
 Or do you use conductive glue?
  
 Dave


----------



## Dave1951

Aw...I can't even link you to an offsite picture, not enough permissions. ...Sorry
 Dave


----------



## Dave1951

Yes I bought HE70/60's strip everything out and bin it, I only use the electrostatic elements and the amplifier.
 The next least expensive headphones are STAX and they are full of metal in the elements so no use.
 Dave


----------



## Dave1951

Hi,
 You can link to the X-ray now the administrator has kindly allowed the posting containing the dropbox link.
 Dave


----------



## chinsettawong

The X-Ray picture looks interesting.
  
 There are many ways to make a stator.  You can make it from a piece of plastic then paint the surface with a conductive paint, for example.  
  
 You can cut a piece of plastic to make a spacer.  You glue a diaphragm on it and then coat the diaphragm with antistatic gel.  Then you make a small conductive connector on the other spacer to connect the cable and use it as a bridge to connect the cable with the conductive diaphragm when you sandwich them together.  Something like this:


----------



## Dave1951

Ah!......
 So you take the side of the diaphragm that doesn't have the spacer glued to it, and coat it right to the edge painting over the conductive tag too.
 Then glue the second spacer over the coated diaphragm and tag..
 is that correct?
  
 Do you have to solder the wire on to the tag really quickly? i.e does soldering iron heat affect the Staticide connection?
 This is what I was always worried about with the Sennheiser units I was using, though I never damaged one. As I remarked before they just went low output after about 18 months of continuous use.
 At least now I know how to fix one when it dies,
 Thanks.
  
 The stators will have to be non metallic and coated as you say with some 'radio translucent' conductive paint.
 I have no feeling as to how conductive the stator has to be compared to the diaphragm, have you seen any constructors experimenting with this aspect?
 I don't suppose it matters for normal audio enthusiasts, they can use copper clad pcb.... I will have to experiment.
 I wonder if the rule is something like:-  as long as the stator resistance is 10 times lower that the diaphragm it will work ?
  
 Sorry for all the questions but I would rather learn from the 'Elmers' as I have a mountain of other things to do on this project.
 I really appreciate your taking time to tolerate a 'newbie'.
 Dave


----------



## chinsettawong

Hi Dave,

Since you already have headphones that don't work well, opening them up and seeing how they're put together for yourself would answer a lot of your questions already. I don't glue the other spacer to the diaphragm. In my later builds, I use plastic screws to clamp everything together. 

Sent from my SM-N9005 using Tapatalk


----------



## n3rdling

Pretty sure the HE60s use conductive paint on plastic stators.
  
 Don't think you want a high resistance on the stators, they should be very conductive.
  
 Is this for use in a MRI room?


----------



## davidsh

I can calculate the effects of adding a resistor in series with the stator if you like. Mainly loss of sensitivity and high frequency roll off


----------



## Dave1951

Hi
 Yes that's a good idea and having now read most of this forum I feel much more confident in daring to disassemble my electrostatic elements.
 At the moment I don't have any low output elements and the headphones are all in daily use so I don't have any to experiment with either 
 Thanks for the information about your assembly of the diaphragm and making the connection.
 I was interested to hear that you now bolt the elements together just like my Sennheisers....LOL!
  
 I am assuming you use the "Staticide ESD Safety Shield" version of the Staticide products, as they claim this is a 'permanent' coating?
 Their other fluids and wipes appear to only be a temporary ESD 'fix'.
  
 Finally, I notice you show the glue you use as UHU POR.
 Reading the instructions for this glue it says it is a 'contact adhesive' i.e. you coat both surfaces and let them dry for a while before bringing the two parts together.
 Do you use the adhesive in this way?
 I couldn't decipher from your text exactly how you employ it when gluing your diaphragms.
  
 I am surprised that the adhesive holds the diaphram's tension with a spacer glued to only one side.
 I have no experience of this adhesive, but you describe the glue as 'rubber' glue (rather than a hard setting epoxy) which to me would suggest there may be some 'give' in the joint once the external tension is released?
 Presumably you don't see any 'creepage' or relaxation of the tension once the adhesive is cured?
  
 Many thanks for your advice I am overwhelmed by your helpfulness.
 I now need to try to find someone who can convert your pictorial dimensions off this forum into a CAD file and then see if our Med Phys Dept has a CNC router.
 What CNC machine do you have BTW are those cheap ones on Ebay (approx £400) good enough in case I have to go it alone?
  
 Thanks again.......
 Dave


----------



## Dave1951

Hi N3rdling 
  
 Yes these headphones are used in an MR environment hence the requirement for them to contain no metal and my X-raying them in the first place. (Picture attached)
 I suspected that the Sennheiser stators were plastic but having never dared to take one apart didn't know whether they were conductive plastic or coated with a conductive (yet low metallic content) paint.
 I am battling with making new headphones that are much slimmer to fit in a 7T scanner which has a lot smaller bore, hence my appearance on this forum. Because I am almost certainly going to have to 'roll my own' electrostatic elements!
  
 And Davidsh
 Yes I can understand the effect of putting a resistor in series with the stator which using a resistive coating (rather than metal) is in effect.
 I suppose the critical factor is what the effective capacitance of the element presents that will decide how resistive the stator can be to keep the frequency response in the 'sonic' window.
  
 This is a great forum, thanks for your input chaps..keep the comments coming 
 Dave


----------



## davidsh

The typical capacitance of the stator-stator is in the order of 100 pF by the way.


----------



## chinsettawong

Hi Dave,

I used to use Staticide ESD, but I ran out of it. If you've read through the thread, I'm sure you know that I now use a floor cleansing liquid to coat my diaphragm. It's readily available in big supermarkets in my area, and it's cheap. 

I use contact adhesive for gluing the diaphragm. Other kinds of glue don't stick to Mylar that well. You can put a lot of tension on the Mylar and a good contact adhesive will hold it. No problem. I apply the glue to the spacer and let it dry for a couple of minutes. Then I press the spacer against the Mylar and they bond tightly right away.

Wachara C.


----------



## inuponken

Updated my clone.
  
 Reduced tensioning for more bass but becomes unstable so I changed thickness of the spacers.
 It lowered sensitivity but no problem with my KGSS (not HV) and DIY T2.
 Very stable and bass is deeper than my SR-407.
	

	
	
		
		

		
			




  
 Diaphragm = 2u Mylar film (e-bay)
 Dust filter (front only) = 0.9u Super ultrafilm (http://www.indoorspecialties.com/)
 Frames (cups): 3/4” Red oak board + wood stain + Gross Polyurethane paint (Home depot)
 Stators: t=0.94mm FR4 PCB (e-bay PCB depot) + “KRYLON Digital Photo & Paper Protectant” splay for the coating (office).
 Dust filters: t=0.94mm FR4 PCB (e-bay PCB depot)
 Spacer & Diaphragm: t=0.5mm FR4 PCB (e-bay PCB depot) >* t=0.8mm FR4 PCB*
 Contact Cement: DAP Weldwood original contact cement (ACE hardware)
 Plastic Rings for the ear pad: Cut out from Compact Disc
  
 Locking Rings for ear pad: from HE-5 Ear pads (e-bay)
 Top plates: 3/16” black acrylic sheet (e-bay)
 Nylon screws, small wood screws, shrink tubes…
 Punching metal plates: Kenwood Excelon Speaker Grills (e-bay)
 Cable: KOSS ESP950 extension cable (Koss service center)
 Stax connector: from Kevin
 Headband : form my SR-40 (Garage sale) + coat hanger
  
 Tension = 180g (water bottle 120g + Clamp 60g) x 16pcs = Total 2,880g >* 11.8g (Clamp only) x 30pcs =Total 354g (stopped at wrinkles are gone)*
 2 gallons bucket for tensioning (ACE hardware)
2in.Spring Clamps for tensioning x 16pcs (Harbor Freight/Home depot) >  HDX 3/4in Mini Spring Clamp x 30pcs (Home depot)
Ozakra 16.9-floz empty bottles x 16pcs (from recycle bin in my garage)
Vinyl coated wire rope = water bottle <> Clamp (from my wife)
 And dxf files from Wachara. 
  

 I am asking my wife to make ear pads for JF clone but I don’t know when she can finish…


----------



## chinsettawong

The drivers look really nice. Congratulations!

How will you make the headband?


----------



## inuponken

Thank you.
  
 I'm still thinking how to attach the 1/8" steel rod to the back panel because I have several ways to attach.


----------



## chinsettawong

That looks interesting.  Let me know how well that works.


----------



## ayaflo

Hello all,

I am doing for a second time a simple circuit for the esl cans I am making...I am stuck with the step up trafo for the audio signal and though torroids make all the difference from an EI core, torroids are unavailable for a few weeks here. I also tried the PA line trafo and apparently I need to wind my own and it costs $30 to wind to specification.

What are the alternates ? The closest I got here is a 240 to 27v step down that gives 10 amp current so it should be rated for at least 270W. Once i reverse this will this trafo be able to handle a 40 watt 4 ohm imp. Rated amp and in turn be able to step up the voltage for the stators? 

PS- The last ESL speaker I made worked a few seconds till the trafo gave way so I can't take the chance now.I did check out the thread again but doubts remain.


----------



## chinsettawong

Hi Ayaflo,
  
 Are you making headphones or loudspeakers?
  
 Either case, you need a lot higher turn ratio than 240 to 27V can do.  For headphones, the turn ratio IMO should be at least around 1:40.  For loudspeakers, I would go higher than 1:80.
  
 Try finding a pair of 240V to 6V transformers to use with headphones.  That will give you a step up ratio of 1:40.  If you can't find them, you can use a pair of 240V to 12V for a similar result by simply series the 240V windings and parallel the 12V windings.
  
 Good luck.
  
 Wachara C.


----------



## ayaflo

chinsettawong said:


> Hi Ayaflo,
> 
> Are you making headphones or loudspeakers?
> 
> ...


 
  
 The last time I reversed a 240 to 6V trafo, it either shorted in the 6 V side due to the 20-23V (65W) that my A/V reciver was feeding it or the 240V side due to the huge step-up and poor isolation that couldn't handle the step up.
 I think for a 6V trafo, the secondary should at least have a 5-10 Amp current rating (so the trafo rating would be close to 30-60 VA/W) to accept such loads as my 65 wpc amplifier.
  
 Anyway worth sharing I thought is  a very convenient method, I am using perf-boards for the stators. These perf-boards have all their points connected across columns, therefore soldering across one row will give me a stator board without any extra material for unwanted capacitance. 
  
 Thanks for the wish, I need it.


----------



## davidsh

The problem should not be the current rating, I'd think, but rather that the trafo you used isn't designed to swing 23/900 volts. The current used by the transformer ought to be very low, ideally, as the ES headphone doesn't require much current.
 It'd probably be best if you could find a low current, high voltage rated trafo.
  
 Someone correct me if I'm wrong.


----------



## ayaflo

If you look for a low current high voltage trafo then you are not getting the step up needed. I know the current should be low and voltage high for the stator peak to peak voltage to work against the bias. however the transformers load rating is important since I am practically feeding my amp into it as an elemental design and what the trafo can take should be noted else it can short. The only option is to use multiple transformers to carry the load and this will work.some torroids also work since 25 watt torroids are way too common now.


----------



## chinsettawong

Your problem could have been your coating on the diaphragm that isn't good enough or the bias voltage that isn't high enough.  If you have everything correct, I doubt you need so much power to feed your transformers that would burn them in the first place. 
  
 How big is your active area?  How thick is your spacer and what is your bias voltage?


----------



## ayaflo

I used dish soap last time... This time I am using floor cleaner. I am sure it's not the coating because I examined it. I highly suspect an internal shorting since tranformers with poor insulation are very common, especially once you reverse it, it can't handle the step up.

This time my bias is 609v and the spacer thickness is 1 mm. I will report back with the active area a few hours from now.

Thanks and best regards,


----------



## chinsettawong

Dish soap is certainly not that good.  Please also know that not all floor cleaners work either. 
  
 If you are going with 1 mm spacer, you can use a lot higher bias voltage.   I have tried 1.2KV in the past with no problem. 
  
 Good luck.
  
 Wachara C.


----------



## quintile

Hi all.
  
 I am new here and must admit I am not (currently) working on DIY headphones. I am however, trying to repair
 a pair of Micro Seiki MX-2 electrostatic headphones, and I believe the people on this list may be able to help me.
  
 The MX-2 used a diaphragm of "photo etched" polyurethane which is not stable long term - the diaphragms of my
 headphones have disintegrated into dust. The diaphragms are only 47mm in diameter, and the stator spacing is
 about 0.4mm. The bias is generated by an oscillator from a 9v battery, and sadly this is died too so I don't know the
 HT voltage - I believe it is in the 200-300V range.
  
 I have a few questions if anyone can spare the time:
  
 Approximately what tension should I be aiming for? some people seem to suggest as high as possible before
 the Mylar rips. Some people suggest as low as possible which still removes all the wrinkles. what is the effect
 on the frequency response?
  
 What target resistivity should I aim for? 10e8 seems to be suggested, is this still current best practice?
  
 How should I measure resistivity - has everyone bought a surface resistivity meter? I DVM only goes
 up to 30M ohms.
  
 I have read about the different dope that people coat their diaphragms with, but I don't understand why rubbed
 graphite is not more popular - In my experiments (with lock lubricant, not colloidal aquadag) I found the resistivity
 tends to drop rather too low, but this may be my lack of experience. It looks a good material, not being hygroscopic
 and no problems with ageing.
  
 Finally, the most difficult problem The MX-2 uses a small electrostatic capsule which is easily replaceable. This has
 metal stators held in two interlocking molded plastic  rings. The diaphragm is glued to a metal ring which
 is held between the plastic rings and contact is made from this ring.
  
 The difficulty here is there is only a point contact to one side of the diaphragm, and the "contact" through the
 conductivity of the glue.
  
 Does anyone have any experience of conductive glues which would adhere well to Mylar and metal? If
 no one has any better suggestions I am going to try uhu por and mix some graphite with it but this will
 be hard as it dries rather quickly.
  
 I have sourced some 1micron Mylar and also, as an alternative to rubbed graphite,  some EPA surface cleaner
 http://www.teknis.co.uk/p-1114-epa-surface-cleaner.aspx
 though I have no way to know if it is stable long term (many years).
  
 Sorry for so many questions, Thanks for any help.
  
 -Steve


----------



## chinsettawong

Hi Steve,
  
 Here are my answers to your questions:
  
 1.  I don't really have the target tension for your diaphragms.  You just have to try it by yourself.  If you have too much tension, you'll have less bass.  If you put too little tension, then the diaphragm will collapse to one of the stators.
  
 2.  The target resistivity is anything between than 10 - 100 M ohm per square.  But if you don't have a high voltage multimeter, it can be quite difficult to measure.  
  
 3.  Rubbing graphite on  the diaphragm can be tricky.  But if you think that you can do a good job, just go for it.  I'm sure that it'll work just as well.
  
 4.  Can you take a photo to show how your spacers are like?
  
 Wachara C.


----------



## quintile

Below is an picture of the stators an the diaphragm support ring.

the stators are metal grids held in a plastic ring. the inner surface of one of these is flat, but the other has a recess into which the diaphragm ring fits. this has the effect of tensioning the diaphragm as the two stators are pressed together.

Note the small holes in the edge of the three items. These allow sprung wires to connect to the three elements.

The stators are held together with a small strip of adhesive tape around the edge of the two stators.

I have tried assembling a new diaphragm with 1micron Mylar using UHU POR glue and Teknis epa anti static liquid. http://www.teknis.co.uk/p-1114-epa-surface-cleaner.aspx

 I was very pleased to get a conductivity, after gently rubbing the diaphragm, of 10nS = 100M ohms.

I failed to get sufficient tension first time, even after heat shrinking it, but I will keep trying.

-Steve


----------



## sutsug

I repaired my Micro Seiki with cellophane and 'wood glue' and 'charcoal' from an artist pencil. Cellophane stretched out with tape on a mirror. Charcoal rubbed on paper sticks to your finger. Dip it in a wood glue/water solution and rub it on the foil. Glue the rings on the foil with wood glue. Cut them out loosely with a scissor. Melt the excess foil and hole and 'bald spot' away with a soldering iron. It worked the first time (except for some whistling that disappeared after a few days. Maybe moisture) but I do miss a full bass-sound.

Schematic Micro Seiki: http://postimg.org/image/thycx8uy9/full/ They say it was made by Stax but it uses only four wires to the headphone. Inside box: http://s13.postimg.org/wl8tmvuqv/microseiki_623.jpg

Something else: I disassembled a Samsung Microwave (warning: deadly voltages even unplugged) and found this behind the window: http://postimg.org/image/lx36upf4j/ A beautiful 0.5 mm thick sheet mesh!


----------



## quintile

Well, it all worked rather well.

Thanks for the pointers to schematic.

using the ESD fluid worked well, but I am a bit disappointed by the lack of real bass.
I wonder if the problem is excess diaphragm tension?

I pul the diaphagrams in orientated so the tension is increased when the stators are put together.
I may try reversing them. I glued the diaphagrams to the rings under a little tension, though not much.

I was very pleased to find that Bose quiet comfort QC-1 headphone EarPods fit the micro seiki
Headphones -they are a bit of a tight fit but they work. (I bought them on eBay from China of course).

I am going to try and measure the diaphagrams resonance frequency with a cheap microphone,
I think this may indicate where the LF roll-off may begin.

If not the diaphagrams tension then I guess it's just the driver area that is limiting the of response, I
Am already using the lightest diaphragms I can find 1 micron.

If anyone has any other suggestions of what limits LF response, I would be very interested.

-Steve


----------



## CosPhi

Hello
  
 I have some minor question regarding the perforation of the stators. You're using a triangle-based tile, which gives a higher efficiency for empty/total area, and also, somewhere in this long thread, there was someone saying that the best/maximum ratio should be 60% (opened area vs total, if I got it right). OK so far, but, from what I see in the pictures all over the thread and mostly "ogling", it shows that the holes are (in general) 2mm diameter and the spacing is (looks like) 1mm. If I am wrong, don't read up the next part 
  
 Before I go on, I've tried my hand in some basic geometry and came up with this formula for "x" in the picture: http://tinypic.com/r/102r1cl/9 (can't upload here):
  
 2 * r * { sqrt[ pi/ratio) ] * 1/3^0.25 - 1 }
  
 or, more simplified:
  
 r * [ 1.905/sqrt(ratio) - 2 ]
  
 The ratio is not the percentage but the brute division, as in for 50%, ratio=0.5. This gives the dimension of the spacing required to meet a certain ratio. So, for a 60% opened area and 2mm holes, ratio=0.6, r = 1mm =>
  
 x ~ 1 * [ 1.905/sqrt(0.6) - 2 ] ~ 0.46mm
  
 This can be easily verified with the reverse formula:
  
 ratio = ( 2 * pi * r ) / [ a^2 * sqrt(3) ]
  
 where a = 2 * r + x , which (again, ogling) => ratio ~ 40.3%. Even for a 50% ratio, x should be ~0.7mm, not 1mm.
  
 So, at this point, I'm confused: either the ratio is exaggerated (or I got it the wrong way), or the ratio is good and my ogling should know better. Can someone please provide some measurements for the holes on their stators (and a clarification for the ratio)?
  
  
 Thank you in advance,
 Vlad


----------



## chinsettawong

Hi Vlad,

I don't think that we are aiming for anywhere near 60% open area. For all my stators, I am aiming for about 40% open area.

I have tried stators with higher open area on my full range ESL, but the stators are too weak and need supports to help with the stiffness. The more open area stators do sound very nice though.

On commercial headphones such as Stax's, the stator holes are much smaller. I don't know what their open areas are, but I don't think that they're more than 40% either. 

Wachara C.


----------



## analogsurviver

chinsettawong said:


> Hi Vlad,
> 
> I don't think that we are aiming for anywhere near 60% open area. For all my stators, I am aiming for about 40% open area.
> 
> ...


 
 Something like that.
  
 The most open stators I remember were those built by Sanders in late 70s - piano wire rods all across the surface, with every second wire removed - and that yields less than 50 %, once the clamping periphery and some stiffening across the rods is applied. 
  
 If it were possible, AKG would have gone with electrostatic principle for the K-1000 ; as the design requires as acoustically open driver/baffle, they had to invent a dynamic driver with more than 70% acoustic openess.
  
 The aichile's heel of electrostatics is their stator mechanical resonances. Flick any ESL with your fingernail - what it results in sound, is what should have never been there in the first place.
  
 Perhaps time to re-invent/re-use conductive fabric stators a la Sennheiser Unipolar series ?


----------



## jgazal

analogsurviver said:


> The aichile's heel of electrostatics is their stator mechanical resonances.




What are the natural resonance frequencies of a stainless steel stator, a quartz glass stator, a ceramic compound stator and a FR4 PCB stator?

Can one speculate that natural resonance frequencies of a stainless steel stator are in the treble and mid range while from a FR4 PCB stator are in the bass and mid range? 

If a signal coherent with the natural resonance frequencies of a peculiar stator is synthesized and played, how many dbs come from the diaphragm and how many come from stator resonance?


----------



## analogsurviver

jgazal said:


> What are the natural resonance frequencies of a stainless steel stator, a quartz glass stator, a ceramic compound stator and a FR4 PCB stator?
> 
> Can one speculate that natural resonance frequencies of a stainless steel stator are in the treble and mid range while from a FR4 PCB stator are in the bass and mid range?
> 
> If a signal coherent with the natural resonance frequencies of a peculiar stator is synthesized and played, how many dbs come from the diaphragm and how many come from stator resonance?


 
 It is the _composite _- a clever electrostatic driver design uses the necessary evil, the clamping surround, also as means of damping of the stator material(s). 
  
 It is not how loud the unwanted sound is  - but the quality of that resonance, mechanical Q is important. If the driver rings - no use of  in theory superior driving principle.
 Please see the measurements for Stax IEMs - smaller, better than its larger siblings ! And there are dynamic drivers that can top even that ...- some are actually capable of the proverbial "stopping on the dime"...


----------



## CosPhi

So then, from your replies, I got it wrong, it's 60% closed area, not opened, but the more opened area the better, provided there's enough material strength in the stator, and the stator is as plastic (as in not elastic) as possible. Which is much like asking for a Cauer filter with a Bessel phase... Well then, 40% opened area isn't so bad. 
  
 Vlad


----------



## analogsurviver

cosphi said:


> So then, from your replies, I got it wrong, it's 60% closed area, not opened, but the more opened area the better, provided there's enough material strength in the stator, and the stator is as plastic (as in not elastic) as possible. Which is much like asking for a Cauer filter with a Bessel phase... Well then, 40% opened area isn't so bad.
> 
> Vlad


 
 My friend coined the best one:
  
 We all like our sports bulldozers with low mileage - for free !


----------



## Nemeske88

I don't know if I am posting to the correspondent forum, but I am asking the following:
 I have read once that there is a significant difference between SB (Self-biasing) and non-self biasing transformers regarding the sound quality.
  
 I am asking if this information true and if yes, can anyone tell me in which aspects one can percieve the difference?
  
 Thank you for your reply in advance


----------



## analogsurviver

nemeske88 said:


> I don't know if I am posting to the correspondent forum, but I am asking the following:
> I have read once that there is a significant difference between SB (Self-biasing) and non-self biasing transformers regarding the sound quality.
> 
> I am asking if this information true and if yes, can anyone tell me in which aspects one can percieve the difference?
> ...


 
 It all depends on RC time constants. 
  
 SB (self biasing ) transformers contain LOTS of batteries in series ( till you get to that 580 V for Pro models - do the math...) - and therefore their bias supply is the most stable of them all - veeeeeeeery slowly this voltage is dropping due more to the self-discharge of batteries than anything else - even real world capacitors like headphone electrostatic drivers, have next to infinity resistance and therefore next to no drain.
  
 RC constant of the ES drivers _*should *_take care of any ripple that gets trough in any AC powered bias supply; and although this ripple can be made small, it can not be reasonably (and safely....) made totally insignificant. Generally, this is not audible, except in extreme cases. Yet, if it was not a problem, we would have not be seeing improvements to bias supplies in both headphones and loudspeakers operating on electrostatic principle.
  
 It is icing on the cake, makes no real sense if "cake" is rotten; but when it is not ...


----------



## Nemeske88

Thank you for the useful information. I checked the schematics on the internet and I've only seen some high voltage capacitors, no batteries. I presume these are the 'biasing voltage keepers' those must be kept 'charged' with the audio signal.


----------



## davidsh

nemeske88 said:


> Thank you for the useful information. I checked the schematics on the internet and I've only seen some high voltage capacitors, no batteries. I presume these are the 'biasing voltage keepers' those must be kept 'charged' with the audio signal.


 
 Yes, I think that's what you are referring to, charging up the bias voltage with the audio signal 
	

	
	
		
		

		
		
	


	



 I don't know what it does to sound quality, I'd think it isn't significant, depends on implementation.


----------



## analogsurviver

nemeske88 said:


> Thank you for the useful information. I checked the schematics on the internet and I've only seen some high voltage capacitors, no batteries. I presume these are the 'biasing voltage keepers' those must be kept 'charged' with the audio signal.


 
 It was only Stax that produced SB transformers - even for _*speakers *_( I wouldn't like to see the bill for battery replacement - some 3 thousand button cells per chanell ).
 This is if we are talking about true electrostatics, which require polarizing voltage to be supplied by the power supply.
  
 If it is electret, which means permanently charged, then you do not need any power supply. Schematics for the two can be completely equal ( if electret is also push-pull design ), the only difference being power supply - or the lack of it.
  
 There is no such thing as charging by the audio signal - or at least there should be none.


----------



## davidsh

analogsurviver said:


> nemeske88 said:
> 
> 
> > Thank you for the useful information. I checked the schematics on the internet and I've only seen some high voltage capacitors, no batteries. I presume these are the 'biasing voltage keepers' those must be kept 'charged' with the audio signal.
> ...


 
 But there is 
	

	
	
		
		

		
			




 The Stax srd-6 for example


----------



## Nemeske88

This is a self-biasing transformer for earspeakers, the SRD6 SB.
 I am no tech, but I see only HV ceramic caps, and there are no batteries


----------



## analogsurviver

davidsh said:


> But there is
> 
> 
> 
> ...


 
 Nope - please read again.
  
 SRD-6 has AC power supply.
  
 SRD-6SB has no AC supply - and batteries inside.
  
 http://www.stax.co.jp/Pdf/OLD/SRD6SB.pdf
  
 It is true that RC constants of ES drivers are long - but not long enough to be capable of somehow bleeding the required polarizing voltage off the audio signal and hope for a full charge after a prolonged "next to silence" in say classical music. It is either electret (permanently polarized) or AC or DC ( Self Biasing in Stax' parlance ) power supply for true electrostatics. 
  
 This is the schematics for the SRD-7 - which should differ from SRD-6 in better distortion spec only.
  
 SRD-7SB employs instead of mains AC voltage multiplier circuit lots of button cell batteries in series to reach the required voltage.


----------



## analogsurviver

nemeske88 said:


> This is a self-biasing transformer for earspeakers, the SRD6 SB.
> I am no tech, but I see only HV ceramic caps, and there are no batteries


 
 No AC cable on this SRD 6SB ?


----------



## n3rdling

The bias is generated from the audio signal thus no need for ac plug thus self bias thus SB.


----------



## analogsurviver

n3rdling said:


> The bias is generated from the audio signal thus no need for ac plug thus self bias thus SB.


 
 Sorry guys, did not know that.
  
 For how long do(es) the SB version(s) hold their charge for the proper operation if there is no audio played for a while ?
  
 I've found the schematics for the SRD-6SB :


----------



## Nemeske88

In my opinion, those are that ceramic capacitors those hold that charge until they discharge by leaking or something.


----------



## mtoc

wow, if there's any progress, please shared with us. friends and I will diy the KG eletrostatic phones!!!


----------



## chinsettawong

mtoc said:


> wow, if there's any progress, please shared with us. friends and I will diy the KG eletrostatic phones!!!


 
  
 What would you like to learn?


----------



## mtoc

I'll learn silently first


----------



## chinsettawong

mtoc said:


> I'll learn silently first


 

 It's better to share what you're doing in public so that we all can learn together.


----------



## Ghost Pack

Hi
  
 I've been lurking in the shadows here for quite a long time and I'm completely amazed by everyone's ability. You guys inspired me to start designing my own headphones, and after a few weeks of designing and ordering parts, I think I'm ready to start construction.
  
 I thought I'd share my current design on this thread and was hoping you guys could give me pointers and tell me if I messed anything up too bad. 
  
 Amplification: Stax SRD-X Normal
 -Normal Bias
 -Possibility of upgrading to pro w/ external bias?
  
 Mylar:
 -DuPont 3um
 -DuPont 0.5um
 -Saran wrap (possibly for dust covers?)
 -Anti-Static gel
  
 PCB:
 -0.060" Copper Clad Laminate Sheet (1.5mm)
 -0.031" Copper Clad Laminate Sheet (0.78mm)
  
 Vibration Damping:
 -1/16" Butyl Rubber Sheet
  
 Driver Specs:
 -Stator separation is ~0.8mm from stator to diaphragm on each side
 -0.5mm stator thickness (on active surface)
 -Active area measuring 74mm x 49mm
 -4mm difference in radius between the spacers and the stator holes to allow for bass buildup
 -37.25% open/closed surface area on stator (excluding supports and bass ring, probably more like 28% with)
  

  

  

  

  

  

  
 The stator is slot milled from 1.5mm to 0.5mm before holes are drilled, so as to minimize edge interference while keeping hole diameter to a minimum. The holes in the center are larger to mimic the open section found in the sr-009 driver.
  
 I'm not sure what ratio of size to separation to use for my holes, I think with this current design I might not have enough open surface area. I'm a little bit worried about structural integrity. I'm also not sure what thickness of mylar to use. With 0.8mm separation and only 230V bias I might not be able to use thicker mylar or higher tensions.
  
 Thanks ahead of time for any advice you guys can give me!


----------



## chinsettawong

Hi,
  
 Your design looks good.  But I would use thinner spacers. With the bias voltage of only 230V and 0.8 mm spacers, you will probably have to crank up your volume a lot in order to get enough loudness.  But it will surely work.
  
 Please try it and let us know how you like it.  
  
 Wachara C.


----------



## Ghost Pack

The thinnest I can get is 4.32mm. Do you think that will be enough? Also, is there a cheap way to measure driver sub-bass responce? I currently have this mic, which does well for simple measurements but is wildly inaccurate past 180 Hz.
  
 As a side note, I created a "Version B" stator with a open/closed surface ratio of 43.2% (versus the original ratio of 37.3%). I'll mill both out tomorrow, but without a way to measure sub-bass I'll have to wait until I finish the frame to test the differences.


----------



## chinsettawong

Yes, 4.32 mm is nice.  It'll be a lot better than 0.8 mm for 230V bias voltage.
  
 As for using mic for measurement, I think it's better to use your own ears.  If you think they sound nice, then it's a success.


----------



## GvTT

Hello,
  
 I came across this thread several days ago. Reading the whole discussion took quite a while and was very informative. My compliments first to Wachara for his builds, his will to share so much knowledge and to tame and guide all the ideas in this thread. A big nod from my side!
  
 I have been thinking about building my own ESL headphones since more than 20 years and never got to it -shame on me-. Many answers I had have already been answered here. What got me started was an article by Philippe Hiraga in L'Audiophile. Still being in school back than.
  
 Now I own a Stax Lambda Signature and a SRM1/MK2 (thanks to Kevin G. here, he gave me the right advice how to repair it).
  
 Reading the thread I gained a few ideas that I would like to share and discuss here, I also found some topics only described but not explained. Please correct me if I am wrong, I have just engineering knowledge, no building experience.
  
 Please allow me a remark on the Resistance of the membrane:
 The membrane gets moved by the voltage applied to the stator (Coulomb Law). The deflection of the membrane will be half-sine or parabolic like. If charges can move too easy on the membrane, they will be attracted by the stronger electric filed in the middle, where the distance is smaller. So the charge would shift to the center, reenforcing the pull in the center. This could lead to higher distortion and/or instability. Therefore you need to have a fairly high resistance.
  
 For the stator I have the idea shown at http://up.picr.de/24335672lm.jpg
 based on the following: (sorry, I have no permission to post pictures yet)
  
 I do not understand the center hole on the Stax 009. To me it seems too small to significantly reduce the forces acting on the center of the membrane. On the other hand applying more force to the edge of the membrane might help to move it more uniformly.
 (I think that the center-hole is truly for acoustic reasons. As the membrane movement is biggest at the center, it makes sense to me, to open up the center)
  
 The stator itself has an eigenfrequency within the audible range. Getting the stator more stable will always be good. So I have to make it stiffer, where most of the bending takes place and/or reduce the mass where most of the motion takes place.
  
 I want to control/reduce the forces on the center of the membrane.
  
 So I chose an oval stator (minimizing the dominance of eigenfrequencies of circular objects), started the copper about 3mm away from the spacer (to keep capacity low) and increased the hole size toward the center.
  
 The active membrane would be 78x102mm, open area is 32%. But increasing toward the center, where the membrane moves most of the air, so it's hard to tell, how it would compare to an equal spaced stator.
  
 I am curious to read what you think about this.
  
 Many greetings
 Georg


----------



## chinsettawong

Hi Georg,
  
 It's always good to see someone interested in building ES headphones.  I have tried to explained all of my knowledge in this thread.   But since I'm not an engineer,  there is a limitation to what I can share.  I am more into the actual making rather than going into too much about the theory.  It helps from time to time to have an engineer helping me out.  Thank you.
  
 You have a good idea on how to make the stators.  Please go ahead and make them and share with us how they turn out.  That's the only way to prove what you think is true.
  
 There is one thing that I would like to comment on the active membrane size you're proposing.  As you might have known, I've been making a lot of headphones, and I know for sure that with the width of 78 mm, you'll have a very difficult time getting the diaphragm to tension just right.  If I were to make another pair, my width on the active diaphragm for the oval shape headphones would not be more than 76 mm.  I think 74 mm is just right.  I would probably increase the length a bit to compensate for that.  So it might be around 110 x 74 mm.  
  
 By the way, here is your stator picture:  
  


 It looks really nice.
  
 Have fun!
  
 Wachara C.


----------



## GvTT

Hello Wachara,
  
 thank you for the kind welcome.
  
 I will follow your suggestion and go for 74 x 110 mm. Having no experience here and not really intending to start with a failure, I kindly accept your advice. I totally agree, that there is no way around building and listening.
  
 I updated the stator, (copper not shown): http://up.picr.de/24345854bg.jpg
 Next I will design the spacers, cable connectors, etc. The G-code needs to be created and I have to switch my CNC milling machine on (has been resting for a year now).
  
 Before I start milling I want to find a way to measure the free air frequency, so I can generate membranes with different tensions to test.
  
 Do you think one could test the membrane for stability before gluing it to a stator, on the strecher?
 [As for a stretcher I tend more and more to an inner tire on a frame. I would coat the Mylar on the stretcher, bring a spacer and a stator in contact with it, so that the Mylar is stretched over the spacer. The stator connected to ground, the spacer to 580V + 280V (860V) [high valued resistor needed for safety!!!]. I think one could see if the diaphragm becomes unstable before gluing] 
  
 Kind regards
 Georg


----------



## Ghost Pack

Sadly my first few attempts at CNCing my stator design ended in failure (Laminate PCB is just too weak a material to hold up to so many 1mm holes. I'll increase my my hole diameter to 1.6mm, my pocket depth will be reduced to 0.8mm, and I'll switch to the suggested triangular pattern (as opposed to hexagonal) to increase stability.
  
 Anyone have experience with the machinability of FR-4 vs Laminate PCB?
  
 The 1mm hole model performed quite well in analysis, but it just proved too difficult to machine. It might be worth re-visiting the design when I have access to electroplating equipment, as I could use stiffer materials such as stainless steel and then plate the stator in copper or silver.
  
 I might be a bit ambitious for a first time EStat maker.


----------



## Ghost Pack

gvtt said:


> Hello,
> 
> I came across this thread several days ago. Reading the whole discussion took quite a while and was very informative. My compliments first to Wachara for his builds, his will to share so much knowledge and to tame and guide all the ideas in this thread. A big nod from my side!
> 
> ...


 

 Really amazing observation, and it explains why the large centre holes appear in high end Stax models.
  
 In your design, is every layer of holes a different diameter, or are you using a few set diameters for several layers at a time?


----------



## scotsstax

hi spritzer or chinasettawong wachara etc !! and all the rest k gilmore ,and all stat lovers!! sorry to but in , im new to the forums ,im  trying to rebuild my sr 404 sig membranes  with 1 micron .......phew, im at my wits end trying to get it wrinkle free and not to rip, i had it once the coated the mems with fine graphite ,once in the brass ring", and they arced so bad they burned some stator paint off!! any ideas how i can fix this?? and the + - connections came apart so i delicately soldered them to the same point but on the back of the stator, is any antistatic pc cleaaner gel good for membranes? and do you know what i can do with the burned stator? ,all the best ps whats the best glu im using evo stik contact but its hard to get off once a mistake is made is modellers cement glue better ps i use a srm3...cheers!! pps i just held the assembly together using a dry towel, what paint can i use to re paint the stator burn? its not near the holes nearer the brass ring edge 4 mm sq id say... and is it ok to solder the stator connections on the back of the  stator? i  ,i scraped a 2 mm sq patch on the same point and delicatly soldered them  is this ok im in the uk and finally is adding ink to the antistatic coating gel improve the charge sound etc ,i blame the damm grapthite causing the burn soz for long post, but im quite poor, and want them fixed, also have som n bias lambdas, but they sound crackily ,not bad but im a stikler for perfection!! as we all are!! any help from the really knowledgeable guys will be greatly appreciated will changin the thick dustcover material on my sr lambdas, to 1 micron help with openness or should i leave alone ..??? many thanks cheers guys and gals!!


----------



## GvTT

ghost pack said:


> Really amazing observation, and it explains why the large centre holes appear in high end Stax models.
> 
> In your design, is every layer of holes a different diameter, or are you using a few set diameters for several layers at a time?


 
  
 Hello Ghost Pack,
  
 I just intend to use different drill diameters. My stator is goind to be flat.
  
 I considered the option of a curved stator, giving more space in the center. But this would really be hard to machine. As I am a beginner I will go the route with only one unknown, for me the variation in drill diameters.
  
 I seriously consider using copper covered UD-CFK as stator. I can get a young-modulus of the laminate (using pitchfibres) of 200 to 400 GPa, what is above steel, and this at 1/4 of the weight. Compared to glass fibers, pitch-fibre UD-CFK should be 4 to 10 times stiffer, at a slightly lighter weight. I think this could theoretically shift the 1.5kHz stator eigenfrequency out of the audible range, although I do not know if this would improve anything.
  
 But: as I mentioned before, I will only change one parameter at the beginning. Need to define my baseline.
  
 Many greetings
 Georg


----------



## davidsh

It should show up on measurements if the stators really are resonating, I'd think. And if it doesn't it is probably insignificant. Interesting.


----------



## chinsettawong

Hi Scotsstax,

I'm sorry that I might not understand your questions very well, but I'll try my best.

If I'm not mistaken, the driver of SR404 is built by actually gluing the staors and spacers together. To open it, you actually have to rip everything apart, right? I've only opened up the SR507 drivers before, but they are constructed differently. For SR507, you only have to unscrew some screws of the deiver holder to disassemble it. The stators of SR507 look to be perforated matel with powder coating. If they are the same as SR404, you can use woman's finger nail clear paint to paint over the burnt area to fix it. 

I personally don't like to use 1 micron Mylar as a diaphragm. I think it is too thin and it's very difficult to tension it just right. However, it certainly can work.

I always use the antistatic gel or the floor cleanser as my coating material. I prefer them to graphite or anything else.

I also prefer contact cement glue to any other type of glue. 

Good luck!

Wachara C.






Sent from my SM-N9005 using Tapatalk


----------



## scotsstax

hi chinasettawong!! love your work !! just awe inspiring!!., can i run a  frequency responce graph on my pc with a mic goin in to the usb port to get even membrane tension??? thanks as ever my freind in diying staxes and orpheous clones  take care !!


----------



## chinsettawong

scotsstax said:


> hi chinasettawong!! love your work !! just awe inspiring!!., can i run a  frequency responce graph on my pc with a mic goin in to the usb port to get even membrane tension??? thanks as ever my freind in diying staxes and orpheous clones  take care !!


 
  
 I've never done that, but sounds interesting.  Please try it and let us know your results.
  
 Wachara C.


----------



## scotsstax

will do maestro!! all the best from rob aka scotsstax


----------



## scotsstax

also maestro, can weak bass be a sign of  only using  washing up liquid as a coating on the membranes?? im gettin ok detail, but bass is weak any suggestions appreciated mate!! as in coatings tensioning , ps im in the uk!!
 all the best  scotstax


----------



## scotsstax

sorry to annoy you maestro, what is best to remove contact glue??
 many thanks!!


----------



## scotsstax

sorry for more questions maestro!, which membrane coating, will stay on for 30 years or more and what can i clean the membrane with after applying the coating!!                                                                thank you again sir your stax are gold!!


----------



## davidsh

scotsstax said:


> also maestro, can weak bass be a sign of  only using  washing up liquid as a coating on the membranes?? im gettin ok detail, but bass is weak any suggestions appreciated mate!! as in coatings tensioning , ps im in the uk!!
> all the best  scotstax


 
 I can't imagine weak bass has anything to do with the coating.


----------



## chinsettawong

The coating can cause weak bass when it has too much resistivity.  That means the diaphragm can't properly charge up.  You need to crank up a lot on your volume, but then the sound just isn't right.  So, yes, it could have been a wrong choice of coating material.
  
 About the coating material that can last 30 years, I'm sorry that I really don't know. If anyone knows, please let me know too.


----------



## chinsettawong

I'm really itching to try to make a pair of really small, in ear, type of electrostatic earphones - similar to Stax SR002.  Does anyone have any experience on how they sound?
  
 I can use my 3d printer to print the housing.  I'm thinking of 0.75 mm holes on the stators and 0.5 mm spacers.  I would like to use the amps I have which all have bias voltage of 580V.
  
 It would be fun to try something different.  What do you guys think?  
  
 Wachara C.


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## kevin gilmore

the sr002 is absolutely the best thing on the planet for female voices.
 something like it that's actually comfortable would be a winner.


----------



## davidsh

As long as you make sure not to fry your brain with the amp


----------



## chinsettawong

kevin gilmore said:


> the sr002 is absolutely the best thing on the planet for female voices.
> something like it that's actually comfortable would be a winner.


 
  
 Thanks Kevin.  That's very encouraging.  I'll try to design something and report back.


----------



## chinsettawong

davidsh said:


> As long as you make sure not to fry your brain with the amp


 
  
 I have a bit worry about that too, but let's see.


----------



## n3rdling

chinsettawong said:


> I'm really itching to try to make a pair of really small, in ear, type of electrostatic earphones - similar to Stax SR002.  Does anyone have any experience on how they sound?
> 
> I can use my 3d printer to print the housing.  I'm thinking of 0.75 mm holes on the stators and 0.5 mm spacers.  I would like to use the amps I have which all have bias voltage of 580V.
> 
> ...




You mean like this? 



I'll update within the week.


----------



## chinsettawong

Nice!!!


----------



## scotsstax

hi wachara!!, or  as i call you the stax and diy statics maestro!!!! is my weak bass down to diagphragm tension coating ,i only had liquid soap also ive got to turn my srm3 amp up more but the quality is there bass quality is nice and mid are great , but again too much volume is needed  from the stax srm3 this wasnt like this before ....ps how you get your membranes as flat mate??? any other tips like membrane tension, etc i would appreciate very much as you are the only one who replies!!
 many thanks stax guru!!


----------



## scotsstax

oh yes wachara do it!!!!! if anybody can,.. YOU CAN!!
 best of luck mate!!!


----------



## chinsettawong

Hi scotsstax,
  
 Please call me Wachara.  
	

	
	
		
		

		
		
	


	



  
 I think it is easier for you to just try to recoat the diaphragm with a better coating material.  If you can go to a computer store and buy a bottle of computer screen cleanser that has an antistatic property, chances are that it will work.  Tensioning a diaphragm to the right tension isn't easy.  You might have to do it many times just to get it right.  It takes a lot of trials and errors.  
  
 I have suggested many times about my diaphragm tensioning technics.  Nowadays, I only use a wood frame with an inner tire to tension my diaphragm.  Something like this works well for me:
  

  
 It takes a lot of trials and errors to tension the diaphragm to the "just right" tension.  
  
 Wachara C.


----------



## inuponken

Extension cable for the ESP950 is no longer available. They stopped selling...


----------



## inuponken

Wachara,
  
 Sound from the JF clone is awesome!! 
 I spent a lot of time to find a right tension. 
  
  

  
 I am making another pair.


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## chinsettawong

Your frames look super nice.  Congratulations!
  
 Wachara C.


----------



## scotsstax

WHAT GLUE do you use to glue mylar to the stator as my glue is evo stik cement and its like syrup!!! when you try and run your finger over the stator to evenly spread the glue.... it goes all lumpy the glue i mean !!!
	

	
	
		
		

		
			





 any ideas? what do you use for glue ??
 cheers!!


----------



## chinsettawong

Come on!  I've answered this glue question to you already.  I use contact cement for gluing the diaphragm,  That's the only type of glue that works well for me.  It's yellow colour with bad smell.  We also call it rubber glue around here.
  
 Wachara C.


----------



## scotsstax

sorry didnt think you would mind.......... i wanted to know if it was thick glue or thin you used, but hey if its a problem then... fine.....


----------



## chinsettawong

It's not a problem.  It's just that what I have here might not be what you can get there.  I like the thin glue better.  But both should work equally well.
  
 Wachara C.


----------



## chinsettawong

This is what I use:


----------



## inuponken

I'm using this.


----------



## scotsstax

thanks wachara!!


----------



## scotsstax

is it quite thin sir?? or syrupy???


----------



## geemo4

Quote:


chinsettawong said:


> I'm really itching to try to make a pair of really small, in ear, type of electrostatic earphones - similar to Stax SR002.  Does anyone have any experience on how they sound?
> 
> I can use my 3d printer to print the housing.  I'm thinking of 0.75 mm holes on the stators and 0.5 mm spacers.  I would like to use the amps I have which all have bias voltage of 580V.
> 
> ...


 

 Hi  Wachara,
  
 i am new in this thread. I like that you are sharing all your information. I appreciate this.
 When i finish my actual project i will join you and try to build my own headphones.
  
 You are asking about the SR-002. I have a pair of them and as i got a broken cable
 i opened them. If you need some details may be pictures or meassuring please ask.
 I may also reopen it if you need details.
  
 I am with Mr Gilmore that they are very nice, but they need perfect seal which is very hard to find.
 I tried like this:
  
 - I used Moldex earplugs. These i cutted in halfes. Using the bigger end. Made a whole with a singe hole puncher and manteled them to the headphones.
 - You can sgueeze them and quickly insert in your ears so that the expanding foam will rnake the seal.
 - i combined this with an elastic headband of a headlight/torch, which gives a certain pressure to the headphones.
 - you should look that the headband is not covering the backside holes of the headphones, as this changes the sound again.

 I always wanted to make otoplasties, but i didn´t do it till now.
 So i am happy following what you may develope.
  
 If i can help you please PN or reply here.
  
 geemo


----------



## chinsettawong

Hi geemo,

It would be a great help if you could share with me some photos and measurements of the driver. What I really like to kmow is the spacer thickness and the diameter of the active diaphragm. 

Thanks for your help. 

I just went out to buy a 0.5 mm endmill. Boy, it is so mall and fragile. I'm not sure if my CNC can handle it. We'll see. 

Wachara C.


----------



## geemo4

Hi Wachara,
  
 i think the issue about re-designing the Sr-002 will be:
  
1.) The shape of the outlet:
  
 Why did Stax people use an oval ? May be for maximum surface. So it will be the question
 what to develope - an better oval or a round which fits in the ear.
  
2.) The way from the membrane to the outlet.
  
 A change in geometry may change the sound.
  
 geemo


----------



## geemo4

chinsettawong said:


> Hi geemo,
> 
> It would be a great help if you could share with me some photos and measurements of the driver. What I really like to kmow is the spacer thickness and the diameter of the active diaphragm.
> 
> ...


 

 Hi Wachara,
  
here are some information i have still in mind:
  
 - The spacers where little white washers about 2-3 mm (Outer diameter -inner diameter) The thickness is hard to remember but i guess
 0,5 mm may be less.
 - The membrane was held by a brass coloured washer.
 - The stators: You could not see holes in there. It had a sort of white surface in the middle.
  
 Al the stuff was not screwed or glued - it was just hold together by the housing, which was 2 parts. When you strip off the shell
 where the cable comes out you can see 3 clamps. They look like static crocodile mouths. You cannot push or pull the clamps for release.
 You just pull the jack backwards. Then you have the single speaker. You can open the housing like opening a remote control. Its not very
 tough. Then there is the stack of the slices/ disks.
  
 To reassemble it you must see that everything is in the right place. The stators and the membrane have these metal tongues / latches,
 which are sitting in a socket which is part of the housing shells. When you clip the housing shells together again you need to see
 that everything is in the right place. But it works - i tried 2-3 times.
  
 After that the cable-jack will be pushed on the open 3 latches. Finally you push the cable shell over the cable outlet / socket/plug. This will
 also avoid that the two main housing shelves are opening unintended.
  
 geemo


----------



## chinsettawong

For me, the drivers are no problem to be made, but to make good housings for them could be challenging. Here is what I have made right now.











Fitting in the ear isn't that good yet. 

Wachara C.


----------



## chinsettawong

This is how my stators and spacers will look like.  Even with 0.5 mm holes, those are only as many holes I can drill.


----------



## geemo4

I found some pictures on the web. Maybe you can use them.
 Source: http://www.head-fi.org/t/163022/stax-sr-001-appreciation-thread/45
 Post #60
  
 I extracted a few pics:


----------



## geemo4




----------



## chinsettawong

Thank you very much.


----------



## geemo4

I am glad i could help you. But these pics where from the net. So if there is more you need please PN me or reply. Then i will open mine.
  
 I just did a little scale up/down procedure to identify the grid dimensions of the stator. So here are the results:


----------



## geemo4

Some more data:
  
 Outer diameter housing ca 28mm
 Inner diameter housing ca 26 mm
 Membrane diameter with brass ring ca 25 mm
 White spacer washer outer diameter ca 25 mm
 White spacer washer inner diameter ca 21,5-22,0 mm
 Stator diameter (hard to say cause of the glue) ca 22 mm
  
 Thicknes Speaker shell ca 6mm
 Overall "thickness" from back to outlet ca. 22 mm
  
 All dimensions where roughly measured / calculated with Microsoft Paint
 and if necessary estimated. So please double check before you start
 working. If there is an specific measurement you need, please PN or
 reply, then i will double check it.
  
 greetings
  
 geemo


----------



## chinsettawong

Thanks so much about the measurements.  I think what I'm making now is a lot smaller than that of Stax.  Let's see how it goes.
  
 Wachara C.


----------



## geemo4

Hello Wachara,
  
 yes its worth a try. But why did Stax designed them in that uncomfortable way ?
 I think they did for some reason. Maybe stabilty of the stators ? May be the size
 of the chamber ?
  
 Shure did release the KSE1500 recently. Its an Inear electrostatic headphone,
 which is smaller than the Stax Sr-002 ones. (3.000 Euro incl a headamp / DAC)
  
 It seems they have sthg like 8-10mm driver size.
  

  

  
 picture sources: headfi thread, Shure homepage


----------



## scotsstax

hi spritzer, while trying to re do my membranes,of my sr lambdas, the stator contact point just dangled and bloody snapped!!, my question is , can i just solder finely only the wire to the back of the stator?? any advice will be extremly helpful, im at my wits end with these damned things,!! but i love the static sound!!! many thanks ...rob. also the brass stator rings seem bent slightly any ideas how to fix them?? many thanks!!


----------



## 39points

Oh man, looks really awesome, good job


----------



## wppk

Hello there !
 haven't read the complete 134 pages of this thread, but I am asking myself something about why not making stators with a 3d printer ? Today, some 3d printers can work with metals, and even gold. is it a stupid question ? would avoid to have to buy a dedicated machine and aknowledge specific techniques about it on how to make the whole stator out of copper parts. No ? And so, more of us could make our own static headphones...
 hope I am not making a repetition with something already talked about here


----------



## chinsettawong

wppk said:


> Hello there !
> haven't read the complete 134 pages of this thread, but I am asking myself something about why not making stators with a 3d printer ? Today, some 3d printers can work with metals, and even gold. is it a stupid question ? would avoid to have to buy a dedicated machine and aknowledge specific techniques about it on how to make the whole stator out of copper parts. No ? And so, more of us could make our own static headphones...
> hope I am not making a repetition with something already talked about here


 
  
 I'm sure it's possible.  If you are able to make them easily, please go ahead and try it, and please let us know how it goes.


----------



## chinsettawong

scotsstax said:


> hi spritzer, while trying to re do my membranes,of my sr lambdas, the stator contact point just dangled and bloody snapped!!, my question is , can i just solder finely only the wire to the back of the stator?? any advice will be extremly helpful, im at my wits end with these damned things,!! but i love the static sound!!! many thanks ...rob. also the brass stator rings seem bent slightly any ideas how to fix them?? many thanks!!


 
  
 I'm afraid that Spritzer might not be here to help you.  
  
 I also have a Stax stator where the contact just broke off.  I'm sure you can just solder it right back and it won't harm anything.  Try it.  You have nothing to lose.
  
 Wachara C.


----------



## wppk

I am not able to make it by myself, and I don't have such a printer.but I Found this post and found your work so remarkable... that even if I didn't answer yet, I found all your inventions/work so great ! And I saw that one can do anything with these printers, then, why not the stators, which are, I assume, the most diffcult part to make. Also, some parts of the headphones could be modelised on a computer, and done this way. Writing this, I just wondered if it could be made, and hoped that someone could try. personally, I am not making headphones, but sometimes repairing them, when I can.


----------



## Kerry

There's a company called Xometry in the US that can print various metals including stainless steel.

Give it a look.


----------



## GvTT

Hello wppk,
  
 some of the answers to a 3D printed stator are allready in the thread:
  
 1.) you only want the active area of the membrane conductive on the stator. Having a conductive material in the mounting area will just increase the capacity, and hence be counterproductive
 Hence the stator should have 2 different material, one conductive, one not.
  
 2.) the stator should be stiff, so it will not get into resonance (eigenfrequency). I think it would be difficult to make stators stiff enough when using a thermoplast.
  
 So you would end up with a composite print, maybe a metal stator printed and an additional frame.
 I am wondering what advantages a free structure could create (like a metal mesh, etc.). I would think this could be benefical but at quite some cost. In this case I would consider a printed metal plate with a mesh backing for stability. A thermoplastic frame around it. You would also need to grind the surface flat, as metal prints will be not precise enough.
  
 I agree that it is an interesting idea, but I get the impression that it can't be done on the "cheap" if you want to get good results.
  
 I thought of using a carbon stator, but I would give it a FR4 frame, so I have no extra capacity.
  
 Read the whole thread, it's brilliant. There is so much information and detail in it.
 And please share your results with us, no matter if it's a success or not. You will help others to get to something better.
  
 Greetings
 Georg


----------



## wppk

thank you both,Kerry an Georg, well, as I said, I am not intending to do it myself, I was just imagining a possibly new idea. Not knowing if it was really new.
 Maybe it is because I am french,  but there is something I don't understand, Georg, when you talk about the FR4. What is FR4 ? if it is not too long to explain.
 yes, I feel like reading the whole thread.
  
 there is also something very interesting for me in what you say here, and it brings a question or more, because I succeeded in repairing several of my stax lambda pro headphones ( I have a recording studio, giving french dubbing for movies lessons and my students are happy to work with these, which I really want them to do, to give them an idea of what quality is, and then, make them feel like making quality in their acting) but, couldn't on some.I started to read on head-fi about it, but couldn't find any thread where people had done what I did to repair them, and how to make it when their is a persisting problem. To explain : My stax ( BTW the lambda pros are far better than the 007 or 009 for monitoring, and my favorite is a (very rare) " spirit lambda pro" for that) had, of course, because they were old, the usual static issue caused by the protective membrane teared off by aging, and, after a while, the "heat" of my head made condensation, microscopic , but important enough to reach the stator and make little short circuits. and then static noises.
 I noticed that, because they worked perfectly well when I had not used them for a while, and, after one out two hours, started to make these disturbing static noises. most people say that no one can repair these, because the parts are glued, and then, opening is destroying them. Also, that the smallest dust particles can also give these static problems, and when opening them, dust gets in it and the driver is wasted. Well, I had nothing to loose, indeed, with those among my stax which didn't work well anymore, and I decided to try to mend them by myself. I had tried before to have it done by someone who said he was a specialist, but when I received my headphones back, nothing had changed.
 well, I had to find Mylar to replace the damaged one, and a good glue. That is what I did. Opened the driver, not until the membrane that make the sound, but only reaching the protective one, and made it so that a new protective membrane was here and couldn't move. It worked really great, and effectively completely repair 4 lambdas, like that. But for those which had an imbalance, I didn't find a way to mend. And for some, too, I still had static after that (not on the four ones I mentioned, that are definitely repaired) . probably because of dust on the central membrane. dismounted the driver completely, and changed the membrane, which was damaged, with the same Mylar I used for the protection membrane. It worked, but the sound was weak, like I already thought that it would, and I was even surprised to have any sound, because the Mylar I had found was not conductive. Tried, then, to cover the Mylar with a very very thin gold leaf, the kind of gold leaf which is used by painting menders, you know, to fill holes in gold, and platter the frame of paintings with gold. I had that because my mother used that when she was still on earth... but I had no better result. Bought a conductive spray, had no better result. Now, what you say :"you only want the active area of the membrane conductive on the stator." is something new for me. Do you think that it could have worked if I had not made that on the complete membrane ? I have seen other people on head-fi saying that to recoat a membrane, one could use a simple anti static liquid... Would that be true ? I am quite lost now in my mending, for I would like to repair my other stax, and have been stuck for days now at this point. Left a classified to find a lambda with only one driver working, and I just found one form a very nice dutch man and head-fier. Will receive it soon. But I have other stax lambdas to repair, and so, I would like to know how to make a complete repair in any situation. to re-balance unbalanced drivers. To avoid the statics. And to change the membrane.
 Maybe all the solutions are on head fi, but not all together in one post and thread, and I think that would help to have it in an easy to find place, with all necessary details.
 many people have an old damaged lambda pro, I think. Maybe they would be happy to repair it you don't need too much apparatus and machines, just a cutter, soldering iron, soldering lead, glue, also another kind of glue, which has to be heated to melt to be used ( sorry can't think of the right expression in English) long lasting Mylar, observation and patience.
 and the knowledge that I don't have about when the repair cannot by completed with my system.  
 Does anyone have experience and solutions for that ?


----------



## GvTT

Hello wppk,
  
 although I think others like Wachara can answer your questions better, I will try to fill your questions.
 First of all I have to mention that I have not yet built or repaired any ESL speaker. I have the tools and material ordered, started building a Mylar stretcher (inner tyre stretcher).
  
 When I spoke of FR4 I was referring to the glass fibre reinforced epoxy plates use for makeing PCB's in electronics.
  
 As for your tries to make the membare conductive: you need a very low conductivity, in other words a very high resistance. This is mandatory to keep the static charge from moving on the surface of the membrane when the membrane if moving (making sound). Hence gold, conductive sprays, etc. are not the prime choice. Some people rub carbon in, use Elvamide and other used antistatic clearners, like Wachara. His choice sound logic to me, is prooven, so I will use this method in my first trials.
  
 There was a french magazine in the 70th?, publiched by Hiraga, the L'Audiophile. One of their articles covered the built of an ESL headphone by Philip Hiraga. Maybe you can loan it via a library. The description is not as complete as in this thread, but might be easier for you to read, as it is in French and much much shorter.
  
 As glue to fix the membrage Wachara uses "UHU contact", what you should be able to get easiely. It is available here in Germany, and UHU is marketed in France as well. As Mylar is not easy to glue, I recommend this too.
  
 When making the membrane assembly, the trick seems to me to get the right tension. I will try to measure it's frequency response on tab with a microphone prior to gluing it. As to this tread it sould be somewhat between 100 and 150Hz, and mainly affect the bass, as long as the membrane stays stable.
  
 As for the active area of the stator:
 an ESL speaker presents a capacitive load to the amplifier. This load is defined by the spacing of the stators and their conductive area. By reducing the conductive area to the area where the membrane can actually move, you minimize the capacitive load withpout loosing sound pressure. The amplifier just has to do less work. (leaving the stator conductive everywere is just like adding a resistor in parallel to a conventional speaker. You can still listen, but your amp has to work harder, probably not increasing sound quality by this).
  
 Greetings
 Georg


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## wppk

WOW ! that's an answer ! thank you very much for all your so nice explainations. so nice  of you !


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## GvTT

Hello,
  
 a link for those that like math:
http://www.high-amp.de/html/electrostatic-principle.html
 On this page it is explained in more detail why the membrane should have a high resistance.
 Andreas Rauenbühler is referring here to a membrane staying flat while moving.
 This assumption simplifies the math but reflects the general situation.
  
 You find his main page at:
http://www.high-amp.de/html/frame.html
  
 Greetings
 Georg


----------



## wppk

oh dear ! it 's far too simple for me ! 
 seriously, the concept is easily understandable, but the math..... I always had problems with math.. Happily, people like Andreas exist for people like me to put the result in their ears only, nor even passing thru the head. Too bad, I would have liked to be able to do so excellent work.
 thanks georg


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## chinsettawong

Looking at the formula, my head is already starting to swell.


----------



## Muamp

Hi chinsettawong,
  
 I came across your blog entry by chance, and that made me decide to become a member of Head-Fi forum.
 So far what I have read of the 135 pages is awesome information, and I love your latest ESHS designs, professional finish!
 I have been DIYing my own ESHS for about a year now in my spare time, and would love to post some photos of my _still prototype_ panels and energiser, but as a new member I am not yet allowed to post photos, just text posts. I will be allowed to post photos after a while as a member.... that's if your interested in seeing them?
 But, I will also want to pick your brain, especially on matters like the mechanics. I have a home CNC for copper clad drilling and cutting and PCB making, but not much to produce / mould / print plastics etc.
 I guess that many of my questions will be answered by the time I have read all 135 pages in this thread....
 I will keep reading, and probably asking some questions real soon....
  
 David (Muamp).


----------



## chinsettawong

Hi David,
  
 I would love to see your work.  Please do share your pictures (lots of them) and your experience with us.  I'm sure that we can learn from each other.
  
 Wachara C.


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## chinsettawong

I managed to cut some parts today.  They didn't turn out as good as I would like to, but let's see how they'll make sound.
  
 The stators are cut out from 1 mm PCB and spacers are 0.5 mm.  I'll try to cut some stators from a 0.6 mm PCB tomorrow.  The holes are 0.5 mm and the gap between two vertical holes is 0.25 mm.  The active area is 8 mm.  Now I need to find some really small cables to with the earphones.


----------



## GvTT

Hello wppk,
 hello all,
  
 I found the link I promised wppk: http://www.amateuraudio.fr/images/audiop1.pdf  (Philippe Hiraga, L'Audiophile 1989)
 This article started my interest in ESL Headphones.
  
 @Wachara: I think you should go much thinner with spacers and the stator, considering the small diameter.
 The deflection of the membrane is going to be far less than in a full sized headphone. The resonance frequency of the stator is much, much higher, you will not need the thickness of the plates as machined. I would expect the sound not to pass freely through there. I don't have the formulas at hand, but for doing the scaling, I would try to keep the resonance frequency of the stator in the range of a full sized one (or choose then thinnest material I dare to work with if this is the limiting factor).
  
 I would not be surprised if you can go with 0,2 to 0.25mm spacer thickness and the same for the stator. The required membrane tension is probably much lower then in full sized headphones. But this is just a feeling, I am curious to read on your results.
  
 The parts look really nice. Congratulations to your CNC. Drilling 0.5mm that close is not everybody's favorite. Form the picture I can only guess some missalignments. Did you pre-drill with a sturdy centering drill prior to drilling the 2xD with 0.5mm?
  
 Greetings
 Georg


----------



## chinsettawong

Hi Georg,
  
 I know I should go with much thinner materials.  However, I don't have those on hand at the moment.  
  
 I was really surprised that my DIY CNC could actually do a pretty good job on such small parts.  There was no misalignment.  It's just that my CAD, for some reasons, did not allow me to cut the circle and the tab in one go.  So, I had to cut the circle and the tab afterword.  It turned out that the cuts were overlapping.  
  
 Anyway, let's make them sing first and then we can do some modifications later. 
  
 Wachara C.


----------



## ThePCWizard

Interesting Design you have for your headphones, I don't have access to the materials needed to make electrostatic headphones, but I now have some design inspiration for a pair I've been planning!


----------



## GvTT

Hi Wachara,
  
 as for the scaling of the speakers to find the right dimensions for you "in ear" I came up with this:
  
 Full size speaker (headphone)
 diameter: ca. 80mm
 spacer 0,5mm
 => membrane displacement +20% safety = 0,5mm => displacement = 0.4mm
  
 In Ear:
 diameter: ca. 10mm
 membrane displacement = 0.4mm * 80mm/10mm = 0,4/8 = 0,05mm

 If you reduce the spacer to 0,2mm you increase the electrostatic forces by factor 2.5.
 This will increase the membrane displacement by a little less, not knowing how much, I assume it being proportional.
 => Membrane displacement expected: 0.125mm (0,05mm * 2,5)
 Adding 20% safety, I come up with 0,15mm
  
 (spacer 0.175: factor 2.86 => 0.05 * factor * safty =  0.17mm)
  
 So I would try 0.2mm spacer thickness.
  
 You could try to machine the spacer down or mill a recess in the stator.
 If you recess the stator you need to find a different way to connect the stator electrically.
 One way could be to drill a hole, insert a copper pin from the rear, almost flush with the surface and solder it. Afterwards you have to grind the solder spot flat, flush with the surface.
  
 As for the stator thickness: a plate stiffness is proportional to the power of 3 of it's lateral size. => Half the diameter of the plate means a stiffness increase of 8, mass going down by 4 => Eigenfrequency increases by factor 32. And this is just for halfing the diameter.
 And again, for those who like math:
https://en.wikipedia.org/wiki/Bending_of_plates
https://en.wikipedia.org/wiki/Vibration_of_plates
  
 In other words, the stiffness of the stator should not be any issue. As long as you can handle the material you will (most likely) be fine.
 Have you thought about etching the stator from a metal-foil?
  
 Greetings
 Georg


----------



## Muamp

I still cannot add photos to threads or to change the default avatar. How do I get permissions to do this?
  
 David.


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## wppk

hello there
 I want to thank you very very much indeed, because owe to your explaintations I was able to change the main membranes of all my stax lamdbas and they work perfectly now. Well, just finishing the last now but there is no reason why it should not work.
 I couldn't control the tension of the mylar, but the two ways sound identical, evenif not scientificly measured. didn't use the same glue as you did, had no opportunity to find it yet, will tell you, if you whish, if it is tille working well after a while
 i am very happy to have been able to do that. Thanks to you again !


----------



## Muamp

It would appear I have to write 5 or more TEXT posts as a new member before Head-Fi will allow me to post pictures of my ESHS.
 I want to get involved with this tread, but because, I guess rules to stop spammers and advertisers etc, I am forced to wait until I have written more text posts.
  
 David.


----------



## Muamp

At last, I am allowed to add my photos:
  
 This is just a small selection from the last years work in my spare time. I can bore you silly with many more.
 I have put them in a sort of chronological order.
  

 My very first attempt with mild steel stators and transformer energiser.
  

 I attempted to make my own audio transformers on torroidal cores.
 This is a core from a 9 volt power transformer. It wasn't very successful.
 The winding was by hand with a half metre bobbin.
  

 This is my transformer energiser and a home made 18w+18w amp.
  

 Small on-ear panels with mild steel stators, I later used wire mesh.
  

 Still with 0.7mm thick steel perforated with 2mm holes at a pitch of 5mm.
 Neoprene spacers and "clingfilm" diaphragm, which sounded brilliant!
  

  

 And this is how it looked when tested.
  

  

 Testing the panel with a condensor measurement mic' and Audacity as a signal generator.
  
 CONTINUED IN NEXT POST......


----------



## Muamp

MORE....
  

 My first attempt at a valve energiser. It is the TubeCAD of November 1999.
  

 Modification based on the same circuit.
  

 Some more mods' and a PSU on PCBs cut on my home CNC.
 SMPS's now used for valve heaters, much better.
 PCB mount Triads for the power rails.
  

 Heater SMPS and Vdc bias with a 48v transformer and x8 multiplier,.. more detail as to why I prefer this method later....
  

 Close up of the Triads, PCB mounted.
  

 This is the PCB I have just CNCed for the valve energiser. I will build it later this week, when I have time.
 I use CadSoft Eagle FreeWare and PCG-GCode ULP, also free.
  

 These are my CNC panels. Various on 0.5mm FR4 and 1mm FR4.
 Some here are the standard 2mm holes with pitch of 5mm, others are 1.5mm holes, with I think 4mm pitch,.. I can check....
 Also some plastic spacers on 0.5mm sheet plastic cut with a compas cutter.
 I will also try Neoprene spacers and both Mylar 2um and clingfilm diaphragms.
 Later, another day I can show my home made diaphragm stretcher, it is a copy of one I saw on Google a while back.
  
 I have many questions for you guys, hope I haven't bored you too much.
 One day I hope to be at the same level as Wachara C.
  
 Cheers,
  
 David (Muamp).


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## davidsh

Bore me silly 
Nice work


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## chinsettawong

Hi Muamp,
  
 Thanks for sharing the pictures.  How do you like headphones?  How big is the active diaphragm area?


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## Muamp

The CNC panels are outer dia. 90mm, inner dia. 70mm.
 The steel panel is inner dia. 80mm, outer hexagonal.
 The on-ear panels are 1" inner dia. cut with a hole punch. I only have a 1" punch, so it had to be 1".
  
  
 Muamp.


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## GvTT

Hello,
  
 I have been asked what coating to use, regarding availability in Europe.
  
 Here are a few things I already read in this thread or at other locations:
  
 - graphite powder (rubbed in, buffed) => [ risk of dust, crackling, reports of not too long lived...]
 - soap => [ sensitive to humidity, reports of short live]
 - elvamide => [apparently a mess to work with, never read a detailed report about problems, just things like "ït's troublesome"]
 - nylon (dissolved) => any comments?
 - antistatic cleaning gel => recommended by many in this thread, seams to be working fine
 - (antistatic?) floor cleaner => seems to me like something between the cleaning gel and soap
  
 - antistatic vinyl record cleane => read about this somwhere else, long ago, but sounds intriguing.
       should be quite wear resistant. I am just a little worried, it might be conductive. Any comments on this?
  
 The reason for this post is the antistatic vinyl cleaner. I am really interested if anyone has used this and can report here.
  
 Kind regards
 Georg


----------



## chinsettawong

Hi Georg,
  
 If you already have the vinyl cleaner, please try it and let us know how well it performs.
  
 A few years ago, when I want to test some coating materials to see if they can perform, here are what I do:
  
 1.  I tension the Mylar on my inner tire stretcher.
  
 2.  I rub on different coating materials on the Mylar surface at different location and use a permanent pen to write on the Mylar which type of coating material it is on each location.
  
 3.  When the coatings are dry, I use a gigaohm meter to check the resistance and make a record.
  
 4.  I recheck the resistance again on the next day for the next 3 weeks and make a record.
  
 Most of the antistatic cleaners that I've tried measured the same or with similar results after 3 weeks.  There're a few that didn't measure well even on the very first day, and of course didn't improve after many days have past.
  
 The floor cleaner that I recommended was tested with very good result and therefore I 've been using it for the past few years.  It's cheap and readily available here in my country.
  
 Wachara C.


----------



## davidsh

If you are worried about low resistance of the anti static vinyl cleaning stuff, I guess you could check with a normal DMM whether the resistance is measurable.


----------



## wppk

hello
 would anyone be intersted to know that I tested the uhu contact glue for the membrane as I was (very kindly) advised to try, and that it didn't work well for me, and then, I found another glue, which works ?
 If yes, I will write about it.
 for the question of the antistatic product, does anybodu know what to find easly in France ? I have tried something that worked but the antistatic effect faded away... I will try other products here and say if I find a good one, if it helps


----------



## chinsettawong

Hi Wppk,
  
 Please do share with us your findings.
  
 By the way, there are many kinds of contact glue on the market.  The ones that work well for me are those "*yellow rubber glue*".  It has bad smell and certainly is solvent base.


----------



## wppk

ok
 thank you for the information
 I just tested this and it works fine
 http://www.simplyspeakers.com/speaker-repair-adhesive-mi-3035.html
 there is a smell too, but not horrible, they advise to use the glue in an airy area, anyway.
 it is efficient and faster than the others I tested.
 I was talking to Georg, ( so nice man ! ) and he said that some people would be interested in knowing how I repair stax lambdas. Is it the case ? And is it the right place to do so, or must I use another post, or create one ?
 thanks


----------



## chinsettawong

What problem do you have with your Stax Lambda?
  
 There is nothing special about it.  I'm sure that you can shoot your questions here and some of us can help you.


----------



## wppk

I have to replace the membrane ( not the protective one, I did it, but the product I used for the antistatic doesn't last, so I am going to try others).
 I don't have lots of questions, in fact, I have been repairng seven lambdas yet, ( protective membrane) and as stax lambdas a said not to be reparable, I thought that maybe it would interest some people to know how I repaired what I could repair.
 but maybe other people already did it and wrote it on head fi ? I never found that, and when I didn't know how to repair them, I talked to someone who proposed to repair my first lambda, wich had static noises. He told me that as far as he knew, he was the only person who was repairing lambdas. But when I got the lambda back, the issue was still there. so as I had nothing to loose, I decided to try to mend them by myself, and I did. wat I was asking on this thread a few minutes ago was if some people would be interested to know how to do it, and then, try to repair their lambdas by themselves. knowing that I couldn't fix all problems of all my stax, and that today, I am searching ways of making a whole repair. It can work, because I changed the sound membrane, it worked perfectly well, but finally, the product ( antistatic) I was using lost it's effect, so I have to find another one, and also, the best glue for the mylar.
 of course, I cannort guarantee to people who would try to mend their lambdas that it will be working, but it worked for me, until I had an imbalance problem, added to the static noises, and then, I have to repalce the sound membrane, as firstly said.


----------



## chinsettawong

Please do share with us your experience.


----------



## wppk

ok
 it will take some time because I will have to take pictures and son on. but I will do


----------



## wppk

do you know if other people are repairing lambdas ?


----------



## Muamp

- graphite powder (rubbed in, buffed) => [ risk of dust, crackling, reports of not too long lived...]
- soap => [ sensitive to humidity, reports of short live]
- elvamide => [apparently a mess to work with, never read a detailed report about problems, just things like "ït's troublesome"]
- nylon (dissolved) => any comments?
- antistatic cleaning gel => recommended by many in this thread, seams to be working fine
- (antistatic?) floor cleaner => seems to me like something between the cleaning gel and soap
- antistatic vinyl record cleane => read about this somwhere else, long ago, but sounds intriguing.
 should be quite wear resistant. I am just a little worried, it might be conductive. Any comments on this?


Hi GvTT,

Elvamide and Nylon (disolved) are one and the same. Elvamide is nylon crystal(s).
The method to disolve the crystals is complex and dangerous if you do not have a fume extraction cubical.
You need to disolve the crystals by heating them in Methanol or Ethanol, which produces fumes that you do not want to inhale!
If you breathe the the Methanol fumes (for prolonged time) it can cause blindness or death.
Best avoid this method!
I use RS Anti-Static Spray (RS 514-486). I have been using it successfully for a year. Panels that I sprayed a year ago are still working fine.
It is also cheap!
In USA they commonly use Licron Crystal spray. There are a couple of suppliers in the UK that sell it, but it costs about £34.
Because it is expensive, I have not tried it....

Muamp.


----------



## GvTT

Hello Muamp,
  
 thank you very much fo you input on the coatings. I will see that I can actually measure the resistance when I coat. There has been an interesting article in www.hackaday.com not long ago on measuring very small currents (https://dannyelectronics.wordpress.com/2016/01/28/the-nano-ammeter-you-already-have/) what might be usefull to measure the resistance of a coating.
  
 Thanks as well for correcting me on Elvamide, I was not aware that this is actually Nylon.
  
 ====================================
  
 The link to the RS Antistatic spray is highly appreciated, I will put it on the order lift for the next batch.
  
 ====================================
  
 @Wppk: please give us more detail on your fail with the UHU Contact.
 I recently bought UHU Contact Gel. Tonight I tried it on Mylar.
  
 I cleaned a plate of copper (ScotchBright),
 Applied UHU Contact Gel to a ca. 6mm wide section. (Clear)
 To another ca. 6mm wide section I applied Pattex Contact Gel (yellow)
 I applied it as thin as I could (was quite difficult as it dried before I could distribute it the way I wanted)
 About 2 minutes later I pressed some 3ym Mylar (DuPont Terfphane) into it, rubbed it flat with my fingers.
 I could not smell strong dissolvent fumes any more, so I did not wait the time given on the glue canisters.
  
 About 1h later I tried to pull of the Mylar, with the following result:
 - when pulling in plane, both (UHU and Pattex) sides tore, the Mylar plastified first. I could not notice an creeping or peeling.
 - when peeling the remains off (pulling in normal direction to the gluing plane, no shear force in the glue), the Pattex was quite a bit stronger than the UHU.
 - The UHU gave the thinner film, the more flat joint.
  
 I will repeat this with a longer curing period.
  
 Both UHU and Pattex require both surfaces to be coated with glue (contact glue). Since I think this is not feasible for membranes I did not wait the recommended 10 to 25 min for the glue to dry. I wanted some dissolvent left active in the glue.
  
 +++++++++++++++++++++++++++
  
 @Wachara and others: how long do you let the glue dry before you cut the membrane out of the stretched Mylar?
  
 Greetings
 Georg


----------



## wppk

Hi Georg
 I respected the terms of the notice for the uhu, and, simply, it didn't glue , or very unefficiently.. The point is, in my opinion, that the uhu contact glue one can find in france ( hard to find) is not the same as the one you use, and here, we have several models of uhu contact glue, under the same name.


----------



## wppk

also, the mylar I use may not be the same as the one all of you use ?
 The only ggod mylar I found here  (good because of the thikness and the lenght in time) was in a DIY store, and its purpose is to cover the furniture in a house when one leaves it for a long while.
 even if I doubt that its properties are very different from other mylars, it may not be unuseful to say that.


----------



## GvTT

Hi,
  
 how are you getting a thing uniform glue film?
 I can apply a thin layer, but I do not get it uniformly think. In my tries it was drying so fast, that I could not really spread it as evenly as I would like.
  
 Do you dillute the contact glue?
 Checking on the internet I found that ethyl acetate can be used to dissolve Pattex and similar glues, what would include UHU Contact
  
 UHU contact gel: Polychloropren based
 Pattex contact: Polychlorbutadien (what seems to be the same - please correct me if I am wrong)
  
 I was thinking of mixing some glue with ethyl acetate to make it easier to apply it to the surface in a thin film.
  
 Greetings
 Georg


----------



## chinsettawong

Don't worry too much about the uniformity of the glue film. This kind of glue is quite flexible and if you clamp your driver well, it shouldn't matter much.

I don't worry too much about it. 

Sent from my SM-N9005 using Tapatalk


----------



## Muamp

Just (kind of) finished my valve energiser.
 All four PCBs are fixed to an MDF base with front and back panels. I use insulating hard foam to mount the boards. It enables me to have a very firm fix, but also allows for easy removal for future work.....
 Power socket on back panel and recessed phono sockets on front. I will also put a Stax pro socket on the front. (Waiting for the pins to arrive from Taiwan, which I read about in an earlier post).
 The top will be matt black, as will be the front and back panels, with four sets of circlular vent holes, one above each of the valves and a series of three rows of vent holes at the back for the PSU.
  

  

  

  
 I can now spend some time on panel building!
  
 Muamp (David).


----------



## chinsettawong

Hi David,
  
 That's a nice looking amp.  What tubes are you using?
  
 Can't wait to see your finished amp.
  
 Wachara C.


----------



## Muamp

@ Wachara C.
I am still using the ECC83's and 5965's, a modified version on the TubeCAD design, November 1999.
I will, oneday build a similar cct with EL84's for the O/P tubes, but since this cct is so good, I don't see the need at the moment.
I will now spend some time on panel building, I have only had my CNC since last December, so now I want to do many FR4 PCB stators and spacers.
Are you using a T2...? can you tell me about it, what tubes and how it compares to to TubeCAD cct...

David (Muamp).


----------



## GvTT

Hello,
  
 neat! I really like the idea of the hard foam!
 Seams easier than bolting the board down, probably even the better support.
  
 Tubecad is always a good source for information, curcuits, etc. John is also very helpful! If you do modifications/improvemtents to his circuits, please let him und us know!
  
 Greetings
 Georg


----------



## GvTT

Hello,
  
 I spent this weekend with my family and the workshop, milling my first set of stators.
  
 The stators are drilled, they need the final trimming on the outside, but this will have to wait:
  

 The stators are cut by hand from a 1mm FR4 plate.
  

 Now on the machine. Starting the pattern with 1.6mm (progressing to 2.9mm)
  

 The result: 4 drilled stators and 4 cut spacers. You can clearly see the regions with different whole sizes.

 A nightmare to deburr. Does someone have a trick here? How do you clean up the edges?
  
 Today I did just the drilling 1.6mm / 2.2mm / 2.6mm / 2.8mm and the hole for mounting (3.05mm).
  
 Next step is the milling of the outer shape and the stators.
  
 Greetings
 Georg


----------



## chinsettawong

Hi Georg,

Nice looking stator! 

About deburring, I use sand paper. No special technique required.


----------



## chinsettawong

muamp said:


> @ Wachara C.
> I am still using the ECC83's and 5965's, a modified version on the TubeCAD design, November 1999.
> I will, oneday build a similar cct with EL84's for the O/P tubes, but since this cct is so good, I don't see the need at the moment.
> I will now spend some time on panel building, I have only had my CNC since last December, so now I want to do many FR4 PCB stators and spacers.
> ...


 
  
 Hi David,
  
 That's interesting.  What voltage are you running the amp at?  How do you like its sound?
  
 I don't use DIY T2 that often.  But DIY T2 is so far the best among all the amps that I have - DIY T2, KGSSHV, KGST, eXStatA, TubeCAD amp, and SR007t.  DIY T2 uses 4 of EL34 and 4 of 6DJ8.  It has so much power that can drive all my headphones with ease.  There is no comparison between TubeCAD amp and DIY T2.  DIY T2 is way more supeior.  
  
 Wachara C.


----------



## Muamp

@ GvTT
 Thanks for the thread links to the T2. I will read this later in the week.
 The main differences are my energiser uses single Metal Oxide resistors on the anodes. They are rated at 3W, 500v operating voltage. These do not produce any noise in the circuit, which was mensioned in the TubeCAD article. These Metal Oxides resistors were probably not around back them.... . The heater supplies are four separate 12v switched mode power supplies. The four tubes are each supplied with it's own supply, where the heaters on each tube are powered in series at 12v and commoned on each cathode. With the potential difference between the ECC83 cathode and 5965 cathode being at about 283v it is far too big to use one heater supply per channel unless it is floating, which is something I don't like doing. The SMPS's on the heaters eliminate mains hum.
 The DC bias voltage is 543v (48v RMS from the transformer feeding an 8* multiplier; 2^1/2 * 48 *8 = 543v). The common is fed to the CT of the HT. I do not use a virtual common by using a resistor network between the plates.
 There is not a volume control. I use either a preamp (Rotel RC971) or feed the energiser directly from my PC sound card... The plate voltage peak to peak when using the PC as a source measures a maximum output of around 1200v (measured on an oscilloscope), more than enough even with ESHS plates using each spacer as wide as 1.1mm.
  
 @ Wachara
 The HT is about +/- 310v. Maybe a bit more...
 I only have two energisers. My original transformer energiser, and this valve energiser.
 The valve energiser is obviously far bettter, especially at higher frequencies where the transformers really struggle above 15-16kHz...
 The transformer energiser has now been placed in the garage....
  
 Muamp (David).


----------



## wppk

hi there
 I have repaired another lambda owe to your kindness and to the fact that you told me what product to use to make the mylar conductive.
  
 first, the driver will seem ugly and dirty to you ( and they are) it is due to the fact that I have been working on these ones again and again and they were close to the trash, as I could never succeed in  mending them. but now they work very fine !
 Georg, by the way, I nearly repaired the one with the broken stator I told you about, but I still have bad contacts sometimes, that give imabalance from time to time, and the imbalance goes away depending on the hand pressure I put on the recomposed driver, so I am wondering wether, on some stax, the imabalance could come from a ill position of the elements of the driver, and not only because of the membrane to be changed
 so the parts of the driver you will see are ugly, because each time I finished a repair operation,  I had to glue the whole with glue that melts with heat( don’t know the english word, then, as I probably will have to use it quite a few times in the explaination, I will call it hot glue. sorry, but I am still french and not on my way to become english nor american before a few decades) please correct me when you read. I insist on the fact that my other mendings are cleaner than what you will see.
 my hands are dirty too, lol, because I am in a wide repairing moment, and one of my printers (I am a writer and I print my books myself), had a big issue. so I have black ink on my hands.(yes, the printer is repaired too, after a three days fierce struggle against the machine)
 what I will show here is what I do, I offer no guarantee that you will be able to have the same result (seven lambdas repaired now out of eight I own) but I think it will have good results on many old lambdas that don’t work anymore, and it would be too bad to leave them in a box if you have some. In my opinion, as a sound engineer and french dubber for movies, they are the best headphones ever for monitoring. and a big pleasure to listen to.
 well first, I will show how to replace the protective membrane. This is most of the time the only issue of a lambda, and the point is that when we use it a long time, the warmth of our head makes condensation, humidity, this humidity is not stopped by the membrane, which has holes, and makes short circuits that give the static noises about which many stax user are talking about. the statics can apparently also be given by dust. But I repaired the stax in a non dust-free room, and I had no static issue after mending, only for my last lambda, but I think it is coming from a bad contact.
 if you want to be sure you have this very problem of the protective membrane, try your stax, use it long enough for it to sound static problems. Then, stop using it. If, the following day, at the moment when you put the headphones on your head, you have no static noises, it means that the humidity has gone, and then, no static problem. If you still have static problèmes, then, there maybe dust on the central (sounding ) membrane, or if you have an imbalance, you probably have dust on it, or a problem with it.
 But for the time being, let’s talk about the protective membrane, that I will call the PM. ( and MM for the main membrane, the one that makes the sound)
 To change your protective membrane is very possible if you are patient, attentive, and take care not to brake the copper pieces of the stator that are used to solder the wires. they are very fragile, don’t move them nor change their position.
 first, you have to remove the cans, which is very easy, gently removing its attaches on the sides. Take a photo of your lambda before you dissassemble it, because there are possibilities to mix things when reassembling it, things must be put back in a certain way.
  
 unplug your stax form the amp. and be very careful, there are 540 volts in there, said to be tethal. I advise to wear plastic gloves
  
 No need to remove the pads, you have four screws on the corners here

  
 then, to remove the parts that hold the driver, push on the part where you can see I do, This will make the part pop out, don't be too strong, but it needs to be firm anyway.
  

  
 notice the position of the wires that you will unsolder and solder after the mending
 the wire with a continus white stripe is the +, the center is very probably the 540 volts wire,
 le last one on the left is the -.
  
  

 Once unsoldered, maitain with a bit of tape the stopper next to the wires, or it can fall down somwhere, and you can make mistakes while reassembling
  

 remove the driver from the parts on which it is glued. Insist, it will come.
 the PM is this membrane which was on the side of your ear when you listened to the headphones. The MM cannot be seen at that time, so you cannot make a mistake.
 the PM is held by a very thin metal ring, maybe a tenth of a millimeter,  use a cutter to remove it, and you don't have to keep it or reuse it, it doesn't affect the sound.
 here are two of these rings :

 when you have removed it, the damaged PM came with it.
 you have to remove, then, the ticker plastic ring that was just stick to the thin ring. still with the cutter. 
  
 on the picture, it is on the left. You must leave the driver intact, meaning the black-cooper-copper-black rings on the right. the left ring is just there to hold the PM.

 Then, you will need new mylar. The best I found wis used in houses, on furniture, when one leaves for a long while. It is supposed to last, then. And even if I can't be sure of it, because my oldest repairs are only six month old ( The mylar is still perfect now)
 I think it is a good product to use for that. it must be very thin, mine is 7 microns. but probably thinner could work,as originally, stax uses thinner. But when I listen to my repaired stax, if  I compare the sound from an original driver to a repaired one, I cannot hear any différence.
 and (maybe i am repeating myslef, hope not ?) I have very good ears.rather special. When I was at the information days of the army, long ago, they were very surprised, and told me that in a case of war, I would have worked in a submarine, listenig to every sound
 I could then hear for 5 hz to 50 000. Know, I am fifty, so It must not be the same. But I still can hear quite good, and it is important to say that, I think, when you are explianing that you are repairing your stax.
  
 so, on the picture just up there, you can see the side of the driver. there are two copper parts in the "center", these are the stators, and you will only have to separate them with a cutter if you have to change the MM.
  
 to change this PM, you have to find a good glue. I tried many, and even another one, that I wrote about previously on the thread, but today, I could see that it was not the best glue for the lambda membranes.
 here is the roller glue I am using
 http://www.hobbylobby.com/Scrapbook-Paper-Crafts/Glues-Adhesives/Runners/E-Z-Runner-Vellum-Tape/p/13855
  
 then, you have to glue the side of the plastic ring with this roller. You can replace the mylar in the first seconds, but after, you won't be able to do it without tearing it.
 cut a piece of mylar a bit larger than the ring, and take care there is no hole in it, no noticeable dust on it. put the mylar on one side, then, turn the driver, mylar-glued side next to your belly. Block it on your belly, and stretch very gently the mylar, to put the opposite side of it on the glue. Your don't need to have a very strongly strecthed mylar. if you do, it will affect the sound on certains frequencies.
  

  
  
  

 here is the result. you can stretch it a bit more, gently with your thumb on the ring. make sure there is no hole, or you will have to redo it.
 normally, the glued spaces are white or grey when using the good glue I gave the link to. On this picture, I used another glue which was not good enouch, and I had to redo.
  
  

 cut the remaining mylar with a cutter blade
  
  
  

 glue the result on the edges of the ring , with the roller
 once glued :
  

  
 put the ring back on the driver
  
  

  
 result

  
 using a hot glue pistol, put glue all around on the sides, the edge of the whole and make it thin with the end of the pistol


 result :

  
  
  

 glue the ring that will be stuck against its standing part
  

 result
 put it back on its standing part
  
  
  
 use the same hot glue to glue the driver back to its standing part.


  
 result

  

 re solder the three wires



  
 when putting back in the can, take care that the thinner part of the pad must be in front of the thicker part of the can

  
 put back the stopper

  
 remount the screws and the cans, you're done !
  
  
 If you still are expermienting sound problems, then the MM very probably is the source. here is how I change it
  

 with the cutter, seperate the two copper parts, the stators, as shown here. Sometimes it is hard, sometimes easy. take care to the blade, don't get wounded !
 you only can do that after you have removed the glue wich is originally on the sides of the driver, still with the cutter.
 after that, be gentle with all your moves. it is very fragile inside.
  
  
  

 the MM will appear here, mine is terribly damaged, because as I knew exactly what and how to do, I was not very gentle. Stax makes me suffer, I have to revenge somhow !
  
  


 the MM is removed and the ring cleaned. You can clean the stator if needed, with something which will not leave humidity : alcohol, for instance, or an compressed air .
  

 glue the copper (side) , take care not to put glue on the rest of the stator. if you do, clean it with alcohol
  
  

  
 make sure the mylar is ok
  
  
  

 put it on one length and press to glue well
  

 do the same on the opposite side, stretching a bit
  

 do the same on the other sides, one by one
  

  

  

 put a bit of the static liquid on a handkerchief, and put the product on the mylar (one side is enough). don't spread the liquide on the whole mylar, only on the effective part of it (not on the sides, you can leave half a cm without product on the sides. if you put it on the whole, it will not work as well as partly.
  

  

 glue the side of the ring with the roller. no glue on the rest of the mylar is much better !!!
  

 stick it back. Don't wait too long to do this. Glue the other side of the stator wich will be stuck also back
 then, glue the edges of the reassembled stator with the hot glue, and follow the same explainations as for the PM for the rest.
 You're done !


----------



## wppk

very good job indeed Georg !!!


----------



## Muamp

Can anyone help me with this?

I have just taken delivery on "10pc CMC 8P Tube Socket Gold plated Pin Hex-Snap 2x10mm Hole". These are the pins to make a Stax Pro Socket.
I was a bit suprised, thinking they would be bigger. I had read somewhere that XLR pins were the same size as the Stax Pro. These are smaller.
Could some one measure the diameter of the Stax pins on the plug. Ideally if you have a micrometer, even better.
Cheers.


----------



## Ghost Pack

muamp said:


> Can anyone help me with this?
> 
> I have just taken delivery on "10pc CMC 8P Tube Socket Gold plated Pin Hex-Snap 2x10mm Hole". These are the pins to make a Stax Pro Socket.
> I was a bit suprised, thinking they would be bigger. I had read somewhere that XLR pins were the same size as the Stax Pro. These are smaller.
> ...


 
  
 Stax pins (Male 5/6 pin amphenol connectors) are exactly 2.38mm in diameter, with clearance to 2.4mm. Sounds like you accidentally got a 165 or a 91T series connector.
  
These are the ones you want. There should be a female connector down near the amphernol 5 and 6 pin connectors that's the exact dimensions.


----------



## Ghost Pack

> Originally Posted by *GvTT* /img/forum/go_quote.gif
> 
> 
> A nightmare to deburr. Does someone have a trick here? How do you clean up the edges?


 
 I've found that a sharp razor blade works very well on soft copper, and if you can get the entry angle right you can de-burr a few holes at a time.
  
 Also, if you don't have any already, I'd recommend high flute count double compression bits for relatively burrless holes in FR4. I was getting really crappy cuts with regular dill bits and end mill bits.


----------



## GvTT

Hello wppk,
  
 thank you for sharing this with us.
  
 I did not expect that it would be such a mess taking the STAX apart. It all seems glued and bonded together.
  
 I have a few questions though:
  
 a.) is this the Mylar you got from the store selling furnature covers?
 (Mine looks a bit different, not so opaque. The stuff I got from DuPont is high gloss, see through like glass...)
  
 b.) you stetch the membrane just by hand? Wow!
 No stretcher or anything?
  
 c.) then you apply the antistatic clearner, you stay away about 5mm from the spacer. Do you make contact in one section or do you keed the distance all around?
  
 Glad to know it works. My Lambdas are still working fine, even if I think that they lost tension over the years.
 It is allways a great help to know what you will find when takig things apart. You pictures really help there.
  
 I just finished the woodwork of my inner tire stretcher. I will post picutes one it's complete.
  
 Greetings
 Georg


----------



## ThePCWizard

I'm designing my own custom headphone drivers and I wanted to ask you guys, could I use mylar as a membrane on something like this? I know they're not electrostatic drivers but it doesn't hurt to ask.


----------



## chinsettawong

Hi Wppk,
  
 Thanks for sharing the information with us.
  
 May I give you a tip?  For cutting away Mylar, the best tool to use is the tip of a soldering iron.  It'll melt through Mylar and give you a nice cut.
  
 How you manage to stretch the Mylar without using a stretcher is amazing.  Please do share with us more details.
  
 Wachara C.


----------



## wppk

thank you Georg and chinsettawong, and to all those who gave me good reputation !
  
 Georg, I am not sure to understand your first question... I bought it very cheap from a diy shop (like 7 euros for 10 square meters) , and it purpose is to cover furnitures. I tried other mylars but they didn't give good results.
 b and for chinsettawong  : no stretcher, and the glueing is immediate. as many very simple things, it is quite hard to explain. I put the glue. Press rather firmly the mylar on one large side, as shown ( take care that when you put the mylar the fisrt time, it is  stretched from the right to the left, so that nothing gets wrinkled in the end, then, I turn the driver the other way round, block it on my body, and gently stretch, then put the mylar on the opposite side. pressing then on the new stuck part, gently. then I spin the driver, and stretch it a bit more, on the short side. before puting the mylar on the ring, I make sure that there is no fold. After, I spin it the opposite way, and do the same for the last side to glue. After, I press rather firmly all around the ring , where the mylar is glued. If needed, I gently stretch again, with my thumb, to have the whole well set. I have to take care not to wait too long before I put the glue on the other ring, wich will fit the first, and then, make everything strong. and then, making sure  one last time that the mylar is perfectly tight, I make the two rings front again, and press them firmly. Then, I put the hot glue on the sides of the driver, still in a short delay. No real hurry in all that, but no time to waste neither. 
  
 thanks Chinsettawong for the tip. But doen't it make the tip too dirty ?
  
 for you c question, Georg, I don't really calculate, because I don't have much time to end the gluing process, so, I put the antistatic product making my best not to fill the mylar. of course, then, it is not precise at all.
  
 the pc wizard : sorry, I don't really catch it ... where do you want to put the mylar and what for ?
  
 all the best


----------



## Hutnicks

Just a quick hint. Dremel makes a woodburining/soldering iron that comes with a tip which will take an exacto blade. You used to be able to to buy the screw in tip as an accessory. It with a number 11 xacto blade is perfect for fine cuts.


----------



## wppk

thanks for the dremel info
 i have to say that one of the stax I have repaired ( photos I left ) went out of balance. I don't know why. have to find... and will tell you if I do .
 for the time being, the repair that works for long is the PM protective membrane changing. for the other one, maybe I will have to find a stronger glue.
  
 so, the following day : I repaired one lambda. the problem was not the membrane, but the stator, which doesn't fit well now, can't figure exactly what is going on. so it makes noises. and the sound is not as good as it should be.


----------



## GvTT

wppk said:


> ...
> for you c question, Georg, I don't really calculate, because I don't have much time to end the gluing process, so, I put the antistatic product making my best not to fill the mylar. of course, then, it is not precise at all.
> 
> ...


 
 Hello Wppk,
  
 sorry for not expressing it in more detail when I asked "question C".
  
 There is surely nothing to calculate there, at least nothing that would be worth giving a try.
 My question was concerning the application of your coating:
 you connect the bias voltage to one of the spacers. This spacer should be in contact with the coated mylar, so the charge can populate the membrane.
 So I was wondering if you made a section where the coating comes to the spacer.
  
 If this is not the case, either your Mylar must already be coated or/and it should take a long time for the charge to build up. In this case the headphone should be very quiet at the beginning.
 (Maybe your Mylar is already treated, as it's purpose seams to be to cover furnature. This would be easier with a material that will not stick to everything by electrostatic.)
  
 Do you have a clue how thick your Mylar is?
 Maybe you can provide some more information on this material. Something is strange to me with this stuff. (Don't misunderstand me, something seems strange, not meaning there is something wrong with it.
 That you might only treat the center of the membrane and can stretch the membrane by hand (and get good sound) is amazing. This might be the stuff you could use in a DIY kit ;-P
 I would be interested in having a closer look at your mylar, maybe we can arrange for a sample to be shipped to me (Germany). I would try to measure the conductivity, thickness and elongation under load. This might give a hint if it's just pure mylar.
  
 Greetings
 Georg


----------



## wppk

well in fact I have no section with the coating coming to the spacer. it's glued all around, with no gap.
 I don't think my mylar is already coated, because it sticks a bit on what it touches. and if I don't use the product I added in  my explainations, the sound is weak. and when I use the product, it works at once, without waiting, with a wonderful sound. the sound is getting poorer when I have problems withe the position of the stators when reassembling the driver.
 when I bought the mylar, it was said to be 7 microns thick (written on the package)
 don't worry I don't have problems with your finding it strange. who wouldn't find strange things in all that ?
 the mylar I bought was found in a Leroy Merlin DYE shop in Dijon, burgundy, France. where we have probably better mustard and grand crus than mylar, I assume. Of course, I can send some to you (talking about the mylar, not the wine or mustard). please give me your postal address in a pm. that would be very interesting to have your observations on it.
  
 I'd like to add, too, that is true that I have a weak sound when I don't coat the mylar. that is the reason of my writing on this post ( one of the reasons indeed). The point was that I had changed the MM, and used a product that was antistatic. and it pefectly worked; After a while, the sound went weak, and I supposed that it came form the fact that the product I had used had lost its antistatic properties. So I asked for another product that would work and last, and that is what you gave me here, thank you again.


----------



## chinsettawong

Hi wppk,

I don't think the product you use for diaphragm is Mylar. It might have been the similar product as food wrap plastic. I have tried it a long time ago when I first started making my headphones. Yea, with that plastic, you surely can stretch it by hands. It can elongate so much before it tears. It can sound quite amazing too.

With 7 micron Mylar, I don't think you can stretch it like the way you described. It's just too strong.

About your sound getting weaker after a while, it might have been the problem with your diaphragm not stable and collapsing to one side (sticking to one stator). 

This kind of plastic, while is OK for testing purpose, is not good for long term usage, IMO.

Wachara C.


----------



## khbaur330162

Quote:



wppk said:


> the mylar I bought was found in a Leroy Merlin DYE shop in Dijon, burgundy, France. where we have probably better mustard and grand crus than mylar, I assume. Of course, I can send some to you (talking about the mylar, not the wine or mustard). please give me your postal address in a pm. that would be very interesting to have your observations on it.


 
 Hello. I am interested in this elastic Mylar. Can you provide manufacturer and/or a link to where it can be sourced?
  
 Best Regards


----------



## chinsettawong

If you just want to try for fun, something like these can sound pretty good too:
  


  
 Here is what my friend made using a similar product:
  

  
  
 Wachara C.


----------



## wppk

hello
 I have no other information than those I have written, sorry ... leroy merlin is a shop in  france. if you type in in google you can find it.


----------



## wppk

ok whachara C, Thanks a lot. does anyone know where I can find the right mylar in france ?
 in fact, it is not comparable to the wrapping mylar you are talking about, I tried with that, a dit is too loose. the mylar I use is stronger, and if you stretch it itv does not react the same wya, it will break very sooner than the food wrapper. And I do think it is 7 microns.
 I have sent a sample to Georg. He wxill probably say interesting things about it.
  
 for the other pictures and the link to the very cheap headphones, I find if fun and clever. and yes, the sound is very good with the mylar I use. if the stators are well positioned.


----------



## khbaur330162

chinsettawong said:


> Spoiler: Warning: Spoiler!
> 
> 
> 
> ...




  
  


wppk said:


> hello
> I have no ther information than those I have written, sorry ... leroy merlin is a shop in  france. if you type in in google you can find it.


 
 Oh, okay. This stuff would probably lose tension over time? For some reason I heard stretchy mylar and was thinking I might get lucky with a dirt cheap, NASA inspired, cutting edge material kind of thing. I'm looking at something like Essar Stretch because of its elastomer properties. I think it could have potential to sound really good as a diaphragm material.


----------



## wppk

wachara, Have you tested this other kind of plastic which is used for windows, and can be stretched by the heat of a hair dryer ? I tested it to make the PM ( protective) but is changed the sound in a bad way, so I quited for the mylar I found after. but as it is much firmer, maybe it could worrk ? I think I will try
 http://www.castorama.fr/store/Film-isolant-de-survitrage-700-x-75-cm-PRDm955990.html
 if it works, that would be very interssting, because it would solve the problem of the stretching. fisrt glue it then, warm it, and it will be perfeclty stretched


----------



## wppk

yes, it probably looses tension, even if I think that the question is more coming from the glue. I don't know the essar
  it is good to try many things antway


----------



## khbaur330162

wppk said:


> wachara, Have you tested this other kind of plastic which is used for windows, and can be stretched by the heat of a hair dryer ? I tested it to make the PM ( protective) but is changed the sound in a bad way, so I quited for the mylar I found after. but as it is much firmer, maybe it could worrk ? I think I will try
> http://www.castorama.fr/store/Film-isolant-de-survitrage-700-x-75-cm-PRDm955990.html
> if it works, that would be very interssting, because it would solve the problem of the stretching. fisrt glue it then, warm it, and it will be perfeclty stretched


 
 I worked in a hardware store and the stuff we carried for this purpose in the US was pretty thick. I want to say in the 40-60 micron range.


----------



## wppk

yes, you are probably right... I had forgotten this point...


----------



## khbaur330162

wppk said:


> yes, you are probably right... I had forgotten this point...


 
 No worries.


----------



## chinsettawong

Hi wppk,

It's not worth trying all kinds of plastics when you know the kind that really works. Mylar can be bought easily from Ebay. It's not so expensive, IMO.


----------



## davidsh

It sorta is when in EU (import taxes etc.) and you just want to try it out..


----------



## wppk

yes, but the problem for me is that there are different kinds of mylars and I don't know where/which to buy on ebay. which thickness, which brand, does it exist in france or not... I searched quite a good deal last year, but nothing I could be sure of. It seems that in France very very few people are involved in headphones making or fixing.
 would you have a link for me ? that would be very nice of you.
  
 BTW for my knowledge , what do you pronounce mylar ? maïlar, like in my lar, or meelar ?
 in french it is meelar


----------



## chinsettawong

I think it's pronounced "mai lar".
  
 If you have read my older posts, I mentioned again and again that I used 3 microns Mylar as I find it to be the best sounding out of many thicknesses that I have tried.
  
 There are many sources where you can get Mylar film.  Ebay is the cheapest that I can find.  Eraudio in Australia is another great source.
  
 The real technic is to tension your Mylar to just right.  That takes a lot of practice.
  
 Wachara C.


----------



## wppk

thank you and sorry for having made you repeat.... I didn't read the whole thread yet. I apologize


----------



## wppk

for information, when I type mylar , with or without thickness info, on ebay, I don't find a 3 micron mylar. the point is probably that in france, we seem to still be in the middle ages, and the links that appear for people living in the US or elsewhere are not always displayed for legal reasons. It happens soemtimes here that if your are intersted in a item, and if we click on it to buy it, a message says something like " sorry, but you cannot buy this item, because of the country you are located in, which doesn't allow this sale. "
 If I type 3 micron mylar film, I have about twenty results only, with mostly 180 micron results ( and nothing about 3 micron). which seems far from what you say on this thread, wachara, ( I am reading and reading) that means that there is a great choice.
 so I clicked on the australian society you  kindly told me about and they have a 3,2 micron , which is not exaclty 3. but I guess it works.
 the thing is that it would be easier, for a french, to find convinient mylar film in france or europe, and I have been searching quite long, about one year ago, and didn't find anything interesting. I had finally found an apparently convienient mylar, but the society who sold it couldn't ship it to me because I was a person and not a society, and because they only sold by huge quantities. I found my way to ask a comprhensive person to send me a sample ( lol, I received a 20 meters long sample...for free !) but it didn't fit what I needed : a mylar for the protective membrane. It was much too rigid. problem that I solved by finding the "mylar" I used, and it perfectly worked. I should try tio find back this 20 meters roll I had received, and try it for the Main Membrane. but I find it very rigid for the purpose... don't know yet.
  
 on another point, georg, you asked me to test the mylar I use on a portion without glue, did I understand well ? I cannot figure out how you could measure the difference after. wouldn't it be easier for you if I sent a stator to you, so you can do exactly what you want and you don't have to explain everything to me, as I am not always at the top with technical english language ?


----------



## wppk

I have something to say about this post of the begining of the theread, as I am still reading, hope it is not repeating something someone would have said already. If yes, I will delete this. 
 I had a he 60, and Spritzer very kindly explained to me how to put a new PM (protective membrane) that, if I remember well, didn't exist originally, and caused the moisture-squeal issue that is talked about in this post.  I added a plastic film as Spritzer told me, and as he had told me that several tests had been already made about it that showed that it didn't colour the sound, I was surprised to notice that it changed the sound a lot on my he 60. The fact is that as a voice talent, I am often recording my voice only, a capella, and I could hear a big difference with or without the PM. On voice only, because when I was listening to music, I couldn't hear a difference in the sound, with or without the PM. On the music nor on the voice. that is a point hat could be important for ( rather rare people, I agree) people who, like me, are using their static headphones for monitoring purpose, on their voice.
 The point is that with the "mylar" I am using now, for the PM, on my lambdas, there is no sound coloration at all, on music nor on a capella voice. Unhappily, I cannot try again on the he60, because I don't own them anymore.


----------



## wppk

wppk said:


> I just want to post this information here so that some of you that have a similar problem as mine can solve it.
> 
> My DIY headphones start to develop the weird squeal.  It only happens after I've been listening to them about half an hour or more.  The longer I listen, the more obvious the squeal is.  It's very annoying.  At first I thought that there could be some loose connections or some dust in the drivers.  But on close inspection, I find that it's actually the moisture (humidity) that is the real cause.
> 
> ...


 
 I have something to say about this post of the begining of the thread, as I am still reading, hope it is not repeating something someone would have said already. If yes, I will delete this. 
 I had a he 60, and Spritzer very kindly explained to me how to put a new PM (protective membrane) that, if I remember well, didn't exist originally, and caused the moisture-squeal issue that is talked about in this post.  I added a plastic film as Spritzer told me, and as he had told me that several tests had been already made about it that showed that it didn't colour the sound, I was surprised to notice that it changed the sound a lot on my he 60. The fact is that as a voice talent, I am often recording my voice only, a capella, and I could hear a big difference with or without the PM. On voice only, because when I was listening to music, I couldn't hear a difference in the sound, with or without the PM. On the music nor on the voice. that is a point that could be important for ( rather rare, I agree) people who, like me, are using their static headphones for monitoring purpose, on their voice.
 The point is that with the "mylar" I am using now, for the PM, on my lambdas, there is no sound coloration at all, on music nor on a capella voice. Unhappily, I cannot try again on the he60, because I don't own them anymore.


----------



## MuZo2

Search for Electrostatic Speaker Membrane Dupont Mylar C 3um 40M, its shipped from Taiwan.


----------



## wppk

thank you !!! it works !


----------



## wppk

I have had another idea. Hope again it is not repeating, if yes, I will remove. I didn't have time to read the whole, yet, going on...
  
 Wachara said it was important to tense well the mylar, and spritzer said "tight as a drum". so, As a drummer, I have drums, and I decided to use one of the toms , the smallest of my roland TD20 to try to tense the mylar. This time, I am using the real mylar I talked about just before, which I had for free.
 the tom :

 after having removed the 5 screws, the" skin " comes out :
:
 putting the mylar on it :
  

  
 taping it on the internal side of the skin :

  
 puting back the o ring :

  
 screwing with the tool ( manually it is very long)

 light screwing

  
 tight srewing

 finishing by hand with the key for the drum

 the spacer of the lambda cannot be put on the mylar, because of the attachement between the two spacers. I remove it with the dremel

  
 and glue it on the mylar.
  

 now I am waiting to see if it is well held. Maybe this idea could help to make a very precise streching ? but I have no instrument to measure it.


----------



## chinsettawong

Your drum tensioner should work fine. However, you'll soon find out that finding the just right tension is quite difficult - too much tension and you lose bass, too little and you have stability problem. You'll see what I mean soon. 

By the way, keep reading the older posts.


----------



## wppk

ok
 I'll see that.
 yes I will read but I have very little time right now
 I have a glue problem. Wil try others. the one given by Georg doesn't work ( uhu contact) I saw you also spoke of it but the one in france is probably not the same


----------



## MuZo2

chinsettawong said:


> Your drum tensioner should work fine. However, you'll soon find out that finding the just right tension is quite difficult - too much tension and you lose bass, too little and you have stability problem. You'll see what I mean soon.


 
 So only way is trial and error ? and also how do you get same results on right and left driver?


----------



## wppk

as far as it concerns my drum tensor, yes.
 only trying and trying will do.
  
 for the equal tension, maybe tense it at the max, and then untense manually with the key, counting the times I turn it to loose the tightness... I can think of no other way.
  
 I found a good glue ("pattex 100 pour 100 repair gel" , easily found in france in supermakets-don't make the mistake with another glue wich seems like it but doesn't have the "repair " mention", and doesn't work), but tore the mylar accidentally. will start again


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## wppk

I just thought of another way : the solution  is to glue to spacers at the same time on the same mylar. then, they will obviously have the same tension. there is room enouch on the drum to do so


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## wppk

and for Georg : I will glue only one side of the mylar on one spacer, so tho other side of the mylar wil be in contact on the other spacer


----------



## chinsettawong

muzo2 said:


> So only way is trial and error ? and also how do you get same results on right and left driver?


 
  
 Obviously you haven't read my old posts.  
  
  


wppk said:


> I just thought of another way : the solution  is to glue two spacers at the same time on the same mylar. then, they will obviously have the same tension. there is room enouch on the drum to do so


 
  
 That's how I have been doing mine.


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## wppk

well I am proud I had the same idea then. but not to have had it at once...


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## wppk

Really sorry to make you repeat things wachara. I have been leading several forums on other questions, and I know how unpleasant it is when people don't read and ask you to restart what you have already given with the heart. It is a question of respect, to read before asking... I am really sorry about that. I know how one can feel bad about it, and I hope you can understand, too, that I am french, and how good my spoken english maybe, as english people say when we talk together ( you can hear me speaking english here-sound ordered for a movie by an english client-  http://wppk.fr/ec/airf.mp3  ), I am not as fluent at reading as at speaking, and there are a lot of specific terms on the 140 pages of this thread, things that I don't always catch at once, and it is then longer for me than for native english, to understand the whole, well, I would rather say, most of it.
 my apologize for that, and I would really like to know that beyond my respect for you, there is admiration for what you did, and an enormous, huge, tremendous THANK YOU !


----------



## GvTT

Hello wppk,
  
 I have a few remarks on the most recent posts, but I will not quote:
  
 searching ebay for "mylar dupont" gives quite a few results.
 Unfortunately the amount is much more than you will ever use when staying with headphones. If you decide to buy 3mu, I will take some of this and participate in the purchase.
 I have a small amount of "well matured" 3,5mu terphane from Dupont, what should be Mylar, but I ave to research it. It dates back from the early 90th, when I hoped to build an ESL headphone, but being a youngster, did not know enough not to start. So I never started. Not, thanks to Wachara I think I know enough and work my way through it.
  
 --------------------------
  
 As for a membrane stretcher:
 I do not like your ideas using a drum tightening mechanism. I think a "weight" or "inner tire" stretcher is much better.
 The drum mechanic relies on a mechanical movement of the ring. If you get your Mylar really evenly under this ring, the result will be good.
 A weight or the pressure in an inner tire represents a force, not depending too much on the position. So if the Mylar is tight in one section, the tension will increase in the others. This will produce a much more even tension.
 (Last weekend I built a wooden frame of 30mm x 20mm wooden bars, framing an DIN A4 paper (roughly letter size), a 16 Inch inner tire from a bicycle fits nicely around it)
 You can find pictures of both types of stretcher in this thread. If you use weights, make sure they pull individually on the Mylar and are not mounted to a ring that pulls the Mylar (I believe this is inferior)
  
 ----------------------------
  
 About the Mylar (Glue)
 did I write glue? It should have been antistatic cleaner. I intended to measure the ohmic resistance of he record cleaner. of your coating.
  
 ______________________________________________________
  
 Many mention in this thread that tightening the Mylar takes a lot of practice. The is something I will have to learn.
 To speed up this process I intent to tighten the Mylar, press a spacer to it an measure the free air resonance frequency before I glue the stator.
 By this I know what it in the headphone.
 In a second step I want to do the above but also coat the Mylar, press a stator and spacer against it and apply a bias voltage + 400V (total of about 1000V) to see if the tension is high enough for the membrane not to touch the stator under max loads.
 For this an inner tire stretcher seems perfect.
  
 If you have any questions to the above note, please feel free to ask.
 Greetings
 Georg


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## wppk

Hello Georg
 I have to read the whole thread before saying more.
 for the mylar, I am making a last test with the one I sent to you, using my drum tensioner. after that, we'll see.
 thanks


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## wppk

the more I am reading the thread, the more I feel ridiculous with my explainations that seem to be things to discover but appear not to be. I am at the page 35 or so, now, will go on, but I think there is nothing about repairing lambdas, because as I searched that thru the forums, I didn't find it. So on this point I will go on. Don't answer me if it means repeating something already said.
 so now, I found a glue, but I still have doubts about it strength; That is still my big problem, and I asked Georg if he could send me some really working glue
 I finished reparing one lambda driver this morning. As watchara said, my first fixing the last time was lacking bass because of too much tension. as I have no system for measurment and didn't reach the page about this point yet, and as I am quite impatient to have a result, I tested antother idea : tensing the mylar ( the real one, not the "mylar" I used for the sweat cover, ) over the skin of the drum only, separated form the drum itself, with tape. Always positionning tape on one side, and then on the opposite side, until the mylar was as balanced-tensed as possible, and clear to see, meaning no wrinkle, no fold, and not tensing stronger than that. When put back in the driver, this is really sounding beautiful ! no lack of bass, and no static or strange noises, for the moment, nothing odd. I'll have to see if it goes on.
 another point : I am repairing 4 lambda drivers. One of them has always been sounding louder than the others, and even the other lambdas I have. important difference, about one third of the balance of an amp. I know that stax made different drivers and that the serial number was necessary when asking a new driver when they were still available. so, maybe it is just a question of specific serial. but I wonder how it is possible, because then, I would have another driver which would sound as loud, which is not the case. anybody knows what's going on on that point ? Thanks


----------



## wppk

here is the mylar manually tensed on the skin of the drum, with tapes.
  

  
 the glue is sader metal two compnents. Very uneasy to use but the only working for the moment. partially working, beacse out of three specers I bounded, only one was glued. i think that is because it is necessary to melt the components of the glue just before using it and be fast gluing the spacer. if you put the same glue ( already mixed one minute ago for the first spacer) on the second spacer, it seems it has lost its maximum gluing properties, and then, doesn’t work. it means mixing the components newly with each spacer. After, it is necessary not to leave glue on the center of the mylar, I could clean that with a wet cleaning hankerchief.  in  order to achieve the gluing, I pressed my finger on the other side of the skin, manitaining the spacer with a finger of my other hand, on the whole ring of the spacer. I waited a night for the glue to be dry.  after that, one has to remove the glue taht remains on the upper unglued side of the spacer. And I used my other glue, (the roller) to put on the recieving part of the driver, so that tyhe mylar could be held on both sides. Using the sader glue on the receiving part of the driver would have been too difficult, because it needs time a a lot of precision, and  any stain would have been impossible to clean in time.
 important to say, to, when reassembling the two spacer, It is necessary to find a metal piece, like a piece of a resistor, cut at the good size, to be used as a pivot in the little ring were the wire will be soldered after. so it sets the two spacers right in front of each other.  
  
  
 I have another question : on one of the stators, there is a stain.
  

 When I fixed it before ( but the glue didn’t stand long) I could notice no difference in sound with another driver, but I am wondering if it would not be necsseray to clean it, and don’t really dare to do it, because I don’t want to damage it, as the stain seems to be deeply set in the copper.  I have not been using yet this sort of wax that is found to clean copper dishes, but I think the stain would not leave without that… does anyone know  if to do and what to do ?
 thanks
 Luc


----------



## wppk

spritzer said:


> I use the large stone oven in my bakery at its lowest setting which is about 140°C.  Leave it there for a few minutes (depends on the size of the frame) but I put them in a box due to what's normally in those ovens.  Quad used an oven as well to cook their panels.


 
 Hi birgir
 I am not sure to understand well... would you have a picture, or a more precise info ? if you alreday posted some, don't answer, I will find it reading 
 cheers
 luc


----------



## davidsh

Wild guess: He's maybe taking about electrets drivers? Usually, heat is part of the process in biasing electret drivers.
Besides, why are electrets seemingly seen as inferior to real electrostats?

Luc, I don't think the stain will make much difference to the sound.
Regarding loudness there are not many factors relevant in the case of different lambdas. Spacer thickness seems most likely to matter. Else, perhaps the louder lambda has more metal vs. hole area on the stators.
Basically, you should think about electrostats being very similar to capacitors in many ways.


----------



## chinsettawong

Birgir was trying to do a heat treatment on the diaphragm. But in my experience, Mylar doesn't need further heat treatment after its mechanical tensioning. You can try it if you want.


----------



## wppk

thanks to both of you.
 I have succeded in reparing one lambda driver. the tension is good, the sound is perfect, with no issue nor unstabilty problem. But I made it because I was lucky and unlucky at the same time :
 I prepared three spacers glued to mylar on the same drum tensioner. only one out these three was glued correctly, because I applied the same glue to te three in one go. as I explained just before, with this glue, it has to be new on each spacer. 
 then, I tested the one on which glue had worked. And this is the lambda driver I just talked about today.It is perfeclty working. and that was luck
 I then glued the two other spacers on the drum, and the glue worked. so I tried to fix to other  drivers with them. But probably because the glue poured a very little bit on the inside part of the mylar, and left a different level on some places, I couldn't use at all one of them, or very difficult/impossible to have a good sound. The last spacer had the same problem with the glue pouring very lighly, but it probably wasn't as an issue, as it firstly worked. But the problem you told me, wachara, started, surely it is tensed too loose, and I have the stability problems you told me about, meaning a temporary and repetitive imbalance.
 I will have to redo, but I am lacking courage today... it will come back, probably.
 so as a conclusion to this, I was lucky to fix the first driver, and unlucky because I couldn't get harmonised tensions. The glue is a problem too...
  
 I cleaned (and removed) the stain.
  
 about the louder driver . I couldn't see if there were different holes, because the only issue on this one was the sweat cover, and I don't want to open it, of course.
 I tried to use resistors to get the good balance, but the result is not as I would like it to be, and I have very poor knowledge about resitors.... Tried on the bias plug , didn't work. tried on the + , and it worked, but I had to add several resitors one after the other ( I own quite a good deal of resistors in a box ) to only partly get the result I want to reach. didn't affect the sound, but the level is better harmonised, now, I need to change the balance knob on the amp about 15 per cent to have it all right. don't have the slightest idea of which resistor would work best.
 so, with these steps in fixing, I finally have a repaired lambda, but not perfectly balanced. that is better than nothing, as it is stable, and as the solution is just to turn a knob. But I am of course not totally satisfied with that, and I don't know how I can get the right tension on my drum tensioner. I still have read following pages of the thread, but of course, not finished at all.
 thanks again
  
 Luc


----------



## wppk

I have another silly question. long ago, when I was a teenager, I tried something odd, plugging a headphone on the jack input of a tape recorder. And It worked !
 dull, dark and bad sound, but I could hear the result as if it was a mic ! It amazed me, as you can guess.
 After that, I tried it the other way round. I had a beyer m88N mic, that I plugged on the headphone jack output of the recorder. and it worked too !!! but then, the sound was wonderful. Much better than my headphones, which were good ones. I had no knowledge on how to solder, cut wires ans so on at this time, so I could only dream of listening to a stereo set, with two mics.
 beside the fact that of course, I would immediately be sent to a hospital for insane people, if I had been glimpsed at with those two mics on my head, it didn't stop my dreaming. And in those recent days, I was wondering what the result would be with static mics. If one had the possibility to do it, with the good self made plugs, and a 48v power supply on each mic, it could be very intersting, I guess, to see if ( why not ?) and how it works. Then, it would be possible to have ELS headphones with 48v, and if the result is as astonishing as it was with a dynamic mic when I tried this, I would be worth the try.
 what do you think ?
  
 Please, don't send me the male nurses and the ambulance, lol.


----------



## davidsh

Adding the resistors might cause some high frequency roll off and phase delay, else it should work.


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## wppk

ok, thanks davidsh


----------



## davidsh

Too bad it's single sided ES technology, but this is an interesting concept: http://www.innerfidelity.com/content/ces-2016-highlight-warwick-audio-ultra-thin-electrostatic-driver-material#MzYCqkxWWIQXtEGm.97
  
 I like the idea, taken to the extreme one could automate the manufacture of ES drivers. They claim to make the to-be drivers by the roll!
  
 The potential of the idea is huge as I see it, though of course the end product has the drawbacks of high drive requirenments etc. that is characteristic to electrostats.


----------



## edform

davidsh said:


> Too bad it's single sided ES technology, but this is an interesting concept: http://www.innerfidelity.com/content/ces-2016-highlight-warwick-audio-ultra-thin-electrostatic-driver-material#MzYCqkxWWIQXtEGm.97
> 
> I like the idea, taken to the extreme one could automate the manufacture of ES drivers. They claim to make the to-be drivers by the roll!
> 
> The potential of the idea is huge as I see it, though of course the end product has the drawbacks of high drive requirenments etc. that is characteristic to electrostats.


 

 The singe ended nature of the panel isn't inherently a problem with modern electronics since the distortion it introduces as the diaphragm moves away from the stator can be compensated by pre-distorting the signal to suit. In the digital domain this is essentially trivial.
  
 The bit I really like about this product is that large panels are available that might make a new look at the Jecklin Float productive and weight is so small that outrageously ugly, but possibly very high performance open ear units will be possible.
  
 Ed Form


----------



## jcx

http://www.google.com/patents/US7095864  seems likely


----------



## ayaflo

davidsh said:


> Too bad it's single sided ES technology, but this is an interesting concept: http://www.innerfidelity.com/content/ces-2016-highlight-warwick-audio-ultra-thin-electrostatic-driver-material#MzYCqkxWWIQXtEGm.97
> 
> I like the idea, taken to the extreme one could automate the manufacture of ES drivers. They claim to make the to-be drivers by the roll!
> 
> The potential of the idea is huge as I see it, though of course the end product has the drawbacks of high drive requirenments etc. that is characteristic to electrostats.


 
  
 This is an electret and not an electrostat and therefore will have LF excursion problems. If you see the FR file in their site, it shows a steep roll off under 1KHz IIRC.


----------



## GvTT

Hello everybody,
  
 I have had my mill running quite a bit this weekend:
  

 Finishing the outer edge of the stators with a 4mm miller.
 The mill is too small to machine the whole stator in one clamping, so I had to turn the parts when they are done on one side.
  
 And this is the result:

  
 The next thing will be to remove some of the copper on the stators to reduce capacity. Then I will smooth everything and paint the stators. A workshop cleaning will be necessary too. The I finally come to the Mylar.
  
 The inner tire stretcher is already build.
  
 What do you use to control the pressure? (a normal bicycle pump? an additional release valve?, ...???)
  
 Greetings
 Georg


----------



## davidsh

Just want to say that removing the surplus copper from the stator will reduce the capacitance, though not significantly. The capacitance of the cable is mostly significantly greater than that of the electrostat itself. So don't bother if it is of much trouble


----------



## chinsettawong

Hi Georg, 

Those parts look great. 

About inner tyre pump, I use a small handheld pump. Slowly observe the diaphragm. My elongation target is only around 0.5-1 mm. You might want to try a few times until you get it just right.

About etching out the unneeded copper, if you prefer the sound of Stax SR007 to SR009, then you don't need to do any etching. But if you like SR009 better, then you do. You can try to experiment and see it for yourself which way you like better.


----------



## davidsh

Why is that going to make much of a difference, except for slightly higher capacitance?


----------



## chinsettawong

Yes, it does make quite a lot of difference to my ears.


----------



## davidsh

I guess, I would prefer a logical explanation. I don't like to trust other people's ears when I don't have to, but it isn't like I'm going to make my own 'stats any time soon.
  
 I'm just saying that from a theoretical stand point it might be better to look into optimizing the cable, if capacitance is of concern. Of course, the resistance of the cable won't matter if within reasonable limits.
 For a Stax headphone the driver capacitance amounts to ~1/5th of the total capacitance.
  
 An easy way to lower the capacitance is to make your cable shorter.
  
 Whether to be concerned also depends on the amp that you are using and how loud you listen as you might experience problems in the high frequencies if the amp can't swing the current needed. I think the result merely is that the frequency response becomes rolled off in the treble, though I am not certain.


----------



## GvTT

Hi,
  
 I roughly calculated a cable:
  
 3m cable, 1.2mm copper diameter, 2x 6mm apart (bias in the middle), PVC as insulator gives me
   Inductance: 5,5μH
   Capacitance: 1.8nF
  
 My stators (2x 0.5mm spacer):
   unetched: 57.4pF
   rim and outer area etched: 28.4pF
  
 As DAVIDSH mentioned, the cable dominates.
  
 I tried to modulate this as a lossy line and a capacitor in Spice. There I get corner frequencies of 100kHz. So this is out of scope as explanation.
  
 The calculation clearly shows that the capacity between the stators is significantly reduced by etching them. Especially with my stators, that have most of the copper on the outside.
  
 I did not consider the edge of the spacer the edge of etching (I like this sentence  but a line about 5mm away from the spacer.
 This is reasoned by the fact that a force on the edge of the membrane will contribute very little to it's displacement.
  
 So, if the cable is dominant, what causes the difference in sound? (I take wachara's observations as serious as davidsh's comments)
 And, even more important, how would a good cable look? (Could a sense line adjust the amp to correct the cable?)
  
 Unfortunately I have not had the chance to listened to an SR007 or SR009.
  
 Greetings
 Georg


----------



## edform

ayaflo said:


> This is an electret and not an electrostat and therefore will have LF excursion problems. If you see the FR file in their site, it shows a steep roll off under 1KHz IIRC.


 

 It is not an electret. It uses a rather high bias voltage - in the order of 1600volts I believe - and is a pure, single-sided electrostatic device.
  
 Ed Form


----------



## davidsh

gvtt said:


> Hi,
> 
> I roughly calculated a cable:
> 
> ...


 
 I am no electronic experts, but I do know a little about physics. The biggest problem with high capacitance in your 'stat is that it requires the amp to deliver significant current at high voltage swings, high frequencies. I have not done the calculations, but for most amps driving a single Stax headphone, playing music, I honestly do not think current delivery will be a general issue, though it certainly could be in some cases.
  
 The best way to reduce cable capacitance is to seperate the conductors from each other as much as possible. And keep the cable short. It doesn't have to be costly if you are a little creative, and it isn't rocket science, though there will be other effects contributing to the capacitance in the low pF range, I'd guess.
  
 1.8 nF is a high capacitance for a 'stat.
  
 The typical maximum current of most 'stat amps is some 1~10mA to my knowledge. With a capacitance of 1.8 nF you'd be using a maximum current of ~1.4 mA at Vpeak = 300V at 20kHz to put it in context. Mostly, you will not need such high voltage swings in the high frequencies for reproducing music.
  
 An example where the high capacitance could be problematic is if there's significant ultrasonic content, noise etc, for whatever reason in the music you play (aliasing, high-res music files containing HF-noise etc.). Then the sound quality may suffer, though I am not sure how the amp would react (perhaps somebody else might know). I would guess it'd clip somehow.
  
 If you have an oscilloscope around it is possible to measure the capacitance of your 'stat, though that takes further explanation. Of course there are instruments for measuring this as well.
  
 High frequency roll-off will be of no concern as the corner frequency will be very high in general, as you noted yourself.
  
 I hope that clarifies a couple of things.


----------



## davidsh

edform said:


> ayaflo said:
> 
> 
> > This is an electret and not an electrostat and therefore will have LF excursion problems. If you see the FR file in their site, it shows a steep roll off under 1KHz IIRC.
> ...


 
 How is that so with such a small seperation between stator-diaphragm? One would expect problems with stability, corona discharge, collapsing diaphragms and all that lovely stuff because of the very high electric field. Must yield a high sensitivity, however.


----------



## ayaflo

edform said:


> It is not an electret. It uses a rather high bias voltage - in the order of 1600volts I believe - and is a pure, single-sided electrostatic device.
> 
> Ed Form


 
  
 Ah apologies, I was under the impression its an electret. Either way per their website its 450V bias.


----------



## GvTT

chinsettawong said:


> ...
> 
> About inner tyre pump, I use a small handheld pump. Slowly observe the diaphragm. My elongation target is only around 0.5-1 mm. You might want to try a few times until you get it just right.
> ...


 
  
 Hello Wachara,
  
 if you are talking about 0.5 to 1mm elongation while stretching, what is the reference length you are referring to?
  
 It make a big difference if I stretch 200mm by 1mm  (0,5%) or 20mm (5%)  please provide some more detail.
  
 ----------------------------------------------
  
 I will do some test and I intend to measure the free air resonance before gluing.
  
 Greetings
 Georg


----------



## chinsettawong

Hi Georg,
  
 Please refer to the dimension of the inner tire diaphragm stretcher that I use.
  

  
 I draw a few lines on the wood frame.  Before I pump in the air, I draw a line on the diaphragm directly on top of one of the lines I draw on the wood frame.  Then I pump in the air and observe how much the diaphragm elongates.  Anyway, this method can only serve as a very rough guideline.  I still have to do and redo many times to get the just right tension.
  
 Wachara C.


----------



## khbaur330162

Could you devise a method for vibrating the diaphragm at a certain frequency and monitoring its resonance frequency? If your desired tension has a resonant frequency of (x) Hertz when excited by a vibration of (y) Hertz you only need to monitor the current resonance frequency (z) of the Mylar when excited by (y) and match (z) to (x) with respect to the aforementioned relationship. When this relationship is calculated and a methodology is perfected via the use of a relatively large tensioning table you can create many, many diaphragms of nearly the exact same tension all at the same time.


----------



## GvTT

Hello khbaur,
  
 now you are whistling my tone!
  
 I mentioned before in this thread that the tension of the diaphragm is directly indicated by it resonance frequency (eigenfrequency). Any impulse on the stretched membrane will activate a vibration in it's eigenferquencies, on a stretcher there will me more than one.
  
 You could also use a loudspeaker with a tuneable output to make the membrane swing in resonance. But in this case you would need to monitor the amplitude (maybe with a laser?
  
 BUT: this would only help you, if you intended to make many of the speakers. For setting up just one (as in DIY) I would not consider this relevant, as the size and shape of the diaphragm will be different for all the different designs.
  
 We first need to define what we expect of  tension of the diaphragm:
 - prevent the diaphragm to stick to a stator (number one for me) -> the speaker is statically stable
 - an interaction of the resonance frequency with the lower audible spectrum while listening? (e.g. bass increase while driving the speaker in a half closed surrounding? -> way beyond my thoughts)
  
*So I suggest to test the diaphragm while being on the stretcher (before gluing) for static stability.*
  
 I have not had an idea how to do this in a safe and reliable manor. My thoughts go along the lines of applying an increased bias (maybe 780V [580 bias + 200V amplitude]) to speaker components only pressed (but not glued) to the membrane. But is this, what we want? Unconditionally stable? (I guess, that would be good, considering aging, different amps, air pressure, taking phones off, etc.)
  
 Once you know what you are aiming fore (stability wise) you could use the eigenfrequency as a reference, but only for this one specific speaker design.
  
 Greetings
 Georg


----------



## khbaur330162

gvtt said:


> Hello khbaur,
> 
> now you are whistling my tone!


 
 Hello, I'm glad to hear this. Your thoughts interest me greatly.


gvtt said:


> I mentioned before in this thread that the tension of the diaphragm is directly indicated by it resonance frequency (eigenfrequency). Any impulse on the stretched membrane will activate a vibration in it's eigenferquencies, on a stretcher there will me more than one.


 
 I apologize, I've spent a considerable amount of time away from Head-Fi altogether as of late. I hail from the Orthodynamic Roundup corner and only frequent this thread from time to time. As my current path in this hobby proceeds I have a feeling I'll be spending an increasing amount of time here with you guys, but all that being said, I have regrettably missed a LOT of what's been said. If I may ask, if the eigenfrequency is directly indicated by the Mylar's tension, then this model sounds far too simplistic for me. However, for the sake of argument, I will go along with this model. You state any impulse on the stretched membrane will induce multiple eigenfrequencies. I am lead to believe you are correct in saying this.


gvtt said:


> You could also use a loudspeaker with a tuneable output to make the membrane swing in resonance. But in this case you would need to monitor the amplitude (maybe with a laser? BUT: this would only help you, if you intended to make many of the speakers. For setting up just one (as in DIY) I would not consider this relevant, as the size and shape of the diaphragm will be different for all the different designs.


 
 I hear you loud and clear. In my mind you could (perhaps even should) use a magnetostriction sound producing element in order to excited the stretched Mylar. A downside I see with this is you need to be in physical contact with the stretched Mylar which will, in my mind, inherently impart any number of potentially unwanted characteristics to the stretched Mylar's behavior as we excite it with various frequencies via the magnetostriction element.  As for monitoring the amplitude of the eigenfrequencies, a laser (perhaps even a series of moving lasers) seems like a good approach.


gvtt said:


> We first need to define what we expect of tension of the diaphragm: - prevent the diaphragm to stick to a stator (number one for me) -> the speaker is statically stable - an interaction of the resonance frequency with the lower audible spectrum while listening? (e.g. bass increase while driving the speaker in a half closed surrounding? -> way beyond my thoughts)


 
 Given my interest in planar magnetic over electrostatic technology there are, at this moment in time, disagreements between yours and my definitions of "stable" as the word pertains to diaphragm tension. While a diaphragm sticking to your stator is catastrophic, for me it may merely sound like an audible clipping of lower frequencies. Where our definitions agree is we both aim for diaphragm stability in the sense that both our diaphragms produce coherent sound waves across the entire audible spectrum, and the amplitude of all frequencies being produced are, more or less, equal. You may be attempting to create a diaphragm (with respect to given variables such as bias voltage, diaphragm shape and size, etc.) with a specific FR curve, however, I am aiming to produce an "ideal" sound producing element which, for me, is to say as close to flat across the entire audible spectrum as I can. By doing this I hope to be able to achieve any FR curve I want through equalization. This is important to me given the notion every human's ear canal is shaped differently. What sounds "good" to one person may be different from another's. In order for different people to all arrive at a headphone that sounds "good," equalization may or may not be necessary.


gvtt said:


> So I suggest to test the diaphragm while being on the stretcher (before gluing) for static stability.


 
 If I'm following your train of thought I would test before and after gluing.


gvtt said:


> I have not had an idea how to do this in a safe and reliable manor. My thoughts go along the lines of applying an increased bias (maybe 780V [580 bias + 200V amplitude]) to speaker components only pressed (but not glued) to the membrane. But is this, what we want? Unconditionally stable? (I guess, that would be good, considering aging, different amps, air pressure, taking phones off, etc.) Once you know what you are aiming fore (stability wise) you could use the eigenfrequency as a reference, but only for this one specific speaker design.


 
 If you are able to create any number of diaphragms which are all matched you would also be able to test any number of variables outside the parameter of Mylar tension (diapgrahm shape, size, coating, eignenfrequency amplitude with respect to other variables, and so on).


gvtt said:


> Greetings Georg


 
 Well met,
 Matt


----------



## GvTT

Hi Matt,
  
 thank you for your response.
 By mentioning that I mentioned a topic before I did not intend to tell that you should have read the thread before. It is a very long thread, well  worth reading, with plenty of information. There has not been a discussion yet if there is a good method to find the right tension. I ment to direct you to some older post on this, but indeed, this could be misunderstood. My apologies for this. 
  
 I will try to explain the issue I tried to express:
 an Eigenfrequency (mathematical term) is a frequency an object wants to swing in. It is also called resonance frequency or (I think) resonance frequency. There are always more than one resonance frequency. Normally you find several of first oder and then the higher orders (2nd, 3rd, etc... but there are often irrelevant).
  
 If you consider a string under tension, it will swing in a sine like wave, with only one maximum (1st oder Eigenfrequency).
 If you gently hold your finder to the middle of this string, it will swing in 2nd order (sine wave with 2 maxima). Musician use this to tune their instruments.
  
 If you know on an object it will always swing mainly in it's first order Eigenfrequencies. A circular membrane has a very dominant first Eigenfrequency (drum). An ellipse has whole cluster, but none of the Eigenfrequencies are as cominant as in a circle.
  
 So if I tab on a membrane, I will get a vibration in Eigenfrequency as response.
  
 Instead of taping I could use a loudspeaker. When the speaker emits a sound in eigenfrequency of a close by membrane, the membrane will start swinging. The amplitude will reach it's maximum when you meet it's Eigenfrequency (without damping, the maximum would be infinite, but this will not happen in real world [but the object might brake]).
  
 This is explained in more detail at wikipedia (https://en.wikipedia.org/wiki/Resonance).
  
 If I use a loudspeaker to activate the membrane I will not need a physical contact, the air will do this job.
  
 -------------------------------------------------------------------------------------
  
 So if I have Mylar under a give tension, physically fixed along a border line (by pressing a spacer against it) the membrane inside the spacer will swing at about the frequency it will after gluing and cutting it.
  
 I have not tried this method, but I would be really surprised if this does not work.
  
 BUT, the air must move very freely on both sides of the diaphragm. If you hinder the air moving, you increase the damping. This lowers the resonance frequency (as can be seen in the link above). This is also exact;ly what happens if you seal a headphone to the ear: the eigenfrequency drops due to damping, ideally below the lowest frequency you want. You can also use this resonance to increase the bass, but then the free air resonance and the damping must be chosen carefully.
  
 ---------------------------------------------------------------------------------------
  
 I appreciate you commented, taking my previous post into small sections.
 Rescanning your questions:
 -  I want to measure before gluing. (The stretcher produces the tention, not the glued spacer, but the spacer defines the area free to swing)
 - yes, this method should be suitable to reproduce a result.
  
 I am not sure what to aim for:
 - stability f the membrane not to com in touch with the stator (lowest tension possible)
 - roll off between 25 and 50 Hz to get a bass boost
  
 Many greetings to Chicago
 Georg


----------



## khbaur330162

gvtt said:


> By mentioning that I mentioned a topic before I did not intend to tell that you should have read the thread before. It is a very long thread, well  worth reading, with plenty of information. There has not been a discussion yet if there is a good method to find the right tension. I ment to direct you to some older post on this, but indeed, this could be misunderstood. My apologies for this.


 I intend to read most of it sooner or later, it's just that time, money and patience don't always permit me to do the things I'd like to do. I recognize this thread as a wealth of knowledge, please don't misunderstand me, either. No offense was taken, I just wanted my circumstance to be better understood by our audience.
  


gvtt said:


> I will try to explain the issue I tried to express:
> an Eigenfrequency (mathematical term) is a frequency an object wants to swing in. It is also called resonance frequency or (I think) resonance frequency. There are always more than one resonance frequency. Normally you find several of first oder and then the higher orders (2nd, 3rd, etc... but there are often irrelevant).


 Understood, and, for the most part, I agree with you. Thank you for the clarification. You have a perspective which is currently different from my own, yet I appreciate you taking the time to express it to me and I do see great value in it. While I believe you are correct on this point, I'd like to ask that you reconsider higher order eignenfrequencies as relevant. I will try to go further in depth on this later on in my post.
  


gvtt said:


> If you consider a string under tension, it will swing in a sine like wave, with only one maximum (1st oder Eigenfrequency).
> If you gently hold your finder to the middle of this string, it will swing in 2nd order (sine wave with 2 maxima). Musician use this to tune their instruments.


 As you later state, however, we are not dealing with strings (one dimensional wave propagation) so much as we are dealing with movable membranes (two dimensional wave propagation). I fear that our shared definition of eigenfrequency, as it pertains to diaphragm behavior, must evolve in order for us to move forward. Also, are you familiar with the Yamaha HP-1 headphone? The orthodynamic driver implemented in that headphone is what some call a "pinched" planar magnetic driver. The center of the circular movable membrane is physically pinched at its center much like you say a guitarist will hold a string on a fret.


gvtt said:


> If you know on an object it will always swing mainly in it's first order Eigenfrequencies. A circular membrane has a very dominant first Eigenfrequency (drum). An ellipse has whole cluster, but none of the Eigenfrequencies are as cominant as in a circle.


 Are you familiar with the Sony ECR series of headphones? Their diaphragm is a scalene pentagon. Sony implemented scalene pentagonal diaphragms in this series of electret headphones in order to "smother" diaphragm resonances. I say "smother" because I lack a better word to use. Basically, they are attempting to redirect propagating waves on the movable membrane such that the waves don't interact with themselves and produce relatively high eigenfrequency amplitudes at all. The scalene pentagonal diaphragm concept is attempting to reduce eigenfrequency amplitudes without the use of mechanical damping. I am highly interested in this approach.


gvtt said:


> Instead of taping I could use a loudspeaker. When the speaker emits a sound in eigenfrequency of a close by membrane, the membrane will start swinging. The amplitude will reach it's maximum when you meet it's Eigenfrequency (without damping, the maximum would be infinite, but this will not happen in real world [but the object might brake]).
> 
> If I use a loudspeaker to activate the membrane I will not need a physical contact, the air will do this job.


 Understood and agreed.


gvtt said:


> So if I have Mylar under a give tension, physically fixed along a border line (by pressing a spacer against it) the membrane inside the spacer will swing at about the frequency it will after gluing and cutting it.
> 
> I have not tried this method, but I would be really surprised if this does not work.


 I agree, but measuring eigenfrequency amplitude becomes more difficult as moveable membrane surface area decreases, right? How will you measure the effects? In my mind it will be easier to measure variables with my own ears going by trial and error. Hopefully this does not drive me insane.


gvtt said:


> BUT, the air must move very freely on both sides of the diaphragm. If you hinder the air moving, you increase the damping. This lowers the resonance frequency (as can be seen in the link above). This is also exact;ly what happens if you seal a headphone to the ear: the eigenfrequency drops due to damping, ideally below the lowest frequency you want. You can also use this resonance to increase the bass, but then the free air resonance and the damping must be chosen carefully.


 I would be greatly appreciative if you would join a forum I created called Crop Circle Audio (http://cropcircleaudio.forumotion.com/​) and talk more in depth about this point in the *Driver Design and Theory* section. I'm sure others, myself included, would be very interested in discussing this further. While I feel much of the discussion is related to headphone measuring (it's difficult to choose a section to even discuss this topic within) I feel we're still in the design phases more than anything at this point. If I was to be honest with you, though, while I see the merit in harnessing eigenfrequencies in order to shape your FR to a desired curve, I would still like to design an "ideal" sound producing element whose FR curve can be shaped through equalization. I more than likely hold this opinion because I do not currently know why people choose a V-Rock equalization curve more than others unless this has to do with recording/mastering or some other dismension to sound I'm failing to grasp.


gvtt said:


> I appreciate you commented, taking my previous post into small sections.


 No problem, I feel it's easier this way for people, ourselves included, to follow our train of thought. It can be a slight hassle given I have to go into the source editor function and mess around with code (which I know little about), but it's worth it, imo.


gvtt said:


> I am not sure what to aim for:
> - stability of the membrane not to come in touch with the stator (lowest tension possible)
> - roll off between 25 and 50 Hz to get a bass boost


 What if you glued the spacers to the tensed Mylar when tension is chosen by your best guess as to what will sound good. You use that in order to create an ear chamber and driver housing of unspecified volumes in order to shape the the eigenfrequencies by means of mechanical, acoustic damping as opposed to Mylar tension?


gvtt said:


> Many greetings to Chicago
> Georg


 











 Your friend from across the pond!
 Matt


----------



## GvTT

Hello Matt,
  
 I reply to some of your points:
 - higher order eifenfrequencies: in engineering they are often not relevant, in Audio I think they give the flavor. I completely agree. But you cannot influence their frequency without changing the first order, they are always multiples. You can only take influence on their magnitude by design.
  
 - yes, we are nit dealing with strings, I used this as one of the most simple examples. But I do believe we have not to deal with wave progression. We are exciting the whole membrane at once. It is not like we excite a sting or membrane on one end and can see the wave move along it's extension. If a speaker is design properly, fairly symmetric
  
 - pinching any point of the membrane near the center will cause a big loss in bass, as it basically would eliminate the 1st order eigenfrequency. So instead of 100Hz resonance you would find 200Hz. This, I think is not a good idea. I do not know the Yamaha HP-1 but I would expect the construction to be heavier then an ESL driver. Do you have a clue of the weight of the membrane per mm^2? If the membrane is heavy you should being up the eigenfrequency in free air to the lower audiable range
  
 - pentagonal shaped membrane: interesting idea. I do know speakers using this concept. In an ellipe I would expect the lowest eigenfrequengy to be along the major axis, the next dominant to be along the minor axis, the 2nd oder to be along an axis between major and minor axis (this beeing a double 2nd order). A pentagon (also a square) should have a first oder EF a tad more dominant than the ellipse but the 2nd oder much more diffuse (even lower than in a square). Hmm, this would give the tone a different flavor. This can be simulated very easy, I just don't have the time.
 I have never listened to headphones with different shapes and the same style. I know Wachara as, marbe he can give us his impressions on this topic.
  
 - finding the right tension I will also have to go by trial and error. But I want to know, how tight my membrane is. This way I will end up with a series of know tensions to chose from.
  
 - Joining your forum? I will check is, but my time is so limited, I had to drop other things to follow this tread. And, bare in mind, I am not n audio expert, I am educated in aeronautical engineering and have a strong interest in mathematics and physics. This gives me a different approach to many things, but I have limited practical experience in audio, and very limited in DIY headphones.
  
 - My plan is to know the tension in the Mylar before I glue, so I have spacers with membrane and know tension. This is the sole idea for the first step. 
  
 Greetings
 Georg


----------



## khbaur330162

gvtt said:


> - higher order eifenfrequencies: in engineering they are often not relevant, in Audio I think they give the flavor. I completely agree. But you cannot influence their frequency without changing the first order, they are always multiples. You can only take influence on their magnitude by design.


 I believe you are mistaken to a slight degree here, but I cannot prove my belief correct or yours wrong, I can only indicate my own, as well as others', speculations. I will go in further detail on this later.


gvtt said:


> - yes, we are nit dealing with strings, I used this as one of the most simple examples. But I do believe we have not to deal with wave progression. We are exciting the whole membrane at once. It is not like we excite a sting or membrane on one end and can see the wave move along it's extension. If a speaker is design properly, fairly symmetric


 I believe we do have to believe in wave progression on the diaphragm and I'll tell you why. As you later state, pinching a circular diaphragm at its center will reduce bass drastically. This is because the center of our diaphragm is where we reach max excursion. Because we reach max excursion at this point, when we compare driving forces (when our diaphragm is at max excursion, or at any other point for that matter) we will find our driving forces are not equal across the entire diaphragm's surface area. Because of this we observe rather chaotic diaphragm behavior which includes what I am lead to believe is wave propagation. Because of these standing waves which propagate on your diaphragm we can actually observe eigenfrequency interaction! Eigenfrequency interaction causes what I and others call "resonances." These resonances can be eigenfrequencies of multiple orders interacting with each other causing observable "interference." So, if you were to ask me again, I would still tell you we are dealing with wave propagation in a less-than-ideal, two dimensional plane which we bend and smear in a three dimensional space which is cause for any number of motor force->diaphragm interactions. How many dimensions are we dealing with? Too many for me to comprehend fully! 


gvtt said:


> - pinching any point of the membrane near the center will cause a big loss in bass, as it basically would eliminate the 1st order eigenfrequency. So instead of 100Hz resonance you would find 200Hz. This, I think is not a good idea. I do not know the Yamaha HP-1 but I would expect the construction to be heavier then an ESL driver. Do you have a clue of the weight of the membrane per mm^2? If the membrane is heavy you should being up the eigenfrequency in free air to the lower audiable range


 I do not know the weight/mm^2 measurement of an HP-1, but I concur in that it will be, on average, much more dense than your typical ESL diaphragm. Due to how many variables there are in our hands, however, I'm not sure the density comparison between ESL and planar magnetic membranes is fair. I can attempt to get you a very rough idea on weight/mm^2, however, if you are still interested in that measurement.


gvtt said:


> - pentagonal shaped membrane: interesting idea. I do know speakers using this concept. In an ellipe I would expect the lowest eigenfrequengy to be along the major axis, the next dominant to be along the minor axis, the 2nd oder to be along an axis between major and minor axis (this beeing a double 2nd order). A pentagon (also a square) should have a first oder EF a tad more dominant than the ellipse but the 2nd oder much more diffuse (even lower than in a square). Hmm, this would give the tone a different flavor. This can be simulated very easy, I just don't have the time.
> I have never listened to headphones with different shapes and the same style. I know Wachara as, marbe he can give us his impressions on this topic.


 The Sony ECR series of headphones implement a scalene pentagonal diaphragm. Scalene meaning no one side of the pentagon is equal in length to another. The waves propagate on our 2D membrane, hit their boundaries, reflect back, and interfere with one another in such and such a way that the harmonics may be a little more complex to simulate than previously anticipated. I have heard and owned the Sony ECR-500 a few times and I enjoy their flavor a great deal for acoustic guitar, certain jazz, female vocals, and so on. They are bass light, however, given that they are electret and not electrostatic, and given they have a radiating surface area roughly equal to a 55mm circle, it is understandable they lack lower frequency slam. They have a rather unique flavor in my experience and it's one I happen to enjoy. I've decided to attempt to design a planar magnetic headphone driver heavily influenced by the Sony R&D that went into the ECR series of headphones.


gvtt said:


> - finding the right tension I will also have to go by trial and error. But I want to know, how tight my membrane is. This way I will end up with a series of know tensions to chose from.


 I'm not sure exactly how to go about doing this, I'm sorry. I would create very large spacers that were as close to a perfect circle as I could make in order to clamp my tensioned Mylar (oversized spacers would be large enough that I could use the tensioned Mylar within them to make multiple matched sets of diaphragms using smaller spacers). Past that? I'm unsure of a relationship that exists between eigenfrequency wavelength, eigenfrequency amplitude, diaphragm density, etc. Something you could do is just excite the oversized membrane with a gradually increasing tone starting at 0Hz and see what frequency the eigenfrequency amplitude maxes out at via laser interference? Whatever frequency you arrive at becomes your "tension" value?


gvtt said:


> - Joining your forum? I will check is, but my time is so limited, I had to drop other things to follow this tread. And, bare in mind, I am not n audio expert, I am educated in aeronautical engineering and have a strong interest in mathematics and physics. This gives me a different approach to many things, but I have limited practical experience in audio, and very limited in DIY headphones.


 Understood. I am no audio expert, either, just someone in their garage goofing around. I am not educated but have a strong interest in headphones and, I'd say, psychology, philosophy/ethics, the world/nature, plants, music, girls (talk about variables), etc. Your experience in DIY headphones seems very useful to my forum's cause: "To create a community that is focused on fabricating the best open source headphones in the world for as little money as possible using only free time." I understand your time is precious and valuable to you as is my own. Please consider!


gvtt said:


> - My plan is to know the tension in the Mylar before I glue, so I have spacers with membrane and know tension. This is the sole idea for the first step.


 Understood. I don't even know what units you'd be using to measure tension of the Mylar in, tbh. Again, I'm afraid you're over my head.


----------



## chinsettawong

Gentlemen!  May I point you to one of the threads where my friend was doing a FR test of my headphones driver?  From there, you can probably get some useful information.
  
 http://www.diyaudio.com/forums/headphone-systems/145143-building-wachara-headphone.html
  
 By the way, the spacers used were 1 mm and the mechanical tension of this strecher was not at its ideal weight for the headphones.
  
 As for me, I don't care much about how my headphones' measurement is.  I trust my ears more than anything.  
  
 Wachara C.


----------



## arnaud

khbaur330162 said:


> I believe you are mistaken to a slight degree here, but I cannot prove my belief correct or yours wrong, I can only indicate my own, as well as others', speculations. I will go in further detail on this later.




Don't mean to be rude but please stop rumbling and pretending you know this. GvTT is right on the money actually and if you don't know what en eigenmode for tightened drum skin, wikipedia is your friend  : https://en.m.wikipedia.org/wiki/Vibrations_of_a_circular_membrane

Also, not sure what the heck you guys are going on about with laser vibrometer and all that stuff. You check the first natural frequency by playing a white noise through the assembled unit and sticking whatever smartphone in the near field to visualize the peak, it should be obvious (see links in sig). Also, once you understand what a standing mode is, you'll realize it's silly to try check some resonance frequency prior to gluing the film on the spacer...

Finally, what is optimal tensioning? I think wachara must have said it like 50 times in this thread but I guess this one is bound to come back every now and then.

Cheers,
Arnaud


----------



## khbaur330162

arnaud said:


> Finally, what is optimal tensioning? I think wachara must have said it like 50 times in this thread but I guess this one is bound to come back every now and then.


 
 Sorry to have wasted your time. Thanks for the much needed direction.


----------



## arnaud

khbaur330162 said:


> Sorry to have wasted your time. Thanks for the much needed direction.




Not to worry, I actually skipped most of the walls of text .

Actually had some fun exchanges with GvTT in pm afterwards and he has a quite practical method for quick check of first resonance frequency prior to full driver assembly... He'll post it here I am sure.

As I mentioned to him, for controlling tensioning stax has been using weights and I trust they must have got good at finding the most convenient approach, being at it for over 59 years  (see stax interview link in my sig).

I have measured and also simulated stats resonance frequency in both open and loaded configurations before (some of it in this thread, I think it's in the sig too). Basically, stax phones free air resonance is typically around 150Hz while the loaded resonance is completely depending on the pads stiffness / depth and how leaky that earpad acoustic chamber is. Physically speaking you switch from mechanical resonance phenomenon unloaded to a couple structure-acoustic-porous type resonance when loaded.


----------



## khbaur330162

Very interesting stuff, arnaud, I'll be sure to check it out when I get the chance. Also, if you haven't given much thought to the forum I created, it is to you and others whatever it looks like right now, but I have a direction that I'd like to take it with time. If I can make our collective knowledge surrounding planar headphone drivers more accessible and easier to navigate for newcomers then this can only mean good things for the hobby, imo. It's going to take some time as well as critical thinking concerning what the best method might be to create a free to join, open source, and open enrollment environment that's suitable for teaching people about audio engineering as well as giving people space to explore, however, I think this model's success is completely and undeniably governed by the community's backing support. Open source amplifiers have been around for how long? People have accomplished a LOT on that front. All I'm trying to do here is translate that model into making headphone kits which would be available through a group buy mentality that sound flippin' amazing and are cheap enough to obtain where almost anyone interested can join in on the fun.
  
 One thing to remember is not everyone is at the same level of discussion. So whether or not the Crop Circle Audio forum needs to have milestones that members have to reach in order to unlock deeper parts of the forum is yet to be seen, but it's an idea I've tossed around for a little while now. Let's face it, if you can't add anything to the conversation then why are you in the room? It's perhaps rude to say, but we're trying to be as efficient with everyone's time as possible. Sometimes it's a learning experience to throw a kid who can't swim into the deep end, and other times it can be a traumatic experience that leaves a child scared of water for the rest of their life. A forum's architecture is very important, imo, and can either be beneficial or extremely detrimental to the demographics of people you draw to your site and its overall success. I think it goes without saying you're welcome to join Crop Circle Audio and you obviously have a lot to offer the community. If this does not interest you, however, I'll most likely be stalking you at some point in time in an attempt to organize your thoughts, perhaps expand on them, and simultaneously "dumb them down" so 3rd and 4th graders have an opportunity to step into your mind without being scared away.
  
 The last thing I want to do is bore you so hopefully you recognize a value in what I've said here and we can talk more at some point.
  
 Best Regards,
 Matt


----------



## Hutnicks

khbaur330162 said:


> Very interesting stuff, arnaud, I'll be sure to check it out when I get the chance. Also, if you haven't given much thought to the forum I created, it is to you and others whatever it looks like right now, but I have a direction that I'd like to take it with time. If I can make our collective knowledge surrounding planar headphone drivers more accessible and easier to navigate for newcomers then this can only mean good things for the hobby, imo. It's going to take some time as well as critical thinking concerning what the best method might be to create a free to join, open source, and open enrollment environment that's suitable for teaching people about audio engineering as well as giving people space to explore, however, I think this model's success is completely and undeniably governed by the community's backing support. Open source amplifiers have been around for how long? People have accomplished a LOT on that front. All I'm trying to do here is translate that model into making headphone kits which would be available through a group buy mentality that sound flippin' amazing and are cheap enough to obtain where almost anyone interested can join in on the fun.
> 
> One thing to remember is not everyone is at the same level of discussion. So whether or not the Crop Circle Audio forum needs to have milestones that *members have to reach in order to unlock deeper parts of the forum is yet to be seen,* but it's an idea I've tossed around for a little while now. Let's face it, if you can't add anything to the conversation then why are you in the room? It's perhaps rude to say, but we're trying to be as efficient with everyone's time as possible. Sometimes it's a learning experience to throw a kid who can't swim into the deep end, and other times it can be a traumatic experience that leaves a child scared of water for the rest of their life. A forum's architecture is very important, imo, and can either be beneficial or extremely detrimental to the demographics of people you draw to your site and its overall success. I think it goes without saying you're welcome to join Crop Circle Audio and you obviously have a lot to offer the community. If this does not interest you, however, I'll most likely be stalking you at some point in time in an attempt to organize your thoughts, perhaps expand on them, and simultaneously "dumb them down" so 3rd and 4th graders have an opportunity to step into your mind without being scared away.
> 
> ...


 
 I find this bothersome. I also find it moderately annoying when a poster tells of some trick or tip they received in a PM. and does not post it, that is little more than a taunt at best.  I understand fully the reasoning behind both. Unfortunately there must be a better way to manage online information than withholding it. Read only access would allow people into the room, without having to explain all the minutiae which is understood as common knowledge at that level.
  
  What I am seeing and hearing these days is that essentially the concept of information sharing has taken one giant step backwards to email levels. Pity as there are some out there who could actually add valuable comments and techniques to a lot of the "hidden" information.


----------



## khbaur330162

*"I find this bothersome. I also find it moderately annoying when a poster tells of some trick or tip they received in a PM. and does not post it, that is little more than a taunt at best.  I understand fully the reasoning behind both. Unfortunately there must be a better way to manage online information than withholding it. Read only access would allow people into the room, without having to explain all the minutiae which is understood as common knowledge at that level.​*"
 I am with you on this. Before you jump the gun on me I'd like to reiterate:
 "Let's face it, if you can't add anything to the conversation then why are you in the room? It's perhaps rude to say, but we're trying to be as efficient with everyone's time as possible. Sometimes it's a learning experience to throw a kid who can't swim into the deep end, and other times it can be a traumatic experience that leaves a child scared of water for the rest of their life. A forum's architecture is very important, imo, and can either be beneficial or extremely detrimental to the demographics of people you draw to your site and its overall success. [...] If this does not interest you, however, I'll most likely be stalking you at some point in time in an attempt to organize your thoughts, perhaps expand on them, and simultaneously 'dumb them down' so 3rd and 4th graders have an opportunity to step into your mind without being scared away."
 The belief that I'm telling arnaud everything on my mind is a false one. What's actually on my mind, what I choose to share, with who I choose to share and when I choose to share is my prerogative. My thoughts are constitutionally my own, no? So, in a sense, everything I post on Head-Fi is a private message because I only post what I want the people of Head-Fi to hear from me at any given time. If you so decide to bug my house or develop mind reading technology then we'll cross that bridge when we get there.
  
*"What I am seeing and hearing these days is that essentially the concept of information sharing has taken one giant step backwards to email levels. Pity as there are some out there who could actually add valuable comments and techniques to a lot of the 'hidden' information."*
 I don't for a second doubt this. Where are these people and what do they have to share? What are they hiding and from whom? Is it Hillary Clinton? Is it your mother teaching you from right and wrong? Is it your teacher who thinks a lesson could not possibly be grasped by someone of color or of a certain age? It's ironic we bring up the topic of school in this discussion seeing as each grade is a milestone, right? An I.Q. test probing a person's mind in order to weigh and measure whatever a society deams as "intelligence." They might say we're testing for your problem solving abilities, but they never asked me to paint them a picture. What of my hand eye motor skills? Is athleticism not a form of intelligence? Why was I not asked to climb a mountain?
  
 I'm afraid we've gone off topic. If you wish to discuss the matter further with me I'd be glad to discuss this in the *General* section of my forum or via PM.


----------



## GvTT

Hello,
  
 the PM's I exchanged with Arnaud are not a secret: I have posted my idea more than once in this thread.
  
 I intend to measure the tension on a inner tube stretcher before gluing the Mylar.
  
 To Arnaud and Wachara I explained that in my opinion a weight stretcher will give more forseeable result than an inner tire stretcher. But it takes more effort to build. Hence I will try the inner tube stretcher and measure.
  
 Unfortunately this simple idea cause controverse discussion in the thread. Hence I told Arnaud and Wachara that I will stop posting on this until I have used it and post more details.
  
 The method Arnaud is referring to:
 - put the Mylar on a inner tire stretcher
 - gently press a spacer to the Mylar
 - use a microphone to to measure the resonance frequency when you tab the membrane
  
 This will give you n idea of the tension you have. It is also a hint to the resonance frequency you will expect of the finished driver. But the final resonance will be lower due to damping. I already posted this before with a link to wikipedia.
  
 _______________________________________
  
 My apologies to all about all the mayhem my last posts caused.
 I will post more on this when I have actually used this method and can report results.
 Until then I want to refer all interested readers to wikipedia
https://en.m.wikipedia.org/wiki/Vibrations_of_a_circular_membrane
https://en.wikipedia.org/wiki/Resonance
 It is all in there (especially the blue curve on the topmost graph in the 2nd link)
  
 Greetings
 Georg


----------



## scotsstax

hi spritzer can you help me please... i have a stax srm3 with broken transformer,  i can fix it but need to know the secondary voltages ,before rectification so i can replace the trafo with a toroid ,,many thanks...rob.


----------



## scotsstax

sorry for goin g off topic mate but have you any idea of the secondary voltages  a stax srm3 transformer puts out, before rectification.,or know anyone eho does?? cheers rob.


----------



## Julez

I am also planning to build my own electrostatic headphone. I want to make a huge Jecklin Float type headphone.
 My plan is to go with 100x120mm active area. The drivers will be made of PCB in 1 or 0.5 mm thickness. I want to
 make a 3d printed housing and be able to move the drivers into proper position (distance and angle to the ears) as
 every head is different.
  
 I have allready started to repair Stax drivers from an SR-5, SR-Omega and a 507 Lambda (the glued drivers are a
 pain as it is practically imposible to disasemble the divers if there is a problem). SR-Omega and SR-5 are screw
 together and can be easyly reopend. I use a frame that was cut at the corners and can be pressed apart with screws.
 I glue the Mylar (1.5 micro) with doublesided tape to the longer sides of the frame and tighten it with the wooden
 latch to the frame with a protective ducktape between the Mylar and the latch.
  


  
 I was successful in making drivers from my SR-Omega that are working fine without any dustissues for a few months.
 But as Wachara said before: It was a trail and error to get the proper tension. I use 1.5 micro Mylar and stretch tight.
 Then I use a head gun and warm the mylar to about 150°C and stretch it again. I do this two or three times. At the end
 I try to get the tension nearly the same over the whole surfcae checking it by knocking with my fingernail to different
 parts of the membrane. The I glue the metal rings onto the mylar by putting a glassplate exactly underneath the mylar
 and then another glassplate on top of the metal rings. I use some heavy books to have good pressure on the metal rings
 while the glue (I use Pattex 100% glue without solvant). It takes about 1-2 hours to dry enough to flipp the stretcher and
 I do the same with the glassplates to put pressure on the rings when gluing the spacers to the other side of the Mylar.
 After another 1-2 hours. I have tried diffrent types of glue and had the problem that many epoxy glues or contact
 cement where drying to fast form me and therefore did not stick properly in the end. The Pattex has another advatage
 in my opinion. It is strong enough to hold the Mylar when dryied but can be cut open again without too much hassle.
 Another thing I had when gluing mylar with glue containing a lot of solvent was that some parts of the Mylar where
 affected and turned milky.
  
 When the glue is dried I cut the membrans out with a soldering iron that I also use to carefully remove the rest of the
 Mylar around the drivers. I coat the membrans on both sides (as Stax does it) with a thinned antistatic agent applied
 with a sponge. I make shure to also coat the inner side of the metal spacer as this is where the bias gets to the
 membrane (the glue is an isolator). I tired to measure the resistance of the dried antistatic but my meter showed
 nothing (It can measure up to 2gigaohm with up to 1000V). So I think my resistance must be higher than 2 gigaohm.
 My experience with the Omega is that it has no charging time to reach full volume and it is of corse equally loud on
 both sides. I also reworked an old non working Jecklin Float with this method. Of corse I did only coat one side of
 the Float membrans because of the design. It has only one metal stripe to connect to one side of the membrane.
 And as there are no seperate spacers (they are integrated in the stator) I could not coat the membrane on the side
 faceing the stator. I just coated the opposite side and then (still in the stretcher) put the other stator on the coated
 side (after coating was dried) and screwed both together as Wachara does this with his designs. I had to manipulate
 the stators and drill bigger holes into it to be able to use screws. Again it allows for better maintainance if there is a
 problem with the driver. Sorry but I forgot to make pictures of the Float drivers during the work. But here are pics of
 the Omega and Lambda drivers:
  


  
 Basically I found out what Wachara allready stated. 1.5 micro Mylar is very tricky to handle and
 it takes a lot of trail and error to get the right tension. I never had too much tension on a driver. 
 Only not enough. You are right if the tension is nearly maximum and another tiny bit of stretching
 and the Mylar would rip apart. I only got the right tension with heat treatment. With the coating it
 is another story. Like I said I could not measure the resistance. I am not really shure it was because
 of too high resistance or bad contact. The agent I use is not commercially available. It is a basic
 solution for making commercial antistatic. I used 20 parts alcohol (in Germany called Spiritus) and
 one part antistatic and applyed a thin layer of the mixture (as thinn as possible but covering the
 whole Mylare surface). When the coating has dried I apply it to the other side and let it dry again.
 Then I use a very soft brush when assabling the drivers to clean everything carefully (including
 the membrans on both sides). Ready. Or there is noise and I have to open the driver again and
 clean everything. Sometimes serveral times.
  
 I hope this is helpful for anyone trying this at home! If there are still questions feel free to ask!


----------



## listen4joy

really intresting topic, but i just want to ask chinsettawong  is the *Orpheus * clone is close to the real one in terms of SQ? what is the total price of building it? which drivers did it use? do you build it and sell for others?


----------



## wppk

chinsettawong answered already to all these questions many times.
 so, just as for me, ( I still havent' read it all) I think it would be better to read the thread, of at least, some parts of it, you will find the answers repeatedly, I think.


----------



## chinsettawong

wppk said:


> chinsettawong answered already to all these questions many times.
> so, just as for me, ( I still havent' read it all) I think it would be better to read the thread, of at least, some parts of it, you will find the answers repeatedly, I think.


 
  
 Thanks wppk for helping me answered.
  
 By the way, when I had the real Orpheus with me, I still prefer the sound from my Orpheus clone.  
	

	
	
		
		

		
			




  
 I do not sell any of my work.  Please read the thread and if you are interested in building them, I'm always here to help.


----------



## edstrelow

julez said:


> I am also planning to build my own electrostatic headphone. I want to make a huge Jecklin Float type headphone.
> My plan is to go with 100x120mm active area. The drivers will be made of PCB in 1 or 0.5 mm thickness. I want to
> make a 3d printed housing and be able to move the drivers into proper position (distance and angle to the ears) as
> every head is different.
> ...


 
  Many years ago I was a post-doc in a University department of Electrical Engineering where the senior technician made electrostatic drivers for ultrasonic air-borne sonars. These had to be made to a  consistent standard and had to pass a set of  frequency response measurements.  To get consistent tension, he used a system of weights  to stretch and  tighten the mylar before gluing  I don't have any pictures though and he is long retired.


----------



## Nemeske88

Dear Forum!
  
 I am writing if anybody could help me with a little technical help, I don't know if I'm knocking at the right door...
 I am now about to remove the old and put some new dustcover into my Quad 57's panels.
  
 I am asking what kind of cellotape should be used for the procedure?
 I can source 50mm wide PP, PVC, BOPP tapes, but I have no idea which one should I buy?
  
  
 Thank you for your help in advance!


----------



## chinsettawong

It's better to ask your question here: http://www.diyaudio.com/forums/planars-exotics/
  
 There are many knowledgable people who can really help you there.


----------



## Nemeske88

thank you for your reply. I will check it immediately!


----------



## DaveK1977

It's been a while and some stuff got in the way for a while, but here's a fully working driver that I built today to verify that the materials were sufficient and the old Koss energizer works.  I plan to use these materials and methods to now build a pair of drivers into an existing pair of headphones.


----------



## chinsettawong

That's nice!  Keep going.


----------



## DaveK1977

I completed a pair of drivers, but only one worked.  I'll rebuild the other tomorrow.  The one that worked sounded really good and clean.  The audio from the video isn't bad, but doesn't and can't convey how it really sounds.


----------



## chinsettawong

Good job!  How big are your drivers? What is your spacer thickness and bias voltage?


----------



## DaveK1977

chinsettawong said:


> Good job!  How big are your drivers? What is your spacer thickness and bias voltage?


 
 Thank you!  The outer diameter of the drivers is 85mm, but the actual size of the driver itself is a square that's about 55mm on each side.  The "spacers" are 3M VHB double-sided tape, taking a hint from how Martin Logan assembles their speakers.  It's about 1.14mm thick.  I'm using an old Koss E9 energizer that supplies a bias voltage of about 360v, but works differently than the modern amps do.  It's all as cheaply as I could possibly do and make it work, just to test, and that energizer was $30.  It has to be used with the old Marantz receiver in the first video's thumbnail because that's the only power amp that I have access to that has common ground between the speaker outputs, which the Koss energizer uses.


----------



## chinsettawong

Using whatever you can find to work with is actually a very good idea.  From there you learn the basic and you can gradually improve on your design.
  
 Congratulations and keep us posted with your progress.


----------



## DaveK1977

chinsettawong said:


> Using whatever you can find to work with is actually a very good idea.  From there you learn the basic and you can gradually improve on your design.
> 
> Congratulations and keep us posted with your progress.


 
 I still had to buy a ton of stuff, but what I basically did was cut a lot of corners.  I'm now shifting gears to get a pro bias source so I can build to an accepted standard for driving it and use amp plans from online.  It sounds quite good when you're in its beam, but I'm eager to build this into a pair so that I can really hear it.  I'm a little concerned because it clearly is spiking the higher it gets.  We stopped the frequency sweep at 17 kHz because the amp had started clicking at 17.5 frequency.  Sustaining 17 was fine and really loud.  I hope that building it into the shell will settle some of that more level due to the proximity.  It's been fun, too.


----------



## -JFK-

Hi all, 
  
 I wish to build ESL speakers since year, but big lake of time and space, so now I will start with Headphone.
  
 There is the link to my very first 3D conception : https://drive.google.com/open?id=0B3k06KRLerMUX3FZTS1lamFKVWM
  
 I have access to a 3D printer, laser engraver, 3 axis CNC (all DIY).
  
 Could you please tell me what you think about my design ?
 Parts 2 and 3 are concentric, part 3 is for the electrical conduction to the diaphragm.
  
 I still have questions about the coating, I will try the same way as chinsettawong. Do you think that any anti-static gel will do the trick ? (Sorry, I have not finit to read the all tread i'm page 44)
 If you can point me to the best way to coat it, I appreciate.
  
 And the last question are about to find a drawing to made the amplifier, I'd like a way to easily adjuste the diaphragm bias and anodes voltage via potentiometer.
  
 Waiting your reply !
 Thank you.


----------



## chinsettawong

Hi JFK,
  
 Your design looks OK.  However, nylon stocking for dust cover isn't good enough.  I use Mylar for the dust cover too.
  
 I'm curious as to what kind of 0.01 mm tape are you going to use.  I'm not sure if the tape is strong enough to hold the diaphragm under tension though.  I guess it's best that you try it and let us know how you like it.
  
 Since you have all the tools to get all the things done.  Just go for it.  
  
 There are many antistatic gels on the market.  What I can get here might not be available where you are.  I now use floor cleaner as my coating material and it works great for me.
  
 Keep us posted of your progress.
  
 Wachara C.
  
 PS.  I also make full range ESL.  If you can make the headphones, ESL aren't more difficult.


----------



## -JFK-

Thank you for your reply. 

Could you please post a link about your floor cleaner? I will try to find something identical. 

And if possible a good link about diy amplifier. 

Of course if needed, I can share the 3D files (Solidworks). Open source power! 
And finally, if someone want me to make 3D file of your hand drawing for CNC processing, no problem.

For the amp, i was thinking to use Icepower 300asc modules as I can buy it at my job for 47€ each, then use simple transformers for high voltage. 
What do you think about it?
Edit: just checked, can get 50asx2 too, should be enough for a headphone? 
The diaphragm bias voltage is around 600V.
What about the stators voltage? Around 600V too?


----------



## chinsettawong

If you have read the thread from the beginning, you should have noticed that I have already recommended a very easy to build all-tube amplifier on the very first page.  Or if you want some high end DIY amps, you should check out those designed by Dr. Kevin Gilmore.  They are some of the best in the world.
  
 Also about the coating material, Staticide 6300 is very good.  For floor cleaner as the coating material, I use this:
  

  
 Best regards,

 Wachara C.


----------



## bui501-tech

.


----------



## bui501-tech

Chinsettawong -- Holy Cow!  I became an audiophile only a few months ago shortly after moving to Bangkok.  It wasn't long after that that I stumbled upon electrostatic headphones, then DIY electrostatic headphone discussions, and then now, your DIY thread.  
  
 You are absolutely awesome!  I am an electrical engineer of almost 30 years and was proud of being able to restore my beat up old Stax SR-303 and amp, but I was stunned when I saw what you were able to do as a DIY'er -- with a DIY CNC, no less!  I hope to one day make my own electrostatic headphones, but I can only dream of coming even remotely close to a fraction what you've done.  What a feat of engineering and craftsmanship!
  
 Wonderful Work!


----------



## chinsettawong

Hi bui501-tech,
  
 Thanks for your compliment.  If you are still in Bangkok, perhaps we can meet up sometime, and I can show you my works.  
  
 Wachara C.


----------



## bui501-tech

Chinsettawong,
 I'm living in Bangkok for the next couple of years.  I'd love to see your work in person one of these days.  They look beautiful in the photos you've posted in this forum.
 Best Regards,
 Vinh (bui501)


----------



## -JFK-

Hello, 
  
 Did someone have try this kind of conductive glue for the diaphragm to the FR4 copper PCB ?
 http://www.thinkgeek.com/product/b70c/
  
 I still don't know why, but I want to coat the diaphram on both side and use that kind of conductive glue for the contact to the PCB. 
  
 What do you think ? I'm wasting my time ?


----------



## chinsettawong

Yes, I think you are wasting your time.


----------



## -JFK-

chinsettawong said:


> Yes, I think you are wasting your time.




Could you please post a link to the glue you use (I have still not finished to read the entire thread or doesn't remember...) 
Tx


----------



## Kerry

Any reason not to use Staticide 6500.  I can't find the 4oz bottles of 6300 and don't feel like spending $120+ for a quart.  The 6500 spray seems to be the same as 6300 but in an aerosol.
  
 Thanks


----------



## Congo5

I use it for same reason, found on amazon.
 spray can of 6500.
 it works, none are easy for me to apply the right amount the first time...every time.
 one set have been working for a year so far.


----------



## chinsettawong

Staticide 6500 should be very good too.


----------



## Kerry

Thanks. I'm getting close to starting my build and wanted to start sourcing what I need.


----------



## bui501-tech

sky44 said:


> [size=medium]Hello Wachara,[/size]
> 
> [size=medium]Yes, Stax compatible connectors are possible DIY.[/size]
> 
> ...


 
 Philippe - Oh, Wow!  I just started reading this thread this weekend (originally drawn to it by chinsettawong's posts), and I am continuing to be more and more impressed and more and more inspired by folks like you, Chinsettawong, and others who have come up with some amazing ideas and builds.  I haven't seen anything that matches Chinsettawong's hand-made electrostatic headphones yet, but your idea for the home-made stax connectors caught my attention because I just ordered a DIY amp kit from spritzer to build my own amp and was toying with the idea of adding a second output to the amp when I'm done.  I realize your post above is ancient, but just wanted to thank you and let you know it's still helpful to those of us who are new to the DIY audio world (especially DIY electrostatic headphones/amp world).
 Regards!
 -Vinh


----------



## chinsettawong

Hi Vinh,
  
 Welcome!
  
 About the Stax plug and jack, you can now make them very easily using ABS filament printed from a 3D printer.  
  


 Have fun reading.  
  
 Wachara C.


----------



## bui501-tech

Chinsettawong,
 For the locally-available floor cleaner that you're now using, do you have to re-apply the coating after a while, or does it stay on permanently?  Do you have to mix the floor cleaner with anything else (like graphite powder) or do you just use it straight from the bottle?
  
 On a related topic, I've been reading through your (older) posts and saw that you've used graphite and staticide earlier in your earlier builds.  The graphite powder and staticide sprays and coatings I can order from U.S. online vendors.  And I can find Swash floor cleaner easily here.  What would you prefer as the coating in terms of permanence and audio quality if sourcing weren't an issue?
  
 Regards,
 Vinh
  
 Quote:


chinsettawong said:


> If you have read the thread from the beginning, you should have noticed that I have already recommended a very easy to build all-tube amplifier on the very first page.  Or if you want some high end DIY amps, you should check out those designed by Dr. Kevin Gilmore.  They are some of the best in the world.
> 
> Also about the coating material, Staticide 6300 is very good.  For floor cleaner as the coating material, I use this:
> 
> ...


----------



## bui501-tech

chinsettawong said:


> Hi Vinh,
> 
> Welcome!
> 
> ...


 
 Wachara,
 LOL -- you mean YOU can easily make those Stax plugs with a 3D printer!    I learned how to use a lathe and milling machine way before the computer age, but I've only just decided to learn how to use a CNC machine just so I can try to build my own electrostatic headphones like you.  It'll be a while before I learn how to use a 3D printer.  
 Cheers,
 Vinh


----------



## chinsettawong

Yes, I can certainly make the plugs and jacks easily using my 3D printer.  It's the reverse principle of what a CNC router does.  For a CNC router, you cut away the material to make what you want, but for a 3D printer, you build up a tiny layer at a time to build up your design.  It's not that difficult to learn to use it too.  You should try.  
  
 Wachara C.


----------



## chinsettawong

By the way, if you can get Staticide 6300 or 6500, I think they are better than the Swash floor cleaner.  Even though the floor cleaner works well for me, but yes, from time to time, I do need to reapply it to my diaphragms.  As for graphite powder, I don't recommend it.
  
 Wachara C.


----------



## -JFK-

Hi all, 
  
 I'm waiting the 0.6 and 1.6mm PCB. So I'm "building" a simple amp based on :
 -IcePower 50ASX2 : http://www.icepower.bang-olufsen.com/files/solutions/icepower50asx2_datasheet_1_5_20150709.pdf
 -Triad VPL2-10000 : http://www.mouser.com/ds/2/410/VPL2-10000-781293.pdf
 So the ratio of the transformers are : 1:180.
  
 (The left part of the setup is the bias) 

  
 I'm happy for a first try, that work !
  
 Then I received a sample of Antistatic liquid for the coating : Staticontrol AS90E40 :

  
 Any remarks ?
 Regards.


----------



## gaetan8888

*About using kapton for electrostatic headphone*
 Hello

 Anybody do have experiences or opinions about using 7 micron kapton plastic film for a diy electrostatic headphone ?

 Thank

 Bye

 Gaetan


----------



## kevin gilmore

Kapton has high electron mobility so I think it would be very hard for it to hold any kind of charge.


----------



## -JFK-

Hello, 
  
 I will use 0.6mm spacer and 1.6mm stator (cheap and easy to find single sided PCB).
 Do you recommend diameter 2mm or 2.5mm for the stator holes ?
 (Ovale shape, active area : 105x85mm)
 Tx.


----------



## chinsettawong

I always use 2 mm.


----------



## -JFK-

Hello, 
  
 For the curiouse ones, this is the first prototype that I will build : (waiting the delivery of my FR4 PCB and mylar)
 Active area : 105x85mm
 Diaphragm : 3um Dupont C mylar
 Coating : Staticontrol AS90E40
 Spacers : 0.6mm
 Stators : 1.6mm / dia.2mm holes
 Bias : from 200V to 1200V adjustable
 Step-up transformers : 1:180 with IcePower 50ASX2 amp.
  
 https://drive.google.com/open?id=0B3k06KRLerMUMVFwQmJkSVdXam8
  
 And the viewer if needed (free) : 
 http://www.edrawingsviewer.com/
  
 What is the impact on the sound if I didn't remove the surround copper on the spacer ?
  
 Any comments are welcome !
 Regards.


----------



## chinsettawong

It looks good.


----------



## -JFK-

What is the impact on the sound if I didn't remove the surround copper on the spacer ?


----------



## chinsettawong

It will sound warmer.


----------



## gaetan8888

kevin gilmore said:


> Kapton has high electron mobility so I think it would be very hard for it to hold any kind of charge.


 
  
 Hello
  
 Even if I coat the Kapton with graphite powder ?
  
 Thank
  
 Bye
  
 Gaetan


----------



## gaetan8888

Hello
  
 I've just received few sheet of 6 micron Hostaphan.
  
 How about using that Hostaphan ?
  
 Thank
  
 Bye
  
 Gaetan


----------



## chinsettawong

Hostaphan should be as good as Mylar.  Go for it.


----------



## -JFK-

Hi Wachara, 

Witch software do you use for CAD and for the CNC (GCode?)? 
Thank you.


----------



## chinsettawong

I take my gears to a local DIY meeting today.  Our theme this time is DIY VS Vintage.  Many people take their amplifiers and loudspeakers to the meet.  Here are some photos that I take at the meeting:
  

  

  

  

  

  

  

  
 I let them try out my Orpheus Clone and JF Clone.  Most of the people prefer JF clone for its wider sound stage and more relax feeling.
  
 Wachara C.


----------



## chinsettawong

By the way, I've upgraded my KGSSHV to KGSSHV Carbon.  It's very gooooooood.


----------



## bui501-tech

chinsettawong said:


> I take my gears to a local DIY meeting today.  Our theme this time is DIY VS Vintage.  Many people take their amplifiers and loudspeakers to the meet.  Here are some photos that I take at the meeting:
> 
> ...
> 
> ...


 
 Wachara,
 Let me know the next time there is a local meeting. 
 Cheers,
 Vinh


----------



## OnyxOcelot

Hi -JFK-
  
 Could you let us know a bit more about the amp you are building?  Or show us a schematic?
  
  
 I have built several pairs of ES Headphones for my 'normal' (230V) bias Stax energizer, but would like to build headphones and speakers with a higher bias requirement.  I have very little experience with circuit design, but am working my way slowly through a circuit design coursebook ("Learning the Art of Electronics," if anyone is interested), and would like to design a similar variable-bias amp when I am able.  
  

 Any guidance is appreciated!
  
 Thanks,
 OO
  


-jfk- said:


> Hi all,
> 
> I'm waiting the 0.6 and 1.6mm PCB. So I'm "building" a simple amp based on :
> -IcePower 50ASX2 : http://www.icepower.bang-olufsen.com/files/solutions/icepower50asx2_datasheet_1_5_20150709.pdf
> ...


----------



## -JFK-

Hello, 

I have choose the lazy way for this first try. 
For the bias I finally use that : http://www.ebay.co.uk/itm/131581679768
But they are very noisy, I will have to build my own. 

For the step-up transformers I have wire it like that:


My CNC is ready. I will start soon building the cells.


----------



## -JFK-

Hi Wachara,

 Witch software do you use for CAD and for the CNC (GCode?)?
 I'm using Solidworks for CAD but have some difficulties to generate GCode...
 Thank you.


----------



## OnyxOcelot

Thank you -JFK- !
  
 I would also like to build a similar variable-bias power-supply soon, but need to spend a great deal more time learning about high voltage electronics first!  
  
 Also, I use Solidworks for CAD, and output .DXF files to Vectric Cut2D (http://www.vectric.com/products/cut2d.html) to generate G-Code.  It works fine once you've figured out which post-processor (which determines G-Code parameters) works for your particular CNC.  What are you using to run your CNC?  An Arduino, or dedicated computer?  
  
 OO


----------



## -JFK-

Hello, 

I use an arduino with GRBL.
Find the righ post processor is my current problem...


----------



## -JFK-

Hello! 

First try! 
For spacers, no problem :



But for stators... I have to buy carbur drill! 
The HSS are not strong enough...


----------



## chinsettawong

For PCB drilling and routing, I use something like these:


----------



## Muamp

Hi Wachara C.
  
 I have been meaning to post some photos of my now boxed TubeCAD energiser and some more CNCed FR4 panels, but I have not had a chance to use the workshop for the last 3 months,..... I fell at work and broke my leg and hip,... hospital, wheelchair, two crutches and now just one crutch!.. Tomorrow I start CNCing again! I just finished boxing the TubeCAD energiser before the accident.
 Now for some serious panel building.
 Whilst recovering, I got hold of a Stax SRM-252s energiser and SR-207 headspeakers. I know they are bottom of the range, but my panels on the SRM-252s sound good!
  
 David.


----------



## chinsettawong

Hi David,
  
 I'm sorry to hear about your accident.  Wishing you a speedy recovery.
  
 I always like to see what people build.  So, when you have a chance, please show me your work.  
  
 Oh, I have no doubt at all that your DIY headphones sounding good.  I always compare mine against Stax SR007 and SR009.  After comparison, they are back in their boxes as I feel that my headphones sound just as good, if not better.  
  
 Wachara C.


----------



## OnyxOcelot

Well, from the looks of things, you seem to have figured it out!  But, for reference, I use the "Tiny G" post-processor.  Synthetos -- the company which made the Arduino G-Shield for GRBL -- also made Tiny G, and they support similar sets of G-Code.
  
 https://github.com/synthetos/TinyG/wiki/What-is-TinyG
 https://www.synthetos.com/topics/vectric-aspire-post-processor-for-use-with-tinyg/
  
  
 Quote:


-jfk- said:


> Hello,
> 
> I use an arduino with GRBL.
> Find the righ post processor is my current problem...


----------



## -JFK-

Thank you a lot, I will check that. 
Currently for 2.5D no problem but for 3D I still have error in G-Code... 
I think that I will have time tomorrow. 
Now, I building the hardware for tensioning the mylar. 
I will not use scale on the mylar but the frequency fondamental of the membrane to get something more accurate and repeatable. 
I will post pictures once done. 
Tx!


----------



## OnyxOcelot

Here is my new Mylar stretching rig, in case anyone is interested!  
  
 Some design details:
 -- Dowels run through the corners, with springs around the dowels pushing the frame apart.  
 -- Turnbuckles allow me to tension or loosen the frame evenly.  
 -- Each piece of frame that touches Mylar has rubber on it to prevent tearing at edges.
 -- I use spring clamps to hold the frame top and bottom together.
  
 Happy to answer any questions is someone wants to build a similar device!


----------



## chinsettawong

Interesting stretcher.  Have you already made some diaphragms out of it?


----------



## OnyxOcelot

Yes, I've made one pair of diaphragms with it.  It is VERY easy to use and seems to work relatively well.  I don't have a good way of comparing / measuring diaphragm tension, so can't speak to its effectiveness, but I can get the mylar drum tight (so that it has a clear note when tapped) relatively easily.  Next time, I will try using heat (a hair dryer) to allow the mylar to stretch further.
  
 One note, I suspect it stretches furthest at the corners, so maybe having more corners (making a similar design but using an 8-sided shape) would spread this tension out and allow one to stretch the diaphragm material even tighter without ripping.
  
 Quick question: I have had some difficulty finding the best way to make a housing for my headphone drivers.  Does anyone have any suggestions on this?  I'd like as simple a solution as possible for the housing and strap.  Currently, I use a pair of gutted out old headphones, but nothing fits quite right.  I have tried on my mini-mill but it is a bit weak to work with wood.  Or perhaps oak is too hard of a wood...  maybe I could find a much softer wood...
  
 Quote:


chinsettawong said:


> Interesting stretcher.  Have you already made some diaphragms out of it?


----------



## chinsettawong

If your stretcher can do a good job making the diaphragm, you really don't need to do further heat treatment. In fact, if you do it, the diaphragm tension will not get any better. In my experience, it even makes it worse. You can try it. 

As for me, I prefer to make the stretcher big enough to make a pair of diaphragms in one go. By that way, you get a matched pair everytime.


----------



## -JFK-

Hello, 

This is my first attempt for the membrane tension! 
Material:
-20" bicycle wheel. 
-16" bicycle air chamber. 
-Medicine pump
-mylar, double side tape, tube... 

The air chamber diameter is too big so I have choose to fold it one time. 



Why a medicine pump? 
-Because it's easy to release pressure! 
Don't forget to remove the air chamber valve

Then, simply put the tensioner on the mylar and tape it. 
Reverse all and:
Without tension:

With tension:


Last step:
A little kick on the membrane and check the frequency resonance. 
Adjuste the frequency with more or less pressure in the air chamber then glue the stators (my next step!) 

Any remarks are welcome! 
Regards


----------



## lauren312

Thanks to this topic, I have learnt a lot of new interesting ideas to do it myself. I’ll follow the guidelines to make my own one. Hope to be successful at the first time I try.


----------



## MuZo2

-jfk- said:


>


 
 Great idea. Looking forward to the finished result.


----------



## chinsettawong

I like your hand pump.


----------



## -JFK-

Hello, 

I don't know why, but from the beginning, something tells me that "double sided coating" is the way that I should go... 

So I just bought graphite powder and want to mix it in contact cement glue (French word is "colle contact neoprene"). 

After some digging over Internet, I will try 50/50, glue/graphite mix. 
If needed, I will add some "white gaz" (French : "essence C") to smooth it. 
If anyone of you have skills in glue, just let me know if I'm on the right way! 

Then, I just fix a broken megaOhm meter and like to know if someone know how to measure the diaphragm conductivity and values. 

Any information on how to apply the coating is welcome too

See you next step... Thanks!


----------



## chinsettawong

Hi JFK,
  
 You should try to read the thread.  The discussion on diaphragm coating has always been brought up again and again.  If you want to use graphite powder, don't mix too much with the glue.  You really don't want the diaphragm to be very conductive.  I've tried the mixture of graphite powder, PVA glue, and water.  While it works, the glue tends to absorb too much moisture from the air and eventually fails.  I really don't recommend it.  But if you just want to try it for fun,  then just go ahead.  Putting the glue on the diaphragm also adds a lot of weight to the diaphragm, and that isn't good.
  
 Double sided coating isn't necessary.  I doubt if you will hear any difference.
  
 Wachara C.


----------



## -JFK-

chinsettawong said:


> Hi JFK,
> 
> You should try to read the thread.  The discussion on diaphragm coating has always been brought up again and again.  If you want to use graphite powder, don't mix too much with the glue.  You really don't want the diaphragm to be very conductive.  I've tried the mixture of graphite powder, PVA glue, and water.  While it works, the glue tends to absorb too much moisture from the air and eventually fails.  I really don't recommend it.  But if you just want to try it for fun,  then just go ahead.  Putting the glue on the diaphragm also adds a lot of weight to the diaphragm, and that isn't good.
> 
> ...




Sorry, 

I was not clear. 
I will coat the diaphragm with "staticontrol" solution. 
The mix glue/graphite is to glue (and electrically connect) the diaphragm to the cooper side pcb spacer.


----------



## Julez

Coating one side or two does not make any difference in sound. I first could not belive it but I tried it on one headphone.
 I coated one driver on both sides and the other only on one side. There is absolutly no difference between the two sides!
 I think the advantage of coating only one side is that it is faster and you can expect less trouble with dust. If you coat both
 sides I don't know if there is any advantage. But Stax does coat both sides. So at least they must think it is better to coat
 both sides. I will stick now to only coating one side. That works very well even on repaired Stax headphones wich had both
 sides coated before my repair. And compard to the same headphone in original condition there is no difference in volume.


----------



## chinsettawong

Are you sure that Stax coats the diaphragm on both side? I once open up a SR207. After a close investigation, I'm pretty sure that it's coated only on one side.


----------



## Julez

I thought so. At least on the older models. But the coating on the newer Lambdas is really thin so it is hard to see. Maby I will
 try to measure the coating resistance on a Lambda driver from a LNB and see if it is coated on both sides. Maybe Stax is after
 all only coating one side. I can see no real advantage to coat both sides. It can only cause more trouble than coating one side.
 And after experiencing there is no difference at all in volume and frequencyresponse I will only coat one side from now on.


----------



## Julez

I thought I share that discovery so people can be shure that coating one side does work well without any differences to coating both sides.


----------



## Julez

Hi Wachara,
  
 you are right. I just measured a 507 driver on both sides but could only get a result under 2 gigaohm on one side. I had to measure
 less than one cm of coating to get a reading of 1.8 gigaohm. So the resistance of the 507 driver is pretty high. I heard a few times
 Stax uses coating with about 200-500 megaohm. On my measured driver this is not true. I would say resistance is about 2.5 gigaohm
 per cm. The coating is so thinn that it is not really possible to see the coating. So Stax seems also to only coat one side. At least
 on the Lambdas.
  
 I thought otherwise as I experienced if the contact between the two membrane rings on a 007 has failed it will be down 6dB on that side.
 Soldering a bridge between the two rings immediatly solved the problem. I had this with two 007s. I thought this is due to only appling
 the bias to one side of the membrane. But this can't be as it does not make any difference if one or both sides are coated.
  
 I also experienced if only one side is coated with about 200-400 megaohm the membrane will glue to one stator if I push the heaphone
 towards my ear. I recoated with a solution where I doubled the solvant (pure alcohol) and now the membrane will not glue to a stator if I
 push the driver towards my ear. So if you use an antistatic like my Kontakt Chemie Antistatik 100 (it's a spray) you should make a thinn
 solution of the antistatic with a solvant and you apply it very thinn. I allways put a lot of the solution on the membrane and then turn the
 driver 90° to let the unneeded coating drip back into the bottle of my coating mixture. I do this in a selfmade dustfree flowbox and I filter
 the coating through a fiber filter with about 100micrometer holes. If you barely see the coating after it has dried completely it should be
 good. Best to measure the resistance with a proper measuring instrument (wich can be bought for about 30USD). Then normally it is
 working as it should and there is no dustproblem since I do this method of coating the membrane. But I use this only since a few days.
 Let's see if the coating stays stable for a longer period.


----------



## chinsettawong

I have been using the floor cleaner I recommended for the past few years and I have no problem with it so far.  I can coat it extremely thin too.  In fact after the coating is dried and buff the diaphragm and the diaphragm is crystal clear with no trace of coating to be seen.  I think that's what a good coating should give.


----------



## Julez

Yes that supports defenitly what I also found out. The coating must be very thin so it is really hard to see. Than one gets the needed surface resistance. I just had problems when I tried to apply the coating with a sponge as somehow allways some prticles (of the sponge or what was in the sponge) ended up being baked into the coating making that ugly tone indicating a dustproblem. Rubbing that off with a very soft brush often destroyed the coating and led to up to 10dB less output on that driver.


----------



## -JFK-

Someone have try to spay the coating and let it dry? 
In that way, we don't need to touch the diaphragm so no dust transfer, and it "should be" applied really homogeneous.


----------



## chinsettawong

This is what my coated diaphragm looks like.
  

  
 I put my coating on using a lint free cloth (microfiber?) and buff out after it's dried.  Then, I check for the dust by looking at the diaphragm from the side, and I use the cloth again to clean away all the small particles.


----------



## Julez

Looks like no coating. I think that is ideal. Where I live (Düsseldorf) it is pretty dusty. I think that is the reason why I have to do this in a dustfree box.


----------



## gaetan8888

Hello
  
 I've buy a graphite tube, how can I do a very thin coating with graphite ?
  
 I would use hostaphan plastic film.
  
 Thank
  
 Bye
  
 Gaetan


----------



## -JFK-

gaetan8888 said:


> Hello
> 
> I've buy a graphite tube, how can I do a very thin coating with graphite ?
> 
> ...




Hello, 

Many people report that antistatic solution work very well and it's easy to use... 
Why do you want to use graphite? 
Well, you can try a highly diluted solution of cement glue mixed with graphite and try to spay it?


----------



## -JFK-

Hello, 

Did someone can post a link about the dust screen that you use? 
Or it's the same mylar film randomly wrapped (crumpled) ? 
Thabk you.


----------



## Julez

You can use the same film you use for the membrane. Just crumple it very tight so it wil be a small ballthat is  very compressed. Than you carefully have to unwrap it. After that you can use it as dustcover. Strechtch it lightly (so it will not flutter when pushed by the air of the driver) and glue it on top of the driver (or wherever you want it to be glued to).


----------



## OnyxOcelot

Slightly off topic but I am curious to head how people make the headphone bands.  So far, I've only used parts of old headphones, but would like to make my own.  I have access to a small sheet metal brake (a type meant for making the chassis of electronic devices), but nothing else in terms of metal working tools.  So, here are my questions:
  
 What type of metal do you use for your headphone bands?  Spring steel? 
  
 Do you hot or cold bend these metals?
  
 Any tips on metal bending techniques would be appreciated.


----------



## chinsettawong

The material use is actually up to your creativity.  As for my latest JF Clone, I use brass welding rods and hand bend to shape.  The back plates that hold the rods are 3d printed.


----------



## -JFK-

onyxocelot said:


> Slightly off topic but I am curious to head how people make the headphone bands.  So far, I've only used parts of old headphones, but would like to make my own.  I have access to a small sheet metal brake (a type meant for making the chassis of electronic devices), but nothing else in terms of metal working tools.  So, here are my questions:
> 
> What type of metal do you use for your headphone bands?  Spring steel?
> 
> ...




I'm not at that step, so I can't help you... 
I'm thinking to use 3mm metal rod with cold bending... 

This is my first diaphragm! 
Not easy at all to apply homogeneously the cement glue on the copper and the diaphragm without put glue on the active area... 
Any tips for me? 
I will try to put it only on the copper side.


----------



## -JFK-

Wachara : how do you apply your floor cleaner ?
 A small drop and you rub it with a cloth ?
 Thank you.


----------



## chinsettawong

Yes.


----------



## Muamp

chinsettawong said:


> Hi David,
> 
> I'm sorry to hear about your accident.  Wishing you a speedy recovery.
> 
> ...


 

 Hi Wachara C,
  
 Sorry for taking so long to reply, now my leg is better, I have to return to work which gets in the way of my audio hobby!
 This is my boxed TubeCAD energiser. There are circles of vent holes above the valves and along the back above the PSU.
 It still gets pretty hot.
  
 I used to use this energiser all the time before it was boxed, now it is boxed I use a Stax energiser.
 I am now thinking about the Mjolner KGSSHV...? It is supposed to be very good.
  

  

  

 David.


----------



## Muamp

This is a Stax clone plug and cable that I made last weekend. I cannot source Stax style plugs too easily so I had a go at making some with my CNC.
 The cable is extra-flex 55/0.1mm Conductor Stranding 1kV. Being extra-flex it is soft / easy bend and I think ideal for this purpose.
 I chose to use six separate cores bound together every 25cm with a clip keeping them separated. Most of the time in normal use the six cores are quite separated from each other, minimising the capacitance of the lead. I know the cores can be close together or coiled... but using a calibrated DER EE-5000 LCR the capacitance of the lead is 39pF between any two cores when no panels are connected. If you hold the cores together then the capacitance rises up to 50pF, still quite low, probably due to the extra-flex cable having extremely thick insulation.
 I do not know how this compares to Stax ribbon cable... I will read up on it and find out.
  

  

  

  
 David.


----------



## MuZo2

Anyone tried making in ears?


----------



## Muamp

Hi MuZo2,

See post 2019 in the thread.


----------



## chinsettawong

Hi David,
  
 I like your connectors.  Are they made of PVC?
  
 About your amp,  I think you'll have a problem in the long run putting the tubes in the close box like that.  It's better to  have a good ventilation for tubes.
  
 If you are going to build a new amp, please do consider KG's KGST or KGSSHV Carbon.  I have both and love them very much.  
  
 Wachara C.


----------



## Muamp

chinsettawong said:


> Hi David,
> 
> I like your connectors.  Are they made of PVC?
> 
> ...


 

 Hi Wachara C,
  
 No, they are not PVC. I think PVC would have been easier to cut. They are infact 5mm thick Model Craft Polystyrene sheet sold by Rapid Electronics. It is easy to cut with a hot wire which also means it melts if you do not use a special plastic CNC mill bit. It looks and feels just the same as ordinary sheet plastic and very rigid. Do not let the word polystyrene make you think of wrapping material like the expanded polystyrene which comes to mind. This is great if you can cut it correctly. Although I will probably use PVC in the future!
 The barrel is white plastic 20mm electrical conduit. (20mm outer, 16mm inner).
 The gold plated pins are from a Rapid Electronics 3 pin XLR plug sold as a separate item for people wanting to make custom  / bespoke XLR cables. Same size as Stax pins!
  
 I have been reading up on the KGSSHV. Can I purchase parts / kit for a Carbon version?
 After building the TubeCAD, making my own PCBs and no information other than the article on their website (which is very good...) It would be good to build my next one on pre-made and tested boards, with an inventory of easy to get parts.
  
 David.


----------



## chinsettawong

Hi David,
  
 Your material used is interesting.  I wonder how you manage to solder the wires without melting your plastic.
  
 I use my 3d printer to print the parts, and the ABS plastic I use has a quite high melting point.  So, it's very good for withstanding the heat from soldering.
  
 You can find more information about KG amps at the other site.  From time to time, they have a group buy.  In fact there is one going right now.  But, I'm not sure if it's too late to join though.
  
 Wachara C.


----------



## -JFK-

Hello !
  
 First test working !!!! So happy !
 Well, I have a big electric arc problem, but I think that it come from my bias generator.
 I need to build one from scratch.
 And/OR the step-up transformer ration that is too high (1:180)
  
 Any remarks are welcome !
 Regards.


----------



## Muamp

Hi -JFK-
  
 Nice panel, looks great! I see you are using the Jazzmans cct. Charlie's web pages are a good read.
 Your bias cct looks like a CCFL tube supply, I guess that will give you about 800v DC, should be ok....
 The arcs are most likely the diaphragm shorting to the stator(s). The diaphragm edges must be trimmed right back to the edge all around the spacer. If even a tiny almost invisable piece is left it will arc. Check the circumference all the way around and scrap with a sharp knife if any diaphragm is still overlapping.
 Mmm,... A transformer energiser with a step up ratio of 1:180 is a bit high. In my old transformer enegisers I used various ratios, 1:70, 1:97 and 1:127. It gets to a point where the core in the transformer saturates and cannot step up any more.
 Nice work!
  
 David.


----------



## chinsettawong

Nice!  
  
 By the way, what is your spacer thickness and bias voltage?  The step up ratio of 1:180 is too much, IMO.


----------



## -JFK-

Hello, 

After some adjustment, the bias was a way too high (1000+v)! 
If I set it from 300v to 550v there is no arc at all. 
My bias power supply is at 7$ on ebay. Very noisy and difficult to set precisely. 
I will build one from scratch. 

What are the symptoms of a too high step-up ratio? 

With the IcePower 50ASX2 it seem's that I have enough power. 

Spacers: 0.6mm
Stators: 1.6mm
Bias : 300v to 550v
Mylar: 3um
Coatting: Staticontrol

https://drive.google.com/file/d/0B3k06KRLerMUU0RldHRWY3I3WGs/view?usp=drivesdk


----------



## Muamp

Hi -JFK-,
  
 A 1000v volt bias!
 Wow, Is it a CCFL cct? CCFL tubes normally run at 800v DC. What are you using to measure the voltage? Do you have an oscilloscope? But then I have not seen a CCFL cct with a potentiometer to adjust the O/P.....?
 The bias cct that Charlie Mimbs uses on the Jazzman site is a very good and easy to build Bias cct, which isolates from the mains, still providing 240v and then 8* multiplier. This is too high for head speakers - so tap off at an earlier point (ie at the 1st point, Pk*2). Either that or a similar cct with a transformer o/p voltage of 48v and then the same 8* C-D multiplier.
 48v RMS -> 48 * 1.141 = 67.872v Pk
 67v * 8 = 536v DC
  
 Isolated Mains 240v RMS -> 240 * 1.141 = 339v Pk
 339 * 2 = 678v DC    (voltage doubler cct)
  
  
 What are the symptoms of a too high step-up ratio?
 If the core of the transformer saturates through too high step up ratio it will just magnetically break down and the o/p will drop to very low or zero o/p. It will not damage the transformer, but will not work if too high either.
  
 David.


----------



## -JFK-

This is the bias power supply I use for this test:
http://www.ebay.com/itm/201472584304

Do you have a link to Jazzman charlie Mimms?


----------



## Muamp

Charlie Mimbs web URL is below.
He makes large ESL panels (not headspeakers) but the information is very useful and his wood working skills are incredible!
http://jazzman-esl-page.blogspot.co.uk/2010/01/update-new-toroidal-step-up.html
http://jazzman-esl-page.blogspot.co.uk/

Another good read is Frank Verwaals free PDF book:
http://home.kpn.nl/verwa255/esl.html (The Design of Electrostatic Loudspeakers rev.03)
It is the most complete / readable book on ESL design.
The other downloads from his site are also very good.

David.


----------



## -JFK-

Hello, 

I have set the step up transformer at 1:90.
It work much better, no arc with the bias around 500v.
I think that I have to much power with the IcePower 50ASX2. 
I need to find a way to limit it. 

Is it possible to use one bias power supply for right and left?


----------



## Muamp

Hi -JFK-
  
 "I think that I have to much power with the IcePower 50ASX2.
 I need to find a way to limit it."
  
 Too much power should not be an issue.
 For the sake of an example:
 P = Sqr(V) / R
 for nominal impedance of 8 Ohm and 20W amp :   20 = Sqr(V) / 8       V = 12.7v
 for nominal impedance of 8 Ohm and 50W amp :   50 = Sqr(V) / 8       V = 20v
 The more power your amplifier feeds the step up transformers, the higher the voltage across the input terminals will be.... and the lower the step up ratio needs to be.
 Some people used to use very powerful amplifiers and very low step up ratios in order to improve the sound, BUT, it comes at a cost - HEAT and finally smoke followed by a new amplifier. The example has a nominal impedance of 8 Ohms, but at 18kHz, the impedance may go as low as 1 Ohm or so, due to the load being purely capacitive.
 Yes, lower powered amplifiers and a 1:90 ratio is good, but just turn the volume control down on the amplifier.
  
 "Is it possible to use one bias power supply for right and left?"
 Yes, of course you can use one bias cct for both channels.
 Two different bias ccts for L and R can be used, but I cannot think of any gain in doing so.
  
 David.


----------



## 100VoltTube

How much does it cost to make one of these designs?
  
 I'm interested in making one (probably jf clone with angled drivers, or stax sigma clone), but don't know if it would be out of my price range.


----------



## -JFK-

100volttube said:


> How much does it cost to make one of these designs?
> 
> I'm interested in making one (probably jf clone with angled drivers, or stax sigma clone), but don't know if it would be out of my price range.




Hello, 

For headphone +amp
Excluding tools, at my side it will not exceed 200€.


----------



## Muamp

Hi 100VoltTube,

For me it's not so much cost, but time.
With a name like 100VoltTube I guess you already have electronics and valve knowledge, for building an energiser.
If you like to build things then the time and cost is worth it.
I now get more from building panels and headsets than energisers.

David.


----------



## 100VoltTube

Hi
  
 I honestly don't have a ton of DIY experience. I do know my way around electronics fairly well, but nowhere near as well as others. I chose my name because it was what I was thinking about at the time, and it sounded like a decent name.
  
 I realize that time is the main thing you need to invest in most projects, but I was just trying to get a ballpark on price, like whether they would cost ~$100 a pair or more like $20. Or even $500. I have also read somewhere on this thread (I think) that it is fairly hard to get the materials for just one pair; you have to buy 1 square meter of mylar minimum, or something like that, making it fairly hard to price per pair.
  
 Do you have any design recommendations for a first build?


----------



## chinsettawong

Hi 100VoltTube,
  
 DIY headphones are not cheap.  You first need to invest quite a lot on your tools.  However, if you already have access to the right tools, then you can make them very cheaply.  All you need to make your drivers are 1 mm and 0.5 mm PCB and some Mylar.  Ebay is a good source for these items.
  
 My JF clone doesn't need a pair of close ear pads.  So, I think it can be very easy and cheap to build.  It sounds fantastic too.
  
 Wachara C.


----------



## 100VoltTube

Thanks a lot
 I don't own any of the required tools/equipment, but there is a TechShop near me with far more than enough equipment in it.
  
 I was thinking that the JF clone would be easy for the same reason. I also thought that it's size would also make it easier than others because its parts will be easier to handle.
  
 I was also thinking that 3D printing a frame for the driver assembly that holds the driver an angle relative to your head (like a sigma, but less of an angle) might improve the soundstage realism beyond what it is already (and make it look worse than it already did 
	

	
	
		
		

		
			





)
  
 I'll look further in to it and see if I can make a pair 
	

	
	
		
		

		
		
	


	



  
 Would you recommend the bike tire stretching rig or something else? It seemed like the tire was easiest to make and use, but it does waste a lot of material.


----------



## chinsettawong

Yes, I do recommend the inner tire stretcher. It's easy and cheap to make. Make the stretching area big enough for making a pair of diaphragms in one go.


----------



## 100VoltTube

I'm considering making a DT880 600 ohm/electrostatic hybrid, but I doubt I have the experience. I should probably make both a 'stat and a dynamic first, but I thought I might as well start the design process now, seeing as it's a fairly complex design to fine-tune.

I was thinking of having the dynamic driver in a 3D printed plastic or CNC'ed wood housing with a ring shaped electrostatic diaphragm around it, in its own housing, to reduce bass distortion.

As for driving it, it would need both a traditional headphone amp for the bass, and a stat amp for the treble. The crossover would be between a passive preamp (for common volume control) and the two power amps. 

One more thing: I'm not quite sure that the DT880 driver would actually be better that pure stat bass, but the T90 likely will be. I would appreciate more opinions on which I should use.

Any other ideas would be appreciated.

I'm posting this in the DIY beyer drivers thread too:
http://www.head-fi.org/t/820482/diy-headphones-with-beyer-drivers#post_12871459


----------



## chinsettawong

In my opinion, electrostatic headphones have plenty of bass already. I see no reason why you want to make hybrid headphones. 
I also make full range electrostatic loudspeakers, and I really like the way they sound. But I guess it all depends on the kind of music you listen to.

Wachara C.


----------



## 100VoltTube

I'm only interested in making a hybrid because it would be a fun design challenge and I could kill time fine-tuning it. A DIY planar magnetic bass driver would be fun to make and use too, with potentially better results than a Beyer driver.
  
 On a side note, do you think that a transformer box hooked up to a ~$500 speaker amp would sound better than an inexpensive dedicated stat amp (eXSatA) when used to drive your jf clone?


----------



## chinsettawong

Yeah, a DIY planar magnetic driver would be an interesting build.  
  
 If you have good step up transformers, the headphones can sound very good too.  However, many stat amps can do a better job.  You should look into building some of Dr. Kevin Gilmore's designs.  For JF style phones, given its size, you need a high voltage swing amp.  I would recommend at least +/- 400V.  
  
 Wachara C.


----------



## chinsettawong

Many people have been sending me PMs to ask me about how to fix their dust covers.  Let me post some pictures here to show you how easy it is to replace them.
  
 Suppose you have a broken dust cover as shown:
  

  
 First you clean up the spacer ring holding the dust cover.  Then take a piece of 1 - 3 micron Mylar and crumple it.  Tape the Mylar on a table.
  

  
 Since the Mylar isn't tension, I find 3M 77 spray glue to be very good.  Spray it on the rings and put the rings on the Mylar to glue them down.
  

  
 Cut out the ring using the tip of a soldering iron.  Also, you can use the soldering iron tip to melt away the mylar on those screw holes.
  
 That's it.
  
 Don't be afraid to do it yourself.


----------



## Muamp

I thought I would have a go at making some large panel On-Ear ESHS.
 I decided to make some innovative changes,.....
 These have 0.5mm thick FR4 stators instead if 1mm and rather than 2mm holes in the FR4 stator I've used 1.3mm holes allowing the same hole space to copper ratio but more than double the number of holes! Because the FR4 is only 0.5mm thick, I can get away with smaller holes.
 Rigidity is my only concern and I may need to add the Stax style "Electrodes" to stiffen the stators.
  





 Still constructing the left panel..... I may make some design changes before building it to do more experimenting...
  
 David.
  
 .


----------



## chinsettawong

Your driver looks really nice. How big is your active area?
If I were to do a new set of stators, I would try double sided PCB with the thickness of around 0.6 mm. This is what Stax uses for making its stators too.


----------



## Muamp

Your driver looks really nice. How big is your active area?
  
 The active area is 70mm. 1.3mm holes.
 When using 2mm holes there are 595 holes in an active area of 70mm. when using 1.3mm holes there are 1369 holes for the same 'open' area.
 Using 0.5mm spacers.
  
 I'm thinking of using a hole in the middle of the stators, as in the SR009....?
 That (I believe) uses holes smaller than 0.8mm on a VERY thin sheet of aluminium re-inforced with 'Stax ElectRodes', (3253 holes if you don't subtract the holes under the ElectRodes and the big hole in the middle). I produced the G code this afternoon to cut one. I'm thinking of cutting it out of sheet aluminium. The thinest alumnium I can get at the moment is 0.75mm thick.... a bit too thick.
  
 David.


----------



## 100VoltTube

You can find aluminium film down to 0.05 mm on ebay.
  
 How good of an amp is the eXSatA compared to other amps you own?


----------



## Muamp

Thanks for that. I will check eBay lists tomorrow.
Mmmm,... Unfortunately I do not have an exStatA, and never had a chance to listen to one either.
I own a Stax SRM252s which even though it is basic and cheap, I love it.
I also have home made Transformer energiser and TubeCAD valve energiser, both ok...., But,
Even though I am a valve fanatic - I prefer solid state energisers, regardless of make or model!
I could go into the modern advancements in valve circuits which I hate,.... CCS's for load resistors,... please, if you want valve - even order (2nd order) harmonic sound, why try to make it sound like a transistor.
Anyway, windge over, if I were to buy one, I would now consider Stax 252s or 323x, even better, I have not heard one yet, but consider Mjolnir KGSSHV (Carbon...).
Kevin Gilmore's designs seem to be ever more popular.

David.


----------



## chinsettawong

Hi David,
  
 The SR007 stator that I investigated was made of probably 3 oz copper clad double sided PCB.  The thickness is around 0.6 mm.  It seems to be very strong and is much stiffer than my 1 mm stator. 
  
 It will be interesting to see your aluminum stators.  0.75 mm aluminum should be study enough.  However, I doubt if you will hear better sound than PCB stators though.  
  
 Wachara C.


----------



## Muamp

Yes, I accept that the aluminium stator might not sound better after all the extra work, But, If I wish to emulate the SR009 as closely as possible, I might have to try it?
 I do not have SR009s, my design comes purrely from Google images, which are pretty good images of the panels out of the cases.
 It appears that the stator is very thin aluminium, not foil, with a re-inforcing frame, Stax call 'ElectRodes'. It also has a large hole in the centre.
 I could just use 0.5mm double sided FR4, small holes, and a large centre hole.
 I can understand how the second layer of copper stiffens the stator. I guess that the outer layer is not electrically connencted.
  
 David.


----------



## chinsettawong

I have both SR007 and SR009.  To me, the thin stators with back reinforcement don't make them better than little thicker and more sturdy stators.  I've often compared my DIY phones with SR009 and SR007.  I really feel that my headphones sound as good.  
  
 The SR007 stators are double sided PCB with plate through holes.  So both sides are electrically connected.
  
 Wachara C.


----------



## Muamp

Mmmm,.. plated through holes, I didn't expect that.
 This may sound like a daft question, are you sure it is not solid copper sheet instead of FR4?
 Can you see the edge of the panel and see the fibre glass edging?
  
 David.


----------



## chinsettawong

Oh, yes.  I'm 100% sure.  I've taken apart and fixed a few pairs already.  I even have their exact measurements.  
  
 One interesting thing that I can't prove is that I think Stax's diaphragm isn't Mylar.  It's tension is much greater than mine, but the bass is terrific.  I don't know what material that is.  Or is it the tensioning technique?
  
  
 Wachara C.


----------



## chinsettawong

Here is a picture of a stator and spacer which I took a few years ago.
  


 Stax uses very thin plastic (Mylar?) spacers to adjust its diaphragm and stator distance.


----------



## Muamp

Thanks for the info'.
 I have recently been testing out lower tension on the diaphragm. What you said makes sense, my LT diapragms have not been as good.
 I might get some 0.5mm FR4 double sided and work with that instead, using small holes, big centre hole and test it with HT 2u Mylar.
 I can't do plated through holes though.....
  
 David.


----------



## kenev

Greetings to all!
  
 I'm new to this forum, joining after getting much interest in electrostatic headphones. Recently, I tried the KingSound ES headphones and I really liked them, but the price is beyond affordable.
  
 Being a DIY guy and having built several solid state and tube stuff, I decided to search for a DIY ES headphones tube amplifier. In the course of searching, I found out that there is a lot of interesting material on building DIY ES headphones. So, I ended to this thread, which is the most extended and detailed on this subject. Although the, so far, 152 pages of posts seems a little intimidating, I decided to start from page 1 and read thoroughly throughout the entire thread.
  
 But, early enough, from page 3, I find that a lot of photos posted by the original thread starter are missing. Probably, going further on this thread, these are not really important, but I'm trying to understand in deep the whole process.
  
 My question is whether there is way to have a look at those images that the text refers to.
  
 Thank you,
  
 Evangelos


----------



## chinsettawong

Hi Evangelos,
  
 I just went to see the 3rd page and yes, for some strange reasons, the old images are gone.  I really can't remember which pictures those are.  However, much have changed since those early days.  The later designs of mine are much more efficient than before.   So, if you want to build something similar, please follow my later designs.
  
 I'm still very active here.  So, if you have any questions, feel free to ask.
  
 Good luck.
  
 Wachara C.


----------



## kenev

Hi Wachara,
  
 Thank you for your immediate response.
  
 That's exactly what I initially thought: that your design must definitely have been through a lot of changes since those early days of 2010.
  
 Anyway, I'm going to study the whole story, following the stages of evolution that your design has gone through and I hope that, eventually, I will be able to build something similar.
  
 I have noticed that you are still very active in this forum - that's a good sign to go on with this.
  
 Regards,
  
 Evangelos


----------



## -JFK-

kenev said:


> Hi Wachara,
> 
> Thank you for your immediate response.
> 
> ...




Hello, 

We are there to help. 
Copy/past is not fun at all! I suggest you to read, learn and finally made your own design! 
We will follow you. 
Regards


----------



## MuZo2

There have been really great ideas & designs here.
In iem diy thread some guys went pro & started their own brands, same with orthodynamic headphones, Mrspeakers is great example. Wondering if some of you guys thought about doing same for electroatats?


----------



## Muamp

I have made my version of SR009 stators.
 I used 1mm FR4 for the test, since it is just as rigid as aluminiun but easier to work with.
  

  

  
 The holes are 1.7mm dia, and the centre is 8mm dia.
 I have listened to various music for about an hour with this panel, and my preference still lies with the standard 2mm holes in a full panel layout.
 Does anybody know if the Stax "Multi layer etched stator" means that the inner side of the stator is NOT flat.
 That is, for example 0.3mm spaced at the edges and 0.6mm at the centre, in the way of a stepped stator....?
  
 David.


----------



## chinsettawong

Hi David,
  
 I'm very sure that the stators of SR009 are flat.  
	

	
	
		
		

		
			




  
 Wachara C.


----------



## Julez

The stators of the 009 are the flattest Stax has produced so far. Purpose of the multilayer is to have more flat and rigid stators at the same thickness as one layered stators. I have opend a Stax 009 and there where several layers (more on the parts with the reinforcement structure). Very excellent manufacturing process. And it has the smallest holes of all newer Pro headphones that I remember (apart from the Omega as that has a wiremesh as stator).
  
 Everything about the 009 shows a lot of love for the detail and the finishing processes make me jealouse because my hohleplates look so diy (not very flat and by far less polished finish). It is by far the most premium manufactured Stax product I have seen (and I have seen every headphone and driver from the inside). Also the rest of the headphone is as good as the inside.
  
 Just one ting that annoyed me was that is is not possible to remove the cups from the headband as it is possibe with every other Stax headphone. So taking apart the 009 is just more annoying because of the non removeable cups.


----------



## chinsettawong

Hi Julez,
  
 Do you have pictures of inside of SR009?  If you do, please show them to us.
  
 Wachara C.


----------



## chinsettawong

For some reasons, I've come to love my JF style headphones more and more.  I find that I'm using them most of the times. 
	

	
	
		
		

		
		
	


	



  
 I really encourage you guys to try to build a pair.  These are a lot easier to make than the Omega and Orpheus clones because you don't need to make good earpads for them.
  
 They even sound pretty good with my SRM252A.


----------



## Muamp

Thanks for the great description Julez.
 I agree with Wachara C. I too would love to see some photos of the SR009 inners.
 Maybe I will stick to my 2mm hole FR4 stators with fleece ear cups for the time being and just do some listening and rest a bit.
 Then maybe I will have a go at some JFs..... My only concern with JFs is that since there is no seal in the form of a cup, do you loose some bottom end? I had that problem with my recent On-Ear ESHSs. So much so I removed the foam pads and replaced then with fleece cups.
  
 David.


----------



## chinsettawong

Hi David,
  
 Yes, you lose just a bit of bottom end.  But, it's not that bad.  With a very big active area and uncover front and back, you gain a bigger sound stage and very natural bass.  The phones with sealed ear pads, the bass sometimes becomes compressed and exaggerated, IMO.  With these headphones, it just sounds more natural.  It's like you're listening to a pair of speakers instead of headphones.  
  
 To tension the diaphragm to the just right tension isn't easy though.  You'll need to try and try until you get it just right.
  
 Wachara


----------



## 100VoltTube

I have been looking at parts to make a pair of float clones with, and after looking at a few threads, I chose to use 3 micron Dupont type C mylar as the diaphragm.
 http://www.ebay.com/itm/Electrostatic-Speaker-Membrane-Dupont-Mylar-C-3um-40M-/172275024448?_trksid=p2141725.m3641.l6368
 Is this the stuff I should use? Also, what are all of you using?
  
 On a different note, I've decided to make an Egmont with negative feedback or a TubeCad (in other words: a "how cheap can you make it" amp) to power them until I have the money and experience to make a KGSSHV, KGST, or SR-X plus.


----------



## chinsettawong

Yes, that's the right stuff.

The 3 microns Mylar is what I have been using to build all my headphones with.


----------



## Julez

Yes I have pics of the inside of a 009 driver. But they are not that good. I will have to open the 009 in the next weeks again. Then I try to make better pics. But close-ups with my standard objective are very tricky to do. I hope the next one will be sharper and show more details.


----------



## chinsettawong

Hi Julez,
  
 Thanks for the pictures.  I'm really looking forward to seeing more pictures from you.  
  
 By the way, why did you take them apart?


----------



## Julez

I wanted to repair them as they where broken. I had to redo the membranes but the coating has has failed again (gets lower in volume on one side). The antistatic I used (Antistatik 100 mixed with isopropanol) seems to be not stable for longer than a few days. I have even tried Staticide EDP/WP, wich was the only Staticide I could get hold of without paying 300€, but it did not work at all.
  
 At the moment even the Antistatik 100 mix does not work and the drivers do not produce any sound (even if they did three months ago). I am now trying to get a working coating (one that works for a much longer period) and are currently experimenting with graphite solutions. The graphite seems to stick better to the membrane (at least it can't be wiped away from the membrane with the finger). But for now I could not get the resistance high enough. And dilluting the graphite solution made it unusable as the coating did not distribute properly. If I can find a working coating I will let you know.


----------



## 100VoltTube

Try Licron
  
 Have any of you tried making a quadraphonic headphone?


----------



## chinsettawong

Hi Julez,

Why do you dilute the antistatic solution down? Try applying it without dilution.


----------



## Julez

Because than it has too low resistance. I checked the pure fluid before applying on the drivers by applying on a strechtched piece of mylar. Best is to have 1-2 gigaohm per cm. Without dilluting it is around 100 megaohm per cm (mesured with resistance meter and two coins one cm away from each other). Unfortunatly it is also a spray and I can't really apply a spray evenly. So I have to get it out of the can before applying it. Next is that I allways get dust onto the membrane when applying coating with a sponge or similar method. I apply the coating mix by filtering the mix through a dustfilter onto the membrane so that all surface is covered and then I tilting the driver so most of the liquid drops back into the bottle. I do this in a selve made dustfree box (here in Germany in the bigger citys I have a lot of dust). It did work before.
  
 Thanks for the hint with the licron crystal spray. I will see if I can get it for a reasonable price in Germany. I read it seems to work fine with speakers (with insulated stators). I have not found a good insulating material yet to insulate my holesheets. Perhaps someone has a good idea. It seems that the sharp edges of the holesheet are a problem to properly insulate.


----------



## chinsettawong

Please try my method. Here in Bangkok, the air quality isn't very good either. I put a small drop of antistatic on the diaphragm and wipe it on the diaphragm using a lint free cloth. It's also called microfiber cloth. It's the cloth you use to clean TV or computer monitor. A good lint free cloth doesn't leave much dust on. After the coating is dry, you clean your diaphragm again using a piece of dry lint free cloth. This time you get a good light source and look at the diaphragm on its side against the light. If there is any dust, you will see it quite clearly. Clean it until you can't see any dust. Please don't dilute the antistatic solution. Once you wipe it nice and even, you'll see that the resistance isn't that low. The resistance of over 100 mega ohms is fine too.
The resistance of over 1 gigaohms is too much, IMO.


----------



## Julez

Thanks Wachara, I will try your method soon.
  
 I measured a Stax 507 driver and the result was around 2-3 giga ohm (I had to measure less than a cm to get a reading with my 2gigohm meter). Higher resistance means that the charge can't reload too fast and therefore burning the membrane should be no problem with dustinduced arcing anymore. The headphones allways worked with about 1,5 gigaohm resistance per cm. Also it should help to protect against moving charge on the membrane (my own headphone has far less flatter stators). I ordered the Licron crystal spray now. I hope this will solve the problem.
  
 BTW has anyone got a good idea how to insulate stators properly?


----------



## Julez

100VoltTube
  
 Thanks for the tip with Licron crystal!
  
 What do you exactly mean by quadrafonic headphone? A headphone with four drivers? Why would you do that?


----------



## chinsettawong

Licron crystal won't give you so high resistance value either. Please don't be too serious about trying to get so high resistance. I have made and fixed so many electrostatic headphones, and I never bother to get the resistance so high. I know that high resistance on the diaphragm is good for preventing the charge migration, but on the other hand, it also makes the diaphragm difficult to fully charge. That's why you have the problem of the sound getting soft overtime. 

In the bias circuit, there is another 5 mega ohm of resister protecting the charging current. So don't worry too much about it.

Wachara C.


----------



## 100VoltTube

julez said:


> 100VoltTube
> 
> Thanks for the tip with Licron crystal!
> 
> What do you exactly mean by quadrafonic headphone? A headphone with four drivers? Why would you do that?


 
 No problem! just repeating what I've heard elsewere.
  
 A quadraphonic headphone headphone is exactly that: a 4 driver headphone. 2 in the front, and 2 in the back. It's like having a 5.1 system on your head, only without the center channel and the subwoofer. It only really has advantages when you are listening to things with surround channels, unless you have more driver area, in which case it would probably have a bigger soundstage.
  
 In theory, you could have a driver with one diaphragm, but multiple regions on the stator, allowing you to move some regions of the diaphragm differently from others, giving you a surround effect without a loss in bass extension as you would have if you just had two equally sized drivers. It's very likely that having a driver like that would have some pretty bad problems, like breakup and added distortion. It would also require more amp channels, which could make it fairly expensive.


----------



## dude5OO

Did you fold Stax' membrane on itself (however many times necessary) and caliper to see how thick it was (in applied-coating aggregate)?


----------



## Congo5

julez said:


> BTW has anyone got a good idea how to insulate stators properly?


 
 not sure what you mean but
 at first I used nylon screws but they are a pain.....
 then started using Polyphenylene Sulfide (PPS) washers, very high voltage, for transistors.
 example: SW-125-150 
 Avid makes them as well just pick the diameter and length you need to get through your stators.
 in this pic you can see two on the Float clone. then you can use metal screws.
 also that green is an insulating varnish from Grangers supply 2800v per mil. seemed to help....
Insulating Varnish


----------



## chinsettawong

Hi Congo5,
  
 Nice to see those headphones.  How do you like the sound?  Which ones do you like the best?


----------



## Congo5

those are two year old pic's I mostly listen to ortho's and build amps.
 but they sound just fine and  use them  to test  new amps
 so far have not burnt any but that would be fixable
  
 I found that other than diaphragm tension and coating the rest is not that important.
 OK active area greater than 80mm...
  
 but shape and hole size, placement hard to hear.
 its close but like the 007 pattern best, lower front
  
   at some point I do plan to make some new ones..
 Thanks


----------



## chinsettawong

Yes, I agree with you that diaphragm tension and coating are among the most important things.  
  
 Please keep us update with your progress.
  
 Wachara C.


----------



## -JFK-

Hi all, 

What is the rotation speed (RPM) and feed speed (mm/min) that you use to drill your FR4 PCB stators? 
I continuously broke my carbide drill before the end... 
I'm currently using for 1.6mm FR4 PCB: 
12000 RPM (the maximum of my motor) 
200 mm/min

Thank you for your help!


----------



## -JFK-

No one? 
Wachara? 
Or maybe this questions have been asked many times.
If yes, sorry, I fail to find it...


----------



## 100VoltTube

I believe it has been brought up before, but I can't seem to find it either. I haven't really looked, though. I'll take a look


----------



## chinsettawong

Hi,
  
 What kind of drill bit do you use?  I normally set my router to run at its maximum speed, about 18,000 RPM.  I think I set my drilling speed at 2,400 mm/min.  Drilling has never been a problem.  However, using the same bit for drilling to route, it's not very good.   As you can see, I always stick with 2 mm holes, and I find it's easy to drill and route using the same thing.
  
 By the way, my drill bit is very similar to this:


----------



## quintile

Hi all.
  
 sorry for the thread drift
  
 I am not building from new but repairing some Micro seiki ms-2 headphones from the 1970s.
 I have done this before with some success though the bass response was limited.
  
 I have bought another pair cheaply on ebay and am keen to experiment, reducing the diaphragm tension,
 This is hard as the design of the headphone cells increases the tension as they are assembled, but trial and error
 will get me there.
  
 So, hat adhesive do people recommend for attaching diaphragms to their support rings?
  
 I have used UHU POR in the past but this is hard to control being quite thick. I have heard of people using
 spray contact adhesive, anyone here had success with that?
  
 If so I assume you just spray the support rings and immediately place them on the diaphragm in its stretcher - using
 it as normal adhesive rather than contact adhesive?
  
 Thanks for any help,
  
 -Steve


----------



## chinsettawong

No, don't use spray adhesive. It's not strong enough to hold the diaphragm with tension.


----------



## SuperPollito

This is most impressive that people are able to DIY electrostatic headphones. Keep up the good work everyone!


----------



## OnyxOcelot

> So, hat adhesive do people recommend for attaching diaphragms to their support rings?


 
  
 I think the most commonly recommended adhesive in this thread -- and the one that I have used successfully -- is Contact Cement.  I use Dap Weldwood Contact Cement, seen here, but there may well be other brands selling a similar product depending on your location.  AFAIK, this (and more commonly, the much less pungent water-based version) is the product most commonly used in cabinet shops to adhere laminate and veneer to cabinetry, so it should hold strong for a long time.  I apply the contact cement to the spacer and immediately place the spacer on the stretched mylar.  I don't wait for the contact cement to dry as one might, if you were applying the glue to both surfaces, as in cabinet making or wallpapering.


----------



## 100VoltTube

I realize that a topic of much discussion is diaphragm tension, specifically measuring and repeating it. An idea I had for measuring it is tapping it and measuring the frequency. You can easily calculate the tension based on resonant frequency and the stretcher dimensions. I don't specifically know the formula, but it should be something like: diameter*tension=pitch, for circular hoops. I'm not sure about rectangular stretchers.


----------



## chinsettawong

Unless you are going to do a production run, I don't think the repeatability issue matters that much.


----------



## 100VoltTube

Repeatibility probably wasn't the best choice of words. I meant being able to repeat others' tension levels.


----------



## wppk (May 17, 2017)

hello there
 I know what I am going to talk about is not really DIY for the making of electrostatic headphones, but I think that this could interest some of you, and mending is part of the subjetc. so I have bought very rare bisset DD45e headphones. said to be, on the net, OEM from stax, and the fact that it doesn't need an energiser puzzled me enough to get it. Also, I find them quite beautiful, and I am fond of rarities, as one can read on other posts from mine. the headphone came with a strong imbalance, so, I dicided to try to repair it. It is really weird that it can work without any energiser, nor electronic elements to make it work inside. I leave picture here, for you to see.
 a first approch of the mending didn't bring anything, so I thought that maybe, the diaphragm needed to be coated at new. So I used the electrostatic liquid I used for stax mendings before, but then, I got no more sound at all... I should put a new mylar, but I would get to the permanent and usual problem of the stretching, I guess.
 does anyone have an idea of how this can work ? and also, on how to mend it ? does enyone have headphones like that, damaged on one side too, from whom I could by a driver ?
 when both ways still worked, and when I balanced it ( the imbalance was important, needed one quarter of the balance knob course to the left ), I really liked the sound ! It is really a stax quality sound, even if the bass is not as deep as with lambdas or 007. Very very pleasant on the mids and highs.
 does anyone have an experience with these ?
 thanks
 Luc
 pictures : amazing to see how it looks like brand new.


----------



## chinsettawong

Hi Luc,

The headphones look awesome. But are you sure that they're electrostatic? If there is no bias supply, the headphones could be electrate electret. 
Have you opened up both sides yet? Do you not see any small step up transformer in there at all?


----------



## wppk

Hi chinsettawong
 yes I am sure. well, this is written on the box and the headphones. Yes, I have open both sides, there is no step up transformer at all. ithe plug a stereo normal jack, so it seems it is not electrate .
 I will send photos in a minute of the box and closer to the "electrostatique" writing on the can ( the box is in french)


----------



## wppk




----------



## wppk

the trademark says BST but it is not the bst we all know, seemingly, if I read well about them.
 its a shortway for Bisset.


----------



## wppk

and below the yellow fabric, there is nothing electronic. just the structure of the can.


----------



## wppk

oops I was wrong, there is a step up tranfo. right in the center of eac
  
 h can.


----------



## chinsettawong

It just doesn't make any sense to me.  At least there has to be the source of bias voltage.  Can you show me how the diaphragm is biased?  From your picture, the diaphragm is glued to a plastic spacer.  How does it bias?
  
 How many wires are there going into the driver?


----------



## chinsettawong

wppk said:


> oops I was wrong, there is a step up tranfo. right in the center of eac
> 
> h can.


 

 Yea, that's what I thought.


----------



## 100VoltTube

Cool and weird
  
 It sounds to me like they have a pre-charged diaphragm. That would also be possible explanation of the volume imbalance.


----------



## wppk

there are two wires for each driver.
 er... what is a pre charged diaphragm ? can I re charge it ?


----------



## chinsettawong

It's possible to tap the voltage from the step up transformer and utilize that for the bias voltage. If it's indeed electrostatic, the bias circuit should be there somewhere.


----------



## wppk

the only place" where it could be is behind the transformer. but I am on the go, now, will come back soon and look


----------



## chinsettawong

wppk said:


> there are two wires for each driver.
> er... what is a pre charged diaphragm ? can I re charge it ?




There is no way to pre charge the diaphragm. You can only use a special material as electrate *electret* diaphragms. 

You say that there are only two wires on each driver. Are there two stators on each driver? Is there or is there not a bias wire to the diaphragm?


----------



## 100VoltTube

I meant electate (I thought it was spelled electrit)


----------



## jgazal

e·lec·tret /iˈlektrit/
noun
a permanently polarized piece of dielectric material, analogous to a permanent magnet.


----------



## chinsettawong

Yea.  Thanks for the correction.  It's "electret" not electrate.


----------



## jgazal

Not a correction. I didn't know how to write it so I just posted what I found. Let me say that I admire your knowledge and the things you build.


----------



## wppk

so, there is nothing more than the transformers. I unmounted all, for you to see. nothing left behind the transformer, and I can feel nothing hidden in the headband, no strange thickness under the leather. . there are two final wires, red and black, ( + and -) to each driver. and there is a green wire, that goes from the transformer to I don't know where yet, because it is linked to a white one, that goes trhough the headband to the right driver form the left one...
 I look further and will tell you


----------



## wppk

so, better than a long explaination pictures
 left side wires
 only the red and blacks were linked to the removed driver

  
 rigt side with driver, and the original wiring. two on the driver. I cannot see where the white wire from the left has gone, it appears nowhere. and now, grren is linked to a red wire that is coming from the other side.


----------



## wppk

so as you can see, there is no bias wire on the diafragm
 the plus is connected to the rear part of the driver. the minus to to front one. the light gray part that you can see on the late picture can be unscrewed and removed. the diafragm is on the opposite side. and after the diaphragm is a metal gril on which is soldered a wire ( connetect to the minus on the driver.


----------



## chinsettawong

It's now clear that they are electret headphones. The electret headphones don't need a bias voltage on the diaphragm. They use a different type of material for making the diaphragms. I have no knowledge of what type of material that is though.


----------



## wppk

Ok, thank you anyway


----------



## Julez

100volttube said:


> Try Licron
> 
> Have any of you tried making a quadraphonic headphone?


 

 Hi 100VoltTube
  
 thanks for the tip with the Licron Crystal! It works fine! It is also less prone to dust issues. Altough it is easy to apply too much and get coating that's too thick. But I have managed to get the right thickness by using a sponge that I dip into the liquid and squeeze it hard afterwards. The coating is then barely visible and works fine. Otherwise I had the feeling it is too heavy and the resolution of the drivers is lower than the original Stax drivers. It is heavily sticking to the membrane wich is a very good thing! But no chance to wash it off and recoat the driver if applied too much. At least not with isopropanyl or water.


----------



## wppk

Hi you guys !
 A frenchman has read what I have written on this post for the mending of the stax lambda I tried. his lmambda was ill balanced, and he was asking for help. He seems to have quite a good knowledge of electronics and he is mending his membrane ( the sounding one, not the protective one) he will tell me news I guess. if you are intersted, I will tell you here, because he says that he has mended it, and that is still working now, with no change. It then interests me a lot !
 I also am saying that here because he give me a link to a very interesting page, here http://www.asrr.org/biblioteca/Revue%20Audiophile/fichiers2/03/casque.html form philippe Hiraga, an HIFI expert in france, whom yous probably have heard about. In there, he says how to make electrostatic headphones , and you know thet your post is read by people all arount the world. It will obviously interest some french people, who can't read you in english. there is a strange % sign in this link, the link works with my computer, but it could be useful, if it doesn't work on your, to remove it and try this then  :  http://www.asrr.org/biblioteca/Revue20Audiophile/fichiers2/03/casque.html
 if you need further explainations on this document, I can translate parts of it, but probably not the whole.


----------



## DaveK1977

Well, I'm back and I finally have a pair working together that could fairly be called a pair.  I can't wait to mount these in a set of headphones and see what they really sound like.
  
 The audio on this video was recorded with a Tascam DR-05 held close to the drivers while they were playing.  For the last few seconds of the video, I let the audio recorded with the video play through.


----------



## Muamp

Hi DaveK1977,
  
 I like the round steel stators, how did you cut them?
 And tell us some details....
 Spacer thickness? Diaphragm material?
 Are they square openings with round stators? open area size?
 I cannot see any fixings holding the stators together, how are they fixed?
  
 David.


----------



## DaveK1977

I'm shaking right now, because I put together a scary pair and put them on and got away with it.  I would have told anybody else not to put it on, but I just had to.  They sounded fantastic.  No regrets.  There's another message coming, but I'll reply to the questions because they're good and will it all easier to share.
  
  


> I like the round steel stators, how did you cut them?


 
I had a man cut them for me, but it hasn't gone perfectly.  I found a listing on eBay for a stainless steel sheet like I wanted, and asked if the seller could cut them for me.  I measured everything metric because the Superlux foundation I was using was made in China and copied a German design, so I knew it was built in mm and should be measured that way.  He cut in English units and they're a bit big.  I will have to scrub some stuff down on the headphones before they'll fit in the cups, but if you're in a metric country, you might do better with that.  An 85mm disc will neatly replace the driver and baffle plate in a Superlux HD-330, and I guess it could be done to a Beyer DT if you had a dead one.
 


> And tell us some details....
> Spacer thickness?I cannot see any fixings holding the stators together, how are they fixed?


 
The spacer is 3M VHB tape, seen in the red rolls in the video.  It's 1.1mm thick.  That's also what holds the sandwich together.  You can buy it in auto parts stores as this variety is sold for attaching emblems to cars, and it's strong.
 


> Diaphragm material?


 
Ultrafilm Mylar, designed for indoor model airplanes.  1.4 micrometers.  Weighs very little.
 


> Are they square openings with round stators? open area size?


 
Yes, the openings are square because it's easier to lay out the tape that way.  They're about 25 square cm.
 
I didn't have my Staticide at the house, so I used Static Guard, a spray for clothing for a coating.  I'm hoping that the Staticide coating will up the volume a little.


----------



## DaveK1977

Ok, so I got impatient and had a listen tonight.  Only one song, so as not to tempt fate, as this wasn't a commercially ready pair, let's just say.  I had to know, and they didn't bite me.
  
 I wasn't quite sure what to expect them to sound like, as it's hard to judge from the measurements and recordings that I made the day of the video.  Obviously they worked in the open air, but they had an obvious upward creep above 12k that really I was afraid of.  At the very least, I thought they might reveal some detail, but I wasn't sure they would be possible to enjoy.
  
 They sounded really amazing.  There was no apology needed for the sound or response. It really sounded balanced and normal, which was definitely good.  I can't try to build a different pair until at least Saturday, so I'm going to shock proof a bit more and try to really listen for a while tomorrow night. 
  
 They weren't loud even turned all the way up.  It's patched together with poster putty, and the drivers don't fit in the hole as outlined above.  There's leakage and dubious diaphragm coating.  I'm sure that by the time that everything fits right and Staticide is coating, they'll be louder.
  
 Keep in mind that this is the first time that I've ever listened to a pair of electrostatic headphones, and I made the drivers.  I'm sure my opinion is rosy, but I was blown away.


----------



## chinsettawong

Hi DaveK1977,
  
 First of all, congratulations on your successful build.  I remember exactly how much joy I had when I successfully made my very first pair.  They just sounded so good that I kept listening all night.  I'm sure you're feeling the same.  
  
 Your perforated metal is OK for making the stators, but please remember to do a good coating on them.  You need a very good insulation on the metal.  Otherwise, you might get an electrical shock if you're not careful. 
  
 Double sided tape is alright for spacers.  However, the thickness of 1.1 mm is too much.  You can't really get louder sound from using Staticide.  You can achieve it by either using higher bias voltage or thinner spacers.  Are you using step up transformers or are you using a direct drive amp?


----------



## Muamp

Like Wachara C. says, the spacer gap being too big is the most likely cause of low volume.
 I used to use steel stators, but I cut the steel with a normal hand held jig saw into hexagonal stators. In this way it is very easy to cut and fits over spacers really well (hexagonal or round). I also used to use neoprene spacers with spray glue to hold them on the spacer. The neoprene was slightly less than 1.1mm but still too thick.
  

 The spray shield was to stop the glue being sprayed onto the stator when applying the Mylar.
  

  
 These were made nearly two years ago. You can get a good finish with Acrylic spray paint.
  
 David.


----------



## wppk

I know this is not an electrostatic mending, but it is the following of what I previously wrote, and it is DIY. So, it still has an interrest, I think.
 I repaired my bisset, because the original driver is unfindable, and another item like this one seems too. I ordered this http://www.ebay.com/itm/121314870113 and used them as drivers in the Bisset/Stax. The result is really gorgeous ! It is very comparable to me srx mk3, with a little bit more bass.
 I am very happy to have found this solution, and I hope it can help people who can't find original drivers like me.


----------



## DaveK1977

What would ideal thickness be?  I thought that this was similar to the spacing of factory built ones.


----------



## chinsettawong

Haven't you read the thread?
  
 The ideal thickness for the active area of up to 80 mm is around 0.5 mm or less.
  
 It's a challenge to get the right tension with that spacer thickness though.


----------



## Muamp

Most DIY'ers on this forum use 0.5mm thick spacers (each side of diaphragm) for ear speakers.
 I use 0.5mm FR4 (copper clad PCB material), as do many others.
 The thinner the spacer, the more sensitive the driver, and therefore also louder. Higher frequencies in the audio range stretch further as well.
 When I used metal stators with 1.0mm spacers, the bass was very strong (too strong for me) but the higher frequencies were lacking.
 I believe some of the Stax go as thin as 0.4mm, but I have only got this information from other posts in Head-Fi.
  
 David.


----------



## DaveK1977

Yeah, I've read the entire thread, but it's actually been a while for most of it.  This experiment has had some false starts and is a long time coming, but the results already were better than I had hoped for the first sample.  I was expecting a screechy sound with very little bass, and found instead a very natural sound.  I'm still experimenting, and I'll probably continue to do so.  Wachara could've stopped after his pairs were validated by Tyll's tests but clearly hasn't, and I'm sure that I'll be playing with this stuff for a while.  Easy to get basic function, but so hard to perfect.


----------



## Muamp

Hi DaveK1977,

Glad to read your enthusiasm in your ESHS design!
A really satisfying hobby.

David.


----------



## 100VoltTube

Hi DaveK1977
 Cool headphones. What seller cut those stators for you? I'm a bit interested in getting stators the same way.
  
 To everyone:
 What are the best stator materials? I thought that flexibility was the main factor in choosing material, but after looking it up, I realized that steel (and aluminium) is many times more rigid based on Young's modus than FR4, and yet FR4 is more popular and common in stators. Is this purely due to the ease of machining, or is it because of metals' tenancy to resonate? Or am I missing something?


----------



## DaveK1977

The seller's name is redplanet22.  He was easy to work with, it's just that the discs were a little larger than 85mm, probably close to 1.5mm too big, though I have not measured it exactly.  If you're asking him to cut for you, use Imperial units.


----------



## Muamp

Hi 100VoltTube,

That is a good question. My steel stators are 0.8mm thin and still a bit more rigid than my 1mm FR4 stators.
The 1mm FR4 is never-the-less rigid enough and very easy to cut, manipulate into the required cutouts. It is also easy to drill hole patterns and sizes to your requirements.
FR4 also benifits from the Fibreglass insulation protecting the listener from coming in contact with the high voltages.
I have tried 0.5mm FR4 for stators which was not rigid enough!

David.


----------



## Muamp

Hi DaveK1977,
  
 This may sound like an intrusive question, but, how much would the ebay seller 'redplanet22' charge for supply and bespoke cutting of the perforated steel?
 The sizes that he cuts may be dictated by the hole punches he has available, and the hole punches he has may be in imperial sizes, so in mm you get the closest he has got, possibly he used 3 3/8" (85.725mm)?
 Do the edges come nicely finished or do they require sanding?
  
 David.


----------



## DaveK1977

No problem.  I did some sanding on the edges because they were sharp, but nothing drastic.  Not all of them were super flat, either, but I was able to tweak around on them enough to use all of them.  You're probably correct about how they were cut.  It was about $35 for 12 discs.  Because of the experimental nature of it, and the fact that some of them simply don't work when put together, having enough to make 6 drivers makes it easier to find two that match.  Also, I can "rebuild" one in just a few minutes with a pocket knife, I just have to be careful not to bend them.  I'm planning on assembling those this weekend, but the pair that I made Sunday I really didn't expect to work this well, so it's kind of a whim that I put them together to listen, which I did for over an hour last night.  No shock.  I forgot to answer Wachara: they're powered right now by a Koss E90.


----------



## chinsettawong

The Koss E90 won't be able to drive your headphones well.  Koss's bias voltage is too low for your 1.1 mm spacer headphones.


----------



## DaveK1977

They're no longer so quiet that they have to be turned all the way up.  I switched sources from my phone to my SACD player, which must have a hotter output.  They have similar sound signatures, but one side is louder than the other.  The one on the right definitely has something in it, but it's only audible at a few frequencies.  It's very encouraging because I think that when I make the other 5 drivers all in one shot, I have a pretty good chance of two of them matching pretty well.


----------



## Muamp

I spent this weekend having a go at an Orpheus clone with a difference based on the question that 100VoltTube asked about why not use steel stators, so I have.
 I cut elongated octagonal cutouts from 0.8mm thick steel perforated with 2mm holes, giving approx. 51% open space. This is the same perforated steel I have used before on my early panels. These were cut for an oval panel since all my previous headphones have had round panels.
 Then, the spacers were CNC'ed from 1.6mm FR4, pocketed out to 0.6mm recess for the octagonal steel stator.
  
 Now the bad bit..... and I guess why FR4 stators are easier to work with. The steel after cutting is NOT perfectly flat, similar to DaveK1977's comments. I cut the panels with a Jig saw, not CNC, and for spacers recess as thin as 0.6mm, just NOT flat enough for me to continue along this idea!
  
 I could spend more time on this later, but for now I will stick to FR4.


----------



## DaveK1977

If you want to know what mine are a clone of, I'll tell you what my inspirations were to make what I have:
  
 1.  My Beyerdynamic DT-990 Pros plugged into my Schiit Vali is as good as it gets to me so far.  That sounds great and is extremely comfortable.  I love the way Beyer's grey velour feels, their earcups are a nice size to me, and their pad designs excellent.  I didn't want to tear one of those apart as they even cost too much broken to do this to, but it's designed so well as to be an excellent platform.  I took apart a cup doing my detachable cable mod to them, and I was impressed with how serviceable it is.  The Superlux HD-330 is a copy and is cheap enough to rip apart.  I had to do considerable reworking of metal pieces to make it fit like a real Beyer.
  
 2.  I saw how Martin Logan builds speakers on How It's Made.  I'm sorry in advance if I'm about to step on toes.  They showed their process well enough for a a tabletop copy of how they make speakers translates to a passable headphone driver.  They actually have huge precision, which is the harder part, but their design shows how to make an electrostatic driver simply and cheaply.  It's so elegant in its simplicity that I don't understand why that isn't for sale everywhere so the price can come down.  They've made it good, safe, and easy to have,
  
 3.  Acquiring enough bits and pieces of actual equipment to use stuff that's safe and flexible.  That means having weird watches in eBay for stuff from Koss or Stax.  Basically tracking down LKQ (Like Kind & Quality) of plastic film, figuring out what to coat with since Swash isn't a common brand here, etc.  I've got stuff to make it work, but I still definitely want a pair of the real thing.


----------



## 100VoltTube

If you want to put your drivers in a real Beyer headphone structure, you can make one out of spare parts. Beyer sells some on their website, and this website has a ton of parts.


----------



## Muamp

Even though I try to make ALL items in my headphones myself, links such as 100VoltTube's link to Beyer spare parts is an excellent source of parts for DIY'ers.
 Links like this can make a big difference to people who wish to make an ESHS but cannot source various parts such as ear cushions and head bands etc. It would be great if we could produce a list of all current suppliers like this, so that anyone can easily source parts they are struggling with.
 Also to include links to suppliers (inc. ebay sellers) for example Stax socket pins, rigid plastic sheet for cutting, FR4 in 0.5mm and 1.0mm and Mylar.....
 I do not mind compiling and updating a list to keep it current, but I would need to know all the various suppliers from existing ESHS DIY'ers; YOU.
  
 David.


----------



## Muamp

So far only one person has responded to my idea of a 'diy suppliers list' and that was with _reputation_.
 If anyone still thinks it is a good idea to proceed, then you can send me the web link(s) as a personal message within Head-Fi or in general reply in this thread.
 If no one responds then I will assume that this is something that people don't want.


----------



## chinsettawong

Hi David,
  
 I like your idea, and I appreciate your taking the effort to do this.  I'm sure it will be a great help to a lot of people.
  
 However, as how this thread works, whatever you do and post here today will be buried in hundreds of pages in years to come.  And people who do not read the whole thread will ask the same questions again and again.  What could we do to avoid that?
  
 Wachara


----------



## Muamp

Thanks Julez and Wachara,
  
 Julez: Thanks for the list of links, that's a huge start. I will try to compile a list in various 'sections' of ESHS panel design when there are lots in the bigger list.
  
  
 Wachara: I appreciate what you say about a post getting lost in the history of a thread. I have read ALL posts in the 158 pages of this thread, but I must admit I spend ages looking back through the pages to find the one post I am looking for.
  
 To start with, a general _small _starter list can be posted within this thread, then if it gets big, possibly start a new thread with the list as the thread start, and just _edit _this post as new info comes in or old info gets updated. Any comments could tag on the end, but the main one as post number one contains the up to date info?


----------



## MuZo2

chinsettawong said:


> Hi David,
> 
> I like your idea, and I appreciate your taking the effort to do this.  I'm sure it will be a great help to a lot of people.
> 
> ...


 

 May be first post is right place for such list. Else a new thread.


----------



## DaveK1977

I sent you a PM about the source for the film.  Most of the other materials are normal commodities, and prices can vary a bit by source.  If you post a list of materials and sources, just make sure to clarify that it may be possible to save money by taking note of what the suggested item is and trying to locate at the time of ordering.


----------



## 100VoltTube

> May be first post is right place for such list. Else a new thread.


 
 It's definitely a good idea. I personally think it would work better as its own thread than a list in the first post of this thread, but that's just my opinion.


----------



## Muamp

Thanks to those who have sent me PM's of their parts lists...
  
 So far this evening I have started to compile a list with 5 headings and this is just the stuff for me and Julez.
 The headings are:
  
 1. Mylar
 2. Stators / Spacers
 3. Plugs / Sockets / Cables
 4. Electronics
 5. Production manufactured spares
  
 It is already a big list, so hopefully even in the _first print_ it will be benificial and useful to many DIY'ers.
 I will keep adding and hopefully get the first print out in a few days time.
 Very tired and I need to go to bed, so I will carry on tomorrow.
  
 David.
  
 PS. DaveK1977, I like your comment on the fun of finding parts.


----------



## Muamp

Hi DaveK1977,
  
 I see what you mean, regarding ebay listings becoming out of date when the listing expires.
 Your suggestion is a good one. Maybe list sellers name and description of item.
 A good example is the ebay sellers of Mylar, they always have Mylar but the link does expire.... and a new different link needs updating in the list.
  
 David.


----------



## Muamp

I have completed the 1st edition of the "DIY suppliers parts list", it still needs more input from you. The bottom of the list includes a list of items that would be good to add.
 It is located in a new thread "Electrostatic ear speaker DIY'ers suppliers list".
 Please keep adding more suppliers, PM me with any details.
  
  
 David.


----------



## DaveK1977

I'll actually have a safe, working pair that I can demo to my family at Thanksgiving.  It's far from over, but this is a fun thing to show off now.


----------



## chinsettawong

Very nice.


----------



## Muamp

Hi DaveK1977,
  
 I was going to ask what the cable was, but then having watched the video I see it is a Koss cable.
 Did you use to have a Koss electrostatic head speaker? If so did you cut the cable from them?
 If not, where did you get the cable. Good audio ribbon cable is something I am still looking for.
 I know I can buy Stax extension leads but at the prices asked, I don't think so.
  
 David.


----------



## DaveK1977

It was a Koss extension cable.  I bought two different E-90s on eBay recently, because they tend to be cheaper than any other standalone amp.  One of them came with the extension cable, which I used for this.  I've never had a pair of electrostatics before building one.  I also have a Stax pro energizer that has to be connected to speaker outputs, and a Stax extension cord that I can use for it.  The Stax cable is a work of art, but very expensive.  The Koss cable is much cheaper and nearly as nice to work with, both of them are much more flexible than anything else I had played with trying to get going with this.  I saved the female Koss plug that I cut off the cord so that I can add a male Stax plug to make an adaptor to go back and forth, rather than having to recable.  When starting out, I bought a length of cable that has 5 conductors and is rated for 600v, which is normally used for industrial PLCs.  It's clearly not appropriate for this due to weight and flexibility issues.  I would consider the Stax pro plug to be a de-facto standard for a connector, so the Stax extension cable is a really good way to eliminate one problem. It's just really expensive.  Buying a premade extension cable gets you a safe, usably flexible cable that's terminated in the plug you're already going to have to use.  That's probably worth buying to someone who's DIY.


----------



## Julez

Hello Dave,
  
 depending on where you are from I would try the 207 spare cable from Electromod.co.uk. Its available for 40Pound plus shipping.
 If you are located in the US I would ask at staxusa.com if they sell spare cables for Stax Lambda headphones. They should not be more expensive as the extension cables but ready to use and already have a y-split in the cable. Plus there are different colors.


----------



## Muamp

Thanks for the info DaveK1977 and Julez,
  
 I currently make my own Stax clone plug with gold plated XLR pins from 3 pin XLR plugs and CNC my own base and top to use with 20mm electrical round conduit for the barrel.
 So the plug is not an issue. Getting Ribbon cable which is thick enough and ultra soft and flexible (definitely NOT computer ribbon cable which is too stiff and too thin) is a problem.
 Currently, for the cable I use 'ultra flexible measurement cable' and either 6 strand plait or loosly held with cable clips.
 So what I am looking for is "thick, flexible ribbon cable" _similar_ to the cable used by Stax. Just a supplier for the ribbon cable, to make the lead.... Googled many times, to no avail.
  
 David.


----------



## chinsettawong

Hi David,
  
 You can buy the extension cord from KOSS directly.  If you live in the U.S., call the customer service and ask to buy it from them.  That's how I got mine.  The last price I bought was very much cheaper than Stax's.
  
 Wachara


----------



## DaveK1977

Ok, the pair that are in the video have since been updated.  I use a thinner wire now, with a little terminal block for the wiring.  They sound quite good.  Definitely good enough to listen to, though I can't excuse the frequency response, which probably looks ugly.  It's never totally deficient, and even has a balanced amount of bass.  It has some sort of mid peak that my DT-990 doesn't have, too.  It has the detailed electrostatic sound, but but there's a warmth as well.  For something made on a project table at home, I'm absolutely delighted with how they sound.
  
  
 Before that video was posted, though, I've now heard the real thing in the form of a Koss ESP-950. That was after the dangerous pair-the first time I'd heard an electrostatic headphone.  The 950 is quite an experience of sound beyond what I'm used to.  I've never had or heard anything that sounds like that, but I've never had or even heard anything at that kind of price point.  The 950's frame has some kind of bind that settles with a squeak every once in a while, but the sound itself is hard to find fault with.  Really beautiful transparency and clarity.  At this point, though, I'm quite happy with how the ones I made sound. Are they up to the 950?  Of course not.  That said, I'm not giving up on them.  I'm listening to them right now.  Now I want to use as many real Beyerdynamic comfort and frame pieces as I can.  I want a fresh set of real pads, too.


----------



## -JFK-

Hello, 
  
 Long time ! (terrible motorbike accident, but I'm alive !)
  
 This is my first prototype and it work !
 https://drive.google.com/file/d/0B3k06KRLerMUU0RldHRWY3I3WGs/view?usp=sharing
  
 Really happy.
 Now, head part to do and optimisations !


----------



## Muamp

Hi -JFK-

Sorry to read about the motorbike accident. Wish you well and a speedy recovery!
That is an awesome panel in the video.
Lovely prototype.

David.


----------



## Congo5

muamp said:


> Getting Ribbon cable which is thick enough and ultra soft and flexible (definitely NOT computer ribbon cable which is too stiff and too thin) is a problem. Currently, for the cable I use 'ultra flexible measurement cable' and either 6 strand plait or loosly held with cable clips.
> So what I am looking for is "thick, flexible ribbon cable" _similar_ to the cable used by Stax. Just a supplier for the ribbon cable, to make the lead.... Googled many times, to no avail.
> 
> David.


 

 I looked for that cable also and the closest I could find is Cicoil, available from Digikey.
  
 12kv rated High Flex flat cable: http://www.digikey.com/product-search/en/cables-wires/flat-ribbon-cables/1638574?k=&pkeyword=&pv316=11&pv316=3&pv78=9&pv78=10&FV=fff40019%2Cfff800ae%2C14313f%2C5040075&vendor=1233&mnonly=0&newproducts=0&ColumnSort=0&page=1&quantity=0&ptm=0&fid=0&pageSize=25
  
 I have not asked Koss for some (probably the best idea) but did find a 100" roll on ebay of Cicoil 10 conductor 20ga and it is nice wire but think 26-28ga would be the right choice.


----------



## inuponken

Just finished my third one.


----------



## chinsettawong

Hi Kubo-san,
  
 Those headphones look spectacular.  I really like your wooden cases.  What kind of wood do you use?
  
 Now that you have 3 pairs of DIY headphones, which one do you like best?
  
 I notice the way you make the headband for your JF clone is different from mine,  Do you make the ear pads for them or do you listen to them without ear pads like the original JF?
  
 Wachara C.


----------



## chinsettawong

-jfk- said:


> Hello,
> 
> Long time ! (terrible motorbike accident, but I'm alive !)
> 
> ...


 
  
  
 Sorry to hear about your motorbike accident.  I wish you a speedy and full recovery.
  
 Your driver looks really well made.  I'm sure it sounds sweet.  
  
 What kind of amp do you use to drive it?  Your bias voltage circuit looks interesting.  May I know its specification and where you get it from?


----------



## -JFK-

chinsettawong said:


> Sorry to hear about your motorbike accident.  I wish you a speedy and full recovery.
> 
> Your driver looks really well made.  I'm sure it sounds sweet.
> 
> What kind of amp do you use to drive it?  Your bias voltage circuit looks interesting.  May I know its specification and where you get it from?


 
 Hello, 
  
 The Amp is a D class from IcePower ref. 50ASX2 SE.
 https://www.google.fr/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&uact=8&ved=0ahUKEwiCx4C2t8PQAhVCOBQKHQGLA-AQFggrMAE&url=http%3A%2F%2Fwww.icepower.bang-olufsen.com%2Ffiles%2Fsolutions%2Ficepower50asx2.pdf&usg=AFQjCNEomZmI_iyeLekN0lN4qjaEepECRg&sig2=9HuFt4s3kh4pnY6P-MRcBg
 The bias come from Ebay, I'm not good with it because the transformer make a bit of noise at high voltage, but for testing around 600V is good. (less than 10USD...)
 http://www.ebay.fr/itm/High-Voltage-DC-DC-Boost-Converter-5V-12V-Step-up-to-300V-1200V-Power-Module-/272192879496?hash=item3f5ff5bb88:g:MoYAAOSwwpdW-59R


----------



## Muamp

Hi inuponken,
  
 Those wooden surrounds look incredible!
 Can you tell us some technical details about them...? Especially how you made the head band.
 Also, what will you do for ear cushions?
  
 David.


----------



## inuponken

Wachara, David,
  
 Thanks.
  
 For the third one, I just modified your design to round shape for more like a 
	

	
	
		
		

		
		
	


	




. I used same PCB, Mylar and tensioning for both phones so sounds are nearly the same.  These phones producing wide sound stage and more bass than my SR-407 and Omega clone!!      
 I used Red oak for the case and poplar for the face cover. Added “GUNSTOCK” wood stain and coated with semi-gloss Polyurethane.
  
 I’m not added ear pads and cloth grills that reduce clarity and presence.
 And Instead of use the punching metals, cut the silver mesh magazine file. 
  
 http://www.containerstore.com/s/silver-mesh-magazine-file/d?productId=10004834&q=mesh%20file
  
 I used BATES stainless ruler BNR-12 for the head band, covered with thin leather sheet.
 Arms and face plates are 3/16” black Delrin sheet.


----------



## Muamp

Hi inuponken,

Firstly, the steel rule for the head band is a brilliant idea. Probably the correct amount of spring and stiffness.
The silver mesh magazine file for the external grids is also good.
Really good inventive ideas!

David.


----------



## chinsettawong

Hi Kubo-san,
  
 You have got some very nice ideas.  Especially the way you make the headband, it's simply splendid.  
  
 Are you saying that even without using ear pads, your new headphones have more bass than SR407?  If that's so, it's a marvelous achievement.  What spacer thickness are you using?


----------



## inuponken

Yes, both phones have more bass than my SR407.  Spacer thickness is 0.8 mm.  
  
 Tension is very low, only used small clips to add tensions then added heat until wrinkle is gone.
 This is my method that after I repeated trial and error many times...   
  
 I think low frequency is also related to the housing, decreased bass when I tested without housing so.


----------



## chinsettawong

I see.  Since your spacer thickness is rather big, it's OK to just heat shrink your diaphragms.
  
 However, you lose a lot of efficiency.  If you can, please try again the 0.5 mm spacers.  All of my phones including JF clone now are using 0.5 mm spacers.  The efficiency is good and the bass is very nice too.


----------



## Muamp

Just finished my latest pair of ESHS, which are my first pair to be completely 100% home/hand made.
 No bought in parts, apart from raw materials are used!
 Listened to them for a few hours last night and definately my favourite ESHS (so far).
  

  

  

  

  

  

  

  

  

  
  
 I am now going to make another pair almost the same as these for another Head-Fi 'er. I promised him a pair more than a year ago. He's been quite patient.
  
 I am also looking into PCB production in China, so that I can get a batch of stators made in one go. The stators will be identical to the ones in these ESHS.
 The PCB company have already rejected my first set of Gerber files, so I will have to check out what it is I have to change in the files I submit.
  
 David.


----------



## chinsettawong

Hi David,

Congratulations! Your headphones look great. Nothing sounds better than the DIY ones. I'm sure. 

Looking forwards to seeing more headphones from you.

By the way, what is your spacer thickness? How do you like the bass?

Wachara C.


----------



## Muamp

Hi Wachara C,
  
 They are just a slight variation from the older ones, but all home made, including the ear cushions. Yes, I did sow them myself.
 Now I only use 1mm FR4 stators. These have 1.7mm holes and centre cut out of 8mm, sprayed with black acrylic on both sides.
 1/2mm FR4 spacers. Since they are 1/2mm spacers the top end is excellent and also similar sensitivity to my Stax phones.
 The tension on the diaphragm is high, but not too high to destroy the bass.
 Dust protectors on all sides. With 1/2mm spacers you cannot get away without them.
  
 I keep thinking about building some JF clones, but..... I have just kept on experimenting with different build materials on my round panels. Now I am definately settled on FR4 for stators and spacers!
 I now only use 1/2mm spacers, but if I can get 0.4mm FR4, which I think I can source in China, I will have a go.
  
 David.


----------



## chinsettawong

Depending on the width of your active area, going thinner than 0.5 mm might not be a very good idea.  I would recommend you try different tensions to see how much tension you like best.  On my Omega clone, I can get the bass very much similar to what SR007 can do.  I really love it.
  
 If you haven't tried, please try the JF style headphones.  Without ear pads, they sound rather different.  The sound is more natural and open.  I love it very much too.
  
 I recently opened up a pair of old SR5 to fix.  The active area is only 50 mm in diameter.  The spacer thickness is about 0.35.  The sound is amazingly nice.  It's unbelievable that these small drivers can deliver such nice open sound and good bass.  It's something worth learning from.  
  
 Wachara C.


----------



## Muamp

Mmmm,.... The smaller the distance between the diaphragm and stators the greater the sensitivity.
 I guess the SR009 must be less than 0.5mm, otherwise it would not have the sensitivity it has.
 It is good to know that the SR5 has a small active area. If I can get 0.4mm FR4 I may give that a go.
 If I can't, I may laminate copper onto 'something' (still to work out what) to give me about 0.4mm spacer, and give small panels a go with small spacers.
 Obviously, I will stick to 1mm FR4 for stators regardless,.. unless the active diameter becomes so small I can get away with 0.5mm stators.
  
 David.


----------



## chinsettawong

The 1 mm single sided FR4 is definitely the number one choice for stators.  But if you can find a good and stiff 0.6 mm double sided FR4, it also can be a good alternative too.  That's what Stax uses for its SR007 series.


----------



## DaveK1977

I'm not sure that the circuit boards that I experimented with would be flat enough to do spacers as thin as you're talking about because those aren't perfectly flat.  Maybe they could be compressed into flatness.  I'd have to be more careful and probably spend a little more money to get stuff that's really up to the standards you make yours to.
  
 I'd love to have access to your machine shop.  You have amazing precision.


----------



## Muamp

Hi DaveK1977,

You may be surprised to know the CNC machine I have cost about £330 including VAT and P&P from China.
Plus a few quid for various collets, end mills and drill bits and your pretty much complete.
A bit of sandpaper, MDF and of course good quality FR4. I use Bungard FR4 because it is the most flat and rigid FR4 I've seen.
I used to write my own G code as machine code directly, but now I use Vectric CUT2D CAD software, ok, that's another £100 I think. Vectric is amazing, you can produce the required G code in next to no time.

David.


----------



## -JFK-

Nice! 

This is what I have done for the CNC. 
I have started from a tweaked laboratory dispenser. 
Made the logical part with an Arduino. 
Added a motor... 
... And let's go!


----------



## Muamp

That is a really good modification.
Even with a vacuum attachment for debris removing.
Is it a vacuum holding the board down?


----------



## -JFK-

muamp said:


> That is a really good modification.
> Even with a vacuum attachment for debris removing.
> Is it a vacuum holding the board down?


 
 No, vacuum only for dust.
 "Simple" was the word for this CNC !


----------



## 100VoltTube

Cool CNC. David, where did you get that CNC machine from? 330 pounds sounds like a great deal.


----------



## Muamp

Hi 100VoltTube,
  
 ebay.co.uk (or .com)
 Search string "3020 CNC".
 The seller I bought from was "ukdirectseller"
 I paid £330 inc VAT and P&P but they now seem to average at £345 - £350.
 Mine was shipped to the UK from Germany making the delivery very quick.
  

  
 They now claim to be able to be controlled via Parallel or USB.
 Since the controller drives the motors in real time from a PC, USB always _had_ latency problems, so it would be good to know how they got around this problem.
  
 David.


----------



## chinsettawong

That's a very good price CNC machine.


----------



## CoffeeCutie

Subscribed!!
	

	
	
		
		

		
			




  
 @Chinsettawong- this work is unbelievable.   I've read a bit more than half of these pages- this is a project I can't pass up.  Your dedication to this thread for the last 6?! years is unheard of in the lands of the internet, keeping the whole experience open source and friendly to boot.
	

	
	
		
		

		
		
	


	



  
 @everyone else-  I feel like (some of the) members of this thread who are building their own electrostatic cans are achieving at a very high level, while relying almost entirely on the internet and observations from existing stax sets...  
  
...We ought to have a proper BOM, *FAQ*, suggested online material resources, suggested prior reading,  suggested build techniques, and suggested small signal/amp design reading.   
	

	
	
		
		

		
		
	


	



  
I am still collecting basic info bits for my first ES build, but once I'm up and running (to some degree of success), I intend to formalize some of this rich info.  I may try for an instructible for format, we'll see.


----------



## CoffeeCutie

Here is my Sketchup v1.0.  I like to hash stuff out so I can see it all fit together...   In between the two green spacers is the membrane, I didn't bother drawing a see-through 3 micron piece of mylar.  The tools I think I will use are 3d printer for everything except for CNC'ing the PCBs.    Those who do sketchup, you can tinker and use my model here at the 3d warehouse.   it includes all the stators and bits and bobs which will ideally all fit together upon assembly, as well as a simple headband gimbal.  Here it is:  https://3dwarehouse.sketchup.com/model.html?id=0f47a4a7-7546-4237-95bb-e01ce5822069


----------



## MuZo2

I dont see anything(slots/features) for headband assembly or for wires?


----------



## CoffeeCutie

muzo2 said:


> I dont see anything(slots/features) for headband assembly or for wires?


 
  
 When it all comes together, there is a 1mm slot for wires.  I haven't come up with a prettier way to get the wires out of the chassis, but when I do I'd like it to have space for a proper jack.  Where do you think the connectors should go?  maybe extend the chassis like audeze does?  Also, just to be clear these drivers fit audeze LCD circle ear pads.  (I think)

  
  
  The stators have solder points in there as well.  Also, there is a head band gimbal (not the whole headband, that is something I'm not sure I want to 3d print) in my warehouse model.


----------



## 100VoltTube

Hi all,
 While doing a bit of research on cross-coupled gain stages, I came across this page. About halfway down, it has an electrostatic headphone amp circuit that I have never seen referenced here (head-fi) or on any headcase forum about DIY electrostatic headphone amps. All the parts are cheap and readily available, and you can easily use it with the standard gilmore PSU, so it should make a fairly simple build. Does anyone have any experience with it?
  

  


> ...We ought to have a proper BOM, *FAQ*, suggested online material resources, suggested prior reading,  suggested build techniques, and suggested small signal/amp design reading.


 
 I like the idea, and wouldn't mind helping out.
  
 CoffeeCutie, that is a nice looking design.


----------



## CoffeeCutie

100voltTube,
  
 What a find!  This is way smaller than the KGSSHV or even KGST I was prepping to plunge into.  The waffling around the internet, nomadically looking for a quad of matched FETs...........     I may need to try this amp regardless if it works- I don't need to "Go Gilmore" and be "Totally TOTL" just yet.    
  
 Also, I am working on the BOM.  It just has the basics right now, like anti stat cleaner gel/proper mylar, stuff to electro etch a solid copper ES plate at home...  (check this! https://youtu.be/jEnNMTMZadw  A nice DIYer clued me in on this process yesterday.  Not my reed valve project, but what a result!) 
  
 Also Also- I built a PLANAR magnetic variant in sketchup.  Fits standard 6mm / 1/4in bar magnets, compatible with copper-etched adhesives on membranes or copper clad other stuff....  Everything is color coded for printing in the model.   Just download it into sketchup and move the part groups apart by editing the component.  
  
 https://3dwarehouse.sketchup.com/model.html?id=cd4673ce-0203-4751-915f-8392886efea0


----------



## 100VoltTube

There are simpler amps, if that's what you're looking for. There's the Nov. '99 Tubecad amp (the one at the beginning of this thread) and the Egmont. There's also Frank's modified egmont (the image below) and the stax SRX, both about as complex as the july '06 tubecad design I linked.


----------



## CoffeeCutie

Thanks, some of these drifted away from my vision as got into the build notes on the bigger KG designs.  The one listed with the PSU by Wachara early on is the one I’ll likely stick to.  SRX and Egmont are ones I hadn’t read too far into, but that modified Egmont looks mighty fine…  
  
 Here is my first second.2 draft for build notes and stator/planar ideas.  (PDF)
  
  
  
  
 rev. 2.1 includes 100VoltTube's addendums from the below post and greater emphasis on the mechanical stretch method.  
  
 rev 2.2 includes more BOM stuff and ES v2 and Planar v2 sketchup chassis pictures and links.
  
 I was trying to figure out a way others could contribute, so here is the (editable) google doc: https://docs.google.com/document/d/16SFqIKQ3sX4PMAW_edOLzj-XkwQ-ZXetLfoMY-OU4eQ/edit?usp=sharing​
  
  ...I try to keep the writing style light...  Cheers!


----------



## 100VoltTube

Nice write-up, but I'm not sure I agree that a 3D printer is necessary. It is most certainly helpful, but you can easily make all of the parts you recommend making with a 3D printer with CNC router or hand tools (correct me if i'm wrong). Also, unless I'm mistaken, most people recommend tensioning diaphragms with an inner-tire stretcher, not heat. One last little comment: please add Blender to your list of 3D modeling programs. Overall, a very good job. I don't doubt that it will help quite a few people who are interested, but are intimidated by the fact that the majority of the info required to make a set of 'stats is scattered throughout a 162 (as of today) page thread. Kudos to you!


----------



## chinsettawong

Hi CoffeeCutie,
  
 That's a very nice write-up.
  
 About the tensioning method for the diaphragm, if you use a 0.5 mm spacer with the active diaphragm of 80 mm like mine, it's impossible to just heat shrink the diaphragm.  Mechanical tensioning yields way better tensioning strength.  And I do recommend mechanical tensioning over heat shrinking.
  
 Wachara


----------



## CoffeeCutie

Heh-
  
 Sounds like a good idea, I made those changes in my former post.  (rev 2.1)  I was not sure what the verdict was with stretching, I vaguely recall somebody cooking their membrane (~140 degrees... ...in the kitchen oven?  ...did I remember that??) 
  
 I included a post from 2006 for a ESL panel membrane using a tire.  I figure the fellow has an alright "general overview" of the process, despite his panel being giant and the process being “invented” by the dude in the mid 1980’s.    Some timeless ideas never get old.  
...


----------



## Julez

When I heat my membranes they do not shrink. In fact they do the opposite. They expand. If I take a finished membrane glued to a spacer (or glued to my stretching frame) the resonance frequency gets lower if heated! So my understanding is it will expand by being heat treated and the effect fades away after a while resulting in the same tension as before heating the membrane.
  
 Nonetheless I do use heat treatment. But in my case I have a strechting frame and I do only strecht the membrane in one direction. So I do the heat treatment for a more uniform tensioning on the whole membrane and as well to get rid of wrinkels wich do appear with my method of gluing the mylar to a frame by myselve to stretch it.


----------



## edstrelow

julez said:


> When I heat my membranes they do not shrink. In fact they do the opposite. They expand. If I take a finished membrane glued to a spacer (or glued to my stretching frame) the resonance frequency gets lower if heated! So my understanding is it will expand by being heat treated and the effect fades away after a while resulting in the same tension as before heating the membrane.
> 
> Nonetheless I do use heat treatment. But in my case I have a strechting frame and I do only strecht the membrane in one direction. So I do the heat treatment for a more uniform tensioning on the whole membrane and as well to get rid of wrinkels wich do appear with my method of gluing the mylar to a frame by myselve to stretch it.


 
 Any chance you could make a pair of drivers for the Stax SRXIII pro using the new thinner membranes?  I would be able to give you a pair of original, low bias drivers (with many holes in them.)


----------



## quintile

Hi all,
  
I am struggling to apply a small enough amount of UHU POR glue.
  
I contacted UHU and they suggested that POR can be diluted using "light gasoline".
  
I am not sure what they mean by this name - it doesn't mean much in the UK,
however I am going to try using naphtha (sold as cigarette lighter fuel here).
  
I hope to get something I can paint on to get an even, thin coating on my diaphragm support rings.
  
 Anyone else tried this or somthing similar?
  
 -Steve


----------



## Julez

I used Pattex 100% 50 or 100gr in a tube:
 http://www.pattex.de/do-it-yourself-mit-pattex-klebstoffe-produkte-new/pattex-klebstoffe/100-percent-line/100-prozent-multi-power-keber.html
 I had the same problem with contact cement. It was dried before I could apply it evenly and clean up the mess. With this glue it takes about 30min to dry so even when you apply it very thin it won't dry until you glue it. I also wait about 1-2h before I cut out the drivers from the stretcher. It can also be removed very easily. But I think it is not good to use when you plan to glue the whole driver together. If you have a assebly where you screw the membrane into a housing it works fine. If you glue the whole driver like a Lambda driver it would be nescessary to support the driver with a epoxy glue or contact cement all around on the side of the driver to stabilize it.


----------



## chinsettawong

Don't underestimate the stretching strength of the diaphragm.  Please try to use the strongest glue you can find.  
  
 Wachara C.


----------



## quintile

ok,

so i tried diluting the uhu por. i used naphtha, sold as cigarette lighter fluid in the uk.

this worked very well, allowing me to brush on the adhesive and apply a small even coating.
uhu did warn that this dilution could lead to a loss in absolute strength but i am willing to risk that.

my target is not making electrostatic headphones, but repairing micro seiki mx-2 headphones from
the 1970s. i have two pairs of these. i am thinking of making some new larger headphones (the mx-2s
have a 40mm diaphragm so tend to lack bass.

As the physical charastics of my headphones are fixed i have come up with a couple of
techniques to judge whether my diaphragms are likely to be good. i would be interested if anyone
has any thoughts on these.

first - diaphragm tension.

i tension the diaphragms (2u mylar) using an embroidery ring lined with 1mm of foam rubber to help
it grip the film. i check the tension by tapping the ring, and measuring its resonant frequency with an
RTA app on my phone.

once i have glued on the diaphragm rings and cut them out i check the resonant frequency of the
individual rings - different due to the different ring size.

These frequencies allow me to get a repeatable tension and to estimate any increase or reduction 
in tension if i decide to change it.

secondly - conductivity.

i judge the diaphragm conductivity by timing how long it takes for the headphones to reach full volume
when i turn on the bias supply (about 10 secs). again i can see if my new coating is making them more
or less conductive by the change in charge time.

finally, just to add to the collective knowledge, i was using Technik anti-static bench cleaner, though
i have just switched to using AF screen cleaner gel, which is available from RS/Farnell/Rapid
electronics suppliers. i think the results where very similar.

[update: the af screen cleaner has resulted in significantly lower efficency. I think 10 sec charge
time (given the circuit the MX-2 uses) indicates too low a conductivity.

anyone think these are good or bad ideas?

-Steve


----------



## CoffeeCutie

Hey Steve!
  
 What app are you using to measure resonance/tension on your phone?  That sounds very clever, though likely good mostly for a ballpark tension estimate (mind you, my current version of a box-inner tube stretcher is only as good as the accuracy of how the membrane is mounted to the tube, which isn't accurate at all) ....So I reckon the more tests available the better for repeatability.
 ...Nice ideas!   
  


quintile said:


> ok,
> 
> so i tried diluting the uhu por. i used naphtha, sold as cigarette lighter fluid in the uk.
> 
> ...


----------



## CoffeeCutie

Also, FYI for those looking for a snazzy CNC machine, I found this fellow's design using 3 different standard conduit measurements and orderable / home printable plastic connection and interface pieces.  The whole CNC including the author's own orderable parts and a spindle shouldn't cost any more than $500 to $600 and a few hours of assembly and reading about how to cut stuff..    All the files are free, so anyone can really assemble their own version to their liking.   
  
 Here is the link:  https://vicious1-com.myshopify.com/
 Parts, 23.5 tube version: http://www.thingiverse.com/thing:724999


----------



## quintile

i am using an iphone app called spectrum.

if you play with the config for it you can get it to label the highest peak in the spectrum with fairly accurate frequency, and also if you set the decay rate to zero it accumulates energy forever (or until you reset it with three taps).

i have only been using this for a few days but so far i have found 35hz is too slack (diaphragm unstable) and 45hz is too tight (weak bass). these frequencies are probably useless to you, they to the size of my embroidery ring, the weight of my mylar and dope, the size of the diaphragms i am going to cut out of it and the bias voltage and stator spacing.

what this technique is useful for is getting relative tension measurements so you can see how much you need to change things.

i have also discovered that UHU POR, my glue of choice for the last year, is not very conductive at all. i think all the DIY headphones described here use a second spacer ring to make the contact to the conductive side of the diaphragm. I am repairing micro seiki headphones which use a single stainless ring to which the diaphragm is glued. this is then the only diaphragm contact, hence the need for conductive glue.

i have started to experiment with Thixofix contact cement which seems much more conductive - i am not sure what real change this will make but i am going to make a set of diaphragms and see what happens.

i have also experimented a little with Tecknik floor polish but this seemed to result in resistivity of 4M ohms per unit area, so i will stick with the bench cleaner which gives values of about 100 times this value.

-steve


----------



## Muamp

Hi Steve,
  


> i have also discovered that UHU POR, my glue of choice for the last year, is not very conductive at all. i think all the DIY headphones described here use a second spacer ring to make the contact to the conductive side of the diaphragm.


 
  
 The normal method for DIY ESHS is to use one UN-tagged spacer for the Mylar to be glued onto and one TAGGED spacer which has the bias lead soldered to the tag (per ear speaker). The coating is applied to the Mylar after gluing. Then they are sandwiched together, the copper on the TAGGED spacer making contact with the coated Mylar glued to the UN-tagged spacer. The glue does NOT need to be conductive.
  
 David.


----------



## Muamp

> I am also looking into PCB production in China, so that I can get a batch of stators made in one go. The stators will be identical to the ones in these ESHS.
> The PCB company have already rejected my first set of Gerber files, so I will have to check out what it is I have to change in the files I submit.


 
  
 This is what I wrote on 27th November in this thread (post 2398, page 160). I thought about getting some stators and spacers mass produced in China. At first I had problems getting my G code / DXF files in to Gerber format. I used the PCB company PCBway.com who were very helpful with instructions and help to produce the correct Gerbers. You get assigned a sales rep' who deals with you via email and they make sure all is in order before production. Eventually my Gerber files were correct, you can view them in GerbViewer to check you will get what you expect. So I placed an order for ten stators, as a test run to see the quality. I used HK post as it was the cheapest option for posting.
  
 Today I received the package from PCBway.com and opened it to find eleven stators (not ten). The quality of PCB production is excellent and far better than I expected. The finishing of the boards are as good as I could have expected.
  
 So, you probably think that I can now place a bigger order and even sell some to prospective ESHS DIYer's - NO.
 Not NO because I want to be mean, NO because you wouldn't be able to use them as stators. As PCBs go, a little bit of warp in the board is ok, no problem, but for ESHS stators they have to be flat, VERY flat and these are definately not flat enough.
  
 Here are some photos, to give you an idea....
  

  

  

  

  
 This photo shows the separation at the middle, with the edges touching....
 Don't get me wrong. I will use PCBway.com again,.... I will give them a go at some spacers (not such a problem) and also for circuit boards for energisers etc, after-all this IS what they are really designed for.
  
 David.


----------



## quintile

it might be interesting to try getting the stators manufactured as double sided pcbs, thus maybe equaling
 the forces on both sides and preventing the warping.
  
 To keep the capacitance low the outer faces could not be earthed but would have to be linked to the inner faces,
 you could even go for plated through holes which (might) have a small acoustic advantage - less turbulence? 
  
 the downside would be having high voltages nearer your body, though you still need a sweat screen so there will
 be something between you and 400v.
  
 just and idea.
  
 -Steve


----------



## Muamp

Hi Steve,

That is a very good idea.
Last night, when I unpacked the PCBs, I only thought about the boards as a single sided entity. I guess that I was disappointed with the warp in the boards, I didn't think about new PCB ideas, only tried to think how I could possibly use them in a frame, but that was NOT a good idea.
Wacharra C. said that the SR007s are indeed double sided PCBs which are plated through. 
Mmmm,... I now have to re-Gerber. I think it is worth a go.
Sometimes I get too focused and miss the most obvious idea, thanks for your input.

David.


----------



## chinsettawong

Hi David,
  
 Your stators look nice.  But, since they are made by professional, I think you can ask them to do a better job.  For your information, the SR007 stators are made of double sided gold plated through holes.  The active diameter of the diaphragm is 78 mm.
  
 I wish I knew how to convert my CAD file into a gerber file.  Do you think that PCBway.com can work with dxf file?
  
 Wachara C.


----------



## Muamp

Hi Wachara C.
  
 I use Vectric CUT2D to draw my designs and then to produce my G code.
 Vectric can also output DXF format. I haven't asked PCBway if they can accept DXF directly. Their web page asks for Gerber, which is the PCB industry standard format.
 I then import the DXF in to KiCAD, a freeware PCB CAD package. It is open source, and is as good as any of the _paid for _PCB CAD software.
 KiCAD is very quick to learn for ESHS use since you do not need to worry about any schematics or PCB layout or track laying for the stators.
 You may need to read up on Gerber files. They are user-readable text files which have many simularities to G code. I read a Gerber tutorial, I will search for the URL, but can't find it at the moment. For me to produce these stators I only needed two Gerber files, one containing the edge cuts and holes, the other for the copper coverage (in PCB terms - the tracks). The PCB thickness, black solder mask and other options are all done via tick boxes when you place your order.
 I am going to re-do the stators with double sided and plated through holes......
  
 David.


----------



## chinsettawong

Thanks a lot for your advice.  I'm downloading KiCAD right now.


----------



## kevin gilmore

it would be easy for me to take my current layouts, scale them to any size, do copper one side, or both sides, and do isolated holes, or plated thru holes and generate gerber or gerber x2 files.
  
 to prevent warping, probably a better idea to use something other than fr4 material. not sure if copper both sides would change the amount of warp.


----------



## Muamp

Hi Kevin,
  


> to prevent warping, probably a better idea to use something other than fr4 material. not sure if copper both sides would change the amount of warp.


 
  
 What alternative to FR4 would you suggest. I have tried CNCing aluminium sheet, 304 perforated steel, various substrates laminated with copper sheet and none have been as good as FR4.
 I came to the conclusion that I would stick with FR4 since nothing on a hobby / small scale production is as good. That is why I thought that a small run in a PCB production company would be worth doing.
  
 When Wachara C. stated, the SR007 stators are plated through double sided FR4, I wondered why double sided, and came up with the conclusion that it was purely to increase rigidity, but now I am thinking it is also to prevent warping.
  
 Kevin, have you got any photos of your current layouts that we could see?
  
 David.


----------



## chinsettawong

Kevin has his design's Gerber file on his file server. 

I'm not sure if PCBway uses an oven or any heat to dry the solder mask. If they do, that could be the source of the trouble too.

Stax doesn't use solder mask though.

By the way, David, what is your stator thickness? If you go with double sided and use heavier copper, you can make the stator thinner than 1 mm. The last time when I measured Stax's, it's either 0.6 or 0.8 mm. And it's extremely stiff.


----------



## Muamp

How do I access Kevin's file server / am I allowed to access the file server?
  
 In PCB production, I don't think that the solder mask is heated.
  
 If I process another stator PCB in a professional production, I will not ask for no solder mask, BUT,..... The standard process is to _tin _the copper which is exposed. This IS the process applying heat via processing the board through a solder bath. So in order to avoid heat, no solder mask AND no tinning is required.
  
 The PCB thickness I selected was 1mm.
  
 David.


----------



## 100VoltTube

muamp said:


> What alternative to FR4 would you suggest


 
 If there is any feasible way of getting it cut, tungsten carbide would be perfect. It's 2x-3x stiffer than steel. Unfortunately, it also is extremely hard to cut (that's why many drill bits are made of it), and it's not totally conductive. It's dust poses a health risk.
  
 Beryllium is easier to machine than tungsten carbide, it's totally conductive, and it's also stiffer than steel (1.5x), but it's semi-toxic, so...


----------



## DaveK1977

I have an AutoCAD file that I drew for stators that I wanted to have made in stainless, but I suppose they could be PCB, too.  I never bothered having anyone look at making them after speaking to a college friend of mine and being told that making it to the standard I was asking would be very expensive for each piece on a small run.


----------



## Muamp

Hi DaveK1977,
  
 PCB production in small runs used to be expensive a few years ago, then the MASS producing Chinese companies starting providing the PCB services to overseas. I guess that they process thousands of orders in a day and have such high turn-around that they can offer low costs (plus labour costs lower in China). They will process small orders (as small as 5 PCBs) at low(ish) cost, but the bigger the order the lower the cost per board. If you order over a 100 at a time, then the cost is very low.
 Bear in mind, the comments above. You need to think about the finish you want, stators are NOT their primary market, printed circuit boards are,... the market they cater for. Producing a stator with FR4 on a CNC - You do what you want in the way you want it, even though it is slow... you are in control of the whole process.
  
 David.


----------



## VandyMan

I've been reading along in this topic for a couple of years and dying to try building my own. However, having a CNC machine in my NYC apartment is impossible. David (muamp), if you succeed in getting the stators made, you will be my hero.


----------



## Kerry

Why do you say that? I have a cnc in my NYC apartment


----------



## Jay Sullivan

.


----------



## CoffeeCutie

vandyman said:


> I've been reading along in this topic for a couple of years and dying to try building my own. However, having a CNC machine in my NYC apartment is impossible. David (muamp), if you succeed in getting the stators made, you will be my hero.


 
  
 Over the internet, I have seen people build small MPCNC machines (by Vicious1) and enclose them with roxul/noise insulation, while still having a way to open the thing.  Seems like a nifty idea for those with thin walls....   Here is an instructibles one for cnc and laser:
  
  
 @everyone: I am curious why we don't use solid copper or other conductive metals to route out.  I am inclined to take some inexpensive 20-30 gauge copper and cnc a stator out of that.  I can't claim to understand coulomb's law, but it seems like a perforated copper sheet would do the same-ish thing as a FR4.  ?


----------



## Muamp

VandyMan,
  
 Thanks for your comments! Much appreciated.
 I have just sent off a 2nd set of Gerbers to the Professional PCB manufacturers. This time a set of 5 Gerbers.
 This process is for a set of 10 test stators, using double sided FR4 and a few _other_ modifications which should (hopefully) make a better stator.
 I will update when I have more info.....
  
 David.


----------



## quintile

Hi,
  
 Just thought I would post an update on my progress.
  
 I have had the Micro seiko MX-2 for a year or so now, I made quite a few diaphragms for them but was always
 left with limited bass. I recently bought another pair very cheaply which encouraged me to experiment some more.
  
 It turns out I was assembling the electrostatic cells incorrectly leading to a much higher diaphragm tension then
 is needed. My new technique of checking the resonant frequency of the diaphragm, first in the embroidery ring,
 and then again when the diaphragm support rings are glued on means I can produce diaphragms more reliably.
  
 the results so far have been very very encouraging with frequency response flat to 20Hz (admittedly with me compressing
 the ear cushions gently by hand).
  
 I do have a question.
  
 I have a diaphragm tension I like but if I press the headphones firmly to my head I can cause the diaphragms to stick to the stators.
 There is no damage and they release themselves over a period of 5-10 seconds but it is not nice. I have insulated the stators
 using a black sharpie pen.
  
 Anyone else experiences this? Is this typical or an indication I should go for tighter diaphragms?
  
 Thanks for any help,
  
 -Steve


----------



## Julez

Hello Steve,
  
 in my experience that is the case if you do not coat both sides of the membrane. I nearly always have membranes sticking to one stator if the membrane is not coated on both sides (when putting the headphone on my head or pull it off my head). They sometimes do not release at all until I pull the plug and short the contacts. Try coating both sides (but both sides must be connected to the bias voltage otherwise it won't work). I hope this will solve your problem.


----------



## chinsettawong

Hi Steve,
  
 My headphones have the same problem if I press the cup against my head when listening.  As you have already known, the spacers are so thin that a slight change in pressure in the cup can cause the diaphragm to collapse to one of the stators.  If it bothers you much, then maybe your tension is just a little too loose.  When I listen, I do not press down on the cups, and I do not have that problem at all.  
  
 Wachara C.


----------



## chinsettawong

julez said:


> Hello Steve,
> 
> in my experience that is the case if you do not coat both sides of the membrane. I nearly always have membranes sticking to one stator if the membrane is not coated on both sides (when putting the headphone on my head or pull it off my head). They sometimes do not release at all until I pull the plug and short the contacts. Try coating both sides (but both sides must be connected to the bias voltage otherwise it won't work). I hope this will solve your problem.


 
  
 Hi Julez,
  
 That is an interesting find.  It's certainly worth trying out.


----------



## Muamp

It is an interesting find, but how to apply the bias voltage to both sides when using an FR4 spacer?
 The glue is holding the diaphragm under tension and the normal way with FR4 would be to apply the bias voltage to other side.
 If the diaphragm is held in a metal ring, I guess this would be easier...?
  
 David.


----------



## quintile

Hi,

 In the FR4 case I think adding a contact to both sides should be straightforward.
 In my experience the glues I use (UHU POR and Alpha (was Dunlop) Thixofix)
 are both conductive enough (compare to the tens of megaohms normally in series with the
 diaphragm).
  
 In my case the diaphragm is only glued to a metal ring so making a contact to the other side
 of the diaphragm is not easy.
  
 I am going to try increasing the tension a little more and see if I can keep my low frequency
 extension.
  
 for fun I have attached my best yet frequency response and a picture of my measurement rig.
  
 I am not happy with the rig and am going to build a multi mike, flat plate as described by Ulrich Hornach
 here  http://www.aes.org/e-lib/browse.cfm?elib=17698. iI you are not a member of the AES and don't
 want to pay then you can see the rig in the related patent: https://docs.google.com/viewer?url=patentimages.storage.googleapis.com/pdfs/US20150003649.pdf page 3.


----------



## 100VoltTube (Jul 4, 2017)

@quintile,
 Those are some pretty serious treble resonances you got there. (at least the one at ~2.6 khz) Can you hear any odd-ness in that area?

 Hi all,
 I've looked around for even cheaper CNC machines then those discussed earlier, and came across this. All the software is free and open-source, so no hidden costs there. One other note: every CNC machine on that site is on sale for a 20%-25% discount, about 5 days a week.

 Does it seem good for our uses?


----------



## Muamp

Hi 100VoltTube,

Just visited the website of your CNC link, the CNC looks good if you live in USA, the cost of postage to the UK makes it about the same price as the 3020s from China.
Lets us know if you buy one and tell us what you think.

David.


----------



## quintile

my fault for not being clear.

these measurements are raw, uncorrected
data from the microphone and the resonances you see are due to the fake pinna and ear canal i have attached.

the reference to a new measurement technique is because using dummy heads
(ears) is fraught with problems of resonances and matching compensation curves.

i published the curve more to show the amazing of response i achieved from a 45mm driver -i didn't think this was possible.

it would be great to hear if anyone has some real equations describing what limits the bass of response if electrostatic headphones.

i agree listening is what counts in the end, but without maths to tell you what to change i feel i am just playing a game of trial and error.

-steve


----------



## Muamp

Hi quintile,
  
 I have the philosphy of making the speaker/panel with the flattest response possible, so that the sound coming from the panel is as close to the original sound as it can be.
 The shape of my ears _will _modify the sound coming from the panel, so that what I hear may not be the exact sound that the panel is producing, but the modified sound will be modified in the _same _way my ear will hear as the original sound in real live listening.
 All my tests are done without simulating the shape of an ear.
  
 David.


----------



## quintile

hi,

yep, this is the argument if the paper i linked. my new measurement rig should be built this afternoon though i need to buy some more mikes.

 the paper suggests you use multiple mikes as a way of getting more repeatable hf measurements - rather than moving the headphones many times.

we shall see, it's all fun and only woodwork and cheap electronics so it's worth a try.

-Steve


----------



## Azrael3000

Hi all,

first post here, so let me first thank all the people involved in this thread. During the last weeks I've read it from the very first to the very last letter. I did take notes while doing this and a friend of mine and me are at the moment acquiring the necessary materials to follow in the footsteps of Wachara et al.

The notes that we took will be completed with pictures and our own experience of building the headphones and we are going to release this document to the public once we have a first working version. This should hopefully summarize this thread a bit and remove some of the noise that accumulated over the years. Once this will happen we will of course want your feedback on it to improve it further.

Now it is mostly clear for us (minus the practical experience) what we need to do to build the headphones. The thing I'm a bit uncertain about is the amplifier. As a first step I would like to avoid building a fully fledged ES amp and instead go for a simple step-up transformer that I can hook up to a standard amp. I was thinking of using Jazzman's toroidal step-up transformer [1] and modifying as it is designed for speakers. Using only 2 (instead of 4) ladder steps should reduce the max dc voltage to 920V, sufficient for our use case. An additional pot on the 230v input will then give us a variable bias voltage. As the ladder doesn't give you a smooth voltage but instead an ac current with offset I wanted to ask whether this will significantly impact the audio quality.

Secondly, the audio input to stator circuit results in approx. 500 V at the stators for 6 V input. Will we need to scale this down for the headphones as well?

Thanks in advance for your reply,
Arno aka Azrael3000

Urls (remove spaced around dots)
[1] jazzman-esl-page . blogspot . com/2010/01/update-new-toroidal-step-up . html


----------



## CoffeeCutie

Hey Arno!
  
 Good question, I am looking forward to seeing the answers you will get.  I was poking around ebay and it seems stax used to build this very box, and Woo audio still does (Woo "wee").  I am curious also about those folks who wind their own transformers.  I have an extra stepper motor and a few normal dc motors I was thinking about building into a coil winder of some kind.   I like this step-up solution, as it seems to simplify an otherwise far more expensive and tedious task of building the ES amp (just to get a system working to test it all out).


----------



## Muamp

Hi CoffeeCutie & Azrael3000,
  
 I have wound audio toroidals and I do not recommend it. Audio transformers are much more critical than power transformers. You can spend a lot of time winding and then discover you get a lot better sound from some cheap power transformers used as step ups (reversing primary/seconday).
 On the 'Electrostatic ear speaker DIY'ers suppliers list' - http://www.head-fi.org/t/826032/electrostatic-ear-speaker-diyers-suppliers-list  I have listed an audio transformer from RS components that only cost about £13 and is very good for ESHS energisers.
 By-the-way, typical DC bias voltage is 580v. The normal max peak to peak audio applied to the stators is 800v p-p  to  1300v p-p depending on energiser.
  
 David.


----------



## chinsettawong

Hi Arno,
  
 It's always nice to see someone spending the time reading the whole thread before asking some questions.  
  
 First of all, I would say that using step up transformers isn't a bad idea.  If you can find good transformers, the sound quality can be quite good.
  
 On Jazzman's page, he is using toroidal transformers as step up transformers.  While they are OK for hybrid ESLs, for headphones that are running full range, they might not be quite suitable. In my experience, these transformers aren't that good reproducing the bass.  Some EI core transformers for push pull tube amps can be quite good.  You want to find the ones with step up ratio of at least around 30 - 40 times.
  
 As for bias voltage, using the simple ladder voltage doubler circuit is good enough.  I suggest you should try it first.
  
 Wachara C.


----------



## 100VoltTube

Hi Arno and everyone else
  
 Step-up transformers may at first seem like a good idea, but they have their drawbacks. Tubecad explains why in the November 1999 issue here. I can't remember which page it's on, but it's there somewhere. On the other hand, the Woo Wee (a transformer based option) fared well in this comparison, so maybe the drawbacks are only theoretical. If you want a way of powering a pair of headphones without spending a lot of money, a pair of these *Edit: not these trafo's. They don't have a CT. Their middle tap is at 40%* (or the ones David found) and a voltage multiplier for bias would be perfect, as long as you're comfortable waiting for 6 weeks. The total cost should be less them $150 (maybe even $100), including chassis. It wouldn't sound perfect, but for $150, you can't expect it to.
  
 You know, you can get a CNC router for $230, a transformer based energizer for ~$150, enough FR4 for a few headphones for $30, enough mylar for many, many headphones for $25, an embroidery hoop for $25, an inflatable ring for ~$25 (probably), licron coating for $40, a koss cable for $15, and wood, metal, and leather for the frame and headband for ~30 (hopefully). That's a total of ~$570, less than a used ESP-950 or even a HD-600 with a Crack or Valhalla 2, that gets you a setup on par (ish) with a SR-009 ($3,825) or SR-007 ($2,100) out of a Woo Wee ($500), assuming everything is made properly. Unfortunately, in some places you can't CNC's that cheap, (you can only get better ones that cost more) but still, that's pretty impressive.


----------



## chinsettawong

I would say that DIYing a pair of headphones might not be as cheap as you think.  Most of the time you'll spend a lot of extra money on something that you eventually don't need.  Also, trials and errors cost a lot of time and money.  However, you can't beat the feeling of your own achievement once the project is successful.  That's something that money cannot buy.
  
 I certainly don't do my own headphones just because they're cheaper.  
  
 Wachara C.


----------



## Ghost Pack

Hi guys!
  
 So I've been on this thread before but my first attempt ended in disaster since I tried to use laminate PCB rather than FR4. Now I have the proper FR4 PCB but I'm not sure what dimensions, hole diameter, or spacing to use.
  
 My maximum active area is 52 cm^2 (70 mm diameter by 48mm diameter oval)
 I only have a stax normal bias amplifier (230v)
 I have 3 um and 0.5 um film
 I have the recommended electrostatic cleaning gel
 0.4 mm double sided, 1 mm single/double sided, and 1.6mm single sided PCB (I can hollow out the thicker pcb if needed)
  
 If anyone has some advice for what dimensions to use I would be very grateful!


----------



## Julez

It was said that an open area of about 40% is the goal. I read in the Sanders electrostatic coockbook that it would be good to have holes with a diameter at least twice the size of the stator thickness to avoid the helmholz-effect where some frequencys get amplyfied. For headphones I would recommend 2mm diameter. You can play with the hole size and see if that has an effect on the sound. For a normal bias headphone 0.3mm gap is used by Stax. So I would do so as well but maybe you can also go with your 0.4mm pcb (you will just loose a few dB in volume compared to 0.3mm). And I would first try the 3um mylar as it is much easyer to handle.
  
 A widely used pattern for the holes (Stax is using it in all headphones other than the original Omega) is called in Germany RV (round offset) where you have a row of holes and the next row is shifted in half the distance between your holes (sorry I don't know how to explain better just look at a Stax stator). 
  
 I would recommend Licron Crystal for coating the membranes (although your cleaner would also work for testing purposes). All other products did fail in my experiments after a few hours or weeks plus they are very prone to develope dust issues. Licron has the advantage that it really sticks to the mylar membrane and do sort of leave a isolation layer on the mylar. But it can't be removed if applyed wrong (even with solvent). Try to apply it as thinn as possible so it is barely visible. I hope this will help you. Maybe Wachara also has some good recommendations.


----------



## Ghost Pack

Thank you a lot! I remember doing 1.5mm holes with 0.5 mm stator last time, which ended up flimsy and shredded with the laminate pcb. I'll go with a basic 1 mm stator with 2mm holes.
  
 As far as the pattern is something like this what you mean? It's a triangular pattern I tried last time.
  

  
 I think remember someone made a calculator for finding the spacing between holes to get a certain amount of coverage. Does anyone still have the link to that?
  
 Also, is there an advantage to adding a large hole in the center or a cluster of slightly larger holes? I know stax includes a larger hole in the 009 stators and there was some discussion about using hole size to get a more even distribution of force on the diaphragm.


----------



## Ghost Pack

Ahh I found the calculator after a few minutes of google search!
  
Here


----------



## Ghost Pack

Out of curiosity, has anyone tried using acoustic isolation rubber as spacers to mount the drivers to the frame? This seems like it would increase bass response just like it does for wall mounted and desk mounted speakers


----------



## Julez

Yes that was the pattern I meant!
  
 I recall the HE60 has such isolation rubber between the drivers and the baffels (Stax Lambda headphones where glued and are now screwed to the baffle). But the HE 60 has also very weak bass imo. However I am shure that the rubber is not responsible for the weak bass.


----------



## quintile

the micro seiki headphones have a small ring of very thin foam rubber between the electrostatic
 cell and he casing in which it is mounting.
  
 I assumed this is used to ensure the cell is firmly held in place, and to prevent
 acoustic leakage from the back of the diaphragm which would cause severe LF loss.
  
 -Steve


----------



## quintile

I am interested to hear if anyone tried Neil Pollock's headphone amps from Wireless world in 1979.
  
 http://www.amateuraudio.fr/images/ww5.pdf
  
 I am sure these are not a patch on Mr Gilmore's designs but I would have thought they would work better
 than some re-purposed mains transformers.
  
 is there a reason why no-one here seems to like this design?
  
 -Steve


----------



## Muamp

Hi Steve,
  
 It is always good to read new and different information on energisers.
 After all the internet searching I have done, not come across this article.
 I love the simplicity! The bias voltage he suggests may be a bit high and the power supplies basic, but this is one I will definately be trying out.
 I will probably use a different Op-amp.....
  
 Thanks,
  
 David.
  
  
 Edited: Looking through my old notes, I found a circuit VERY similar to this by SeekIC.com


----------



## quintile

that circuit is from the same man, he published it as a replacement to the earlier wireless world headphones design.

btw the op-amps here - lm3900 are norton transconductance amplifiers rather than the more common voltage amplifiers. if you want to use voltage amps some redesign is needed. 

norton amps have a zero ohm input inpeedence and an infinite (ish) output inpeedence...

-Steve


----------



## quintile

Hi,

another intriguing circuit. again simple but probably an improvement on cheap transformers.

please note i have no problem with transformers but neither do i underestimate how hard it is to design them to pass the full audio range with a large step up ratio driving an almost purely capacitive load...


http://application-notes.digchip.com/006/6-8831.pdf

-Steve


----------



## kevin gilmore

as it is, those single ended designs have a very limited slew rate due to the collector resistor, and the speed of the output device. you can make it much better with a c2m1000 output device and cascode current source replacing the power resistor. then pick a much faster opamp and make sure the feedback resistors are non-inductive.


----------



## Muamp

I was thinking of using the original cct from Wireless World, swapping the LM3900 for LM359 (60V/uS,... much faster Norton OpAmp) and FJP5027 for the NPN bipolars.
 The c2m1000 look interesting....
  
 David.


----------



## kevin gilmore

you should look at the sennheiser hev60 schematic.  essentially the same thing with mosfet current source and mosfet output transistors and a bunch of opamps.
  
 all of these kinds of circuits are very sensitive to the power supply voltage, so you will need  very well regulated 800v supply.


----------



## 100VoltTube

Hi all, 
  
 What do you do to deal with the cancer-causing fiberglass dust you get when you cut the FR4?
  
 Kevin, what do you think of the TubeCad design from a few pages back? This one (halfway down the page)
  
 On the topic of the seekic circuit, if you were to substitute the output device, or the opamps, what would you need to do with the passive components? Forgive my ignorance; I really have no clue when it comes to solid-state amp designs.
  
 Also, if I were to substitute the output stage with a tube, say a 6SN7, what gain would I want to shoot for?


----------



## chinsettawong

100volttube said:


> Hi all,
> 
> What do you do to deal with the cancer-causing fiberglass dust you get when you cut the FR4?


 
 Always put the mask on when you cut the FR4, and work in a well ventilated area.


----------



## kevin gilmore

there is no reason to use plate resistors when a 2 transistor current source is so much better.
 you will also need a -100v power supply. other than that, pretty standard stuff. using 6s4 vs 12b4 probably very little
 difference, use what you can get. 6s4 can handle more power.
  
 edit: like a lot of broskies designs, that design is not finished and is missing parts. The output stage is dc coupled and there is
 no adjustment for dc control. so another power supply and pots are needed, or servo's.
  
 So the kgst design which is fully finished and very similar is ready to go, fully dc coupled, no caps to the inputs of the output stage etc.


----------



## 100VoltTube

I was looking closer at those modifications you were suggesting, and decided that it would be easier to just start from scratch. Which I did:

 Sorry for the terrible image quality and sloppy drawing. Basically, it's an op-amp driver I found on TubeCad, and a current sourced push-pull 6s4 output. The gain wouldn't be great, but it should be able swing 300v p-p. What I want to know is if it would work well, and what improvements I could make.


----------



## kevin gilmore

without any feedback from the plate of the tube, no way to stabilize that voltage to half of B+ and the tube will quickly head for one or the other rail.
  
 you have to add feedback and bias up one of the opamp inputs to 1/2 of 350v/gain
  
 pretty much like this
 http://gilmore.chem.northwestern.edu/he70-1.jpg
 http://gilmore.chem.northwestern.edu/he70-2.jpg


----------



## Muamp

This thread has been quiet lately, so I will add some recent photos.
  
  
 Firstly, the double sided PCB stators from PCBway. I recieved them in the post about 3 weeks ago, but been too busy to try them. They are definately flat enough and good to use!
  

  
  
 They will be used in these Afromosa hardwood surrounds.
  

  

  

  

 The surround on the left was my first attempt, the holes are far too small. The surround on the right has much larger holes and will be the surrounds to use.
  
  

 This test panel is using a wire mesh (#60) dust shield / outer protector. The mesh looks great but with an open area of only 39% not really suitable. Having said that they do sound very good with the mesh. The mesh is good enough to keep out all dust, so no Mylar dust shield needed.
  
  

 Again, this ESHS will have the same headband, but this one will be mounted at the sides (not middle as in my previous pairs).
 Also, the 'Stax' style plug has a black plastic barrel and hardwood top and bottom.
  
 David.


----------



## chinsettawong

They look really nice. Please keep us posted.


----------



## Kerry

Looks great!
  
 Looking forward to additional pictures.


----------



## wppk

Hi there ! this is a new question concerning a diy repair. If anyone has an explaination, that will help me a lot.
 I have several stax srx markIII, in order to mend them and to make some pro ones for my personnal use, not for resale.
 As many of you here may know, it is possible to build a markIII pro out of a mark III normal housing, using drivers from stax alpha or gamma pro drivers which are said to be the same( in fact they sound different, as I could notice with the alphja and gamma pro drivers I found. The alpha is bassier ans not as sparkiling in the high end, compared to the gamma. But the drivers lokk exactly the same, impossible to see which is which, you have to listen to them, but the difference makes it easily noticeable.
 I repared a mark III noamrl bias, which was ill balanced, by recoating the diafram, wich was rather easy to do and gave very good results. As I had a gamma pro housing, which sounds bassier and not as monitor as the srx body, according to spritzer many time saying it here, (and I agree with him of course) I set the normal driver in it to see if I gained a little basse, and tnat was slightly the case. The newx combination is perfectly working without disorder. I built two mark III pro with the pro drivers forme the gamma and the alpha. From the alpha, thjis is perfect too, with an amazing sound, not as brilliant as the one with the gamma driver, and bassier, as I said. I prefer the brilliant one, which is sooo astonishing, and that makes it the best can I ever had and heard. But here is my problem, on which I spent weeks searching a solution without success, and that make me write to you. when I fell I have finished everything for it to work, I wear it, and it does. for a while, which does not last the same everytime. But then, it starts to get ill balanced, always the right side getting weaker. I tested my amp under all ways, it is perfectly workin with my other stax gear. so, the probleme is in the cans. but this is not the weirdest of the story.
   I have to explain: when I have this imbalance, I dismentle the driver ( I have recoated all the drivers I use and discribe in this post because the srx are very likely to get an imbalance because of the coating leaving with time), reassamble it, and it works fine again. just for a while. So  I decided to try something : I put in the brilliant housing one of the alpha ( bassier) driver ( on the right side) to replace the defective driver). the balance was perfect.... for a while. the imablance came with the new driver, that had no imablance when coupled into the bassier cans. I made different tests, which lead me to conclude that the issue onbly came when a driver was coupled to the left one in the brillant cans, which seemed to have no problem.
   Does anyone have an idea of what is wrong there ?
 Thank you for your answers and time


----------



## chinsettawong

Are you using normal bias drivers with pro bias voltage?


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## wppk

No, of course. Normal bias drivers for normal drivers. pro for pros. BTW, The only difference is the thickness of the membrane ( thiner in pro) and of the rings that support it ( thicker in pro than in normal)


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## wppk

I tested this too, to intervert both. it doesn't damage the membrane. but it makes imbalance problems, that is right. I only tested with another pair I have, but not for long and I put evrything as originally in the drivers.


----------



## Julez

My experience was the same as yours with antistatic coating before 100VoltTube said I should use Techspray Licron Crystal. I tried this and it was the only coating that worked over a long period. Every other coating failed after some hours or maximum two weeks.
  
 The problem with the usual antistatics is that they are often based on a oily substrate that does not stick to the mylar membrane. Licron Crystal does stick like dried cewing gum on your shoes. I was not able to remove it with anything properly and reuse a membrane once coated with Licron (if applyed too thick). This will definitly solve your problem imo. Get some destiled water or isoprop to remove the actual coating and apply the licron as thin as possible with a sponge to the membrane on *both sides* (or you will have membranes sticking to a stator if they hit one). I spray the Licron into a small laboratory botttle (wich can be sealed tight enough that the licron does not evaporate) and then  dip the sponge completely into the licron and squeeze the sponge as dry as you are able to. Then wipe the Licron onto the membrane and make shure it is applyed everywhere evenly and make shure that no visible dustparticles get into the coating while it dries. It is dried (when applyed correctly) in a few minutes. It is thin enough when barely visible only in refelcting light. I know Licron is not that cheap (about 40€ a can) but it is absolutly woth the price and will last (if applyed very thin) for aproximatly serveral thousand (headphone)drivers.
  
 I hope this will solve your problem! ÜPlease let me know if you tried it and how it worked out. If you have problems you can always ask me.


----------



## wppk

Thank Julez, but I think this is not my problem, as I aslo tested several antistatics, and the one I use stays. But mainly, It doesn't seem to apply to my problem, because I use the same antistatic product for all my recoatings, and I don't have any issues with the other drivers...


----------



## chinsettawong

I would check the cable and solder joints again. 
  
 By the way, do you use any damping material inside your cup?  I once fixed a pair of SR-5, and I found that the damping material somehow discharges the diaphragm.  I had to take them out and the problem was solved.
  

  
 Wachara C.


----------



## wppk

I will check the cables...
 I have no other damping than the one on your picture, ( tried many kinds and left it like originally).
 I will try without, but I don't understand why it would discharge some drivers and not others?  I will try on the right side first, which seems toi be faulty. thanks
BTW : I had tried a sponge for damping and it immediatley discharged the driver, in a sec.


----------



## quintile

FWIW I use antistatic floor coating - for use in ESD protected factory areas.
  
 It has worked fine for about 9 months now, I have also used antistatic bench cleaner which worked for
 over a year too.
  
 I do not believe that coating both sides of the diaphragm makes any difference. I never coat both sides
 and have no problems with diaphragms sticking. I get diaphragm sticking if the tension is too low.
  
 -Steve


----------



## wppk

yes, it makes sense to me too, Steve. thanks .
 for wachara : the cables are not the cause : I have used the cables of the faulty cans  to set the successful drivers, and it perfeclty works. I really think this is a very good try to test the damping taken away. But I cannot do it right  now, I have my little boy at home... Will try this evenig ( I am in france) and will tell you. 
 thanks to you three.


----------



## wppk

anotehr problem, I hjad no time to explain, with the faulty driver. it appearde inedependantly to the the imbalance issue and very lately : on the "faulty" driver a repetitive "tik" appeared, or was replaced by a bassier "tonk" that I had never heard in any problematic stax or other. it is nort coming form thje protective membrane. and I cannot see any dust anywhere that could cause this. the sound membrane is OK. spining a bit one of the tiny screws that maintain all the parts of the driver together seems to act on the repetitive noise, but doesn't remove it completely. I use an air pulsed (what's the english name) system to remove dust from the cup containig the membrane...
 hope I will find the way to get rid of it. Maybe it only a remaining dust somewhere, I can't think of anything else. but if you have another experience... ? thanks


----------



## chinsettawong

Yes, I had a similar noise and imbalanced problem.  After taken away the damping material, the problem was fixed.  In my case, the damping material didn't do well with the high bias voltage.  I guessed when it's normal bias, it was fine.


----------



## wppk

that would be great !
 tell me, is the driver of the srd 5 different from the srx ? you are talking of a pro driver. does the srd 5 exist in pro mode ?


----------



## wppk

well. I removed the parts on your picture, wachara, but I still have an imbalance.


----------



## wppk

I think the problem comes from the plastic parts of the driver. I tried it with two of those, but these are probably both defective. maybe the copper part is not well positioned on the rest, and it makes the issue. I will try with another driver body. I tried yesterday with a normal bias membrane, I still had the imbalance.
 BTW, removing the damping changes the sound very importantly, it makes some frequencies bump in mid-bass/mid, and creates a dull resonance. I will try with another damping. I have some material to clean glasses, I will give it a try.


----------



## chinsettawong

Can you show us some pictures of the drivers?


----------



## wppk

I took some and will send them
 But you will not find them in perfect shape, as i dismenteled them so often to find solutions, the least thet one can say is that they are not brand new... I have been working on them for weeks and hours.
 so, I found a rather acceptable imbalance, now, using other drivers that were in better shape. it is not perfect but will do for the moment.
 I have several observations that may help other people facing the same problems as mine.
 first, I have to say that on all of my cans, normal or pro, I removed the black upper rings, with a grill, because letting them on lowers a lot the quality of the sound it you keep them on. Normal, because it makes an important screen. But, I think this may be part of my problem,  cause I believe now that it also protects from temperature.and possibly, magnetic field.
 After you told me, wachara, about the outer damping ( your pictures) I made a lot of different tests that led me to notice that I could'nt make an evidence of it to discharge the membrane, even if of course I believe you but it doesn't happen on my faulty cans. remove it or keep it will not change anything. But I could make one thing sure: the proximity of the ear discharges the membrane or, any way, lowers the sounds even until il cuts it. After a few seconds of letting one can on one hear, it extinguishes it. and the sounds totally gets back after the same while.
 as, for my so many assembling and disasembling, I couldnt have an anti condensation membrane at all my tests, I saw that. Because after having put one onf these membranes, I had no more sound fading.
 But even so, and even if I I could make a good balance with both cans as long as I didn't put them on my head, the balance changes when the drivers are correctly set into the housing, but you can only really hear the difference and then, imbalance once the cans are on your head. Which, as you can easily guess, is very disappointing, when you think you had finally found the real solution, after putting all screws back for the tenth time.
 if anyone has a handkerchief ( antistatic please) to send to france for the tears I shed, it will be apreciated.
 Also, something I can figure out is when I plug back both srx pro on my amp (trm t1). it ils not easily observable nor permanent, but the imbalance of one imbalances the other. And not all cans to the right or to the left. When I plug in the perfectly working srx, there is no imbalance. but when I plug the other, an imablance can appear or leave after a wile, and is also hearable in the other can, which also can reach perfect balance at other times.
 If only the good can is plugged in, I can't remember to have met the same issue.
 the imbalance is most of the time quite subtle, can be corrected on the balance knob by changing just three minutes or five if the knob was a clock. But on the wrong can, it can go up to a 12 minutes change. This is very obviuous to hear with these srx pro, with which you feel any odd thing in the sound so well. That is why it makes them so good for monitoring
 so, I think my problem comes form drivers that could be a bit tricky, and from the difficulty to control the distance from the driver to the ear and the temperature/condensation.
 I cannot explain here oll the tests and tries I had with these. But I can add I put O rings inside the metallic cups, close to the driver ( side of the ear) to make a little bit longer disance. And it works, but it is not very stable.
 BTW , the odd noises, tikks and tongs went away when I changed the body of the driver.
 Wachara, you didn't tell me, are there pro versions /drivers for the cans you fixed ?
 thanks to all


----------



## wppk

here are the drivers, one side per photo.  )
 wachara, do you know what are the long resistors-like components that are soldered on the normal bias drivers to + and -, (and not on the pros) for ? I didn't take picture, but I can if you whish?


----------



## Muamp

Hi wppk,
  
 I know you addressed the question to Wachara, but I may be able to give two possible answers.
 The resistor like components are either:
  
 1. The resistor like components are in fact resistors, very high valve Rs, in the order of 10M +... The SRD5s etc were designed to be driven from transformer energisers. With transformer energisers it was good design practice to use high value resistors on each stator in order to make the capacitive load predominantly resistive. The value of R being greater than the reactance of the capacitive load at HF. The reactance of the C seen on the i/p of the step up transformer becomes less than one Ohm at high frequencies making it very difficult to drive. This is because the transformer i/p impedance is related to the square of the step up ratio. This design theory is very well explained in Frank Verwaals free PDF book (http://home.kpn.nl/verwa255/esl/ESL_English_2011.pdf). The resistors remedy this effect.
  
 2. Having said answer #1, they could just be insulated wire links. After all, if this was the case, it would have been better to put the resisors as close to the tranformer o/p terminals as possible.
  
 David.


----------



## wppk

Hello muamp.
 thank you very much for your explaination. I am afraid this it way too technic for me, it I try to get deep into it. But I understand the general meaning. and the effect.
 You were absolutely right to answer, Wachara is very busy, but always very friendly and helpfull, as you surely are too, and I thank you both very much for your time.
 If I read you well, and catch it better than at the second or third first reads, does it mean that if I use the srm t1, which is not a transformer amp if I am not mistaking, because it has to be plugged to the home electrical alimentation ( sorry for the terms I use, I guess they are not proper in english but may keep understandable, if not, tell me) the resistors are not necessary anymore ?
 If I am still right, a transformer energiser doesn't need to be electrically fed that way, the amp on which it is plugged is enough, right ?


----------



## wppk

Here is the resistor (in blue). I didn't solder it, just put it where it was


----------



## Muamp

Hi wppk,
  
 Yes, if you are not using a Stax style transormer energiser that Stax would have designed to be used with these ESHS then yes you are right, you would not need the resistors. In fact, if you use a solid state or valve energiser then you definately do not want the resistors on the stators. The resistors would probably render the ESHS quiet or silent in a non transformer energiser.
  
 Modern designs of ESHS's would not use any resistor in this manner, even if a transformer energiser were to be used. As it would be a much better design to incorporate *ALL* the circuitry in the energiser and have the headphones  as pure panels.
  
 David.
  
 Edited, Just seen your last post with the new photo. This makes it different. This component could be (need to look up my transformer notes for the name) a way of stopping over-voltage on the stators - voltage limiting on the max Pk-Pk of the stators. On transformer energisers the amplifier feeding the transformer _could _drive the panels far too much, leading to voltages too great across the stators. This stops the over-voltage.


----------



## wppk

Ok David
 (BTW my real name is Luc, nice to meet you ! ) 
 I understand very well.
 Just one point : I tried with or without the resistor, plugging the sxr in my valve amp, and it doesn't change anything to the sound.


----------



## wppk

I have both energisers, with or without transformer.
 what was surprising to me was to see that all the drivers for normal bias of the srx had this resistor, and none of the pros


----------



## Muamp

are the pros designed to be transformer driven   or   solid state / valve driven?
  
 David.


----------



## chinsettawong

I have only seen the resisters used in electret headphones.


----------



## wppk

the pr'os ans the normla sxr and gammas can work on both amps, david. the resistors on the pictures were on srx normal bias, wachara


----------



## wppk

Hello David
 hope I am not disturbing or mistaking, but you say
 Having said that they do sound very good with the mesh. The mesh is good enough to keep out all dust, so no Mylar dust shield needed.
 I am not a headphones builder but repair tehm on what I can do, and this mylar shield seems a must have to me, because it prevents the micro condensation( form our head and ears)  from getting on the stators and creating squeak noises.
 the mylar membranes don't affect the sound, oddly.
 but if you don't use some, I m afraid you are going to experience weird noises. You will notice them after a while of wearing the headphones, and they will leave after a few minutes without the headphones being on your head.
 also, being french, I am not sure of the meaning of mesh. If it doesn't let humidity pass trough it, then mylar will not be needed of course


----------



## wppk

for my repairing : If have ordered julez's advised product to coat the membranes, as I cannot find another solution for the moment . Will see if it changes something.


----------



## Muamp

Hi Luc,
  


> Hello David  hope I am not disturbing or mistaking, but you say
> Having said that they do sound very good with the mesh. The mesh is good enough to keep out all dust, so no Mylar dust shield needed.
> I am not a headphones builder but repair tehm on what I can do, and this mylar shield seems a must have to me, because it prevents the micro condensation( form our head and ears)  from getting on the stators and creating squeak noises.
> the mylar membranes don't affect the sound, oddly.
> ...


 
 No, you are not mistaken. On my test panel I took out the outer Mylar dust shield and replaced it with very fine wire mesh. The main purpose was to provide an outer protection to the headphone panel. That is, to stop fingers from prodding and poking the panel, even though the panel is fully insulated with the FR4 fibre glass and acrylic spray. But it seems that the mesh is so fine it actually stops all dust from entering the panel (obviously the HV attracts dust and it is the dust which causes the notorious 'squeal'). It is very effective at providing protection and a bonus also effective as a dust shield. The mesh does not protect against sweat or condensation, but the mesh is only used on the outside, not on the ear cup side, which still has the Mylar dust shield. Also, all my ESHS designs use fleece ear cups which are 'breathable' and allow the listener to use for extended periods without any sweat build up that you would get with leatherette / leather / suede ear cups. I am happy with the wire mesh and I will try it on my Muamp #3 design, but my only concern is that since the mesh is only 39% open area (according to the suppliers data sheet) it may be too 'closed' for an open back headphone. Then,.... I notice so many production ESHS including Kingsound have very low open areas in their panels......
  
 David.


----------



## wppk

okay, that is clearer to me. sorry, cause I suppose I let you repeat somethnig you had said already. I will probably let your repeat something else or well known by evryone here, but what is the HV ?


----------



## Muamp

> okay, that is clearer to me. sorry, cause I suppose I let you repeat somethnig you had said already. I will probably let your repeat something else or well known by evryone here, but what is the HV ?


 
  
 HV = High Voltage
  
 I think your question was a good one and addressed an issue which has caused many builders issues.
  
 David.


----------



## chinsettawong

I wanna chim in on this topic.  If you have read through my posts, you should notice that I put the dust cover only on the side facing the ear.  I leave the other side without any dust protection.
  
 Since I coat the Mylar only on one side, the other side of Mylar doesn't conduct any electricity.  So, there is no need for the cover.


----------



## wppk

yes, sorry wachara, my mistake comes from the fact that I thought that David was not to put a mylar on the front side. I didn't realise that he was talking about the rear side.


----------



## Muamp

Luc and Wachara,
  
 I appreciate what you say, that the dust shield only needs to be on the inner side (diaphragm conductive side), but with my ESHS I have been putting the conductive side of the diaphragm on the outside, I guess because it makes me happier on the outside. So I have been putting a dust / sweat shield on both sides.
  
 The test panel is in fact using the outside (diaphragm conductive side) with the mesh and still effectively providing a dust barrier on the conductive side.
  
 David.


----------



## wppk

ok, so I had no ill read... even if not understood everything


----------



## wppk

news : after changing cables, drivers in any ways possible, I solved my problem. It came from the bias adjustment in the amp. very strangely, the sound was perfectly balanced with lambda headphones, but the srx, it was snot stable with this adjustment. the srx that was balanced turned to be unbalanced. because of the coating, ( I will test julez's proposition as soon as I receive the product, but until then, I used my ususal coating product) but also because of the amp adjustment. I found an adjustment that is stable for both lambda and srx. ( for info, the bulbs and caps are new in my amp)
 thank you for your so kind help and suggestions.


----------



## wppk

today, I could succeed in repairing my second srx pro The imbalance was still here after tuning the amp. and it came form the plastic of the driver, which had to be more solidly kept together and to hold the membrane differently. I had to add on of these alumnium rings that are in the normal bias and not in the pros, to maintain the membrane properly. Now, both srx are perfectly balanced and sound marvellous.
 I noticed, because I changes drivers place in all possible configurations before, that the fact that the second one is bassier and nos as beautiful in the high is not coming form the drivers, but from the pads which I added instaed of the original ones. they are thicker and larger, so, the srx don't hurt the ears anymore, and the sound is better than with the original pads. I still prefer the version with best higher ends , bass is not lacking however, will buy and try different pads to try to find the ideal one.


----------



## 100VoltTube

So, I've gotten my CNC machine (the one I posted about a while ago) and it works. It doesn't seem to cut wood very well, but should be able to cut FR4 without any problem (I haven't tried yet). I don't have an amp yet, so I'm in no rush to make any stators. I not sure how to tell it to drill multiple holes without writing out every single movement in GCode (GRBL doesn't support subroutines or variables) How do you all do it?
  
 Also, is there anything wrong with using a 6BL7 as an output tube in an amp? On paper it looks better than a 6S4, and it's cheaper.


----------



## Muamp

Hi 100VoltTube,

The best way to cut holes (to generate your G code) would be with CAD/CAM software. The are many out there, some freeware and some cost.... I use Vectric CUT2D desktop which is incredibly good. The CAD s/w is also useful for making any of the other parts, but there are simpler ways to generate hole patterns in G code. Do a Google search for "holes.py". It is a python script which is compiled to run on Windows.... and it will generate G code for any hole array you need! 

If you are cutting wood on a CNC you need a TCT straight single flute end mill bit, otherwise it will not cut too good.

David.


----------



## Muamp

Last night I finished "Muamp#2"
*ALL *home made except the stators, which are the PCB fabricated stators, finally used and test.
  

  

  
 The hardwood is Afromosa.
  

  

  

  
 The stators are the double sided PCBway fabricated PCB stators from China.
 They are flat, rigid and now tested - They are very good and I will be ordering some more.
  

  
  
 Muamp#2 on left and the original Muamp#1 on the right.
  

  

  

  

  

  

  
 David.


----------



## Kerry

Looks nice.

Did you need to ask for anything special from PCBWay in order to get them flat?


----------



## chinsettawong

Those look really nice.


----------



## Muamp

Hi Kerry,
  
 Having dealt with PCBway so many times now, I have a good contact there, Aimee (service07) who deals with all my PCB fabrication needs.
 She takes care of my PCB special needs such as flatness. I asked her to make the double sided boards as flat as possible, but I think they would have been just as good as if I hadn't requested it as a special need. If you get some Gerber files to make your own stators then go for double sided (the single sided are more expensive and no way near as good).
  
 David.


----------



## 100VoltTube

Those look great!
 How did you make the headband?


----------



## Muamp

The headband is 13 gauge wire (British Standard Wire Gauge) covered in silicon rubber tubing (inner dia. of 3mm outer dia. 6mm).
The ends are covered in red and black heatshrink and capped with fibre optic ST caps (since I work in Networks, I have access to fibre optic parts) but the end caps are not too important.
The head cushion is 4mm thick neoprene sheet with double layered fleece (colour coordinated with the ear cushions).

David.


----------



## 100VoltTube

Thanks!
 Also, thanks for the CNC advice!


----------



## Kerry

Thanks David. I order a bunch of stuff from them as well. When I'm ready I'll get the double sided boards made up.


----------



## Muamp

Hi Kerry,

When you get the stators back from fabrication, it would be good to see photos of them.
Does the 'bunch of stuff' include boards for your energiser?

David.


----------



## Kerry

Mostly for my amps along with all the supporting boards.


----------



## wppk

wppk said:


> for my repairing : If have ordered julez's advised product to coat the membranes, as I cannot find another solution for the moment . Will see if it changes something.


 
 For info : I tested the product that I recently received. Doesn't cure any static noise problem on a faulty driver. But the sound is bassier ( without loosing its's high end) and electricity goes stronger thru the driver.


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## chinsettawong

You cannot fix the noise by just recoating the diaphragm. The noises are normally from the small dust in the driver. You need to clean your diaphragm and stators extremely well.


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## wppk

yes, I know But for these specific drivers, I think the noises are not (or nor mostly ) coming form the dust. it is because I opened and closed them so many times for all the tests I have told about, that they don't close well know. I have ordered another srx (normal bias) out of which I will take the housings of the drivers which have never been opened before, and  I will put the pro diaphragms in them. I think I will have a good result. Because with another pair I have mended the same way I don't have these noises, and they are not better cleaned than the others.
 I will give a try to that and will tell you if you want


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## chinsettawong

I sure like to know. Please share everything that you find.


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## wppk

ok. So, the thing that allows me to say that is that, depending on how I press on different sides of the housing while testing with the membrane inside, the sound is different, and also, depending on how much I turn the screws that make the driver stand together, the noises change. I tried to rebuild the driver without the aluminium ring which is inside the normal drivers and not in the pro ones ( they are here in the normal one to add a little thickness, as the thickness of the metal rings that hold the membranes is not as important in normal drivers) but it didn't work well, I add contact problems . that was odd because originally, there is no such ring in pro drivers.
 in fact, the difference between the pro and normal drivers is only the thickness of the two rings on which the membrane is glued, (thicker with pros) and the thickness of the membrane (thinner with pros)
 anyone that could make these rings and glue the thinnest mylar could then make pro srx drivers, in my opinion. but I don't know if it is possible to make such rings, and I have no system to glue and tend the mylar properly, and I don't know how thin the mylar must be for pros.
 that could be great to make that, because there are still quite a good deal of normal bias srx to be found, and so rare pros, and the pros have such a wonderful sound ! would anyone be interested in trying to do something like that with me ?


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## chinsettawong

Hi Wppk,
  
 What you found was not new.  We all know that the spacer thickness on normal bias driver is thinner than that on the pro bias driver.  And that's what makes the difference in bias voltage.  For thinner spacer, you use lower bias voltage.  For thicker spacer, you use higher bias voltage.
  
 The noises in the drivers can be very difficult to cure.  The noise sound changes when you press on the drivers is very normal.


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## wppk

Yes I know it is not new, I had talked about the same thing a few weeks ago on the same post and it was not new then already. The new point is that I am asking if someone can make those spacers, or where to find similar ones ?
 I have cleaned the noisy drivers strongly with pulsed air. just finished 10 minutes ago. for the moment, no noise.
 nothing odd. so, thank you again.


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## wppk

still no noise after a long while testing. seems good !
 another thing : since I tuned the amp successfully, I have no more odd thing happening in the sound if my ear is close to the stators.


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## wppk

I have another question : do you know if, as I was told, the thickness of the mylar is different in pros and normal bias driver ? if not, it would be enough to add thickness to the spacers, with and additionnal thin ring, to make a pro membrane of a normal one...


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## chinsettawong

I don't know the answer to that question, but you can certainly increase the spacer thickness by adding another thin film or paper. Please try.


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## wppk

that is just what I have just done
 spritzer had told me the thickness was different ( thinner on pros) but it is something that is not easy to see at all.
 so I did it with paper. The housing has a deep and a flat part. this is important for my explaination : if I use too paper rings, it seems to be tto thick. so I used the aluminum ring which is normally in a normal driver, very thin, and the paper part. It d'oesn't work fine if one doesn't put the paper part ( cut in a normal sheet of paper) in the deep part of the driver and the aluminium ring on the flat part. I succeeded in making it work for a little while, and the sound is gorgeous, same quality as pro and stronger than with the pro ring and membrane. but I I still have  problem opf stability inside the housing, cause by my dismentling is so many times. sometimes, the membranes sticks to the stators, but it ias strange, because it doesn't happen when I just hold the rebuilt driver in my hand. only when I put it back in the can. no explaination found yet about it.


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## wppk

yeaaaah ! I made it !
 sorry for being maybe too enthousiastic, but it works, and its' even better and stronger than with the thicker spacers of the original pros ! I can compare, because I have another srx turned to pro with pro spacers and membranes. So I have the only srx pro in the world that is better than srx pro ! can you believe it ? I couldn't if I couldn't hear it. so anybody can do the same, using a pro cable, 5 pins, and making the different improvements I made. I ordered new bigger and thicker pads, here http://www.ebay.com/itm/181965226231, thinking they may give a bit of bass more (?) and a better look. and I will tell you.


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## wppk

I was very surprised by something. When I received the normal srx yesterday, I tested it. It worked perfectly. but it wad astonishingly bassy. which as everybody knows, is not common.
 comparatively to my two pros, it was as bassy as the new version I just told about in my latest post. Using normal spacers and membrane, turned to pros just by adding thickness. as bassy, but the highs were far from being equal. so I decided to turn it to pro too. 
 The first driver was just as easy as in a dream to turn so. I had utter problems with the other one, still don't know why, my paper ring didin't work on this one, I had very strong noises and the membrane was touching the stator. tried tens of solutions. And finally found it : used one of these gift papers for christmas, one side of which is metallic and the other paper. Then I got it working. I still have sometimes a very light imbalance coming, it comes form the proximity of my ear, touching sometimes the protective membrane, and if I wait a bit it gets balanced again. the issue will not resist, I think, the new pads, which make my ears further enough, I hope, not to touch anything. 
 the result gives a really very bassy srx pro headphone. much bassier than my two other pros. The one which is with pro membranes and the one with the normal membranes thickened ( this last one being bassier than the first)
 I am very impressed by this result (the highs had reached the level of me pervious pros and the bass was even stronger than when normal) which I would really like to let you hear. As I have no reaction to what I am saying here, which however seems to be something really new, (I cannot find anyone speaking of having done what I did on the net) I am asking myself if I am being not believed. I know it is difficult to believe indeed, so, I understand. but I have to say I am not willing to make a buzz for nothing or to make myself considered and remarked just for a kind of fame or in anything I wouldn't be sure of. If some of you happen to visit burgundy, I will be very glad to welcome anyone who would like to listen to the result and compare.
 I had offered a normal bias gamma to my son. Since I discovered that, I turned it to pro too this afternoon. so, he can listen to it plugged on the pro plug of a stax amp and the result is very good, although not comparable to the srx because the housing of the srx gives a much more monitor sound as you all probably know.
 yesterday, I have read on head fi that the drivers of the sr3 were the same as in the srx. I am not sure of that at all. But if it is, it means that an sr 3 can also be turned to pro, changing also the cable, even if , if I am not mistaking, no pros of the sr 3 were ever built.
 if you want to feel the difference, as I have a pro recording studio, And wonderful microphones, I could record the sound of the last srx I made and just talked about and the previous one. for you to listen and compare the soundfiles I could make out of them. Of course, it will not at all be as good as listening directly and really to the earphones, but you will feel the difference. Unhappily, I have no more normal bias srx now, as I turned them all to pros. but even if it would not be the same difference, I can plug one srx in the normal plug of the amp and then on the pro to listen to the difference.
 except if someone in my area has a normal bias srx and wants to make the comparison recording with me. I don't feel like turning mine back to normal just to be believed. too hard and long a job.
  
 so I have a question. has anybody heard of a bassy version of the srx normal bias, like the one I received yesterday ?


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## Jaab

Do you think we can apply your mode to the sr5 headphone? I have just received a second set 
 that I have to repair (I think it's the cable), would be ideal to be able to compare the difference between both. Have you took photos of what you did? I'm a visual guy! 
 thanks


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## Jaab

I forgot to tell, thanks everybody for this thread, I read all the post and found fantastic what have been done. For sure  make my own electrostatic headphone it's in the top of my list!


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## chinsettawong

Hi Jaab,
  
 All the electrostatic headphones share the same principle.  So, I would say that the same fix can be done on your headphones as well.  However, there are many small details that need to get close attentions.  Otherwise, you might have noisy headphones.  Just be patient and focus on the small details (dust removal, dust cover, and etc).  
  
 Making headphones is fun.  You should try.
  
 Wachara C.


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## wppk

Hi Jaab,
 as I don't own the sr5, I made a mistake. someone ( very active headfier, thank to him)  on head fi said that sr5  drivers were the same as srx. I searched for info on sr5 earphones, but only found sr3, sr5 said to be an energiser. but if you say you have an sr5, it means that it exists and then I have to say I don't know anything about sr3 drivers. As always, what wachara says is obvious. There is a possibility to try. but when opening an srx or whatever driver, you take a risk of experienceing problems. many kinds of problems. for instance, I thought I had fixed the imbalance problem of may latest mending, but I didn't. It works, gets balanced ( I tried many different types of thin rings and the point really seems to be, on this driver, the pressure of the two different parts of the housing of the driver against each other) nbut doesn't hold it. after a while ( ten minutes or a few hours, it is ill balances again. I have to try to find something now that coul hold theses two parts stronger than the screws in it.
 for dust p and noise problems, for what it experienced, using pulsed air to remove dust solves the problem easily. Works on six drivers.
 I have no more photos than those I left on this post.


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## wppk

of course, I cannot guarantee it will work to anybody who will try. But I did and it works ont four normal bias headphones. except for the issue I still have to mend on one driver.


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## wppk

strangely, I plugged in the headphone this morning after a night, and it is balanced. it was not yesterday.. but I didn't change anything between yesterday and today. that is the kind of trick that may happen... quite unpleasant. if I can cure it, I will tell it.


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## wppk

I think I have the answer for this driver. the problem is that, as I previously said, a very thin ring must be put on each side of the spacer to get the right thickness. but the original aluminium rings are not thick enough. but paper is too thick. so, what occurs is that the membrane touches the stator more or less and then the sound decreases if it touches it.
 so, I am puzzled because there is not such problem for any of the other drivers. well, it exists, but it is easily cured by paper on one side and aluminium on the other. as explained too. but on the driver it is not OK. Why ? I don't know. I took a part of another driver in its housing and tried it instead, the problem is the same. I tried different types of rings, cut into aluminium ( very difficult to do ) in mylar... still could'nt find something that fixes it for good. I have to find something thinner than paper but thicker than the original aluminium ring. what could I use ? don't know...


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## wppk

the last solution I am experiencing will not gather your good opinions, for you all who are much more scientists than I am, but let's give it a try and see. Unscrewed widely only one of the screws that maintain the two parts of the driver housing together. it stopped the membrane touching the stator. then, no noise and perfect balance. But to hold it so it doesn't move anymore, I glued the two parts on four points with hot glue. ( it can easiyly be removed it necessary). for the moment, it works fine. but as we say in french, "ce n'est pas tres protocolaire". (not made in protocol order maybe a translation, but not guaranteed to fit our very expression)
  
  
  
maybe it is not good to make many different posts about the same thing ( please tell me Wachara) so I am adding this to my last posting. I happened to have the stator noise once since my last action. just by moving the headphones. So fixed the driver better inside the headphones housing with this type of glue that is a kind of plasticine like.


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## wppk

a wile after : I still have sometimes the stator touched by the membrane. just have to unplug and wit for it to untouch. but I would like to solve the problem. is it a nonsense, wachara, it I put some antistatic product on the copper stator that touches the membrane ? I am wondering if the question is not just the mylar being attracted by static electricity by the stator. it could possibly explain the bassier sound of the membrane. because if the mylar is not tended as orignally, it can then touch the stator and produce a different sound. but if I put some antistatic product on the stator, maybe it will not work anymore. don't dare to try because I am not sure to be able to remove the product form the stator after.


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## wppk

For visual guys : 
 the rings I made and tested.
 and the plasticine glue.
  
 (image missing) 
  
  
 the housing of the driver that contains the membrane.
 on the left; the flat part, with the aluminum ring I made, you can use the original. this thin one can be put on this part.
  
 on the right, the other part, in which i put the paper ring here.
 the black part on the right is there to show what I removed form the final headphones, because it lowers the quality of the sound.
  

  
  
 the tool I used to make the rings
  

  
 (image missing)
  
 after a lot of tests, the very thin wire than leads to the + always breaks. so I had to put a stronger one instead. rather easy to do, don't worry if you break yours.
  
  

 one of these tiny screws
  
  
  

  
 the driver in the headphone housing, with the pasticine to hold it.
  

  
 once in place
  
  

  
 (image missing)
 when I reassemble the total, the driver is not protected more than with the protective membrane, wich is not at all a strong protection. but the membrane is very easy to change if necessary, and on another heaphone I added something that gives that


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## wppk

wachara , if I am not mistaking, I read that your wrote on another thread that warming the membrane with a hair dryer could tense it a bit. That would be a chanc"e to solve my problem then. but i would like to know how to do it exaclty, and if the effectes are long lasting ? thanks to you.


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## chinsettawong

Don't use hot air to tension your diaphragm.  In my experience, it doesn't help.  If your diaphragm keeps sticking to the stators, then your bias voltage is too high or the spacer is too thin.  
  
 Please don't coat your stators with antistatic solution.  It won't do any good.


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## wppk

okay
 very nice of you to answer.
 thank you wachara


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## wppk

just : is my idea of the membrane of one driver being not tensed enough bad ? because I have no problem with another driver with the same voltage and same thickness.


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## chinsettawong

You are dealing with some very old headphones.  Many things going wrong aren't surprising.
  
 I would try thicker spacers.  For pro bias, a total spacer thickness of around 0.45 to 0.5 mm is just nice.


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## wppk

yap. But I don't have a tool to measure that.
 anyway, since my last test I wrote here, the faulty driver became stable. it works !!
 I think now that there is no reason why it could not work fine anymore nor not be mendable.
 thanks for all.
 the sound is astounding. these are by far my best headphones. and I have quite a good deal of them, either static, ortho, or dynamic.


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## wppk

anyway, I do think that bassy srx (normal or pro) is coming from a membrane that has lost a bit of tense. just like when you tense a drum, you have a more or less bassy sound.
 but, as you explained to me ago ( about lambdas) , when you don't have the good tension of the mylar, you have problems of stability and noises. I think it doesn't come from the tension, not direclty, I think it could come from the mylar touching or approaching the stators too much. as my brand new experience tends to show it. now, I have found, after so many tests, the good distance between the stator and the mylar, so it works, and I have no noise nor imbalance. what do you think of that ? does it make sense ?


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## wppk

I was fooled by myslef like a rookie...
 The bass difference is not coming from the membrane being looser... but of course it comes form the pads. As I received the new ones today, I could change them on two srx. and then they had the same sound !
 as I had tested different pads on different srx, I had lost the original sound. but, on the last ones I mended, I used the original pads, and it makes a bassier sound than with previous pads. That is stupid from me, because I should have realised it. My little excuse for itis that I lost the standard sound after making tons of tests. Well, this is not really the standard sound, as it is better when removing the black ring ( photo sent yesterday).
 I also tried with these bigger pads I ordered and showed the link for. We win a bit bass, but the drivers get further from the ears and of course, we loose some "cristality" in the highs. So, I prefer them with the original pads. Ordered new ones already as mine are very old and need replacement. but impossible to find the real original stax anymore, or at a huge price if I remember well. and not being sure they really are available. ordered the good size for somthing that will hav a chance to be compatible. Couldn't find as thin as the original. I will see if it makes it or not, and what it changes.
 one good news among bad : my last repaired stax still is perfectly balanced.


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## Muamp

Just finished a headphone listening test session.
Listening test general feedback:
Muamp#1 preferred aesthetically and acoustically. Muamp#2 not so extended at the top end, but Muamp#1 somewhere between SR007 and SR009, the SR009 having slightly stronger bass. Muamp#1 probably has better top end than #2 because it is completely open back, whereas #2 is only 70% open. Very pleased with the comments which will shape and direct my future builds. Muamp#3 will be Afromosa hardwood, but designed as #1.

David.


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## ts8051

Hello,
 I also constructed ESL headphones with large membrane diameter 12.5cm and the case , headband, etc constructed with a 3d printer. The stators are 0.6mm pcb and spacing is 0.4mm pcb. The membrane is 2 microns. My question is for what reason is the central hole on stators?


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## chinsettawong

Hi ts8051,

If you don't mind, please show us your headphones. I'm very curious to see your rather large stator with only 0.4 mm spacer. I bet you tension your diaphragm extremely high. Do you get good bass out of your headphones?

About the larger hole in the middle, from my experience, it doesn't make any difference in sound. It's what Stax uses with its top of the line drivers and we're just trying to see what's so good about it. So far, I don't really see a good reason for it to be there yet.

Wachara C.


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## ts8051

Hello,
 I can't send the images because i have no permission for this and I dont know how can i post these.
 I tensioned the membrane with High tension.of course. The bass responce is incredible when i operate it with a transitor based stax energizer.


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## Muamp

I believe the hole in the middle is to facilitate maximum open area in the stator without loosing rigidity.
 The extra open area from the centre hole can add about an extra 4% openness.
  
 On a similar note, one thing I discovered last weekend from a listening test session with a group of headphone audiophiles is that my Muamp#2 suffers at HF in comparison to Muamp#1. I can only put this down to the wooden surround reducing the open back area from 100% in #1 to less than 70% in #2, since ALL other specs are identicle.
  
 I am currently constructing #3 to be 100% open back with greater openness in the stator. Have to see whether it makes a difference.
  
 David.
  
 ts8051
 You can post photos after submitting about 5 or 6 text posts.


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## chinsettawong

Hi David,

I also prefer the very open back design. Please try and let us know how you like it.

Wachara C.


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## ts8051

Hello,
 I think that the center hole in stators minimize the active membrane surface because of absense of electrical field in this region.


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## ts8051

About the membrane tension.
 I use a frame made of plexiglass. I apply the adequate piece of membrane and hold it with 3M tape. Then I apply tension step by step from all sides of frame with 3M tape until i cannot apply any additional tension. After applying the conductive material  on one side only, i attach the spacers with glue.


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## Muamp

After one more post, when you can add photos, I would very much like to see the tension frame AND your ESHS.


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## ts8051

The stretching frame is very simple. I was made of plexiglass.


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## ts8051

The other pieces such headband and cases are made with my 3D printer and PLA plastic.


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## ts8051

I cannot post yet photos.


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## chinsettawong

Actually it's better that you save your photos somewhere else and post your links as images here. That's how I do mine.


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## ts8051




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## Muamp

That's a cool looking headband and surround! Some construction notes would be good.
 And still a picture of your stretcher frame would be appreciated.
  
 David.
  
 Edited: Is the active area really 12.5cm? Or is it 12.5cm overall surround dia.


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## ts8051

The diameter of membrane only are is 12.5 cm


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## chinsettawong

That is huge! And you are using that with the spacer thickness of only 0.4 mm. It's really incredible that you still can get good bass. Is Mylar the material you use for the diaphragm?


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## ts8051

yes it mylar 2micron from taiwan.


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## chinsettawong

Hi ts8051,
  
 I really don't know how you do it.  From the picture, you'r using single sided PCB for the stators.  You said earlier that your stator thickness is only 0.6 mm.  Do you use PCB that has a very thick layer of copper?  
  
 For all my headphones, the maximum diameter of the active area is only 80 mm.  And yet, it's not so easy to tension the diaphragm on the 0.5 mm spacer so that it's stable and produce good bass.  
  
 I only can guess that you are driving your headphones using a pair of step up transformers and the bias voltage is quite low too, right?
  
 Please tell us.  How do you drive your headphones?  What is your bias voltage?
  
 Wachara C.


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## ts8051

The bias voltage is 580v as i use stax ergizer. the copper layer on stators is thick 80micron. After mylar tension and apply conductive material, I attach the spacer psb's on it with epoxy glue. Also I clean  with aceton the excess of glue in order to have a clean membrane attached to the spacer pcb. After 24 hours with a small soldering iron I remove the glued pcb's. Please note that in this stage because of high tension and low thickness of pcb's we observe a distortion. When I put these with other pcb's (stators and the other spacer with copper) the whole system is flat. The secret for success is tension and the quality of glue.
 This is not the only ESL headphone is was constructed. Before this I constructed with the same method a rectangular in shape headphone with success.
 Please note that I studing with experiments the ESL Construction from 1985 with i was a student in Physics and studied the N. Pollock article from wireless world magazine.


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## Muamp

Hi ts8051,

Could you please tell us where you purchase your FR4 @ 0.6mm with 80 micron copper. The thin fibreglass with such thick copper sounds like a good choice.

David.


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## chinsettawong

I guess the spacer together with glue should make your total thickness of at least 0.6 mm already. 

Have you compared your headphones loudness with other Stax headphones to see how much louder or softer your headphones are?


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## ts8051

Hello,
My headphones are louder that my stax sr407, but sr407 is more musical.Now i am looking for the reasons caused it and then i will develop new designAlso i observed that my headphones are ply better with transistor based energizer rhan with my stax tube energizer. I suppose that this happens because of vey high capacity berween plates. 
My other designed headphone rectungular in spape with total 20% lower active membrane surface plays better with my tube energizer. Possibly the stax tube energizer cannot accept very high capacity.


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## ts8051

muamp said:


> Hi ts8051,
> 
> Could you please tell us where you purchase your FR4 @ 0.6mm with 80 micron copper. The thin fibreglass with such thick copper sounds like a good choice.
> 
> David.




In Athens, Greece i ordered the pcbs based on my Design.


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## ts8051

My previous rectangular in shape ESL Headphone.
 Active membrane dimensions: 76.2mm X 96.52cm)
 Stator 0.6mm
 Spacer 0.4mm


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## chinsettawong

Nice!  I like your headband very much.


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## dude_500

How's long term durability been for everyone with anti-static cleaner spray?
  
 I've been listening to the same pair of my DIY headphones many hours just about every single day for the last 3.75 years, and nothing has gone wrong except they're now up to a 5-10 warm up period for the coating to charge, after which they sound great. Used to charge almost immediately.
  
 I don't dare take them apart for a new coating because I haven't had access to CNC tools for years now and would be immensely sad to lose my headphones if I broke something, just curious if others have observed this lifetime change on that coating?


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## Jaab

I found in ebay an old fostex T20 it's an Isodynamic headphone (I bought it more by curiosity).
 I received the headphone today as "working perfectly",  at first one driver didn't work
 I checked the jack connector,  it was fine after that the cable with a voltmeter and finally I checked the driver, I thought a soldering default. .. I opened the driver and looks like this:
 2 round magnet taking in sandwich the stator (kind of mylar + aluminum flat wire)
 (there are not my photos!)
  
https://www.google.nl/search?q=fostex+t20+mod&client=tablet-android-samsung&prmd=ivsn&source=lnms&tbm=isch&sa=X&ved=0ahUKEwj-lYCqlZHTAhUDPRQKHZYMDmQQ_AUIBygB&biw=1280&bih=800#imgrc=ayIx0nUC6iTE1M:
  
https://www.google.nl/search?q=fostex+t20+mod&client=tablet-android-samsung&prmd=ivsn&source=lnms&tbm=isch&sa=X&ved=0ahUKEwj-lYCqlZHTAhUDPRQKHZYMDmQQ_AUIBygB&biw=1280&bih=800#imgrc=1MyzoklB0lz9cM:
  
 The problem came from a caoutchouc join inside the driver having shrinked, I tightened the screws of both driver and voila both working now but the sound was so-so. 
 I read some threads about moding the t50rp. I remouved the thick piece of foam at rear of the cup replaced by a piece of felt and tap partially the vent. I was astonished by the sound produced! I didn't expect that whaaou, they don't lake  of bass, the treble are extended the medium gorgeous. I don't understand why they have  abandoned this technology? 
  
 no need any energyser, I can imagine using a bunch of little magnet but the wiring in the mylar
 it's another story... if someone have any idea... I know it's not an electrostatic but just a cousin
  
 (by mistake I created a new thread!)


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## Muamp

Hi dude_500,
  
 You say you no longer have access to your CNC and tools, but since they are DIY ESHS that you made, I guess that you can safely take them apart without any fear of damaging them? Even if the diaphragm gets damaged, it is replacable (no CNC required there). Other than that, I don't figure how you can repair them. Make sure it is the ESHS and not the energiser. Test the ESHS on another energiser or another ESHS on your energiser to be certain where the fault lies.....
 If you do decide to take them apart to re-coat, pretty much any of the 'anti-staic' sprays should be good for re-coating. Since you are in USA, It is easy getting Licron there, which seems popular where you are. Any of these these last for years, certainly more than 3 years or so....
  
 David.


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## chinsettawong

I'm not so sure about my coating.  On my Omega clone headphones, the last coating I put on them was at least 2 years ago, and the phones still charged up and played very well without any problem.  However, all my other phones have been having some imbalance problem.  So, I had to take them apart to check the solder joints and recoat the diaphragms from time to time.


----------



## bui501-tech

Hi, Chinsettawong.  Can you help me with some advice on putting together the parts for my DIY electrostatic headphone drivers?
  
 I've finally got all the parts and materials together to make my own electrostatic drivers, but I'm still a bit puzzled by the order of the steps to assemble the parts.  These are the order of the steps I'm planning for the assembly of the drivers:
  
 1. Stretch the mylar film.
 2. Glue spacers to mylar film with contact cement:  copper side of spacers facing the mylar film.
 3. Apply Staticide coating to film.
 4. Assemble the 2 Stators to either side of the sandwhich using nylon bolts (not using contact cement).
  
 Does that sound OK to you?  As above, I'm planning to coat the mylar film with staticide, but do I have to do that BEFORE or AFTER the mylar film is mounted to the spacers/frame?  I'm using single-sided pc board materials that's approximately 0.5mm thick for the spacers with the copper side facing the film to provide the bias voltage to the film, but I'm confused because if the staticide coating is required to provide the slight bit of conductivity to the film, how do I make the film adhere to the spacers and still have a good electrical connection with the copper on the spacers.  
  
 Best Regards (and have a Great Song Khran Week!),
 Vinh (bui501)


----------



## chinsettawong

Hi Vinh,
  
 You've got everything right.  But you might have missed that you need 2 pieces of spacer per 1 driver.  You use one piece to glue that to the diaphragm.  It doesn't matter that you use copper side or the other side to glue it to the diaphragm.  In fact you'll be using the other piece of the spacer to hook up your bias voltage and to transfer the bias voltage to the diaphragm.  So when you put everything together, it'll be stator+spacer+diaphragm+spacer+stator.  As for coating the diaphragm, I always do it after I've glued the spacer to the diaphragm.  I coat only on one side of the diaphragm.  And that side will get its bias voltage from the other spacer.  
  
 Well, since you are in Bangkok, maybe you can come to see me and I can show you everything that you need to know.  I think it's easier that way.
  
 Happy Songkran festival to you too.
  
 Wachara C.


----------



## bui501-tech

Thank you so much, Wachara!  Maybe we can get together sometime after Songkhran?


----------



## chinsettawong

bui501-tech said:


> Thank you so much, Wachara!  Maybe we can get together sometime after Songkhran?


 

 Sure.  Let's do that!


----------



## ts8051

Hello, 
I agreed with the above and i suggest to use plastic screws M4 in order to put all pieces together as a sandwitch. Also you must tension the diafragm on a separate hard frame and then solder on its non conductive side the spacer. You must glue the two spacers on the same tensioned diaphragm in order to achieve balance between left and right chanel.


----------



## bui501-tech

Hi, Wachara - are you still using just heat to tension the diaphragm or are you using some type of frame to tension the diaphragm prior to gluing it to the spacers?


----------



## chinsettawong

No I don't use heat to tension the diaphragm.


----------



## Muamp

Finished Muamp#3 this weekend.
 Just used them to listen to 'The great gig in the sky' followed by Gorecki 'Symphony No. 3 "Sorrowful Songs"'.
 Awesome, shivers down my spin!
  

  

  

  
 Being completely open back makes such an improvement at high frequencies.
 Muamp#3 has pcbway.com double sided FR4 stators (only soldered on inner copper layer, outer copper layer left open), the same as the stators I sent to the Head-Fi'ers last week. Muamp#4 will be the same, except it will have pcbway.com aluminium stators (not FR4).
  
 David.


----------



## chinsettawong

Hi David,
  
 Your headphones look great.  I'm sure that you're enjoying them very much right now.
  
 By the way, what do you expect from the aluminum stator?
  
 Wachara C.


----------



## Muamp

Hi Wachara C,

Thanks, They are my favourite so far. These use PCBway FR4 stators, same as #2, but being completely open back, so much better at high frequencies.
I think the wood looks better than the all black pair.
After another listening session this afternoon, some still prefer #1... but the difference between the two is very hard to distinguish.
My ears are not as good as the people who sit in on the listening sessions, so I rely on their feedback.
I am hoping that the aluminium stators will be the most rigid I have used yet.... 
Also, there is a possibility of bass similar to that of the SR009, have to wait and see.
I will test the aluminium stators in Muamp#4, so will not know for about two weeks.... haven't started building them yet.

David.


----------



## 100VoltTube

@Muamp Nice headphones yet again. I'm envious of your Pink Floyd experience. 
	

	
	
		
		

		
			




  
 I'm becoming proficient with librecad, so I should be able to make a pair of headphones soon. My time recently has been consumed with an OTL amp build; basically a crack with a different input tube and a different operating point for the output one. It sounds good, but is buzzing.
  
 I have yet to make a diaphragm tensioner or an amp. I'll make an energizer (trafo box) for now, then a direct drive amp. I have been working on a design and consulting Kevin Gilmore. That design should be finished soon.
  
 For tensioners, where did you get your tire from?


----------



## Muamp

Hi 100VoltTube,

The Pink Floyd was good, but if you haven't listened to Gorecki's "Symphony of sorrowful songs"' then I really recommend you do a spotify on it.

I currently use a tyre stretcher, a 12" diameter bicycle tyre. I bought it from Halfords (car & bicycle shop in UK). It fits perfectly on the rim of a 'Celebrations' plastic sweet box. I cut a hole for the tyre valve. Insulating tape or duct tape to tape one edge of the Mylar round the back and onto the other side. Then pump up the tyre.

To test the tension, after the spacer is glued, I use a wooden stick to tap the rim whilst holding the rim tightly. I measure the resonant frequency with a microphone and Audacity software.
Some one early on in this thread said Stax resonance on the membrane is between 120Hz and 150Hz.

I am still experimenting with different tensions. I do tension it VERY tight. I am testing tensions from 3% to 5% stretch. 5% is very tight and has a resonant frequency of about 175Hz. (2um Mylar).
I am still testing, but when finished, I will publish a chart of tension to resonant frequency.

David.


----------



## 100VoltTube (Jul 4, 2017)

Ok Thanks. I thought that you needed a special type of tyre (or tire).

 I actually have a Celebrations tin as well, but I also have a Cadbury's Roses tin handy. Decisions, decisions... (For anyone interested in using a chocolate (or sweets) tin, but doesn't have any, I would recommend a Roses. You would need to dispose of all the chocolate before you can use it as a stretcher. 
	

	
	
		
		

		
		
	


	




) Edit: roses tins are smaller, but not by a ton.

 I have 3 micron mylar, so I might need to stretch a different amount. @chinsettawong might have experience with that detail.

 I will check out Gorecki's "Symphony of sorrowful songs" Thanks for the recommendation.

 With regards to the chocolate tins, in case you were wondering, I am in the US, and it is not normal to have Roses and Celebrations tins lying around. I have Irish family who send them over sometimes.

 Also, for those of you who who have amps with variable bias, how do you do it? The only ways I am currently aware of that provides variable bias efficiently is using a 555 or similar chip to create AC at a voltage controlled by a potentiometer, then to feed the AC through a voltage multiplier, or to use a FET (or tube) as an amplifier, amplifing a control voltage, with a very high voltage power supply created by a voltage multiplier fed by the mains. That last one might sound confusing, and if anyone is confused or interested, I can post schematic.

 Edit: Also, a simple voltage divider with a trim pot will work fine


----------



## chinsettawong

I don't stretch the diaphragm that much anymore. For the last few pairs that I made, I stretched the diaphragm only until it's just enough to give good stability. I had to do and redo again about 4-5 times before I got them just right. It's not an easy job. In the future, I will try to make a small table and use the weights to tension the diaphragm. If I can get it right, then making the next pair would be very easy.

Wachara C.


----------



## Muamp

A month ago, I made a stretcher with eight 2 litre (milk) bottles, all full of water. 1 litre of water = 1kg.
This gives a total of 16kg evenly distributed around a round frame.
I measured the stretch at 1%. This was NOT enough.
I thought of doubling the weights up to 32kg..... a lot of milk bottles.
That is why I went back to the tyre (well,.. inner tube) stretcher. The tyre stretcher will go upto 5% at full stretch.
Then I measure the resonant frequency with a microphone.
Wachara C., If you use weights to stretch, how much weight do you use?

David.


----------



## 100VoltTube

Wachara, would you mind posting your CAD files for a pair of floats? Not the images, but the DXF's or whatever format they're in. 
  
 To all: How do you hold your drivers together? Do you use glue or screws?
  
 With regards to stretching diaphragms, I think that the thickness of the membrane makes a difference. what works for 2 micron membranes won't work for 3 micron.


----------



## Muamp

Hi 100VoltTube,

The way I hold my drivers together is by clamping them within the surrounds. I firstly use insulating tape, tightly holding in 6 places evenly distributed around the circumference. This acts as a way to keep them in place before clamping in the surround. Then the surounds hold everything together when enclosed.
A lot of people drill bolt holes and use nylon bolts.
The guys who make big floor standing ESLs use glue.

2u or 3u - The choice is yours..... Same principles for both. Both good.
I use 2u. If I had 3u I would try it, but happy to stick with 2u.

David.


----------



## chinsettawong

Hi 100VoltTube,
  
 Here is my stator dxf file for JF clone:  https://www.dropbox.com/sh/ox8vc6x8wqyr1pw/AACTBT-cLVb4rvbXRtZKwsTLa?dl=0
  
 I don't mind sharing my designs as long as people don't use them for commercial purposes.


----------



## 100VoltTube

Thanks! Could you post the spacers too? I'm interested in having a reference pair of the exact same design as you so that we can compare to a reference. I notice that for the most part, people have been comparing their headphones to the SR-009 and SR-007, but as far as I'm aware, no one in my area has a pair. There are multiple Focal Utopias, an Orpheus, and a few R10's, but no Staxes other than lambdas that I'm aware of.


----------



## chinsettawong

Hi 100VoltTube,
  
 I've just updated the link to my CAD files.  Please check.
  
 If you have any idea, please share it too.
  
 Wachara C.


----------



## ts8051

Hello,
 I  downloaded the files and please let me know if these are pieces of pcb boards fully covered by copper layer. If yes, there is a mistake in design because the capasitance between stators and spacers is high and there is a problem with high frequencies.


----------



## chinsettawong

ts8051 said:


> Hello,
> I  downloaded the files and please let me know if these are pieces of pcb boards fully covered by copper layer. If yes, there is a mistake in design because the capasitance between stators and spacers is high and there is a problem with high frequencies.


 
  
 Hi ts8051.
  
 Etching out the unneeded copper around the stator or not is totally up to you.  There is actually no problem with high frequencies if your amp is capable of driving it.  I like to etch it out, but some of us here leave it there.  It actually sounds warmer if you leave it there.  Try it.
  
 Wachara


----------



## analogsurviver

ts8051 said:


> Hello,
> I  downloaded the files and please let me know if these are pieces of pcb boards fully covered by copper layer. If yes, there is a mistake in design because the capasitance between stators and spacers is high and there is a problem with high frequencies.


 
 Aside mentioned problem, there is another aspect - that of possible arcing across the sharp demarcation edge of the stator and diaphragm if striving for the highest efficiency when you remove the copper layer under the spacers. Depending on the actual implementation of the driver and amplification, both variants can be viable.


----------



## ts8051

Hello,
 I will try. Now I have a CNC machine and I can try with minimum cost.


----------



## ts8051

Hello again,
 I show that on the stator you have many holes per inch and a center big hole rectangle in shape. Why you have this central hole ? I think that  the high density in stator holes minimizest the strength of electrical field between stators and also zero in the center of stator.


----------



## ts8051

Sorry for the mistake. I was talking about central hole and not a rectangle.


----------



## chinsettawong

Hi ts8051,
  
 Obviously you haven't read through the thread.  
  
 My design has gone through many revisions.  The center large hole is how Stax makes its latest SR009.  I just wanted to find out the advantage of having it there.  If I were to make another set, I would not bother to make that.  Of course, you need to make sure that the perforated stators are sturdy.  I recommend that you use at least 1 mm copper clad PCB to make the stators.  If you can use double sided copper clad PCB, it's even better.
  
 Please understand that I simply share my design and hope that it can be of some help for needed people.  I understand that my design is not the best.  I just wish that my works inspire you guys to try to make your own electrostatic headphones.  Believe me.  DIY electrostatic headphones can sound as good as some of the most expensive headphones you can buy in the market today.  
  
 If you have all the tools already, just go for it.  You'll not regret.
  
 Wachara


----------



## ts8051

Hello,
Until now I was using the PolyCoat from MT Audio design in order to make the membrane conductive, but this product is not available because the MT Audio is out of business. Please let me know if there is a similar product which has the same function. A month ago i was tried to make myself a similar liquid with methanol and naylon crystals, but was no success.


----------



## ts8051

Hello,
Until now I was using the PolyCoat from MT Audio design in order to make the membrane conductive, but this product is not available because the MT Audio is out of business. Please let me know if there is a similar product which has the same function. A month ago i was tried to make myself a similar liquid with methanol and naylon crystals, but was no success.


----------



## chinsettawong

Many suggestions on the coating material have been posted here.  I think any good antistatic cleaner should work.  I use a cheap floor cleaner, and it works great for me.  Staicide 6300 is also a good choice.


----------



## Muamp

These are aluminium stators that I will be using in Muamp#4 which I have just received from PCBway.com.
Fabricated as 1mm aluminium sheet covered with a dielectric and then a copper layer. The copper side is tinned and sprayed with polyurethane clear Spray.








And this is my new cable, still very low in capacitance, plaited instead of bound with cable clips.






David.


----------



## chinsettawong

Hi David,

Do you find aluminum PCB to be much stiffer?


----------



## Whitigir

Muamp said:


> This thread has been quiet lately, so I will add some recent photos.
> 
> 
> Firstly, the double sided PCB stators from PCBway. I recieved them in the post about 3 weeks ago, but been too busy to try them. They are definately flat enough and good to use!
> ...




Nice stators, is there any places that make these readily available ? I am interested in this homemade direction


----------



## Muamp

Hi Wachara C.,

When I try to flex the aluminium stator, they seem stiffer than the Bungard 1mm single sided FR4 and the PCBway 1mm double sided. I have yet to try them in a headphone, but I have no reason to think they will not work. 


Hi Whitigir,

I did offer a run of the FR4 double sided stators last month. It was for stators only.
I intend to test these aluminium stators, and then offer another production run to any Head-fi'er that's interested, but it has to be a privately run transaction (not allowed in Head-Fi DIY forum).
Next time I will offer stators and spacers....... See the Electrostatic ear speaker DIY'ers thread for details of last run.
NB. Aluminium stators are nearly double the production cost of FR4.....

David.


----------



## chinsettawong

The aluminum is not flexible.  If you bend it, it won't come back.  Be careful!  However, it should be stiffer than fiberglass.

Wachara C.


----------



## Muamp

The FR4 stators are cheaper and now I have tried the aluminium, I prefer the FR4.
Sometimes I think I should stick to the saying 'If it aint broke, don't fix it'.

David.


----------



## 100VoltTube

What is it that you prefer about the FR4 over the aluminium?


----------



## chinsettawong

Hi David,

The whole purpose of using FR4 is that it's strong and has good insulation.  If 1 mm thickness isn't strong enough, perhaps increasing its copper thickness could be a better solution.  Anyway, thanks for trying out the aluminum PCB and letting us know how you feel.


----------



## Muamp

Hi 100voltTube,

Overall FR4 has to be the easiest out of all options to work with. It does have a degree of flex, but IS rigid enough to be stators and spacers. Different brands of FR4 make a hugh difference. But as Wachara says, thicker copper or double sided, does make it that much more rigid.
I prefer the FR4 over the aluminium because on closer inspection, possibly due to the pcb fabrication process (not CNC'ed) it is not as purely flat as my Bungard FR4 or the pcb fabricated double sided FR4 when sandwiched together.

Hi Wachara C,

I will be sticking to FR4 from now on..... (Famous last words.....)

David.


----------



## 100VoltTube

I still want to see if anyone will mill tungsten carbide stators. Total overkill? Yes, but come on...

I think single-sided drivers are really what we should work on


----------



## chinsettawong

You should just go ahead and do it.


----------



## 100VoltTube

The tungsten carbide or the single-sided drivers?

I can easily make a single sided driver, but making it sound good would be hard.

The tungsten carbide idea is sort of a joke. I can't even begin to imagine how much it would cost. The material costs alone would be large, but the cost of getting it milled...  Maybe if I upgraded the motor in my CNC machine, got a few diamond bits, and some sort of system to keep the carbide cool, I could do it myself, but that's still hundreds of dollars.

There's a reason we all use FR-4. It's not perfect, but it's cheap and easily cut.


----------



## chinsettawong

What do you mean by "single sided driver"?  Is it the driver with only one stator?  Why do you want to build that?

If you are looking for something challenging and possibly fun, try double diaphragms.


----------



## Muamp

Single sided stators go back a long way, but never really took off.
Sonoma has just brought the idea back to life with their Model one, which also has a few other novel innovations.
Not sure about it myself.... but I like some of the other aspects of the model one.

100VoltTube: You said FR4 is not perfect....... I think it is pretty dame close though. I have spent a lot of time trying to better it with other materials on the CNC and with PCB fabrications, I still go back to FR4. Ok,... If you have access to gold plated ceramic sheets, then yeah have a go. Better still, send some to me!

David.


----------



## 100VoltTube

FR-4 is perfect for our purposes, but *in theory* there are more stiff options that can be cut to more ideal shapes, without sacrificing the field. One example I personally find intriguing is Tungsten-carbide, as I'm sure you know. It is far stiffer than FR-4, and it is fairly conductive, but would work *best* with a gold coating. It, unlike FR4, could have the holes rounded for improved aerodynamics, while still retaining the electrostatic field around the holes.

But... FR-4 makes, by far, the most sense for a normal person to use.

With a single sided diaphragm, there is no stator between your ear and the diaphragm to screw up the sound, but it is inherently nonlinear, so it would need an inversely nonlinear amp. Sonoma, I belive, use DSP, but you could just use tubes at nonlinear operating pionts.


----------



## wppk (May 5, 2017)

Hi there
still going on with different tests on srx and on lambdas.
for srx : i remade a full pro model, meaning used pro membranes in pro drivers coming form pro gammas ( le'ts call it the purepro model. compaired to my three others srx turned to pros with normal membranes and adaptative rings, there is a big difference. the volume is lower on the pure pro and the sound is very noticeably better on the three other models.

about lambdas : still trying to mend the sound membrane. couldn't succed well yet, even if i found a way to tense the membrane on a drum, bigger than on my previous messages. But i notice a point that is surely intersting. the tension is not giving a 400hz resonance when hitting the membrane with the lamda pro.here is a soundile
http://cielapeute.com/ec/320.mp3
in which you'll be able to hear that when slightly knocking at the metal ring when the original membrane is on it, the frequency is 320, and not 400 as usually admitted for the tension. I think is it a good information.
good continuation to all of you


----------



## wppk

chinsettawong said:


> If you are looking for something challenging and possibly fun, try double diaphragms.


hello Wachara. I have tested it in a srx driver. no positive results. Once I had a dull sound, and secondly no sound at all.


----------



## Jaab

wppk said:


> hello Wachara. I have tested it in a srx driver. no positive results. Once I had a dull sound, and secondly no sound at all.


Hi wppk,
when you modify the driver normal bias to pro, do you modify also the connector?
(removing the central plug)


----------



## chinsettawong

Hi Wppk,

Frankly, I haven't investigated into Lamda series that much to make any comment.  But it seems that the diaphragm is glued on the quite thick copper spacer rings.  By changing its bias voltage from normal to pro, do you also somehow increase the spacer thickness?

About the double diaphragms, tell me more about how you do it.  

Wachara C.


----------



## wppk

Jaab said:


> Hi wppk,
> when you modify the driver normal bias to pro, do you modify also the connector?
> (removing the central plug)


Hi Jab. If you are talking about the wire, I don't use the original wire, I used a lambda wire, then there is no central plug.


----------



## wppk

chinsettawong said:


> Hi Wppk,
> 
> Frankly, I haven't investigated into Lamda series that much to make any comment.  But it seems that the diaphragm is glued on the quite thick copper spacer rings.  By changing its bias voltage from normal to pro, do you also somehow increase the spacer thickness?
> 
> ...


i didn't change the bias voltage on lambdas. only on srx. and I only tried two diaphragms in an srx, just adding one in the driver body. 
and on srx, as explained previously with photos, I use added rings to compensate the facte that the rings are too thin. there is originnaly an added metallic ring in normal bias drivers of the srx, but it is not enough if turned to pro. one has to add a ring on the other side. and the biiig problem is that it never works the same for all drivers. I mean, if you use a plastic ring and it works on one driver, it will not work on the other. you have to try lots of different things before you're done, and also, the way you re mount the driver is very important. on some, you have to take care not to make the body parts perfectly fit, nor you will have an imbalance, and on others, you have to press very strongly on the parts of the body before screwing them back, on the contrary. It takes lots of tests before it gets reliable and stable. 
I have notivced somthing important : drivers are said to be the same between the pros and the normal. but they are not. They are somehow différent. I cant see the difference, but I can notice the result : if you use a pro body, and try normal membranes in them, the souns wil be weak compared to when you use pro membranes in  pro bodies. If you use normal membranes with added rings ( as it must be in order to work fine) the sound is even weaker. But if you use a pro membrane or a normal membrane with added rings in a normal body  the sound is louder, and the difference in sound pressure between the two goes higher when you increase the volume.


----------



## chinsettawong

Well, there is nothing mysterious about the drivers.  All you need to do is to check the actual spacer thicknesses in pro and normal bias drivers.  Whether you try to put a normal diaphragm in a pro driver or a pro diaphragm is a normal driver, you just need to make sure that you get the correct spacer thickness for your bias voltage.  Do that, and you'll get consistent in loudness everytime.


----------



## wppk (May 6, 2017)

well... it doesn't work this way for me.
as I said, if I use the pro spacer in a pro driver, the sound is weaker than using a norm spacer in a norm driver with added rings. with the same thickness in the end. I mean, I add rings to norm spacers. so it reaches the thickness of the pro spacers. if I put this result in a norm driver body I have a louder sound than the previous system. If I put this same result in  a pro driver body, the sound is weaker and not as good. this is then the same thickness of the spacer ( norm spacer plus rings)  in both drivers.
also, as I said too, when I use norm spacers in norm driver, if I double the concept, meaning I add the same paper ( or wathever else tested) rings to have the pro thickness in each driver, one works fine and not the other.
and even more : only talking about the norm paper added spacers in a norm driver ( then, turned to pro), if there is an imbalance, it is not coming form the thickness of the spacer. It changes and I can cure the issue when adjusting the parts of the driver body. I am sure now that many of the people who have imbalance issues with their srx can solve this in two ways : the way we all know, which is recoating the diaphragm, and the one I am facing and explaining : finding the good fitting of the two plastic parts of the driver. with or without added rings inside.


----------



## wppk (May 6, 2017)

also, the fact that the sound is weaker in pros with pro spacers in pro drivers, ( pure pro, then), is not an issue. it is just the original sounding of the pros.
what is not "normal" but not an issue nonetheless is that I get a better and louder sound with norm spacers in norm drivers, added with rings, then, turned to pros. This is just what I discovered.
when there is an issue, it comes form the fitting of the drivers body, the thickness of the added rings. Some drivers work with thicker added rings one the right can, for instance, than on the left one. If not perfectly fit and not with the good rings, you will get an imbalance, or repetitive ticks that are not coming form dust.
the other issue, as you said, can be noises coming from dust in the driver,but it is very easlily solved with pulsed air, in an srx driver.
other issues in turning them form norm to pros is that the thin wires on the drivers are very fragile and easily break. the very small screws are easy to loose, too...


----------



## wppk (May 6, 2017)

what I noticed, too, with my turned to pros drivers, (let's call them TPD if you don't mind) is that ,as said already, it needs a lot of patience for them to perfectly fit, but also that it needs a long time of testing. one set will work for two days and will not keep working well. then I have to reopen it and re-fit the plastic parts of the driver. like tuning a piano, not so because it has moved since I previoulsy tuned them. After a few times, it does'nt move anymore, the headphones don't need more fixings. I think the reason is that the recoating (I always recoat when I turn them to pro) product is evoluting. Maybe it gets other properties when driyng on the long go ? don't know for real. but that is what I imagine. because there is no other reason why it could change in time and then stop changing.


----------



## Jaab

Thanks wppk for the clarification,  in my mind I thought the voltage was modified also as the spacer, something to try...
I'm reading other threads and this one can have some interest for your experimentation

https://www.head-fi.org/f/threads/orthodynamic-roundup.111193/page-1323
(the sony described stator it's an electrec)


----------



## wppk

You're welcome, Jaab. 
yes, the voltage is modified. as the TPD needs 540 v, there are plugged on 540v. originally, they were plugged at the norm output, then around 380 if I am not mistaking. 
Thank you for the link. But as you probably know, the srx is not an electrect, it is a an electrostatic, in both pro and norm versions.


----------



## Jaab

The link was just for general purpose (not linked with the srx normal -> pro ),  there is people interested by experimentation of new kind of stator, looks like one stone two target!

I'm a little bit lost with your response (lol)
  srx normal bias + extra spacer  ~ pro  feed with pro voltage (it's why I asked first if the original connector of the normal srx was modified from 6 pins to 5 pins, to feed it as a pro headphone) because you said no modification of the connector I assumed it was feeded with a normal bias voltage!


----------



## wppk

Ok, I understand for the link but I don't know much about what is on ths link.
for the srx I explained : I turned them to pros. so pros always use 540v. the rest is only norm.
I didn't say no modification to the connector. I said I removed the original cable and took a stax lambda cable, a pro one, then it has 5 pins only.


----------



## coinmaster

What I am interested in is what type of amplifier does the HE-1 use inside the headphone. They claim that they use a "high voltage class A mosfet amplifier" inside the headphones to negate the cable reactance but that doesn't make sense to me since the HE-1 amplifier has like 4 of what looks like high mu tubes per channel for amplification and offloading the cable capacitance to the tubes instead of an output buffer would be a non ideal situation, not to mention why would you need a solid state amplifier after a bunch of tube amplifiers. I can see putting a power buffer inside the headphones because it would have vanishingly low capacitance in itself when designed properly but I just don't see the point in the internal "amplifier"

The reason I wonder is because if we are using FR4 as stators then it should be simple to apply such a buffer or "amplifier" using smt components on a pre-etched copper section of the FR4.


----------



## 100VoltTube

I believe the tubes are telefunken 12au7 AKA 208S. mu=20. In electrostatic headphones, the cable's capacitance is a very real problem. By sticking the output stage inside the cups, you no longer have to drive that load. It may just be a buffer in the headphones.
The 8 tubes is a little odd, though. Assuming they are 12au7's, there are 16 total triodes. That's a lot.


----------



## coinmaster (May 12, 2017)

Well, the amp if the is balanced it would be 8 effective triodes and depending on what kind of differential amplification topology they are using you can knock that down to 4 or less per channel, assuming they are in fact dual triode tubes.
I actually have a question pertaining to cable capacitance in electrostatic amps. Why is cable capacitance a bigger deal in electrostatic amps compared to conventional ones? An output power buffer should be able to handle it pretty easily. I suppose an internal buffer in the headphones would make sense because of the lack of power required to drive it through the cable but still, why the general premise of cable capacitance being an issue on normal ES amps?


----------



## Muamp

Hi Coinmaster,

Electrostatic panels are capacitive loads. A panel in an average electrostatic headphone can have a capacitance of about 50pF or more and the cable connecting the panel to the energiser can more than double the capacitance. It is the panel capacitance combined with the cable capacitance that acts as a load on the electrostatic energiser. Keeping the capacitance as low as possible is important. 

David.


----------



## VictorLow

Hi, I read through the thread and built a pair of headphones, i got a SRM 007t to use with them but i would like to rewire it for 220V. 

As you can see i have reconnected the purple and blue from the transformer, to rewire it for 220v I should connect the white wire from the switch to brown, then connect purple to grey. or have i gotten it wrong?


----------



## chinsettawong

Hi VictorLow,

I like to see more pictures of your headphones, please.  

Sorry that I can't help you with the wire connections of the amp though.

Wachara


----------



## chinsettawong

I don't know about you guys, but I don't like the idea of having the output transistors with high voltage and current next to my ears.


----------



## Muamp

VictorLow,

I agree with Wachara, more photos and build info please. 
The power supply looks like a linear PSU, which makes sense for that energiser. The Japanese mains supply is 100v AC. From the photo, it is not possible to say whether the purple and blue wires are for 220v or not.... Really need a circuit diagram, or least info on the transformer. But you do need to be carefull, there may not necessarily be tappings on the transformer for 220v input?

Wachara,

I don't think the transistors in the head-set make it any less safe,..... whether the amplification is done at the amplifier or ear-cup, you still have the same high voltage present on the panel. The Sennheiser idea of reducing the capacitance in this manner does seem a bit odd.... As 100VoltTube mentioned earlier, the valves seem to possibly be just pre-amp and the HV by FETs in the ear cup. I am not convinced it will make _that_ much difference, but then, I have not had a chance to listen to the new Orpheus. 

It would be good if there were reviews showing the Frequency response of the Orpheus, does anyone know of any that have been published?

David.


----------



## coinmaster

Muamp said:


> Hi Coinmaster,
> 
> Electrostatic panels are capacitive loads. A panel in an average electrostatic headphone can have a capacitance of about 50pF or more and the cable connecting the panel to the energiser can more than double the capacitance. It is the panel capacitance combined with the cable capacitance that acts as a load on the electrostatic energiser. Keeping the capacitance as low as possible is important.
> 
> David.


This is what confuses me. If the cable capacitance is double the stator capacitance then that also applies to conventional headphones as well, and in both cases such capacitance can easily be overidden with an output buffer. I don't see why its a bigger deal with ES headphones if there is only an extra 50pf or so compared to conventional headphones.


----------



## Muamp

Hi Coinmaster,

Electrostatic panels are _purely_ capacitive loads. Electro-dynamic speakers have an impedance which is resistive and inductive. Electrostatic panels with capacitive loads, at high frequencies will have very low impedance, possibly less than one Ohm. Reducing the capacitance will have a higher impedance, especially at high frequency. If a cable feeding an electro-dynamic speaker has any capacitance, the overall effect on the load is insignificant, the resistive and inductive parts will be predominant.

David.


----------



## coinmaster

I see, I wasn't sure how it was any different with a purely capacitive load. Can you just increase the stator spacing and up the voltage to reduce capacitance? What is the average p-p voltage required to drive these DIY headphones? Is there some sort of standard ratio between stator voltage differential, spacing, and AC amplitude required to get X amount of decibels?


----------



## Muamp (May 12, 2017)

Hi Coinmaster,

Yes, you can increase the space between the stators to reduce the capacitance and then increase the p-p voltage.
The maximum p-p voltage at headphone stators is normally about 1300v p-p (460v RMS). In my very first panels I made, (from perforated steel) I originally used spacers of 1.5mm each side with an audio transformer energiser which went up to about 2200v p-p. And of course the large ESL speakers have bigger spacers and use much higher voltages.

David.


----------



## coinmaster

Instead of increasing ac voltage, how bout increasing stator voltage? It's easier to increase DC voltage than get higher AC voltages with low distortion.


----------



## jgazal

coinmaster said:


> Instead of increasing ac voltage, how bout increasing stator voltage? It's easier to increase DC voltage than get higher AC voltages with low distortion.



Do you mean increasing bias voltage in the diaphragm/film or increasing dc voltage rails in the amplifier?


----------



## coinmaster

I'm not sure how you are biasing it but I was going to keep the diaphragm at ground level and put bipolar voltages on the stators. So increasing the spacing and voltage of the stators should allow the same result with less capacitance as long as the air dialectric isn't broken.


----------



## jgazal

coinmaster said:


> I was going to keep the diaphragm at ground level



How do you charge the diaphragm resistive coating?


----------



## coinmaster (May 12, 2017)

Ground is a charge potential just like any other voltage.


----------



## jgazal (May 12, 2017)

coinmaster said:


> Ground is a charge potential just like any other voltage.



I don't understand.
Perhaps I should let others chime in.
Nevertheless, just one more question.
In the circuit you mentioned, if diaphragm bias is at ground potential, does the charge in the coating vary as you apply your higher gain AC signal to the stators?


----------



## 100VoltTube

I believe the general goal is at least 300v p-p, but it is nice to have headroom. Most gilmore designs use ±400v rails or more, and can swing almost to the rails.

Determining efficiency and capacitance and so forth is all just math. It's irritating math, but if you want cold, hard values, there's no substitute


----------



## coinmaster (May 12, 2017)

If the diaphragm is attached to ground then no, it stays at ground potential unless I apply the signal to the diaphragm which would certainly make things much easier to design in so many ways. Unfortunately I need to design a pair of stats using ground potential on the diaphragm because I'm going to build an ES/ribbon hybrid and that is the only practical way to do it without major capacitance issues and construction difficulties. Then again maybe increasing stator distance isn't such a great idea after all since the electromagnetic field of a ribbon is supposedly equal to only a half turn of a coil and I'm not sure how much current I'm going to require for that as it is. I could stack the magnets in series but then that would be more mass obstructing air waves. Then again such a headphone design should have ludicrous sensitivity so maybe I don't need to go all out on both ends, or maybe I should.  Bah, so many variables.


----------



## 100VoltTube

In the design @coinmaster is talking about, as I understand it, the diaphragm is at 0v. The highly resistive coating keeps the entire diaphragm at that charge as it moves. The stators are biased, probably at about 600v. that bias works just like the bais in a normal electrostatic headphone. A good way of thinking about it is coulomb's law: 





"where _ke_ is Coulomb's constant (_ke_ = 8.99×109 N m2 C−2), _q_1 and _q_2 are the signed magnitudes of the charges, and the scalar _r_ is the distance between the charges. The force of interaction between the charges is attractive if the charges have opposite signs (i.e., _F_ is negative) and repulsive if like-signed (i.e., _F_ is positive)." (from wikipedia)

That is why diaphragms are biased, and why there are 2 stators.


----------



## 100VoltTube (May 12, 2017)

BTW, you can do single sided very easily with a tube like the QK329 right at the beginning of the signal path. Unfortunately, I'm not aware of anywhere that sells that tube. There may be none left.

Edit: It would seem that they come up on Ebay sometimes. One sold for $226.15 
There goes that idea


----------



## chinsettawong

You can also make your amplifier more powerful in order to overcome the high capacitive load.


----------



## 100VoltTube

Here's an odd idea: A headphone with 2 drivers per side, placed one behind the other, both sealed together. The close one would have very thin mylar for detail, and the outer one would have thick mylar for punch in the bass. They would be wired in series, so the capacitance would be huge, but a powerful amp. like a KGSSHV, should have no problems driving them.


----------



## coinmaster

Yeah I was thinking about this as well. The added bonus would be a push pull effect giving it more SPL.
The problem might be that the thicker mylar won't be able to keep up with the thinner mylar which may smear the sound. It's possible that the dual drivers themselves might be enough to achieve better bass but who knows.


----------



## chinsettawong (May 15, 2017)

Hi 100VoltTube,

If you go back and read my posts, you would see that I actually did try the two stators two diaphragms design a few years ago.  At that time, the result was quite disappointing.  The sound was kind of echoing and didn't sound good.  I didn't know why.


----------



## coinmaster (May 16, 2017)

You tried it with both diaphragms in between the stators? Echoing seems like it may be result of non synchronous operation of the diaphragms or some sort of resonant or geometrical problem.  Maybe the axis offset of either diaphragm relative both polarities caused issues or there was some sort of reflective geometry or resonance in the material. 
I would try with a single stator and and diaphragm on either side of it.


----------



## chinsettawong (Jul 6, 2017)

I tried it many years ago.  And didn't like it.  But if I have the time, I will try it again.

Anyway, here is a picture of my Omega clone VS Stax O2 MKI.








Driving them with my KGST, my DIY phones have better mids and highs.  The bass is about the same.


----------



## wppk

Wonderful !


----------



## Kerry

Impressive as always


----------



## 100VoltTube

Very nice. The casework on the KGST is amazing.


----------



## JoaMat

Indeed very nice.


----------



## chinsettawong

Thank you guys.


----------



## 100VoltTube (Jul 3, 2017)

What voltage rating do the koss/stax cables have? I ask because I'm putting together an order for a trafo box with a varaible bias supply. In its current state, it can put out a bias of 0V to 1.5kV or so. I understand that a bias that high can cause arcing in headphones with 0.5mm spacers, but I want to play around with spacers and bias at some point. If the cables are rated for voltages like that, I'll continue as planned, but if they're only rated at 600V or 1kV, I'll drop a few stages from the voltage multiplier.

BTW, this is the trafo I'm using. It will need resistors to create a fake center tap.
Edit: that trafo will not work. It's only rated at 5mW


----------



## Muamp

Hi 100VoltTube,

That is an expensive audio transformer. Two of them for stereo is very expensive.
Why not use the audio transformer I recommended on the DIYers Electrostatic headphone thread. They are much cheaper and very good, and have centre tap.
I use these in a transformer energiser I have on my test bench.
As for the bias voltage, unless you will be making panels as big as Jecklin Floats, surely 580v - 600v is adequate?

David.


----------



## 100VoltTube

> That is an expensive audio transformer


Not really. In the big picture, it's quite cheap. Look at the $130 lundahl trafos spritzer is using. I can't get the trafos from rs components, as they don't ship outside of the UK. They do look quite nice.
I''m doing some more research into determining transformer performance based on numbers to see if I can find a better deal.



> As for the bias voltage, unless you will be making panels as big as Jecklin Floats, surely 580v - 600v is adequate?


I was under the impression the spacer thickness controls affected necessary bias more than diaphragm area. Anyway, I want flexibility for playing with odd designs, or maybe even making some very-near-field speakers.


----------



## janosch simon

Hey there what an amazing thread  my background is that i was actualy looking for a good dac and somehow ended on a stax forum and there a guy was listening to the meridian explorer 2 with his Stax sr007 and i though hmm whats that and thats how i got intrigued to electrostatic headphones 
i already got alot out of the thread and some pm´s with Wachara and now i feel confident to start my journey but not in the dark 
i own a little cnc mill which has at the moment some problems another problem is that the working area is tiny with only 160x80mm so i cant make very big phones :-/ if i cant fix it i might upgrade to another cnc mill but the whole hifi project already costs alot 
my raspberry music streamer is still missing its dac ( will go with the soekris dam1021-12) and the amp desing im not sure either 
but first i will try to make the stator, spacer and how to strech the membrane until now i cant find 3 mircon mylar in europe and ordinging it form taiwan hmm meh perhabs i will try ordinary houshold foil and report back how it goes  

ah one question is gilmore.chem.northwestern.edu only for me down? i read i all over the place in regards to amp design but the pages wont open for me :-/

and one last question for now why most of you try to imitate the stax conector with 5pins? i mean you need per phone 3 pins so why you only use 1 pin for the bias? for me it would be more convenient to use a connector with 6 pins just a thought  

cheers janosch


----------



## 100VoltTube

I can't access gilmore.chem.northwestern.edu either. I'll PM Gilmore about that.

You can buy stax plugs like this. You can also buy it with the 6th pin in the middle, like on the old normal bias stax. Other places also sell it. You can buy a replacement chord assembly from stax here. Sockets, like plugs can be bought from all over the place, like here. You can also CNC or 3D print plastic parts and use pins from XLR connectors.



janosch simon said:


> will go with the soekris dam1021-12


Lucky European. I was planning on making one, but then they stopped shipping to the US.

I think that mylar can only be ordered from Taiwan. That's where mine came from


----------



## chinsettawong

Hi janosch,

Welcome aboard.  I'm excited to see what you are going to achieve.  Please don't be shy to ask any questions that you have.  I and many of us here are here to help.

About Dr. Gilmore's link, I think he has retired from the university.  Therefore, everything that was there was moved to the other site.  Please ask him about it.

Wachara C.


----------



## janosch simon

yeah exciting times and it SEEMS my cnc mill is back to live i already ordered 1mm and 0.5mm pcb but the controll board of my mill gets sooooo hot i just opened the case  and installed a bigger fan 

at work ( i work for a small laser company) i might be able to cut some glass stators but the scanner we use have only a scan field of 60x60mm hmmm perhabs my boss buys a biggerscanner 

cheers janosch


----------



## janosch simon

as my cnc mill can only do 160x70mm i might start with in ears  did you finish them? who did they work? yesterday watching videos about shure kse 1500 and their bias voltage seems to be 200v hmmmm 
best janosch


chinsettawong said:


> For me, the drivers are no problem to be made, but to make good housings for them could be challenging. Here is what I have made right now.
> 
> 
> 
> ...


----------



## chinsettawong

No, the in ear type isn't easy to make.  I'll try again in the future.

By the way, you can try to make the stators 60 x 110 with the active diaphragm area of 50 x 100.  They should sound pretty good too.


----------



## janosch simon

yay milled today the stators and spacers worked pretty well   the 60x110 looks a little bit tall and slim but my cnc cant do bigger 
one question how you apply the uhu uniform? directly out of the tube or how? when can i upload images how many posts i need to have? 
cheers janosch


----------



## ts8051

chinsettawong said:


> Hi,
> 
> I've just joined this site today.  I just want to say hi to everybody and show you my version of electrostatic headphones and amplifier.  I've successfully made the phones and the amp for about a year now.  I just love them.
> 
> ...


----------



## ts8051

Hello,
Please I am looking for a good electrostatic headphones amplifier tubes or transistors. Also I want to discover how can i convert a normal tube push-pull amplifier to a electrostatic headphones amplifier.

Theologos Sarafidis


----------



## coinmaster

There are a lot of answers to that question based on your amplifier design and your ability to DIY or not.


----------



## ts8051

Hello,
I can make diy amplifiers. My last Electrostatic Headphone Amplifier was the Design fro 1980 N. Pollock from Wireless World. Now there are some Special designs with EL34 or other. As I constructed a tube power amplifier with 2A3 tubes in push-pull, I am looking to construct a Electrostatic Headphone Amplifier by using the pcb Board of this push-pull amplifier but without output transformers. Of course I must make a separate High voltage (580V) power supply. But I am looking such plans of modifications in push-pull tube  amplifiers. Else I want to construct a dedicated tube amplifier foe DIY electrostatic Headphones. 



coinmaster said:


> There are a lot of answers to that question based on your amplifier design and your ability to DIY or not.


----------



## coinmaster

Without a schematic my responses are limited. Google "tubecad electrostatic amplifier" and you should be able to find plenty of inspiration.


----------



## chinsettawong

The better ones are Dr. Kevin Gilmore's designs.  Search for KGSSHV, KGSSHV Carbon, KGST, Megatron, and etc.

These are some of the best designs and I highly recommend any of them.


----------



## coinmaster (Jun 23, 2017)

I took a peak at the KGSSHV schematic, it seems to be just a transistor cascode amplifier with current source loads, not impressive enough to call it "better" than all else. There's a million and one ways to convert a non ES amp into an ES one but without a schematic of his amp it's difficult to say.


----------



## janosch simon (Jun 24, 2017)

hey all  i got the antistatic spray from rs componets which david (muamp) suggested and i already talk with him about how to apply it on the membrane ("Muamp said:Shake bottle. Spray librally all over. Allow 15 minutes to dry. Wipe lightly with lint free cloth") but perhabs you guys also have other practices how to make a good coating  i was thinking about putting the esd fluid in a tray and then let the membrane float on the fluid and then pull out and let gravity pull off the excess?
this should give a pretty uniform coating  just like in alternative photography where you coat  paper with a salt solution just like i described above 

cheers janosch


----------



## janosch simon

again me  first tests were kind of successfull (music audible but far from sounding good) so there are a lot of problems to solve:

when i play music with a bias voltage of around 600v the speaker roars and when i increase the HV it gets louder sure but the  music is very distorted 

could this be a problem with the tension of the foil? i use household foil which is 12 micron thick in germany i couldn't find 3 micron mylar foil. any of you know a source? hmmm 

any of you had a similar problem? with the roar and distroted sound?

cheers and thx
janosch


----------



## chinsettawong

Hi Janosch,

Tell us more about your build.  What is the spacer thickness?  What do you use for coating the diaphragm?  Are you using a dedicated amp or transformers for connection with the headphones?  Pictures would help a lot.

Actually, I find the 12 micron food wrap to sound pretty good.  So, I don't think it is the cause of your distorted music.

By the way, the 3 microns Mylar can be bought easily on Ebay.

Wachara C.


----------



## janosch simon

hey Wachara  my setup is amess at the moment 
- Spacer thickness 0.5mm
- coating is Anti Static Spray from rs-components 
- a very old amp with 2 transformers and a High voltage lab powersupply for the bias voltage perhabs i can test tomorrow Muamps testbench energizer 
for pictures im afraid i still dont have enough posts 
cheers janosch


----------



## chinsettawong

To use 0.5 mm spacer, you have to make sure that you do everything right.  It's not so easy.

What is the size of your active membrane area?  

For pictures, if you really can't post them here, you can easily store them somewhere else and put a link here.

By the way, I would question your amp and the step up transformers.  I'm not sure that they are good for the headphones.


----------



## janosch simon

yeah thats why i will try hopefuly tomorrow the audio transfomer that muamp suggested  
the active area is  50 x 100 like you suggested  pictures i will try this evening 
cheers janosch


----------



## janosch simon

yeah i can upload images  here are some images of the stator and distance frame  the membrane i need to renew this evening


----------



## chinsettawong

Your stators and spacer look nice.  Where is your spacer with the diaphragm?


----------



## janosch simon

as i wrote need to glue it this evening destroyed the last one  but its so much fun this project will keep you guys updated my plan was to build a "high end" hybrid tube and solid state amp but this will cost to much at the moment perhabs i will try to build after my testbench works a middle expsive engergizer 

cheers janosch


----------



## janosch simon

here is a picture of 2 diaphragm with 2 different household foils one is from kaufland brand and the other from toppits. im not happy with how the glue is distributed hmm also the more expensive toppits foil looks cleaner the kaufland has some wrinkels will test both later today.


----------



## ts8051

Hello,
I show the photo of stator and I observed that it has no holes for bolts. Can I suppose that all the stators and spacers are bond with glue?


T. Sarafidis




chinsettawong said:


> Here is a picture of a stator and spacer which I took a few years ago.
> 
> 
> 
> Stax uses very thin plastic (Mylar?) spacers to adjust its diaphragm and stator distance.


----------



## ts8051

Hello,
I am looking the reason for central big hole (1cm diameter). I suppose that around this hole there in no electrical field, thus this membrane area does not oscilate. Possibly there is in order to simulate the spherical waves. Do you know about this?

T. Sarafidis



Muamp said:


> I have made my version of SR009 stators.
> I used 1mm FR4 for the test, since it is just as rigid as aluminiun but easier to work with.
> 
> 
> ...


----------



## chinsettawong

ts8051 said:


> Hello,
> I show the photo of stator and I observed that it has no holes for bolts. Can I suppose that all the stators and spacers are bond with glue?
> 
> 
> T. Sarafidis



No.  Stax puts the driver in an enclosure that sandwiches everything together.  Therefore there are no screw holes.



ts8051 said:


> Hello,
> I am looking the reason for central big hole (1cm diameter). I suppose that around this hole there in no electrical field, thus this membrane area does not oscilate. Possibly there is in order to simulate the spherical waves. Do you know about this?
> 
> T. Sarafidis



I don't know the exact reason for that hole.


----------



## chinsettawong

Hi Janosch,

I noticed that you didn't insulate your stators.  Using 0.5 mm spacers, everything has to be perfect.  Just a tiny bit of dust can cause unpleasant noises in the driver.  Please spray paint your stators to insulate them and clean them really well.  

Wachara C.


----------



## janosch simon

hey wachara   today was a great day  i bought a cheapo lepy 20w amplifier and guess what IT WORKS  the amp from my collegue is damaged so my desing was from the beginning OK not perfect but workable yeah 

where you mean to spraypaint the stators? the copper side or the outside? 

cheers happy janosch


----------



## coinmaster

General question. How do these DIY stats compare to commercial high end stats like the stax 07 and 09?


----------



## Muamp

Where are you from, Coinmaster?
If you are in the London - Essex area, you are more than welcome to come round and back to back audition mine with any headphone you choose. Then you can decide for yourself!
I am sure other stats DIY'ers (in their respective areas) would welcome you as well....

David.


----------



## coinmaster

Oh man I wish I was, you seem like my kind of fellow. I'm from Connecticut, USA. I ask because over the past year I've done a lot design and development of ultra high end amps and unfortunately during one of my prototype tests I had quite a large amount of DC current surge through my HD800s rendering them damaged (they still work but the frequency response is all over the place). From what I've read here and there it seems like DIY headphones can sound just as good or better then commercial ones and if I'm going to get new headphones I might as well make "better" ones if I can. Although no one seems to want to give a straight answer as to whether diy headphones are actually on par with commercial ones.


----------



## chinsettawong (Jun 29, 2017)

Hi coinmaster,

I once sent my headphones to Tyll of Inner Fidelity for measurements.  You can read and compare the measurements against that of Stax SR009 there.  https://www.innerfidelity.com/content/extraordinary-diy-electrostatic-headphones-chinsettawong


----------



## ts8051

Hello,
Can you compare the frequency responce with central hole and without it? Is it possible the central hole to have better frequency responce in low frequencies ? I think that it changes the oscillating modes of membrane.



chinsettawong said:


> No.  Stax puts the driver in an enclosure that sandwiches everything together.  Therefore there are no screw holes.
> 
> 
> 
> I don't know the exact reason for that hole.


----------



## chinsettawong

I don't think so.  And I have no way to measure them.  

On my two DIY versions of JF clone, one with center big hole and the other without, the sounds have no noticable difference.

Since this is a DIY thread, I encourage you to make them and try them out by yourself.


----------



## coinmaster

chinsettawong said:


> Hi coinmaster,
> 
> I once sent my headphones to Tyll of Inner Fidelity for measurements.  You can read and compare the measurements against that of Stax SR009 there.  https://www.innerfidelity.com/content/extraordinary-diy-electrostatic-headphones-chinsettawong


Not really a convincing response to get me to blow who knows how much money on DIY headphones. Personally I don't listen to graphs when listening to music.
Has anyone actually compared their DIY phones to existing high end options?


----------



## chinsettawong

I have Stax SR202, SR407, SR007, SR009, and a Jacklin Float to compare with my DIY headphones.  Yes, I do often do the A/B tests.  I also compared mine against the Orpheus before.

I wouldn't say mine are better, but I really feel that mine are as good.


----------



## coinmaster

What are the realistic costs of making one from scratch for someone without a milling machine? At least a ballpark figure.


----------



## chinsettawong

Wow!  That's a tough question.  Are you going to make everything by yourself?  And how well build are you looking for?  If you read through the thread, some of us here actually drill their stator holes one by one by hand.  That's certainly doable.  But if you want good quality, you might want to invest in a CNC router.  Again, there is a big price range.  I built my own CNC machine.  I don't think I save any money doing so.  It's just for fun.

All other materials are rather cheap.  I like to use the copper clad PCB for stators.  

All in all, if you are looking to invest in the equipments and do everything by yourself, expect to spend around the cost of a SR009 for the minimum.  That's only my personal opinion though.


----------



## coinmaster (Jul 3, 2017)

> Are you going to make everything by yourself?


 Not to the extreme, no.


> And how well build are you looking for?


Someone once called me no-compromise-man. I think that's an accurate statement.
At least in terms audio design, I can care less about looks.



> But if you want good quality, you might want to invest in a CNC router.


What's wrong CADing up some custom stators and ordering them from PCBway or something?


----------



## chinsettawong

I'm only here to help those who like to DIY.  If you want to hire someone to do the works, I don't know much about that.


----------



## coinmaster (Jul 3, 2017)

Ordering custom PCB stators from a PCB fabricator doesn't really count as "hiring someone to do the work", in that case you might as well mine and smelt the copper ore to make your stators or else it's not diy.. Unless you're implying the creation of the stators is the only difficult part in the creation of DIY ES headphones.
In which case I don't know why you would make them by hand when you could get them ordered to spec with better accuracy and reproducability.


----------



## 100VoltTube

@Muamp has some experience getting his stators made by PCBway. He did a group buy (sort of) recently, and he may do one again. I'm sure he can chime in with details about his experience.



chinsettawong said:


> All in all, if you are looking to invest in the equipments and do everything by yourself, expect to spend around the cost of a SR009 for the minimum. That's only my personal opinion though.


I have been able to get this far (all parts ordered, waiting for some to come) spending under 1K, probably even under $500, but I did go for a cheap Chinese CNC router kit as opposed to a nice one and a trafo box instead of a direct-drive amp.

Also, I just looked at the FR4 sheets I've had laying around for some time, and I noticed that the copper isn't too good looking (it's corroded and scratched up in places) How should I clean it? Or does it even matter?


----------



## Muamp (Jul 4, 2017)

Wow, this thread has been busy recently.
@100VoltTube - Yes I did run a batch of stators for others to use. It went well, but I do not have plans to do any more 'group buys'.
The PCBway stators, after a bit of trial and error were to a very high standard and as flat and rigid as my Bungard CNCed stators. Like all aspects, going through a PCB fab' house still has a certain amount of development required, where the first set from the fab' house may not be as good as you expected. The CNC option allows faster experimentation and testing.

I very much agree with Wachara, the costs to set up and DIY (even with PCB fab') can be quite high, and the time to design, test, build, with all the test builds in development are expensive, but you can get results as good as the best which are custom built to your own requirements.

David.


----------



## coinmaster

Any chance a sharing the design file for that PCBway run? I don't need a group buy to order two stators.
What else is expensive other then the stator?


----------



## Muamp (Jul 4, 2017)

Hi Coinmaster,

To make a headphone you will need four stators since there are two stators per panel.
The minimum order size is 10 (edited 5) PCB's and I am about to get some more for myself. If you want I can get you four stators at the same time.

BTW, my stators do not have bolt holes, since I use the surrounds as a means of securing and fastening them together. This may not be everyones choice.
I guess you are familiar with producing Gerber files. If you wish to use a DXF file of the vectors..... then you may prefer to modify to your needs.

David.

Edit: Other costs are mainly from experimentation and improvements.
Once you start, you want to keep going with ideas and sometimes they are improvements and sometimes just lessons learnt.
Also, without a CNC or 3D printer you will probably not be able to make a surround, plug....


----------



## coinmaster

> To make a headphone you will need four stators since there are two stators per panel


Oh right, duh. Not sure what I was thinking when I said 2.



> BTW, my stators do not have bolt holes, since I use use the surrounds as a means of securing and fastening them together.


What do you mean by "the surrounds"



> I guess you are familiar with producing Gerber files. If you wish to use a DXF file of the vectors..... then you may prefer to modify to your needs.


I've used designspark quite a lot so I know a few things.


----------



## Muamp

Surrounds - the casing for the panel. The bit to hold the panel and attach the ear cushion and also to the headband.

You use DesignSpark? Mmmm,..... I have tried three times to get familiar with DS and three times given up on it.
I used to use CadSoft Eagle but now I always use KiCAD (PCBnew), much better.


----------



## coinmaster

Did you custom order all your parts?


----------



## Muamp

Heck, No.
I make every part. I originally made up Gerbers for stators as nothing more than one of the 'improvement' exercises.
I also got stators made up as single sided, double sided on FR4, also Aluminium substrate PCBs as a test,..... this is an example of how it can get expensive. You get addicted to trying, testing and experimenting with different ideas..... It is a part of the fun..... BUT can be time consuming,... you need to take ESHS building seriously as it is not a 5 minute job.


----------



## coinmaster (Jul 4, 2017)

> You get addicted to trying, testing and experimenting with different ideas.


That's my problem, I'm already spending most of my time with amplifier prototypes, I can't afford the time or money to do complete R&D into another subject. I was hoping the people of this thread have worked out all the quirks enough to the point where I could build a high end pair of headphones without spending 2 years on R&D.
Not that I wouldn't go into full R&D mode at a later point, but right now I have everything invested into amplifier design.


----------



## janosch simon

hey gang as my first headphones work i want to get no into detail work :
if i remember correct one member from this thread said that he uses creased mylar foil as sweat and dirt stop but how do you guys fix that on the stator next to the ear? glued loosly on anther spacer?
cheers janosch


----------



## chinsettawong (Jul 5, 2017)

Hi janosch,

You simply make 2 more spacers and glue the same Mylar on the spacers to make the protective covers.  But make sure you don't stretch the Mylar when you glue.  Actually you want to crumple it before you glue.

You put these two dust covers on the front and the back of the driver and now you have an air-tight driver that will not be affected by the surrounded dust and moisture.


----------



## janosch simon

nice will give it a try thx


----------



## janosch simon

Muamp said:


> Hi Luc,
> 
> ...Also, all my ESHS designs use fleece ear cups which are 'breathable' and allow the listener to use for extended periods without any sweat build up that you would get with leatherette / leather / suede ear cups....
> 
> David.



hey David do you produce the fleece ear cups on your own or do you buy them? would love to made the ear cups custom to the size i want 
cheers janosch


----------



## coinmaster (Jul 5, 2017)

.


----------



## Muamp (Jul 6, 2017)

Hi janosch,

I make the ear cushions by using fleece material cut in to two 'doughnut' shapes, slightly larger than the surrounds.
I sow the two pieces together and fill with wadding. It is time consuming.
You could buy from a Chinese ebay seller (even AliExpress). There are many available in round, oval and eclipse shapes of various sizes.
I am currently working on Muamp#6 which will be......, different from my normal designs.

David.


----------



## janosch simon

hmmmm when i get my new cnc mill perhabs i will stick with pads that i can buy 

OHHH david is teasing what are you building? Muamp #6 cant wait to see hope you share something 

Janosch


----------



## janosch simon

hey there  i just finished my second eshp a with new 3d printed case and when it works its amazingly good but with some problem 
here are the build details:
-pcb stator 1mm
-pcb spacer 0.5mm
-mylar 2um foil glued with 3M 4693 glue which is more fluid then uhu por but also the moment it touches the copper of the pcb it gets more sticky and the coating is not even. the mylar is coated with RS-components ESD spray (the cheap one but i also ordered the techspray crystal to test)

compared to my first design where i used plastic screws and plastic washer to put everything together the new 3d printed case is made of 2 parts and fixed very good with 4x M4 screws and 4xM4 nuts.
it seems that because of the better and tighter fixing the mylar now comes to close to the stator and the sound is gone or distorted.
at the moment distance is 0.5mm mylar to the stator.

the questions:
a) how hard do you fix your assembly? i can imagine when i loose my assembly it could work but thats no solution for me 
b) put the stators the other way around and a higher the bias voltage. is there a negative effect when you put the stator electrodes facing outwards and not inwards? except the higher bias voltage?

cheers janosch


----------



## chinsettawong

Hi Janosch,

As I have told you before, using 0.5mm spacers isn't easy.  Everything has to be perfect.  When you have the problem with the unstable Mylar, your diaphragm tension is not enough.  You need to put more strength into pulling your diaphragms.  

If you flip the stators and use the insulated sides to face each other, you increase the gap between the stator  and diaphragm by the same thickness of the insulation.  I don't think that is good.  If you really want to increase the air gap, you want to try it a little by little.  A very easy way is to cut a sheet of paper into the spacer shape and put it in between the spacer and the stator.  Now you increase the airgap by only the thickness of that sheet of paper spacer.  If that's still not enough, you can further add more paper spacers as you want.

Wachara C.


----------



## janosch simon

hey wachara the flipping is not possible with my latest case hmmmm so you think the tension of the mylar is not enough thats highly possible cause i make this now by hand without any consistency 

will try to build this tire stretcher thing and report back  so much fun and btw my bigger cnc 3020t mill is on the way so there will be a lot of different designs  

cheers janosch


----------



## ts8051

Hello,
I use epoxy glue with two components in order to glue the membrane with spacers  Please, what glue do you use?


----------



## janosch simon

hey ts8051 first i used uhu por just like wachara recomended and now im trying  3m 4693 which is a little bit more fluid then the uhu por but first i need my strecher will report back


----------



## 100VoltTube

When milling FR4, how do you hold it down, and what do you put under it? I currently have a piece of 0.5" thick MDF to put under it, and screws with washers to clamp it down from the edges. Is there a better way?


----------



## janosch simon

i just use very strong double sidded tape on a 1"mdf plate works very good but with my new cnc mill which is much faster (240mm/sec vs 2000mm/sec) i cant mill a fullspeedbecause then the endmill breaks 
350mm/sec with an 1.4mm endmill is max and the tape is strong enough to hold it with that speed in place.

cheers janosch


----------



## chinsettawong

I also use a piece of 5 mm MFD with double sided tape for holding the PCB.  It works nicely.


----------



## ts8051 (Jul 18, 2017)

spritzer said:


> 65mm could be perfect in a good housing and with a properly sealed baffle.
> 
> The size of the holes really depends on your D/S gap and really shouldn't be any larger then double the D/S gap.  For Stax that means 1mm or so given their 0.5mm D/S gap.
> 
> I for one don't like to damp much but I've gone to extreme lengths to dampen some drivers which just won't behave.  That said, airdamping is IMO a very good idea as it it traps air next to the diaphragm and can stabilize it.  Most undamped electrostatic drivers have some resonance frequency (usually in the upper midrange, lower treble) and this helps to tame it.  Take a look at the picture below, that's a Stax SR-007Mk2 driver and notice the ring with no holes around the driver.  That's still part of the stator with the diaphragm beneath it but it can't output any sound.  The small Stax SR-003 portable headset goes even further where only a small part of the stators is open.


Hello,
If I accept that the holes must have a diameter 1mm equal to the gap (0.5mm) multiplied by 2 at maximum, please let me know your opinion about the density of the holes on stator ? In my previous made headphones i have 1.8mm hole on stators.


----------



## ts8051 (Jul 18, 2017)

chinsettawong said:


> I've got some free time this afternoon and these are what I have achieved today.
> 
> 
> 
> ...



Hello,
I designed and made STAX style male connectors with my 3d printer. As you can see i designed also the bolts for cover.


----------



## Christer

inuponken said:


> Wachara,
> 
> Sound from the JF clone is awesome!!
> I spent a lot of time to find a right tension.
> ...


Interesting, to me they look a bit like my old Jecklin Floats without the plastic helmet .
Do they sound simliar too Jecklin Floats too?


----------



## chinsettawong

There is no way to compare them using the same amp.  But for my JF clone with KGSSHV Carbon, they sound much better than my JF with my EL34 SE.


----------



## Boonyoung Iamkamol

I'm new ...  watching and interesting 
I would like to listen ..  If Khun Watchara free I like to get opportunity when you're free..


----------



## chinsettawong

Hi Khun Boonyoung,

You're always welcome to try my headphones and amps.  Please PM me and I'll arrange the time for you.


----------



## Boonyoung Iamkamol

Hi Khun Watchara;

Million thanks for you kindly , this is my best opportunity to get direct  information from ..  Normally I will be free on Friday  I stay in Bangbuathong Nonthatburi ..How can I contact you ? if you are not comfortable to give me phone number ..  I have line ID  or Skype account..

Boonyoung


----------



## chinsettawong

ts8051 said:


> Hello,
> I designed and made STAX style male connectors with my 3d printer. As you can see i designed also the bolts for cover.



Hi ts8051,

I didn't notice that the plug was from your 3d printer.  It looked very much like mine.  I like your screw in feature.  Will you share your 3D file with us?

What kind of filament do you use?


----------



## chinsettawong

Boonyoung Iamkamol said:


> Hi Khun Watchara;
> 
> Million thanks for you kindly , this is my best opportunity to get direct  information from ..  Normally I will be free on Friday  I stay in Bangbuathong Nonthatburi ..How can I contact you ? if you are not comfortable to give me phone number ..  I have line ID  or Skype account..
> 
> Boonyoung



Hi Khun Boonyoung,

I've sent you a PM message.  Please check.

Wachara C.


----------



## ts8051

chinsettawong said:


> Hi ts8051,
> 
> I didn't notice that the plug was from your 3d printer.  It looked very much like mine.  I like your screw in feature.  Will you share your 3D file with us?
> 
> What kind of filament do you use?


PLA professional pro1 inofil3d


----------



## ts8051

chinsettawong said:


> Quote:
> 
> 
> 
> ...


Hello,
How can we measure the tension? Does exist a sensitive tension meter ? Can we measure the tension by means of the pressure of a known weight on the membrane?


----------



## ts8051

Hello again,
I downloaded the Advanced FFT analyzer and I checked my Electrostatic Headphones made by me (by means of white noise generator) that the resonance frequency is about 250Hz. In contrast my old STAX SR Lambda Headphones have resonance frequency about 150Hz.
I can explain it because i tensioned the membrane with very high tension. Now I plan to construct with my 3D printer a tensioning mechanism. After R&D about the correct tension, I will put on the tensioned membrane a known weight and i will measure the z position of this weight on the membrane. In the next membrane tension I will adjust the tension of the membrane in order to  have the same z position of the known weight.


----------



## chinsettawong

I believe that I have finally come up with something better than what I've been using for quite a while.  
















3D printers are really amazing.


----------



## ts8051 (Aug 2, 2017)

Hello,
After studying the relationship between membrane tension and resonance frequency I made headphones with resonance frequency 80Hz. I made also a centre hole. The bass response is amazing. Of course the responce in middle and high frequencies are the best. I also observe the excellent stereo image with depth. In the near future I will post some photos.


----------



## Muamp (Aug 4, 2017)

Hi Wachara,

I have still not got a 3D printer.... I keep thinking about it, but always convince myself CNC can do it better. Although there are often certain shapes and small objects,.. clips etc where a 3D printer would certainly help.

P.S. I like the Velcro strapping, what a brilliant idea.

Hi ts8051,

How did you measure the resonant frequency? 80Hz seems a bit low. Either you have a very large panel or low tension membrane?

David.


----------



## ts8051

Muamp said:


> Hi Wachara,
> 
> I have still not got a 3D printer.... I keep thinking about it, but always convince myself CNC can do it better. Although there are often certain shapes and small objects,.. clips etc where a 3D printer would certainly help.
> 
> ...


Hello,
I used a program for my MAC which sweeps logarithmicaly the audible frequency range and the advanced spectrum analyzer program for android.  I realy measured it 80Hz when I constructed the headphones for the First time, but yesterday I measured it again and found it 120Hz. I think that either there are errors in measuring or the membrane became more tensioned which is impossible. The lower frequency which reproduced and was audible by me is 35Hz. In the next days I will measure it with my USB oscilloscope and better microphone and I will produce the frequency responce curve. The real fact is that the bass response is very good for my ears.
The membrane tension was achieved with the following method:
I put on a 25 X 25 cm glass a Paper with a scale in mm printed on it. After this, I was put on the glass the membrane which I glued on it with 3M self adhesive tape. After removing ringles on the membrane I mark on two sides X, Y on the membrane surface with a pencil. The tensioning by applying 3m tape is done on the two X, Y sides only and for 1mm only. Then I fit the allready cut spacers with UHU Por.
On the next days I will do the above with a lower tension than 1mm, possibly 0.5mm and I will see the result in resonance frequency value.

Theologos


----------



## Christer

chinsettawong said:


> I believe that I have finally come up with something better than what I've been using for quite a while.
> 
> 
> 
> ...



Interesting. I would like to audition those babies.
It seems you're getting closer to the Jecklins in size.
Do they dig deep in the bass?
 Lack of real deep bass was always a weakness with my Jecklins.
And how do you amp them?


----------



## chinsettawong

Hi Christer,

You are welcome to meet me in Bangkok and try my headphones anytime.  

I really like how these headphones sound.  The deep bass is not bad at all.  Comparing to the JF I have, mine sounds much better.  

I use my KGSSHV Carbon, KGST, and KG DIY T2 with them.  All of them drive the headphones with ease.  Well, even my Stax SRM252A has no problem driving them.


----------



## Christer

chinsettawong said:


> Hi Christer,
> 
> You are welcome to meet me in Bangkok and try my headphones anytime.
> 
> ...


Hello and thanks for the invitation to audition your Stats.
I will probably spend quite some time in Thailand this winter again and I'll get in touch next time I am in Bangkok.
Cheers Christer currently using HE1000V2 for basically all of my headphones listening sessions.


----------



## 100VoltTube

I don't know if this thread's link has been put in this thread yet, but here it is:
https://www.head-fi.org/threads/diy-electrostats-update-for-brave-ones-at-the-atlanta-meet.125173/


----------



## chinsettawong

Is he still active on the forum?


----------



## 100VoltTube

He seems to be active selling things, but not posting to threads. I'll PM him about his DIY estats and link this thread.


----------



## 100VoltTube

He responded to my PM with this message:


> Hi,
> 
> Thrilled to see so many head-fiers into DIY e-stats these days! It's a long thread that I'll have to catch up on. The headphones and drivers look amazing. The stators and support structures look really cool. I haven't been into estats since getting more into tubes. These days I'm and Audeze fan.
> 
> ...


----------



## chinsettawong

I think I have seen those pictures somewhere, but can't remember where.  It would be nice if he can join us.


----------



## Muamp

I have finally finished the design of Muamp#6. My aim was to keep it as simple as possible, really simple!

MUAMP#6















It is extremely light. Probably less that a third of the weight of Muamp#4.
The cable is a plaited - ultra thin / ultra flexible, silicon rubber coated cable.
The Stax compatible 5 pin pro plug is CNC'ed from Perspex.
The Stators and Spacers are sourced from PCBway - PCB fabrication house, in China. The Stators do not have the centre hole, as in all my others ESHS's.
The ear cushions are from ebay, a Chinese seller. They *are* genuine Lambs leather, and angled, just like the SR-009 cushions.
This is a 'surround-less' design. That is there is NO casing on the electrostatic panel. The copper on the stators doesn't go to the edge and so it is safe, cannot touch the stator voltages.
Since there are NO surrounds, the ear-cushions themselves become the casing.

They sound great, although I have not, as yet, had a chance to back to back compare Muamp#6 with Muamp#4 (the pair I keep for myself).

I will be keeping a load of Stators and Spacers 'in stock' for my own use which could also be available to other DIY'ers who wish to have a go.

David.


----------



## chinsettawong

Very nice!  I really like your earpads.  What are their dimensions?  Could you please post a link to the seller?


----------



## Muamp

The best ebay search string for these ear cushions is "genuine leather ear cushions", it will come up with a few sellers.
dd0529 and go_me05 are two sellers, although I think they are both the same seller...
They come in 100mm outer dia. and 110mm outer dia.
There are various others, which are synthetic, but cheaper.

I still think the fleece ear cushions are better, but they take a long time to hand-make.

David.


----------



## chinsettawong

Hi David,

Thank you so much for your recommendation on the ear pads sellers on Ebay.  I bought a pair to try and I really liked them.  The 110 mm outer diameter ones fit my Omega clone perfectly.


----------



## Muamp

They look great!
How about a before and after photo, next to each other. 

David.


----------



## chinsettawong

Here they are:

Before:







After:






The new one on the left and the old one on the right.


----------



## ts8051

chinsettawong said:


> Hi Birgir,
> 
> That surely is one of the simplest and effective ways to tensioning Mylar.  There is another way that I would like to suggest. In this case you use a piece of glass and predraw some scales on it.  Let's say for each 1 mm you draw a line.  You cut Mylar just big enough to make a pair of headphones.  You tape the four corners of Mylar on the glass.  Draw a line on Mylar to indicate your prestretch starting point. Then you hand stretch your Mylar to your target point by observing the line on Mylar against those on the glass.  When you get to your target point, you simply tape it down. Do the same for all four sides of Mylar. I have some pictures below to show what I mean.  It's basically the same principle of how I stretch Mylar for my ESL.
> 
> ...




Hello,
I followed this method with resonable results. Please do you know how must tension the length for each dimension in % percentage of total length ?

Theologos Sarafidis


----------



## chinsettawong

It’s very difficult to say just how much tension is enough.  As for what I’m making right now, I only aim for about just a little less than 1 mm elongation.  

You can also try to tension it a little more than needed, and then use a hot air gun to treat the diaphragm afterward.


----------



## ts8051

Hello,
please let me know the glass area dimensions on which you tension the membrane, just in order to calculate the percentage of tension. As I mentioned I followed this method with a 25 x 25 cm glass area and with 1mm elongation. Now the resonance frequency is 130Hz and the lowest frequency reproduced 38Hz. If I use a bigger glass area, for 1mm elongation the tension will be lower (the half), thus I wait further improvement.


----------



## chinsettawong

I now only use the inner tire method for tensioning the diaphragm.  The inside dimension of the frame is 23 x 15 cm.











I normally make a few pairs with little different tensions, and test to see which ones I like best.  Very sorry that I don't have the exact number of the elongation figure as it's very difficult to repeat the process exactly every time.


----------



## ts8051

Hello,
If you follow the method you described, and  in an  x attempt the tension is the best with best result in fidelity, how can you measure the result in order to repeat the tension in the future ? We must find a measurement method. Possibly if we can achieve the lowest tension for the best frequency responce in low frequencies, we can apply the air pressure in order to just disappear the ripples in membrane only.  In that case the sequence can be repeated in the future, if this lowest tension is the best.

Theologos Sarafidis


----------



## ts8051

chinsettawong said:


> I now only use the inner tire method for tensioning the diaphragm.  The inside dimension of the frame is 23 x 15 cm.
> 
> 
> 
> ...



Hello,
Please, if you know from your expiriments, if we apply tension on a membrane and the use the heat gun for each channel with a regulated temperature (for instance 400 degrees centigrade) is the tension the same ? Also is it lower or higher ?

Theologos Sarafidis


----------



## chinsettawong

Hi ts8051,
The question about diaphragm tension has been raised up again and again, and my answer is still the same.  It's very difficult to find just the right tension.  Since I do the headphones for my own use, I normally make a few pairs with different tensions and see which ones I like better.  It's rather difficult for me to describe just how difficult it is to repeat the same tension everytime.  You have to try it by yourself to know what I mean.

Using a hot air gun to treat the diaphragm will actually reduce the tension.  So, you can make  the diaphragm with a little more tension then treat it with the hot air gun to reduce the tension a bit.


----------



## ts8051

AmarokCZ said:


> *dude_500*: the blue line is definately not sealed, there must be some leak, a large one!
> I'm using the same film as you were (2um) and with two dust covers my bass frequency response is flat just like yours with 6um (even flatter). Just look at the SR-009 measurements: free-air resonance is ~170Hz but when sealed the frequency response is flat (except the ~40Hz step).
> 
> Here's my response (2um diaphragm, two dust covers, driver in wooden earcup, leatherette earpads, little bit of damping on the back side of driver, bias 580V), finally with calibrated mic:
> ...



Hello,
Please, explain how the dust cover can transform the frequency response. Please also do you know the material of dust cover.

Theologos Sarafidis


----------



## ts8051

ondesx said:


> Hi all,
> 
> Here is some maths about the estimation of the tension for the diaphragm.
> 
> ...



Hello,
From the math above i can say that for a given tension T the resonant frequency f can be lower if the mass M of membrane is higher. So if we have a 6micron membrane the bass response is better than with 2micron membrane. Then i cannot understand why stax uses 1.5micron membrane ? Is it something wrong with math above ?

Theologos Sarafidis


----------



## ts8051

chinsettawong said:


> Hi ts8051,
> The question about diaphragm tension has been raised up again and again, and my answer is still the same.  It's very difficult to find just the right tension.  Since I do the headphones for my own use, I normally make a few pairs with different tensions and see which ones I like better.  It's rather difficult for me to describe just how difficult it is to repeat the same tension everytime.  You have to try it by yourself to know what I mean.
> 
> Using a hot air gun to treat the diaphragm will actually reduce the tension.  So, you can make  the diaphragm with a little more tension then treat it with the hot air gun to reduce the tension a bit.



Hello,
I used the heat gun (150 degrees centigrade) and the tension was increased as the resonance frequency increased from 100Hz to 200Hz. The membrane is 3micron. 

Theologos Sarafidis


----------



## ts8051

chinsettawong said:


> Hi ts8051,
> The question about diaphragm tension has been raised up again and again, and my answer is still the same.  It's very difficult to find just the right tension.  Since I do the headphones for my own use, I normally make a few pairs with different tensions and see which ones I like better.  It's rather difficult for me to describe just how difficult it is to repeat the same tension everytime.  You have to try it by yourself to know what I mean.
> 
> Using a hot air gun to treat the diaphragm will actually reduce the tension.  So, you can make  the diaphragm with a little more tension then treat it with the hot air gun to reduce the tension a bit.





chinsettawong said:


> Hi ts8051,
> The question about diaphragm tension has been raised up again and again, and my answer is still the same.  It's very difficult to find just the right tension.  Since I do the headphones for my own use, I normally make a few pairs with different tensions and see which ones I like better.  It's rather difficult for me to describe just how difficult it is to repeat the same tension everytime.  You have to try it by yourself to know what I mean.
> 
> Using a hot air gun to treat the diaphragm will actually reduce the tension.  So, you can make  the diaphragm with a little more tension then treat it with the hot air gun to reduce the tension a bit.


----------



## ts8051

Hello,
In my new headphones i tensioned the membrane with elongation 0.25mm (the membrane surface is 35 x 35 cm. The result is the following by means of my android mobile phone running Advanced FFT program (the upper yellow curve is the frequency response):


----------



## Muamp

Hi ts8051,

With a frequency response that GOOD, I would say your tension must be spot on..... But as always, the listening test is the best test.

David.


----------



## ts8051

Hello,
As I made many spacers, with my CNC, with a tensioned membraned glued i discovered that even i use scale and 0.5mm elongation the results are varying. Many have simple good response and  one until now has excellent with deep bass. 
I thought that when we tension the membrane we must be able to measure the frequency response before apply glue. For this I study to use a bicycle wheel and with inflate for membrane tension. Then I thought that I can apply at first the conductive material (licron crystal spray) and then assemble the headphone without screws but with strong magnets 10 x 2mm which i was already ordered. Then i will test the frequency respone of this temporary assembled headphone and if it will not good i will apply more tension until i have the best results.
What is your opinion ?

Theologos


----------



## Muamp

Hi Theologos,

I think the use of hanging weights is more accurate for repeatability. When using a tyre stretcher with marker points, getting the same tension is very difficult.
Also, I know lots of people use Licron Crystal, I've used it, but still prefer the RS antistatic spray.

David.


----------



## ts8051

Hello,
If you read my previous message i mentioned the method to check the frequency responce after tension before apply glue.


Theologos


----------



## Congo5

chinsettawong said:


> 3D printers are really amazing.



That is after you learn to use them... 

  So I drew this up and printed some parts to tryout.
will make some changes but it will work just fine.
tried ABS but even at 50% infill it was very brittle
so back to PLA for now as its very strong


----------



## Muamp

Hi Congo5,

You’ve been quiet recently.
I have still not got into 3D printing, but have looked into buying a 3D printer,.... I guess the one you have is capable of printing some big pieces. Is your headband printed?
I still CNC everything, but probably consider a printer at some point. Any recommendations?
Are the headphones in the bottom photo wood effect PLA or real wood?

David.


----------



## Congo5

Yea mostly building amps

those are printed on a Tevo Tarantula, build area is 200mm cubic
The headband just fits on the build plate.

it was $200 and now they have a bigger one called Tornado and its much easier to assemble.
Many Youtube videos on 3DPrinters, that's how I chose that one.
its the headband / mechanism  that I have struggled with, this solves that.
the bottom ones are CNC MDF from a couple years ago, (still work)


----------



## ts8051

Julez said:


> When I heat my membranes they do not shrink. In fact they do the opposite. They expand. If I take a finished membrane glued to a spacer (or glued to my stretching frame) the resonance frequency gets lower if heated! So my understanding is it will expand by being heat treated and the effect fades away after a while resulting in the same tension as before heating the membrane.
> 
> Nonetheless I do use heat treatment. But in my case I have a strechting frame and I do only strecht the membrane in one direction. So I do the heat treatment for a more uniform tensioning on the whole membrane and as well to get rid of wrinkels wich do appear with my method of gluing the mylar to a frame by myselve to stretch it.




Hello,
I my case the membrane shrinks when heated with air gun, so the resonance frequency rises. Please can you tell me what type is your membrane ?

Regards
Theologos


----------



## chinsettawong

Very nice work Congo5.  I really like the way you make your headband.

By the way, on my side, I've upgraded my headphones with professionally made stators and spacer rings.  The stators are made from double sided PCB with plate through holes.  Now it's very easy to solder the wires on either side and the copper trace doesn't get in the way of the spacer rings anymore.  

For some unclear reasons, after the upgrades, my Orpheus clone and Omega clone are quite a bit more efficient.  They sound as loud as my Stax SR009 now.  I have to remake the diaphragms since using the old ones and they are not able to keep stable.  The dynamic and bass also get much better.  You guys should try.


----------



## chinsettawong

I also put the new stators and spacers into the Hifiman HE-5 housing with the 100mm leather earpads from Ebay as per David's recommendation.  Now I really like them.


----------



## chinsettawong (Oct 18, 2017)

ts8051 said:


> Hello,
> I my case the membrane shrinks when heated with air gun, so the resonance frequency rises. Please can you tell me what type is your membrane ?
> 
> Regards
> Theologos



Yes, using the air gun would shrink the membrane a bit.  Your resonance frequencies would rise too.  However, if your tension isn't enough to keep the diaphragm stable, using the air gun can't help it (in my experience).

I have tried 1, 2, 3 and 6 micron Mylar.  And I really like to use the 3 micron.  Some of us here might prefer other thicknesses.  But, that's just personal preference.  Please share with us what you like better.


----------



## Congo5

Those look nice!
what is hole size and spacing?
1.5mm holes, offset spacing, 2.5mm on center?
Gonna try having them made,

 I do double sided because they stay flat better and then only connect one side electrically
that way the outside does not contribute to capacitance 
and coat the stator with electrical varnish
also helps with noise as it can't short bias to stator


----------



## chinsettawong

The Orpheus clone now has 1.5 mm holes.  The vertical spacing between holes for me is always half of the hole size.  So, in this case 0.75.  I can't remember what the horizontal spacing is though.  But, I guess it's pretty similar.

For the Omega clone, the hole size is still 2 mm.  The vertical spacing is 1 mm.  I can't remember the horizontal spacing either.

I haven't measured the difference in capacitance from the old ones to the new ones, but they sound good so I don't bother to do that.


----------



## chinsettawong

And yes, with the proper solder mask, the headphones are very quiet.


----------



## Congo5

nice, very nice, thanks
I haven't tried anywhere  near as many things as you have
So when it works I move on to the next problem
only have  2um film
staticide has worked for 2years on one set so guess its stable
hole size didn't seem to make much difference
I mostly copied your work adapted to my skill and methods


----------



## janosch simon

chinsettawong said:


> Very nice work Congo5.  I really like the way you make your headband.
> 
> By the way, on my side, I've upgraded my headphones with professionally made stators and spacer rings.  The stators are made from double sided PCB with plate through holes.  Now it's very easy to solder the wires on either side and the copper trace doesn't get in the way of the spacer rings anymore.
> 
> For some unclear reasons, after the upgrades, my Orpheus clone and Omega clone are quite a bit more efficient.  They sound as loud as my Stax SR009 now.  I have to remake the diaphragms since using the old ones and they are not able to keep stable.  The dynamic and bass also get much better.  You guys should try.


hey chinesettawong  what you mean by professional manufactured? better cnc machine? or eteched?  looks great anyway 

cheers janosch


----------



## chinsettawong

janosch simon said:


> hey chinesettawong  what you mean by professional manufactured? better cnc machine? or eteched?  looks great anyway
> 
> cheers janosch



I send the Gerber files to a PCB maker and have them make the stators and spacers for me.


----------



## 100VoltTube

But that takes all the fun out of it 

And all of the "fun" when you do something dumb with the CNC machine.

Seriously, though, those are very well-made stators. I'm curious about the cause of the difference in efficiency, and the difference in capacitance.


----------



## janosch simon

hmmm im withyou 100volt  but interessting that he finds a difference hmhmhmhm have to try my new cnc mill 

cheers janosch


----------



## chinsettawong

Well, frankly, I've been very busy with my day work and don't really have time to play much with my CNC machine anymore.  Plus it's something that I have been wanting to find out for a long time after seeing the stators from Stax SR007 which are made from double sided plate through holes PCB.  There is no way that I can make the plate through holes PCB by myself.  

Anyway, I'm glad that they turn out great.

I've been A/B testing my headphones against SR007, SR009 and SR407 for several days now.  These Stax headphones will go back in their boxes soon and I won't miss them at all.


----------



## janosch simon

HMMM i see what do you mean by double sided plate through? so the inside of the holes is coated too?  hmmm and sounds better hmhmhm 

cheers janosch


----------



## ts8051 (Oct 20, 2017)

GvTT said:


> Hello khbaur,
> 
> now you are whistling my tone!
> 
> ...



Hello,
I know the method you need which i was tested it. You must buy very small magnets 10 x 2 mm circular in shape. You will use them insted of plastic bolts. In this method you dont need to drill and glue the tensioned membrane. After tensionning the membrane you must apply the conductive coating as usual. Then you can assemble the electrostatic tranduccer carefully and use the small magnets insted of bolts. Then you can connecte the system to the electrostatic energizer / amplifier and make your measurements with your preffered  instruments. If the measurements are not as you like ayou must apply more or less tension and make your measurements again. At last you will disasemble the system and glue the two spacers on tensioned membrane.

Regards
Theologos Sarafidis


----------



## chinsettawong

Hi Theologos,

I've just played with your idea of heat treating the diaphragms today.  I tensioned the diaphragms to really tight.  They were so tight that the spacer rings were pretty badly bended up.  I put them in my headphones, and there was not much bass at all.  I took them out and treated them with the hot air gun.  I tried to see if I could kind of relieve the tension on the Mylar a bit.  By looking at the spacer rings, I could already tell that the tension had gone down quite a bit.  I put them back in my headphones, and diaphragms sounded very nice,  The bass after the heat treatment was quite a lot more than before.  What happened here?  My idea is that when you heat treat the diaphragm, the diaphragm tension is actually relieved when it's hot.  Then when it cools down it shrinks a bit.  This doesn't make the diaphragm under high tension becomes even more tight.  It's actually doing the opposite.  You can try it and see if you find the same result as what I get.


----------



## chinsettawong

Just an update for my new stators.  Yes, I also try my JF clone with the double sided plate through holes PCB.  For this time, I use 1.2 mm PCB with 2 oz copper.  Well, the result isn't very good.  I think because of the thicker copper, I really can't use 0.5 mm spacers with them.  I just really can't make the diaphragms stable enough with that spacer thickness. Eventually, I have to put in the extra 0.1 mm plastic to make the total thickness of the spacer to become 0.6 mm.  But other than that, the headphones sound very nice.  So, if you guys were to make the PCB like what I do, don't use thick copper.  







Here is to David.  The 100 mm leather earpads as per your recommendation look and feel really nice.  I really like them.


----------



## purk

chinsettawong said:


> Well, frankly, I've been very busy with my day work and don't really have time to play much with my CNC machine anymore.  Plus it's something that I have been wanting to find out for a long time after seeing the stators from Stax SR007 which are made from double sided plate through holes PCB.  There is no way that I can make the plate through holes PCB by myself.
> 
> Anyway, I'm glad that they turn out great.
> 
> *I've been A/B testing my headphones against SR007, SR009 and SR407 for several days now.  These Stax headphones will go back in their boxes soon and I won't miss them at all.*



Your Float Klone is quite amazing sounding...absolutely love your Orpheus Clone headphones as well!


----------



## Muamp

Just finished the Muamp Spyder.












Connected to the Stax SRM-252s







Connected to Kingsound M-03, battery operated energiser. This is good when I take it to work.






David.


----------



## chinsettawong

I really like the way you make your headband, David.


----------



## bigshoe83

Muamp said:


> Just finished the Muamp Spyder.
> 
> 
> 
> ...


These look so awesome, wish I was creative enough to do something like that.


----------



## janosch simon

damn david that little battery thingy me like  guess i have to make soon my stax connector to be compatible  just made a test with new glue and licron spray sounds pretty good but still have the problem with too high highvoltage :/ and the my headband earcups only seal when i press them against head but then NICE bass  

cheers janosch


----------



## wppk

Hi ! 
I found another pair. I am very lucky because it is really rare. Well, in fact , as you can read, I found it one year after. 
the headphones were presented as perfectly working. But they didn't work. But thsi time, I succeded in repairing them. 
The result is absolutely awsome. I must say this is a real marvel. I compared them to my stax srxII pro, which were and still ar my favourite cans, but this is just close to it !


----------



## wppk

oops I was answering to one of my older posts, on this page, about the bisset dd45e. 
https://www.head-fi.org/threads/my-diy-electrostatic-headphones.498292/page-155


----------



## jgazal

Interesting post from Jonh Broskie about electrostatic transducers:
https://www.tubecad.com/2017/10/blog0400.htm


----------



## Azrael3000

So after nearly one year after first finding this thread my friend and I have finally completed our alpha version. It was a lot of fun to work through this thread and then make everything a reality. Thank you Wachara for the inspiration and the help throughout the seven years in which this thread exists.

Here are some pics of our headphones and the step up transformer:
https://imgur.com/gallery/YsZCJ

Our goal was not only to build the headphones but to also compile a guide that avoids the necessity of reading 190 pages of forum threads. Of course during the process of building the headphones we did not really do a lot of writing so our document is in a rather bad state. But over the course of the next few weeks we will work on this document and we hope to publish it here before the new year.

Oh and as I said, this is version alpha, so a lot of lessons learned for version beta next year


----------



## Muamp

Nice work!
Some build photos would be great.

David.


----------



## chinsettawong (Nov 12, 2017)

Azrael3000 said:


> So after nearly one year after first finding this thread my friend and I have finally completed our alpha version. It was a lot of fun to work through this thread and then make everything a reality. Thank you Wachara for the inspiration and the help throughout the seven years in which this thread exists.
> 
> Here are some pics of our headphones and the step up transformer:
> https://imgur.com/gallery/YsZCJ
> ...



Congratulations!  I really like the pictures of the two of you smiling. Keep up the good work.  And please show us more pictures and details of your build.

Wachara C.


----------



## wppk

Hello there 
I don't really now if this will have completely its place here, but as it comes from a stax DIM ( do it myself) maybe it has, and it will probably interest some people. I receiced this morning a combho, stax sr 5 gold, out of wich I took the drivers to make a pro SRX as I often do now. The energizer, <with it , is a sdr7 mkII, with what I think to be an original pro output on it, added to the usual normal bias output. I didn't intend to use this energiser, but wanted to control it. I did it with an srx, then, I was curious to see what would be the result of this old energiser with my stax 007, which I don(t use anymore because compared to the srx, on the original amp sold with it as on my retubed and recaped trm t1, it sounds a bit dark. plugged it in the srd7 mkII. WOW! astonishing ! the 007 sounded balanced, compared to before, and really very very good ! Well, they cannot be of the same use as the srx which I use for monitoring, but now, there real music and life out of it ! 
Has anybody tried that ? I guess so. But the result is great !


----------



## wppk

yap ! nice picture of nice fellows ! Great !


----------



## wppk

and that idea of making a "how to" book is really good ! thanks !


----------



## chinsettawong

Over at the other thread, people are discussing about the new electrostatic headphones that don't have any dust cover.  I would say that it's not a very good idea.  I learned that since the very first day I made my headphones.  Without the dust cover, you run the risk of not only having the dust in the drivers, but also the risk of having the sweat in there.  I would recommend that you insulate the stators well and at least put a dust cover on the side facing your ear.  If you have good insulated stators, the dust cover on the other side is not really necessary.


----------



## zzhetanay

great work I like


----------



## jgazal

chinsettawong said:


> Over at the other thread, people are discussing about the new electrostatic headphones that don't have any dust cover.  I would say that it's not a very good idea.  I learned that since the very first day I made my headphones.  Without the dust cover, you run the risk of not only having the dust in the drivers, but also the risk of having the sweat in there.  I would recommend that you *insulate the stators* well and at least put a dust cover on the side facing your ear.  If you have good insulated stators, the dust cover on the other side is not really necessary.



In your opinion, what are the disadvantages of insulating the stators?


----------



## chinsettawong (Nov 20, 2017)

Wel, I really can't think of any disadvantages.  The only thing that would bother might be the extra thickness of the insulation.  Since the gap between the stator and the diaphragm is already so small, the added thickness makes the gap even smaller.


----------



## maxim87

Hi. I'm new on the forum.

A search on this thread found no answers. Can someone tried it? Sorry if it was already. 

I know that it is impossible to use a conductive diaphragm. But if we make an inverted electrostatic driver? where the stators is supplied +-300 volts, and the diaphragm recieves an acoustic signal. Advantages: simplifies amplifier, potentially dangerous voltage become farther away from the head. Disadvantages: it is not known how to behave nanometer conductive layer will not collapse when exposed to vibrations. I built a small test driver with active area of 5*5 cm, using a 6 micron aluminized Mylar and PCB for the stators. (in plans to make the stators are poorly conductive). Sounds good, after a month of work. What could be more disadvantages except the loss of electric contact over time?

p.s. in future ,when will be available large-area graphene films for headphones, other designs will be irrelevant, except inverted ES, am I right?


----------



## jgazal

Impossible is not appropriate. Once I asked that question in other forum and the answer I received is that although possible, the diaphragm mass increase and it is driven single ended which in consequence increase distortion levels. I would not know by which factor.


----------



## bruma

maxim87 said:


> Hi. I'm new on the forum.
> 
> A search on this thread found no answers. Can someone tried it? Sorry if it was already.
> 
> ...



Hi, there is at least one other option with the bias on the stator (one stator and 2 diaphragm's) shown in this page: http://www.resmayerling.be/electronica/headphone.html it allows the use of aluminized mylar and seems pretty easy to construct. I would be curious how it works.


----------



## chinsettawong

maxim87 said:


> Hi. I'm new on the forum.
> 
> A search on this thread found no answers. Can someone tried it? Sorry if it was already.
> 
> ...



That's interesting idea.  Can you show us what you have done so far?


----------



## Torac (Nov 27, 2017)

Hi, I'm also quite new to head-fi.

Firstly I want to congratulate wachara on his efforts, as his headphones are hugely impressive, and I appreciate the fact he is still active on this thread.

I have been reading this forum for quite a while now, just finished reading all 190 pages, which means I shouldn't repeat things said previously, hopefully. Everything done here is really impressive and I hope to make my own electrostatic headphones too sometime soon, probably in or just after December as I will have time off of college. I have access to a 3D printer and laser cutter at my college so I plan on using those to construct the headphones however I am trying to learn to 3D model a casing similar to the orpheus one made by wachara but am finding it difficult to replicate, especially as I am unsure of the limits of a 3D printer.

I also have one idea that I haven't seen posted in this thread yet. Inside the modern stax earspeakers I have read about their use of a free field eq that makes them sound like speakers in a huge room, I was wondering if anyone knows how to make one of these eq's as I have heard its effect in the l300, l500 and l700 and it sounds amazing.

Here is the model I have made, so far: https://drive.google.com/file/d/1EZt9uiKQctj7wiTE0e03FjR1q5UxWslj/view?usp=sharing


----------



## bui501-tech (Nov 27, 2017)

I’ve been spending my spare time over much of the last six months first learning how to make drivers for electrostatic headphones, and then trying to optimize and make my design consistently repeatable. I’ve finally settled on a couple of combinations (diaphragms, spacers, stators) that I really like. I still don’t have housings yet, but here are a couple of of the final divers (similar, but different).


The first version has an active area with a 70mm radius, 0.5mm thick spacers, and I was happy with it.



 

 

 

After over a dozen iterations, my final design has an active area with 75mm radius, an unperforated center on the stators, and 0.53mm thick spacers. 


 
 I was blown away by the transparency and soundstage the first time I heard it close up.  



Time to start on the housing and frame to hold these babies...


----------



## chinsettawong

Very nice.  Looking forward to seeing and listening the phones soon.


----------



## Muamp

Hi bui501-tech,

Really nice work on the stators, spacers and dust shields. 
Why do you close off the centre of the stators by using no holes, this is the first time I’ve seen this.....
And, what are you using to drive them? From the video I tried to see the energiser, but didn’t figure it out.

David.


----------



## bui501-tech

Muamp said:


> Hi bui501-tech,
> 
> Really nice work on the stators, spacers and dust shields.
> Why do you close off the centre of the stators by using no holes, this is the first time I’ve seen this.....
> ...


David,
On one of the iterations, I had used just slightly larger diameters for the holes on the stators and the max volume I got out of the drivers was lower than the ones I had made that had smaller holes.  So I thought I’d try a version where I’d leave even more surface area on the stators with uncut copper to drive the diaphragm. It worked better than I had expected: dramatically higher volume, much faster.  As a matter of fact I had to increase the spacer thicknesses because the diaphragm kept getting stuck to one of the stators because the force was so high.

I’m using a KGSSHV that I built to drive them.  Funny thing was, I had built that amp specifically because I had run across Chinsettawong’s thread (this thread) and saw the headphones he had built from scratch. His work was so awesome, I wanted to try to build my own headphones, but I needed an amp first to test and drive them, so that started the deep dive down the rabbit hole.

Cheers,
Vinh


----------



## janosch simon

Nice Build Vinh  which hole diameter you use? and what is the stator thickness? Cheers janosch


----------



## bui501-tech (Nov 29, 2017)

janosch simon said:


> Nice Build Vinh  which hole diameter you use? and what is the stator thickness? Cheers janosch


I’m using 1mm holes, and my stators are 1.575mm thick.  I had tried 1.5mm holes in an earlier version and didn’t like it as much.  I also have a bunch with 0.813mm thick stators with 1mm holes that came out well.


----------



## Torac (Nov 30, 2017)

Hi, I have just started designing my own headphones, here is the (hopefully) finished cad file for the stators and spacers:








Dimensions:
Width 103.5mm
Height 82.5mm

Is this any good?

Thanks, Matt


----------



## chinsettawong

Hi Matt,

Is your dimension the outer dimension or the active area's?  If it's the active area's, the width is a bit too much for the 0.5 mm thick spacer.

I think the active area of around 70 x 100 mm should be just nice. 

Wachara C.


----------



## Torac

chinsettawong said:


> Hi Matt,
> 
> Is your dimension the outer dimension or the active area's?  If it's the active area's, the width is a bit too much for the 0.5 mm thick spacer.
> 
> ...


 
Hi Wachara,

Those are the outer dimensions, the active area is:
Width 70.5mm
Height 91.5mm

The outer dimensions are determined by the earpad I'm choosing to use (brainwavz), would you suggest me to change the active area to what you said?

Thanks, Matt


----------



## chinsettawong

70.5x91.5 is good.


----------



## zzhetanay

[QUOTE = "bui501-tech, post: 13878053, участник: 451060"] Я потратил свое свободное время на протяжении большей части последних шести месяцев, сначала узнав, как создавать драйверы для электростатических наушников, а затем пытаюсь оптимизировать и сделать свой дизайн последовательно повторяется. Я, наконец, остановился на нескольких комбинациях (диафрагмы, проставки, статоры), которые мне действительно нравятся. Пока у меня еще нет корпусов, но вот несколько из последних дайверов (похожих, но разных).


Первая версия имеет активную область с радиусом 70 мм, прокладки толщиной 0,5 мм, и я был доволен ею.
[ATTACH = full] 2416568 [/ ATTACH] [ATTACH = full] 2416569 [/ ATTACH] [ATTACH = full] 2416570 [/ ATTACH]

После более чем дюжины итераций мой окончательный проект имеет активную область с радиусом 75 мм, неперфорированный центр на статорах и прокладки толщиной 0,53 мм.
[ATTACH = полный] 2416571 [/ ATTACH]
 Я был потрясен прозрачностью и звуковой сценой в первый раз, когда я это услышал. 

[MEDIA = YouTube] n2d7USCwI2E [/ MEDIA]

Время начинать с корпуса и рамки, чтобы держать этих детей ... [/ QUOTE]
Какое покрытие диафрагмы вы использовали?


----------



## chinsettawong

Hi zzhetanay,

Can you please use English?


----------



## zzhetanay

Ok.What layer of diaphragm cover did you use?Graphite?Nylon + phenol?


----------



## Torac

zzhetanay said:


> Ok.What layer of diaphragm cover did you use?Graphite?Nylon + phenol?


Neither, he uses anti-static gel screen cleaner or floor cleaner.


----------



## zzhetanay

thanks


----------



## bui501-tech

zzhetanay said:


> Ok.What layer of diaphragm cover did you use?Graphite?Nylon + phenol?



I used ACL Staticide 6500 spray.  It’s advertised by the manufacturer as a permanent spray that’s good for plastics.


----------



## zzhetanay

Thanks. How much did you apply it?


----------



## bui501-tech

zzhetanay said:


> Thanks. How much did you apply it?


This works for me:
I spray a very quick, short burst of coating on the diaphragm, spread it gently but evenly with a lint-free cloth, let it dry for 2 or 3 hours, go back and very gently spread/buff the semi-dry coating to prevent “speckling”, and then finally let it dry for the rest of the 24 hour recommended drying time.


----------



## zzhetanay

Thanks.You cover the two sides?For electrostatic panels, this method?


----------



## bui501-tech

zzhetanay said:


> Thanks.You cover the two sides?For electrostatic panels, this method?


Oh, no—I remembered that in one of his early posts, chinsettawong had advised just coating one side of the diaphragm, so that’s what I do for my drivers.


----------



## zzhetanay

Thanks.Coating durable?


----------



## 100VoltTube

Here's a cool idea: http://tubecad.com/2018/01/blog0407.htm


----------



## mrspeakers

Hey DIY folk, are you interested in our Stax Pro compatible amplifier plugs for your projects? We'd be happy to make them available if the answer is yes. 

They're solid machined Teflon with machined OFC gold plated pins and a solid AL casing. Works best with round cables, though with some craftiness flat cables can transition to the hole...


----------



## Jaab

I would be interested but it will depend of the price!


----------



## chinsettawong

Some pictures would be nice.


----------



## mrspeakers (Feb 11, 2018)

Price is TBD, as you can imagine this isn't a cheap high-volume part, so to keep the price attainable for the DIY we may only sell these direct to avoid excess markup.


----------



## bui501-tech (Feb 13, 2018)

chinsettawong said:


> I'm making a new pair of headphones.  This time I try to make the headphones with as less copper as possible - I etched out all the useless copper.  This helps reduce the capacitance on the headphones and makes them easier to be driven by an amp on high frequencies.  It's still a work in progress, but here are a few pictures:


Errr, Wachara - what are you using to hold the sandwhich of stator-spacer-spacer-stator together?  I've just noticed just now that your earlier drivers do not use screws to hold the components together.  I'm using nylon screws and nuts to hold the components together, and it works, but the screws and nuts require an extra 3mm of clearance on each side of the drivers, thus increasing the thickness of the earcups (which I do not like).


----------



## chinsettawong

Well, there are many ways to put the drivers together.  In my early build, I don't use the nylon screws to hold the drivers together.  That works fine too.  Later on after I have seen  how Sennheiser does it, I change my design.  However, I don't use the nuts though.  I simply use a bit thicker top plate and tap the holes on the plate so that I can just screw the nylon screws there.


----------



## bui501-tech

chinsettawong said:


> Well, there are many ways to put the drivers together.  In my early build, I don't use the nylon screws to hold the drivers together.  That works fine too.  Later on after I have seen  how Sennheiser does it, I change my design.  However, I don't use the nuts though.  I simply use a bit thicker top plate and tap the holes on the plate so that I can just screw the nylon screws there.


Oh, Wow!  I never thought to tap the stators -- GREAT IDEA, Wachara!  I'm going to give it a try.
-Vinh


----------



## chinsettawong

Well, actually it’s not the stator that I tap.  My configuration is like this: top plate, dust cover, stator, spacer diaphragm, spacer, and stator.  This top plate is actually the outer most ring that the whole set of driver is screwed fix into.  I also attach the ear pad on the other side of this top plate.


----------



## chinsettawong

@bui501-tech came to see me today at my office.  I showed him all my 3 versions of headphones, KGSS Carbon, and KGST.  He seemed to like my Omega clone and KGST a lot.  He did a very good job on his electrostatic headphones drivers.  They sounded really nice.  He also CNC his own Stax jack and cast the exact duplication of Stax plug.  One of these days I'll need him to come to teach me how to cast the plug.


----------



## bui501-tech

chinsettawong said:


> @bui501-tech came to see me today at my office.  I showed him all my 3 versions of headphones, KGSS Carbon, and KGST.  He seemed to like my Omega clone and KGST a lot.  He did a very good job on his electrostatic headphones drivers.  They sounded really nice.  He also CNC his own Stax jack and cast the exact duplication of Stax plug.  One of these days I'll need him to come to teach me how to cast the plug.



Thank you for an amazing afternoon, Chinsettawong!  I want more than ever to build my own headphones after hearing your headphones, especially the Omega clone.  Those were the best sounding headphones I've ever heard.  And of course, I now want my own tube amp after seeing your KGST in the wooden case.

We can make some plugs after I get back from vacation -- I've already ordered the teflon for the cores.


----------



## Whitigir

mrspeakers said:


> Hey DIY folk, are you interested in our Stax Pro compatible amplifier plugs for your projects? We'd be happy to make them available if the answer is yes.
> 
> They're solid machined Teflon with machined OFC gold plated pins and a solid AL casing. Works best with round cables, though with some craftiness flat cables can transition to the hole...



I will be interested in this for sure ! Waiting on the pricing and availability


----------



## chinsettawong

bui501-tech said:


> Thank you for an amazing afternoon, Chinsettawong!  I want more than ever to build my own headphones after hearing your headphones, especially the Omega clone.  Those were the best sounding headphones I've ever heard.  And of course, I now want my own tube amp after seeing your KGST in the wooden case.
> 
> We can make some plugs after I get back from vacation -- I've already ordered the teflon for the cores.



Let's get together again.  I'm really looking forward to listening to your headphones and KGST.

Since this afternoon, thanks to you, I've been researching on how to mold and cast things.  I think I get some ideas now.  I'll try to make something before you come back from vacation.  

By the way, I did notice that my Stax SR007 didn't get much of your ear times at all.  Did my phones sound better?


----------



## bui501-tech

chinsettawong said:


> By the way, I did notice that my Stax SR007 didn't get much of your ear times at all.



The omega clone sounds a lot better than the stax. I was seriously considering purchasing an Sr007based on its reputation, but hearing the side-by-side comparison of it with your headphones showed me it is possible to make DIY electrostatic headphones that are even better sounding.

I didn’t listen to your larger rectangular headphones as much because it was too large for my head, but I thought it sounded fuller than both the SR007 and your omega clone—you described it as having a wider sound stage, I think?  I really, really like that sound.  

I’m going to increase the size of my drivers.  I’m also going to try the 3μ mylar that I have as you had suggested.  What do you recommend as the max active area?  (I’m using .054mm FR4 as spacers.). So many things to try, so little time...


----------



## chinsettawong

Everything is relative.  With the standard Stax bias voltage of around 580V, for a round shape driver, a 80 mm diameter active area and 0.5 mm thick spacer is ideal.  

When we meet next time, please spend more time with my Orpheus clone and JF clone.  I'm sure that you'll come to like them better too.


----------



## statfi

Newbie to this thread...
Can anyone point me to an electromechanical equivalent circuit of electrostatic headphones?  I.e., something like the Thiele-Small model for loudspeakers applied to electrostatic headphones.
At what frequency is the fundamental drum-mode resonance of the diaphragm?  Pointing me to URL would be as good as a typed answer  !-)


----------



## MrSlim

statfi said:


> Newbie to this thread...
> Can anyone point me to an electromechanical equivalent circuit of electrostatic headphones?  I.e., something like the Thiele-Small model for loudspeakers applied to electrostatic headphones.
> At what frequency is the fundamental drum-mode resonance of the diaphragm?  Pointing me to URL would be as good as a typed answer  !-)


Good luck with that...
Some of the variables that  would have  to be  taken into account would be driver size, film thickness and tension, if you are looking at the resonant frequency of the driver. A manufacturer of  who is producing a consistent product may be able to tell you that, but it's difficult to imagine that they would  divulge that kind of info. 
Maybe mylar film mfrs provide those kind of details?


----------



## quintile

I will bite

I have repaired some Micro Seiki MS2 headphones, replacing the diaphragms.
I have found the best LF response comes from a diaphragm resonance of 270hz
witch seems very high I agree but thats my experience.

I use 2micron mylar and the diaphragm are about 50mm in diameter.

I would say that the LF response of electrostatic headphones is a mystery to me,
I have a set of parameters which seem to work but when I adjust any of the parameters
I cannot consistently improve the LF performance.

-Steve


----------



## chinsettawong

statfi said:


> Newbie to this thread...
> Can anyone point me to an electromechanical equivalent circuit of electrostatic headphones?  I.e., something like the Thiele-Small model for loudspeakers applied to electrostatic headphones.
> At what frequency is the fundamental drum-mode resonance of the diaphragm?  Pointing me to URL would be as good as a typed answer  !-)



I do not understand your question.  But if you want to see some frequencies response curves of some of my DIY headphones, here is the link https://www.innerfidelity.com/content/extraordinary-diy-electrostatic-headphones-chinsettawong


----------



## Muamp (Mar 14, 2018)

Hi Statfi,

An electrostatic panel can be considered as a capacitor, and behaves as if an equivalent capacitor of the same capacitance where to replace the panel.
The panel capacitance can be measured or calculated, Eo.Er.A/D
A = panel area, D = distance between plates (D = 2 * d, which is the distance from panel to diaphragm).
Normally the area would be multiplied by 2/3 or 3/8... depending on the panel to hole ratio.
All this and MUCH more is in the free book, by Frank Verwaal, the URL has been mentioned many times in this thread, but I cannot remember what it is without looking back.....

The resonant frequency can also be measured or calculated, the measurement method can give a wide spectrum of results but gives a ball park figure. Using a microphone, tap the diaphragm lightly and record the sound, even ‘Audacity’ can be used to see the frequency response and show the peak frequency. The resonant frequency will be dependant on the wavelength (2* shortest distance of panel surface), tension of diaphragm and mass of diaphragm. The resonant frequency will be the ‘peak’ in the response, not the LF cut off.

David.


----------



## jgazal (Mar 14, 2018)

statfi said:


> (...)
> Can anyone point me to an electromechanical equivalent circuit of electrostatic headphones?
> (...)
> Pointing me to URL would be as good as a typed answer  !-)



Try this:

https://web.archive.org/web/20150103093849/http://headwize.com:80/?page_id=722

Not sure if it is 100% accurate, but I guess it might be a good place to start.


----------



## statfi

Thanks so much for the references!  Forums work.  
I need to do a lot of reading here and there, but, for building loudspeakers the fundamental resonance is like the first thing you decide on.  With DIY 'stat's I imagine you have to control the tension on the diaphragm when you mount it to a ring.  Is the tension of primary concern, or is it sort of a secondary consideration?
(In another life I built a lot of loudspeaker systems.  In a future life I hope to build ES cans   !-)


----------



## Muamp

Hi jgazal,

Interesting link! especially the J.P. Wilson panel part.
It is the first time I’ve seen that electrical/mechanical equivalent circuit.
Also interesting, the spacer thicknesses he used 0.04” (1mm) and 0.025” (0.635mm) and assosiated comments.

David.


----------



## inuponken

Hi Chinsettawong,

Thank you for sending me the new double-sided stators and spacers for the Orpheus clone.
I made extra spacers with 0.8 mm PCB in case the 0.5 mm spacer is unstable with my diagram tension.



I need protect very thin moisture/dust cover film on the front, however sound clarity decreases if place a speaker grill to the front. It looks ugly, but I end up with a fiberglass window screen.



For the headband, I am modifying Sony MDR7506 Head Band that purchased at e-bay.
This is not genuine replacement part from Sony and quality is inferior to original, but it is good for the price.



Wood frames, the first one failed at drilling so I’m making another pair… painting now.


----------



## bui501-tech

inuponken said:


> Hi Chinsettawong,
> 
> Thank you for sending me the new double-sided stators and spacers for the Orpheus clone.
> I made extra spacers with 0.8 mm PCB in case the 0.5 mm spacer is unstable with my diagram tension.
> ...


----------



## chinsettawong

Hi inuponken,

It's great to see that you're moving so fast.  I really like your wood frame.  

I can't wait to see your finished headphones.  

I want to share with you a new trick I learn.  As you know, tensioning the diaphragms to be just right is extremely difficult.  I now tend to tension them just a bit more than I need.  Then I try them on the phones to see if the diaphragms have good stability.  I then apply a little hot air to the diaphragms.  This makes the tension reduces a little and it makes quite a lot of difference on the the bass.

Wachara C.


----------



## chinsettawong

Hi bui501-tech,

How is your progress on the new headphones?  Can't wait too see yours too.  

Wachara C.


----------



## bui501-tech

Hi, Chinsettawong, 
I'm still working on adjusting the tension to match the larger active area for my larger drivers -- you were right, of course, about the difficulty of getting the diaphragm to stay stable with the larger active area...  My first couple of attempts sounded great for about a minute or so, but then as soon as the volume went up, the diaphragm collapsed to one side.  I think I'm pretty close to a stable combination.  I've only got one test driver working correctly right now, but I should find out in a few days if it's repeatable.

-Vinh


----------



## edform (Mar 30, 2018)

A little off topic, but definitely to do with DIY Electrostatic Headphones...

I'm in process of building my own headphones and would like some advice on the right amplifier or energizer to buy for testing and use. It's obvious from this thread that a wide range of driver systems are in use by various forum contributors, so I hope that your collected knowledge might point me in the right direction.

My absolute top budget is £1500

1. I could buy a used Stax amplifier, probably an SR-006t; they turn up regularly on auction sites in the £600-£900 range, but it's pretty obvious from things you say here that some third-party amplifiers perform notably better. I have owned a couple of 006ts and found them pretty good with the older 400 series headphones I've had.

2. I could buy a third-party amplifier, but the ones with the reputations cost two or three times my budget.

3. I'm perfectly capable of assembling an amplifier from a kit - not from a schematic - but I have had zero luck in finding any kits that are not considerably more than my budget, even as kits.

4. I could buy a top-notch energizer, I'm intrigued by the iFi Pro iESL model, for example [See https://theaudiophileman.com/iesl/ ]

I'd value a short list of possibilities.

Just to keep this post a little nearer the subject of the thread, Here's a view of where my design is at...




All the metal parts are aluminium. The perforated stators are chemically milled and the stator support spiders waterjet-cut, and all the metal is gold-plated before the stators and their support spiders are bonded together. The insulating rings between the stator spider and the diaphragm carrier rings are also waterjet cut. All the bonds will be made with conductive epoxy, including the diaphragms to their metal support rings. The stators are 0.4mm thick with 1mm holes - I tried to use fine metal mesh but bonding it to the spiders didn't work, even using pre-cut film adhesive. The much more expensive chemically milled plates are the best alternative to maintain non-resonant acoustic transparency to as high a frequency as possible. The inside surfaces of the two stator plates are insulated with a thin layer of electrical varnish.

The narrow windows around the periphery of the stator assemblies leave the diaphragm edges un-driven.

The comparatively high cost of these parts is the main reason I must be economical with the purchase of a driver system.

These panels are intended to be used in a Jecklin Float arrangement - actually a hybrid of the Jecklin Float and the AKG K1000. They are quite large at 125x100mm and are asymmetric, even the stator spiders are off-centre on the stators both vertically and horizontally and are not concentric with any corner radii of the panels..

Ed Form


----------



## chinsettawong

Hi,

I'm sorry to let you know that you will not find a complete kit for the electrostatic amplifier anywhere.  There are many great DIY amp designs out there, but, unfortunately, you'll have to do your own homework and buy the parts to build one up by yourself.  With your budget, it's possible to build some very good KG amps such as KGST and KGSSHV Carbon.  

You've got a very interesting design on your stator.  Have you actually built one?  What is the width and height of your diaphragm?  What is the thickness of your spacers?

Please show us more.


----------



## edform (Mar 31, 2018)

chinsettawong said:


> Hi,
> 
> I'm sorry to let you know that you will not find a complete kit for the electrostatic amplifier anywhere.  There are many great DIY amp designs out there, but, unfortunately, you'll have to do your own homework and buy the parts to build one up by yourself.  With your budget, it's possible to build some very good KG amps such as KGST and KGSSHV Carbon.



I figured the DIY route to an amplifier was probably a non-starter. I do not have sufficient experience at building electronics to do it from a schematic, so I will have to buy something complete. Hopefully others might have suggestions.



> You've got a very interesting design on your stator.  Have you actually built one?  What is the width and height of your diaphragm?  What is the thickness of your spacers?
> 
> Please show us more.



I've been experimenting with design ideas for a few months now. I began by attempting to bond woven wire mesh to a rectangular aluminium plate stamped with open windows to simulate the stator to spider bond - I used normal epoxy on non-plated metal just to test practicality, but found I could not consistently achieve a flat bond with the wire mesh tight enough across the openings. At that stage I changed the design idea to making the stator as a chemically milled component in thin aluminium sheet and have now ordered some of these parts and some of the spiders, which are being milled from 2mm aluminium on a waterjet mill - there are inner and outer spiders with the perforated stator plates on opposite sides, and tabbed and non-tabbed diaphragm carrier rings to provide the required three terminals.

The diaphragm is 125x100mm with corner radii of 25mm, 40mm, 50mm and 15mm clockwise, beginning top left. It is carried between two 0.4mm aluminium rings of the same shape and 5mm wide, so the moving area of the diaphragm is 115x90mm with 20,35,45 and 10mm corner radii. I've ordered some of these rings as well.

The panel assembly is stacked with insulating rings each side of the diaphragm assembly, and then the stators assemblies, which have the perforated plates inside the spiders. Because the perforated stator plates are the same thickness as the diaphragm carrier rings, the spacing between perforated stator plates and diaphragm is set by the thickness of the insulating rings. I'm having a quantity of these made by click-cutting from 0.1mm Mylar so that I can play with spacing - the panel housing is a pair of plastic mouldings which are screwed together, clamping the panel-stack, so the assembly can be taken apart in a few moments to change spacing. I'll start with 0.5mm each side, but such large diaphragms may need a little more.

The layout of the panel assembly will be clearer in this view...




I should have all the parts in about three weeks from now and will post more then.

Ed Form


----------



## Ulfar4

Hi, I am building estats too, so i wanted to share with you, guys. It took me few months to get to this stage of build. Driver specs are 70mm active area, 0,6mm spacers and 3um mylar foil.


----------



## chinsettawong

Those drivers look really nice Ulfar4.

Please share with us more info.  I assume those are made of PCB, right?  Do you make them by yourself?  What is the amp you are using to drive those driver?


----------



## Ulfar4

Yeah, those are FR-4 drivers and I only drew it in Eagle and jlcpcb.com made it. Thickness is 1mm and it  is double sided with vias. The distance from center to center of the holes is 3mm and the holes are 1.5mm.




Amp is DIY too, it is simmilar to Senns HEV-70 amp, John Broskie hybrid amp and Dr. Gillmore helped me with feedback which i have badly designed. It is not very fancy, but I wanted something simple to start with. Maximum output is around 250 Vrms. Now I need to get proper heatsinks to try it more, and make some measurements.


----------



## chinsettawong

Hi Ulfar4,

Thanks for sharing your information.  Your stators and spacers are nicely done.  I really like them.   Looking forward to hearing your impression.

Wachara C.


----------



## bui501-tech

I still haven't built the headphone housing for the electrostatic drivers I've made yet, but I thought it would be fun to cut some acrylic frames for a set of PC/desktop speakers for them.  The speaker frame came out looking nice, and they sound really nice with the volume turned all the way up... not really enough bass to be the perfect desktop speakers, but the transparency and soundstage because of the electrostatic drivers sound really good to me.  I used some tiny-XLR sockets for the connections at the speaker frames' back -- there seems to be some capacitance issue with the way I've run the wiring inside the case...  Take a look at my photos.


----------



## chinsettawong

Wow!  Those look super cool!


----------



## FastAndClean

wow people making el stats like it is nothing, crazy thing considering the price of the good el stats those days


----------



## inuponken (Apr 1, 2018)

Diaphragms   0.8 mm and 0.5 mm.


 


 
 
Ear cups. used  t= 0.2 mm (0.5 Oz) lambskin.


----------



## inuponken

bui501-tech said:


> I still haven't built the headphone housing for the electrostatic drivers I've made yet, but I thought it would be fun to cut some acrylic frames for a set of PC/desktop speakers for them.  The speaker frame came out looking nice, and they sound really nice with the volume turned all the way up... not really enough bass to be the perfect desktop speakers, but the transparency and soundstage because of the electrostatic drivers sound really good to me.  I used some tiny-XLR sockets for the connections at the speaker frames' back -- there seems to be some capacitance issue with the way I've run the wiring inside the case...  Take a look at my photos.



Very nice!!!  Where you get the flat cables?


----------



## bui501-tech

inuponken said:


> Diaphragms   0.8 mm and 0.5 mm.
> 
> 
> 
> Ear cups. used  t= 0.2 mm (0.5 Oz) lambskin.


Ok... now I have to learn how to sew leather so I can make my own ear pad.  That is really cool, inupoken!


----------



## bui501-tech

inuponken said:


> Very nice!!!  Where you get the flat cables?


They are koss extension cables. $20+shipping from koss, but you can only order them by calling their customer service number.  I cut off the ends and molded a stax plug from a cast I made of the plug from my stax headphones.


----------



## chinsettawong

inuponken said:


> Diaphragms   0.8 mm and 0.5 mm.
> 
> 
> 
> Ear cups. used  t= 0.2 mm (0.5 Oz) lambskin.



Hi Inuponken,

Are you using those clips as weights?  I don't think you have enough tension there.  I once tried water bottles weighing around 0.75 KG each and the tension was still not enough.

Your wooden frame and ear pads look really nice.  Wow!

Have you put them together and played some music yet?

Wachara C.


----------



## mattmatt

Hi, anybody tried using aluminum sheets? I can source 1mm sheets here locally but I'm having 2nd thoughts about the spacers being too thick.


----------



## Muamp (Apr 14, 2018)

Hi Matt,

I have CNCed 1mm & 0.8mm aluminium sheet and also tried Gerber files to fabricate PCB on aluminium substrate board (I wrote about them earlier in this thread a while back, probably over a year ago). All these were not as good as my 1mm double sided FR4 stators. Predominantly flatness,... Still the best, in my experience (and most expensive) FR4 is the Bungard brand.

But, give the aluminium sheet a go, you may have different ideas and techniques which may produce better results....

Mmmm,... aluminium may not be a good choice for the spacers since they must be insulators.

David.


----------



## mattmatt

That's what in my mind too, hence using a paper between the stator and spacer as insulators. 

My main problem actually is the spacers being too thick, at 1mm using copper clad boards(PCB)

Also, anybody tried household food/cling wrap?


----------



## Muamp

Yes, 1mm spacers will be too thick for electrostatic headphones, bigger speaker panels ok.... although at this thickness you will not get squeal from dust!
There are many suppliers of FR4 in 0.5mm, 0.6mm, 0.8mm.
PCB fabrication houses will do 0.6, 0.8 and 1mm as standard, just send them your Gerber files. If you send to PCBway.com, the one I use, they are high quality and cheap.

I have, along with many other DIYers, tried ‘clingfilm’ or any of the other brand names. My results have been very good. Easy to tension, easy to glue to spacers and since it has elasticity it is good with bass. The longevity is not as good as Mylar. My choice is 2um Mylar, but others use various other thicknesses.

David.


----------



## mattmatt

Would it be okay if I ask what would be the consequences if I use 1mm spacers? Also, the standard PCB here is 1.5mm. would it be okay to use that for the stators or best to stick with 1mm? 

I actually don't want to do shipping for my materials. It's too much of a hassle here in our place that's why i want to source things locally.


----------



## chinsettawong

Hi mattmatt,

With thick spacer, you need to use high bias voltage and step up transformers for your amp.  The 1.5 mm stators are fine too.

Wachara C.


----------



## edform (Apr 14, 2018)

mattmatt said:


> That's what in my mind too, hence using a paper between the stator and spacer as insulators.
> 
> My main problem actually is the spacers being too thick, at 1mm using copper clad boards(PCB)



The performance of stators is a wonderfully complex field with boundaries imposed on transmission by thickness of the plates, percentage of open area though the plates, and distance between the holes These three boundary parameters interact to generate

1. Resonances analogous to the transmission variations in a Fabry–Pérot optical interferometer, improved by decreasing the spacing between the diaphragm and the stator - which has severe limits, obviously.

2. Exaggeration [spreading] of the resonant effects by coupling between the air-masses of the closely spaced tubes and by interaction between the hole-end effects on inner and outer stator surfaces, improved by moving the holes apart - but then no sound gets through, and by making the plates thin - but thin enough means the plates cannot support themselves, which is bad, and become self-resonant, which is bad also.

3. Diffraction effects, where sound from each element of area traveling outwards through a directly facing hole is interfered with by sound that has travelled from the same element via the holes surrounding the primary hole and arrives with slight delays and subtracts or adds to the output of the main hole depending on frequency - It's a complex two dimensional comb-filter system and messes with the HF end.

The best-case combination of all these parameters is actually a very thin plate with a large proportion of open area generated by very large numbers of small holes that are very close to each other - screen-printing wire mesh is absolutely ideal acoustically* but* it has no mechanical strength. The mechanical issue of fixing such a stator in space is a problem that has been addressed in the Hifiman Shangri-La [actually it's quite a crude version of the mesh], so it can be done. The standard argument about lots of holes diminishing field strength is a red-herring with fine wire mesh - look at the protective guards round ultra-HV test facilities, the artificial lightning doesn't get through even though the mesh is high open area.

So, to focus on your idea, thin aluminium plates are a valid way to go - thin is good - but keeping them flat is an issue - it's dealt with in the Stax SR009 by bonding the thin plates to a thick but substantially open spider of the same metal, and is one approach I'm taking - incidentally, I'm amused by a number of 009-style designs in this forum that omit holes where the 009 has ribs - the ribs aren't there to block holes, they're there to reinforce the plates; in plates that do not need to be reinforced the rib positions should be filled with holes!! The possibility that the blank areas are used to control diaphragm resonances, which some may have thought, is certainly not true in the case of the 009 where the spider layout is symmetrical and would tend to favour some higher order resonances if such a mechanism were at work.



> Also, anybody tried household food/cling wrap?



I'm more inclined to wonder why no one has hit on the static dissipative films that have the right level of surface resistivity without needing coatings. Hard to use them in production because minimum purchasable quantities are ridiculous, but blagging samples is not too difficult and even an A4 scrap is several diaphragms.

Ed Form


----------



## bui501-tech

edform said:


> The performance of stators is a wonderfully complex field with boundaries imposed on transmission by thickness of the plates, percentage of open area though the plates, and distance between the holes These three boundary parameters interact to generate
> 
> 1. Resonances analogous to the transmission variations in a Fabry–Pérot optical interferometer, improved by decreasing the spacing between the diaphragm and the stator - which has severe limits, obviously.
> 
> ...




Or MattMatt, 
You could just dive right in and try out your idea, adjusting, trying again like I did after stumbling onto this post almost two years ago. It’s part of the fun of DIY.  For me, I’ve settled on .5-ish mm FR4 pcb stock as spacers and Mylar membranes just like Muamp had described earlier.


----------



## Muamp (Apr 14, 2018)

Hi Ed,

I am one of the DIYer’s who has made FR4 stators with the spokes in a style of the 009s, but with my stators the spokes were not there for the purpose of reducing holes in the stator as you thought, no, they are there to add to the stiffness and rigidity of the stator, the stator being the thinnest FR4 I can get away with whilst still being rigid enough.

I have listened to the Shangri La and I was amazed at how good they sounded, with the wire stators similar to how you intend to make, but I am also very impressed with the 007s. The 007s are still one of my all time favourites along with my DIY Spyders. I have learnt the real test is in the listening.

Static dissipative films that I have seen are all too thick to be diaphragms. I did think of trying some, but not ever found any suitable.

David.


----------



## mattmatt

I still have problems with acquiring 0.5mm thickness FR4 for spacers. I think I can source here stainless steel and have it laser cut. I'll use FR4 with 1.5mm thickness for the stators. Because of stainless steel is also a conductor, I'll make the cut the inside ring slightly bigger than the active area of the stators. Would that be okay? Here's my design as of the moment for the spacers and stators.


----------



## edform (Apr 15, 2018)

Muamp said:


> Hi Ed,
> 
> I am one of the DIYer’s who has made FR4 stators with the spokes in a style of the 009s, but with my stators the spokes were not there for the purpose of reducing holes in the stator as you thought, no, they are there to add to the stiffness and rigidity of the stator, the stator being the thinnest FR4 I can get away with whilst still being rigid enough.



 I was only joshing - you guys have what are plainly fine-sounding, working cans: I've got lots of background knowledge and big dreams!



> I have listened to the Shangri La and I was amazed at how good they sounded, with the wire stators similar to how you intend to make,



I've already done some work on using mesh, but I've not yet had any success with the process of stretching the mesh out flat and uniting it to a support structure. I attended the MACH advanced manufacturing show on Thursday and was intrigued to find that my two piece stator design of a chemically milled perforated plate and a laser cut support spider could actually be replaced with a one-piece 3D-printed aluminium part. Several companies were willing to make the item - but some objects I saw displayed gave me new ideas for a much lighter stator with tall, slender ribs embracing much more of the plate area while occluding a distinctly smaller area than the clumsy laser-cut spider design I had gone for up to this point.

Ed Form


----------



## edform

mattmatt said:


> I still have problems with acquiring 0.5mm thickness FR4 for spacers. I think I can source here stainless steel and have it laser cut. I'll use FR4 with 1.5mm thickness for the stators. Because of stainless steel is also a conductor, I'll make the cut the inside ring slightly bigger than the active area of the stators. Would that be okay?



Why not use a non-conductor? You can get Mylar/Melinex in thicker sheet and I think it will laser cut, although it would probably be cheaper to talk to a company that does click-cutting and have a steel-rule tool made. I'd be surprised if you couldn't find someone to make you the tool for less than 100$ and the production process is really cheap. My diaphragm area is quite big and I don't know whether 0.5mm will be OK, so I'm going this way for insulators and having them made in a thin grade which I can stack to determine a safe working clearance.

Ed Form


----------



## Azrael3000

As promised we made a guide on how to build your electrostatic headphones without needing to read close to 200 pages of forum posts.
You can find our very first version here: https://github.com/Azrael3000/headphone-guide or read the pdf directly: https://github.com/Azrael3000/headphone-guide/raw/master/guide.pdf

This work is under a CC license, so everybody can copy, modify and redistribute this document (with some minor constraints). If you have comments on how to improve it feel free to let us know either on the dedicated forum thread: https://www.head-fi.org/threads/electrostatic-headphone-construction-guide.877412/ or on Github.

Cheers,
Arno


----------



## chinsettawong

Hi Arno,

That's very well written document.  Thanks for putting it together and sharing it with us.  I'm sure this will help the beginners a lot.  

Wachara C.


----------



## chinsettawong

mattmatt said:


> I still have problems with acquiring 0.5mm thickness FR4 for spacers. I think I can source here stainless steel and have it laser cut. I'll use FR4 with 1.5mm thickness for the stators. Because of stainless steel is also a conductor, I'll make the cut the inside ring slightly bigger than the active area of the stators. Would that be okay? Here's my design as of the moment for the spacers and stators.



Your design looks nice.  But if I were you, I would use FR4 for both stators and spacers.  I don't see any advantage of using either stainless steel or aluminium.  The FR4 of the right thickness isn't that difficult to source.  Let me know if you really can't find them.


----------



## inuponken

bui501-tech said:


> They are koss extension cables. $20+shipping from koss, but you can only order them by calling their customer service number.  I cut off the ends and molded a stax plug from a cast I made of the plug from my stax headphones.



Hi bui501-tech, thank you for your information.

It was over half a year ago, they refused to sell it again… When I called them again, they accepted the order this time. ???
I was planning to cut and use my 5m original STAX extension cable.


----------



## inuponken

chinsettawong said:


> Hi Inuponken,
> 
> Are you using those clips as weights?  I don't think you have enough tension there.  I once tried water bottles weighing around 0.75 KG each and the tension was still not enough.
> 
> ...



Hi  Chisettawong,

I have to re-build the front plates to attach the ear pad and it took time to reorder new material.

About the tension,
This is my method that after repeating trial and error.
Please take my method just for reference…

1. Add tension just enough to disappear large wrinkles on the 3um mylar film.
I do not use weights, only added small clips as the previous photos.

2. After the adhesive (contact cement) has dried, apply heat to the mylar with a 1875W hairdryer. 
Continue to heat until the small wrinkles are not come back after cooling.
It is necessary to heat for quite a long time (total >10min.) otherwise wrinkles will come back again after cooling.
While heating, the hair dryer becomes too hot and the thermostat turns off many times… 

I used the same method to my Omega clone, 2 set of JF clone and modified JF clone but they are very stable.


----------



## chinsettawong

Hi Inuponken,

Wow, having to apply heat from the hair dryer for that long isn't fun.  By the way, what spacer thickness are you using?

I use an industrial heat gun for heat treatment if I need to.  It's much hotter.  You can't blow it on a single spot for more than a second or two.  Otherwise, it'll burn through the diaphragm.


----------



## inuponken

chinsettawong said:


> Hi Inuponken,
> 
> Wow, having to apply heat from the hair dryer for that long isn't fun.  By the way, what spacer thickness are you using?
> 
> I use an industrial heat gun for heat treatment if I need to.  It's much hotter.  You can't blow it on a single spot for more than a second or two.  Otherwise, it'll burn through the diaphragm.




0.5 mm.
When the bias voltage becomes 380 V or more, the diaphragm sticks to the stator. I am adjusting the tension now.
The first impression of listening at the bias voltage of 350 V is, there is more presence than my omega clone.


----------



## inuponken




----------



## chinsettawong

inuponken said:


>


Very nice!  I very much like you to try to stretch the diaphragms more plus up the bias voltage and see if you like the sound better.


----------



## inuponken (Apr 20, 2018)

I gave up 0.5 mm… I tried strengthening the tension until the PCB bends, but still sticking to the stator at 450 - 500 V. I ordered 0.1 mm sheets to make shims and try to make it with 0.6 mm space. Probably I can increase the bias voltage to 600 V with the same tension.

I’m listening with 0.8 mm spacers now and there is no problem even if the bias voltage is increased to 800 V.
Wider spacing reduces efficiency but no problem with my DIY-T2 and KGSS Carbon.
It is very wide range sound! I like it very much!!!


----------



## chinsettawong

Well, you just haven't found its sweet spot yet.  

I know it's not very easy, but it certainly achievable. 

Oh, by the way, the wood housing might bend a little because of the humidity.  So when you screw the front baffle onto the wood, you don't want to screw it in too tight.


----------



## Ulfar4

I have some progress with the housing. I only need to add mesh grill and headband and screw it together.


----------



## jgazal

edform said:


> The performance of stators is a wonderfully complex field with boundaries imposed on transmission by thickness of the plates, percentage of open area though the plates, and distance between the holes These three boundary parameters interact to generate
> 
> 1. Resonances analogous to the transmission variations in a Fabry–Pérot optical interferometer, improved by decreasing the spacing between the diaphragm and the stator - which has severe limits, obviously.
> 
> ...



I am curious to know what is the difference of thickness between these stators... Any guess?


----------



## chinsettawong

Ulfar4 said:


> I have some progress with the housing. I only need to add mesh grill and headband and screw it together.



Very nice!  How do you like the sound?  What amp do you use to drive them?  Are you using 0.5 mm spacers?


----------



## chinsettawong

Hi jgazal,

As far as I can tell, the color is different - one is gold and the other one is silver.


----------



## edform (Apr 21, 2018)

jgazal said:


> I am curious to know what is the difference of thickness between these stators... Any guess?



The construction of the 009 stators is pretty complex - careful examination of the edge of the inner aperture suggests there are three layers - a perforated disk and two stacked spiders - and the parts are diffusion brazed. On inspection, the metal thickness of the perforated plate appears to be about 0.3mm. This is an estimate, and someone would have to be willing to hazard several thousand $ worth of headphone by dismantling them in order to be any more precise.

The sandwiched spider component of the three parts is almost certainly a precision-cut layer of brazing material. I talked to a UK company at the MACH 2018 show in Birmingham last Thursday, who specialise in the process involved, and they have since indicated to me that they'd be willing to try joining my parts in this way, but the projected costs are substantially too high and I can't justify them. I reckon STAX have built their own vacuum oven to carry out the bonding in house. Conductive epoxy, while certainly not cheap, is positively reasonable compared to the prices quoted for diffusion brazing.

The ring of holes around the periphery of the reinforcing spiders, which leaves an area of the diaphragm substantially undriven, is acoustically desirable - the edge of the diaphragm is stationary and wasting drive energy on it, and the area immediately inside it, is a distortion inducing mechanism. The hexagonal hole in the centre is interesting, but I cannot see any acoustical benefit in it, although it would be easy for the chaps who are producing their stators with circuit-board to examine the difference it makes.

Ed Form


----------



## chinsettawong

I really wonder about how the thinner stators make the sound better.


----------



## jgazal

edform said:


> (...). The hexagonal hole in the centre is interesting, but I cannot see any acoustical benefit in it, although it would be easy for the chaps who are producing their stators with circuit-board to examine the difference it makes.
> 
> Ed Form



Believe it or not, I recall somebody saying that stators get hot and that hexagonal hole was made to help with air flow. 

If it helps to refrigerate, how can it not affect sound?



chinsettawong said:


> I really wonder about how the thinner stators make the sound better.



I am also trying to understand what has evolved.


----------



## edform (Apr 21, 2018)

chinsettawong said:


> I really wonder about how the thinner stators make the sound better.



1. The air in the holes is a mass bouncing on the spring of the air between the diaphragm and the inside of the plate; it constitutes a low pass filter with resonant misbehaviour of the comb filter type. Worst case is small holes in a thick plate, bigger holes are better, thinner plate is better.

2. The difference in path length for sound leaving the plate via the hole directly in front of any element of area of the diaphragm and sound from the same area that exits through the holes adjacent to the one directly in front is worse with a thick plate and is a low pass filter with periodic, wavelength-dependent misbehaviour.

Both effects are diminished, and pushed very high in the frequency range for an infinitesimally thin plate with a high open area.

Ed Form


----------



## edform

jgazal said:


> Believe it or not, I recall somebody saying that stators get hot and that hexagonal hole was made to help with air flow. If it helps to refrigerate, how can it not affect sound?



I didn't say it would not affect the sound, I said I couldn't see a sound quality benefit. I hadn't thought about heat generation and will have to measure what sort of temperature rises occur.


> I am also trying to understand what has evolved.



Not sure what you mean here.

Ed Form


----------



## jgazal (Apr 21, 2018)

edform said:


> Not sure what you mean here.
> 
> Ed Form



I mean the improvements in SR-009s.

@padam translated Stax claims:



padam said:


> http://www.audiotuning.com/images/Stax/Stax-SR-009S-Pi-UVP-170418.pdf





padam said:


> Sound element with new fixed electrodes
> 
> If the fixed electrode becomes infinitely thinner, the air resistance will be decreased and the permeability of sound waves will be improved. On the other hand, thinner electrodes are poor in rigidity and suffer from vibrations of their own and the sound becomes muddy. The SR-009S evolved further the electrode established in the SR-009 as the integration of present technology. The edges of electrode hole were smoothened through after-etching processing to reduce air resistance, and the permeability of sound has been much more improved. Moreover, gold plating processing with large specific gravity further decreased the electrode vibration. Finally, the sound clarity has been achieved by reducing the resistance of electrode itself.
> 
> ...


----------



## edform (Apr 21, 2018)

jgazal said:


> I mean the improvements in SR-009s.
> 
> @padam translated Stax claims:



1. The perforated part of the stator is very thin which is good.
2. The edges of the holes in the perforated part have been post-etched, which I think means they have been radiused chemically like the square holes this drawing...





This will diminish the influence of tube-end effects which tend to interact across the two plate suraces, effectively coupling the air masses in adjacent holes and tending to lower and spread the cut-off point of the low pass filter formed by the air in the holes bouncing on the driving force at resonant intervals.

Ed Form


----------



## jgazal (Apr 21, 2018)

edform said:


> (...)
> 2. The edges of the holes in the perforated part have been post-etched, which I think means they have been radiused chemically (...)
> Ed Form



Edit: now I read it carefully and you are right.



padam said:


>





>





Julez said:


>





jgazal said:


> (...)
> So as far as I understood the claims are more spaced mesh, smoothing the edges of the holes in the stators (not sure if the perforated part of the stators has a different thickness), reducing resonance with gold plating and lowering earcup thickness to its optimum. I guess there is a reason to use the world evolutionary instead of revolutionary.
> (...)


----------



## edform (Apr 21, 2018)

jgazal said:


> Edit: now I read it carefully and you are right.



Someone has been very naughty with amplifier output on the poor set of 009s in that last image - they have been arcing all the way to the repair shop. I'm not sure where you got the images jgazal, but they're very revealing. Thanks for posting them.

I'm amazed that the inside surface of the stators is not lacquered or insulated in any way.

The gold plating has a single, significant advantage - it is very easy to connect to, where aluminium is not: aluminium's all-but-irremovable oxide layer can develop quite bad diode characteristics at joints. It is also possible that gold on the surface of aluminium parts that are to be brazed together will kill the oxide layer and protect against it reforming, then the gold will simply alloy into the brazed joint - this could be quite a significant production aid.

Ed Form


----------



## jgazal

edform said:


> Somefone has been very naughty with amplifier output on the poor set of 009s in that last image - they have been arcing all the way to the repair shop. I'm not sure where you got the images jgazal, but they're very revealing. Thanks for posting them.
> 
> I'm amazed that the inside surface of the stators is not lacquered or insulated in any way.
> 
> ...



If you click in the top left corner of the quote box you will be redirected to the original post and thread.

I initially thought that hexagonal hole was there to improve resolution. But I am no expert and every knowledge people I read from say it does not improve anything acoustically. Perhaps that hexagonal hole only helps in certain steps of the stators production process. 

I presume joints are made right after some kind of sanding in the connector.  Do you believe some units had imbalance due to oxidized joints?  

Everything you wrote seems plausible to me and matches what I previously know about the subjects.


----------



## edform

jgazal said:


> If you click in the top left corner of the quote box you will be redirected to the original post and thread.
> 
> I initially thought that hexagonal hole was there to improve resolution. But I am no expert and every knowledge people I read from say it does not improve anything acoustically. Perhaps that hexagonal hole only helps in certain steps of the stators production process.
> 
> ...



Soldering to aluminium is a well developed process, but it isn't always terribly reliable. It's one of the reasons that copper-coated aluminium wire is used in loudspeaker voice coils - it's a doddle to solder.

Ed Form


----------



## jgazal




----------



## jgazal (Apr 24, 2018)

Seeing the thumbnail in the 009s official page, the post-etching seems so subtle that I could swear most of the smoothing comes from the gold plating itself...

Actually it seems I am wrong: Designing for gold plating


----------



## evalon

Hi all,

Just wanted to link to this article which covers HF phenomena related to ESL design - although written mainly with loudspeakers in mind I would say that it is also relevant for headphones. I find it to be very practically oriented, yet also with theoretical sections that shed some light on what is actually going in in terms of relating a practical physical design to an expected response. 

Unless one is a member of the AES it is a "pay for" article, yet where I live the library was able to help with a copy. 

http://www.aes.org/e-lib/browse.cfm?elib=18782

Cheers,

Jesper


----------



## chinsettawong

Hi Jesper,

Can you please summarize what you think is good to know from the article?


----------



## edform (May 15, 2018)

chinsettawong said:


> Hi Jesper,
> 
> Can you please summarize what you think is good to know from the article?



Taking this forum to be an educational facility in which citations from technical papers are appropriate [tongue firmly in cheek here] , it seems reasonable to publish the paper's conclusions...

**********************************
This paper develops an improved model of the high audio-frequency acoustic transparency of ESL assemblies and demonstrates a method for measuring the transparency. The ESL model includes the membrane, the two perforated plate stators, the damping cloth, and easily incorporates any grills and dustcovers, if required. The model development begins in Sec. 2 by collating acoustic models of the individual components: the membrane, the perforated plate, and damping cloth. The model of the perforated plate is improved from that of Baxandall by eliminating an inappropriate approximation for perforated plates with a high open-area fraction, by including the Fabry-Perot resonances in the holes, and by correcting a small numerical error in the approximation for the hole-end effects. The origin of the Wood anomaly and means for avoiding it are also explained.

The response of the complete ESL assembly is complicated and not amenable to a simple algebraic description. It is found that an electrical-analogue model, including lossless-transmission-line components, provides a good description of the complete assembly and is easily solved using SPICE software. The collective behavior of the components is found to be very different from the sum of the effects of each component due to the reflections that occur between the surfaces of all of the components. Therefore, the response of an ESL at high-frequencies cannot be determined solely from the attributes of the components taken in isolation.

*The expression for the reactance of the stators provides a good guide for the stator design; the stator thickness should be minimized, the hole size should be small to minimize hole-end effects but larger than 1 mm diameter to minimize frequency-dependent damping effects, and the open-area fraction should be modestly high to ensure that acoustic impedance changes and reflections occurring at the stator surfaces are minimized. *

Although the ESL model is one dimensional, and therefore cannot properly model hole-end effects and diffraction effects, comparisons between the model and measurements of two different ESLs show that the model provides a good guide to the high-frequency response. In particular, the high-frequency peaking often observed in ESL responses, and usually attributed to the transformer resonance, may often be due to inter-component reflections.

*The overall trend of the high-frequency response of an ESL assembly is determined by the membrane mass, much as given by the low-pass filter response. Superimposed on this response are the complex, almost chaotic, ripples arising from the reflections between the various surfaces in the assembly. The amplitude of the ripples in the response are determined largely by the impedance mismatch between the air and the stator holes and range from about 2 dB for very open stators to about 15 dB for stators with a low open-area fraction. The distances between the various reflecting surfaces, and the overall thickness of the assembly, should be minimized to ensure the peaks and dips in the response occur at the highest frequencies.*
*******************************
For information

The Fabry-Perot resonance effect is the source of roll-off and pronounced peaks and troughs above a frequency dependent on the configuration of the plate perforations.

The Wood Anomaly occurs for situations where the wavelength and the grating spacing are the same and gives rise to waves traveling across the surface of the plates allowing zero and first order surface waves to destructively interfere. It produces an initial very sharp dip in output and greatly reduced output for all higher frequencies.

Both effects were first observed in the field of optics but the analogy with acoustical effects is direct and fully explains observed performance of inappropriately configured stators. Headphone radiators, which are small, are only troubled by these effects at very high frequencies since the wavelength of sound at 20Khz is 17mm - rather a big hole spacing for a headphone stator. The other effects discussed in the paper are more important and the general guidance contained in the conclusions shows how to minimize them.

I hope this is helpful.

Ed Form


----------



## evalon (May 15, 2018)

Hi Ed ... Well, I won't add much other than a bit of additional information that I personally find interesting: The free air "band-width" of a 1 um mylar membrane is 97 kHz and it derates linearly with thickness. Thus, a 3.5 um membrane will have a roll off frequency of ~28 kHz. Personally, I also find the article to be most interesting due to the - to me - accessible theory sections which IMHO give a good explanation (and possibly understanding) of why these phenomena lead to any given response.

Cheers,

Jesper


----------



## -JFK-

Hi all,

Based on Young's modulus (rigidity), the FR4 is around 20-30Gpa.
The aluminium is around 60-70Gpa.

I have read many post ago that the aluminium stator as been "aborted" because of the cost and the "finish" done by the process used. (I am right ? I have forgget something ?)
Now, I have my own CNC (24000tr), I'll be able to mill aluminium.
Yes, it cost a bit more, but with a well setted CNC, I should be able to make it "clean".

So, aluminium seem's to be a good choice ?
Thank's


----------



## Garuspik

Thin aluminium + any cnc\or laser cutter + sandblasting = great result.


----------



## chinsettawong

-JFK- said:


> Hi all,
> 
> Based on Young's modulus (rigidity), the FR4 is around 20-30Gpa.
> The aluminium is around 60-70Gpa.
> ...



Go for it and let us know the result.


----------



## Muamp

Hi JFK,

As you state, aluminium is much more rigid than FR4 (for the same thickness of materials), but flatness is also important. A while back I had some aluminium stators made to the same spec as my FR4 stators, which were PCB fabricated using 0.8mm aluminium substrate PCB + dielectric + 0.35mm Cu single sided. The 0.8mm aluminium stators were rigid, but not usable on grounds of flatness! So I did not use them.
I have since bought 0.8mm and 1mm aluminium sheet that I mean to get round to CNC sometime.

Hi Ed,

Just finally sourced 200 ‘sample’ gold pins for making ‘Stax’ pro plugs and cables. They look as good as the expensive pins I source in the UK, but these are from a company in Shenzhen and very cheap. I will measure the pins tonight to see if they are exact / good enough.... If the pins are acceptable, I should be able to source these pins easily to make plug/cables reasonably cheaply.

David.


----------



## chinsettawong

Muamp said:


> Hi JFK,
> 
> Hi Ed,
> 
> ...



Do let me know too, David.


----------



## edform

Muamp said:


> Hi JFK,
> 
> As you state, aluminium is much more rigid than FR4 (for the same thickness of materials), but flatness is also important. A while back I had some aluminium stators made to the same spec as my FR4 stators, which were PCB fabricated using 0.8mm aluminium substrate PCB + dielectric + 0.35mm Cu single sided. The 0.8mm aluminium stators were rigid, but not usable on grounds of flatness! So I did not use them.
> I have since bought 0.8mm and 1mm aluminium sheet that I mean to get round to CNC sometime.
> ...



Good news.

Ed Form


----------



## janosch simon

hey gang  did you see  the video of mrspeakers voce? looks very nice would love to know what kind of damping materials he uses any idea? also would be great if i sells the cable and conector would fit great to my just finished alpha centaury V6 esl amp  and boy does it sound better the my energizer bench setup 

cheers and thx janosch


----------



## chinsettawong

Hi Janosch,

I personally don't like to use any damping material, but that's just my personal preference.

Can you show us your Alpha Centuary V6 ESL amp?


----------



## janosch simon

sure thing buddy  a propper case is missing but i had to test it  the V6 is not available anymore and it had some pcb errors but the designer andreas rauenbühler was so helpfull on the way building it that i can hear now music  this diy esl amp project was wayyyyyy over my skills but i grown with the project  the amp is fed buy an diy streamer with an  soekris dam1021 dac i use the balanced xlr inputs because over rca i got some nasty ground loups  next step is including a volume knob cause i cant change the volume digitaly with my picoreplayer no idea why 

with this amp i can now go back and realy optimize my esl! lot to do but so much joy 
cheers janosch


----------



## chinsettawong

Do you have the schematic diagram?  What tubes are you using?

It looks like a simple amplifier to make.  Congratulations!


----------



## janosch simon

chinsettawong said:


> Do you have the schematic diagram?  What tubes are you using?
> 
> It looks like a simple amplifier to make.  Congratulations!


http://www.high-amp.de/html/hybrid-amp_eng.html shure but its a total diy project and the schematic is very very sensitive nothing for a noob like me D
now im a advanced noob 
the v6 (which is show in the picture) uses EL84 tubes v7 which is now online has 6SN7 tubes and in adreas opinion they sound more tube analog like 

to build the amp you need also his PWS 5.5 and the add-on for the Alpha Centauri which includes the heating for the tubes 

cheers janosch


----------



## YVWM47

Amp looks amazing


----------



## Muamp

Last week I mentioned that I would measure the pins for making Stax 5 pin pro plug/cables.
Been a bit busy so only just got round to it; the pucca Stax pins are identical to XLR 3 pin plug pins, which have a diameter of 2.4mm. The pins I have sourced measure 2.5mm in diameter. I have tried them in all my energisers and they seem okay.
It was my intention to make up 20-30 plug/cables for sale, but recently I have been so busy, and probably will continue to be busy for some time..... I probably will not get around to it. So what I can do is send some pins to DIYer’s on this thread who have posted photos of their work who would like to try them. I do not want any money for the pins, provided you will use them.

David


----------



## bruma (May 25, 2018)

Muamp said:


> Last week I mentioned that I would measure the pins for making Stax 5 pin pro plug/cables.
> Been a bit busy so only just got round to it; the pucca Stax pins are identical to XLR 3 pin plug pins, which have a diameter of 2.4mm. The pins I have sourced measure 2.5mm in diameter. I have tried them in all my energisers and they seem okay.
> It was my intention to make up 20-30 plug/cables for sale, but recently I have been so busy, and probably will continue to be busy for some time..... I probably will not get around to it. So what I can do is send some pins to DIYer’s on this thread who have posted photos of their work who would like to try them. I do not want any money for the pins, provided you will use them.
> 
> David


what cable did you intend to use? I ask, because I would need a new cable and did not find anything adaequate in Austria. I have the pins already (taken from xlr plugs) but I need the cable.
Markus
PS: Koss delivers not to Austria, the Koss extension cable would be my first choice.


----------



## Muamp

I use Unistrand 3726 Black Silicone Rubber Wire 0.25mm 25m Reel (Reference 3726) from Rapid Electronics, part number 01-8050.

I use the wire in a 6 wire 3 way plait as shown in photos of my Spyder ‘stat photos in this thread, and also on my website www.muamp.com.

The cable in this manner is very low capacitance and very light and flexible. It is much better than the cables I used on my earlier ‘stats.

David.


----------



## Ulfar4

Hello guys, how do you measure the capacitance of the stats?
I'm going to finish my amplifier and headphones right now, so then I will post some pictures here.


----------



## Muamp

Hi Ulfar4,

I use an LCR meter and measure between the two stators. I use the DE-5000 which is very accurate. Some multimeters have a capacitance range, but multimeter accurracy is much lower,
If you don’t have access to any meters, then you can calulate it, it is the same as calulating the capacitance of a flat plate capacitor:


C = EoEr (A/d) [F]

A is the area of the plates,  d is the distance between the plates (if you have 0.5mm spacers, then the distance is 1mm), EoEr = 8.85×10−12 F/m.

since there are holes in the stators, you need to take this into consideration when calculating the area of the stators.

David.


----------



## Ulfar4

Thanks, my multimeter does not measure that low capacity, but I have access to much better equipment at university so I'll measure it there.


----------



## bruma

Muamp said:


> I use Unistrand 3726 Black Silicone Rubber Wire 0.25mm 25m Reel (Reference 3726) from Rapid Electronics, part number 01-8050.
> 
> I use the wire in a 6 wire 3 way plait as shown in photos of my Spyder ‘stat photos in this thread, and also on my website www.muamp.com.
> 
> ...


Thanks a lot for your fast answer! I would have to pay 28 Pounds for delivery, so I will wait till I need additional parts and place the order. Atb, Markus


----------



## edform (Jun 25, 2018)

Practical realities.

Having now had various components manufactured, unexpected practical realities have begun to intrude and I've spent recent weeks altering my design to control costs and make production a practical reality. The driving difficulty has been bonding components together with conductive epoxy without beads of the adhesive intruding into the space in front of the stator - it is not a happy moment when you discover that your very expensive parts are scrap   and you are to blame! 

I am close to eliminating a stator cut from woven wire mesh from the list of possibilities because of these bonding difficulties [sad because they are about 30p each], but I have a new foil design on order which is intended to be welded to the support structures. Delivery is a few days away. The foil stock from which this is chemically milled is 0.1mm thick.



The closed areas dotted about the grid of rectangular holes in the image are welding pads that correspond to the three-limb junctions between the hexagons in this support component which is 1mm thick...


The parts fit together so....


A wire mesh stator would be acoustically superior because the wires can be as thin as 35-50 microns making the component acoustically transparent into the 100s of kilohertz region, but I just cannot glue them cleanly, and they cannot be welded - when the wire melts at the junction, surface tension pulls it away from the bond. This is why the boys with lots of development funds available are turning to diffusion bonding which doesn't melt the metal at all. Unlike woven wire, a foil component welds perfectly to the underlying support and laser welding does not distort it, so flat is easy. The bond will be finished by wicking low viscosity cyanoacrylate adhesive into the area between foil and support to eliminate any possibility of buzzing. The welds, of course, make foil and support electrically continuous.

I am certainly not going to show you ruined stator attempts, it's embarrassing, but this image may be of interest...

It's a laser cut, 0.25mm thick part that my number one adviser company made, just for the hell of it - totally impractical, the holes are too big and the separating lands way too narrow [0.1mm]. It took 2 hours to make, so £250 if I wanted to buy it, while reducing the holes from 5mm to 1.5mm and increasing the lands to 0.25mm wide would yield a part that could be made but would cost £1000. The chemically milled foils are £32 each in batches of 4 [one pair of headphones] and about £19 each in batches of 50.

I've also been working on enclosing the driver units - not too difficult - and attaching them to a practical headband which is driving me crazy. I can make test sets simply by enclosing each earpiece in a cloth bag with a strap running over my head, but it's hardly a practical set of cans!

Here is my design slate for the headband with the main components in the right places...

The difficulty is that the earpieces are intended to swivel inwards and outwards on the two pivot pins shown to allow the listener to choose between bass weight and stereo image quality and the earpieces are very big, so suspending them on the head without the headband intruding into the acoustic zone is a nightmare.

Ed Form


----------



## chinsettawong

Hi edform,

You have a very interesting design.   I can really understand your difficulty of bonding the parts together.  However, I do not understand why you want to use the conductive glue for gluing the  wire mesh on the frame.  You can always solder a wire on the wire mesh after the gluing process, right?

Keep going and keep us updated with your progress.  

Wachara C.


----------



## edform (Jun 26, 2018)

chinsettawong said:


> Hi edform,
> 
> You have a very interesting design.   I can really understand your difficulty of bonding the parts together.  However, I do not understand why you want to use the conductive glue for gluing the  wire mesh on the frame.  You can always solder a wire on the wire mesh after the gluing process, right?
> 
> ...



It won't really help if the adhesive is non-conductive, it has to partly enter the weave in order to wet sufficient surface area to form a bond, and finding an adhesive with suitable rheology to flow just the required amount, then working out how to apply a precise amount in the right places, is a process that needs lots of work. In effect I cannot currently make the mesh lie flat with adhesive half-filling the mesh from the support structure behind it.

3M make conductive epoxy films than can be die-cut to the same shape as the support structure and which have extremely well defined flow characteristics. They would work, but the four bonds in each pair of headphones would cost about £250.

Soldering a connection between mesh and support requires a place to do it without it becoming a charge concentrator in the moving membrane zone, so it would have to be in the stacking area or in the connector enclosure, with a strip of the mesh crossing the non-driven area at the perimeter of the diaphragm, presumably lying along one of the support bridges, and then passing beneath the insulators in the component stack. A pig to fit, and the mesh pulls apart like threads pulling out of cloth when you cut a narrow strip. I looked at using some kind of rivet through the a pad formed on the support structure but it's really difficult to avoid raised bumps on the diaphragm side.

On balance, unless I can get access to a diffusion bonding facility, without the shockingly high fees commercial operations charge, and simply cause mesh and support to fuse to each other, the foil approach is looking like the only practical solution. Laser welding, when done by real experts, is a wonderfully clean and controllable process.

Ed Form


----------



## chinsettawong

All that you’re trying to do sound very complicated and I’m not sure that you’ll get much better sound than the simple PCB stators which we have been using here.  Good luck and keep us update of your progress.


----------



## edform

chinsettawong said:


> All that you’re trying to do sound very complicated and I’m not sure that you’ll get much better sound than the simple PCB stators which we have been using here.  Good luck and keep us update of your progress.



Electrostatic loudspeakers are very simple objects but some physical differences make the top electrostatic headphones sound better than lesser models. The route I'm taking reflects my ideas, not just on what those advantages are, but also on what else can be exploited to go beyond the current top levels. I'm not a DIY person by nature, my aim is to prove out my ideas. Besides, I'm having fun


----------



## chinsettawong

Having fun should always be the top priority.


----------



## chinsettawong

Hi Guys,

I need your ideas.

I have been puzzled for a long time and I really can't find an answer.  I opened up a few pairs of SR007 and I found that Stax stretched the diaphragms far tighter than all mine.  Yet, the bass is excellent.  If I were to stretch the diaphragms to that extend, my phones would lose a lot of bass.  Have you guys any similar experience?  

I start to wonder if Stax is using Mylar or other material for the diaphragms.  What do you think?  Or could it be the stators?

Wachara C.


----------



## jgazal (Jul 15, 2018)

chinsettawong said:


> Hi Guys,
> 
> I need your ideas.
> 
> ...



Dear Wachara,

I am not able to meaningfully contribute to the efforts of doing it yourself electrostatic headphones like you are, but since no one tried until now, I will just give you my wild guess.

Although I can’t just refute that other kind of “super engineering plastics” might allow better stretching and more bass, I feel that it either allow more stretch  with lower mass, but it is still more strech.

So after thinking about your question and seeing the video below about fluids, vector calculus and a tiny bit about static charge, I think you could also consider an alternative hypotheses: that your coating might not attach enough atoms to retain an equivalent charge to the coating Stax uses.

Does coating resistance really correlates to charge? For instance n MOhms of resistance from a noble metal deposition does retains the same amount of charge that n mOhms of anti-static agents commonly found in your standard coating?

There must be a reason why some manufacturers use noble metal deposition to coat their diaphragms.

The way I see it, one would need an optimum number of moles of a certain noble metal per surface area.

I don’t know how to test this hypothesis. I know that graphite is not a good option for the long term (does it oxidize?...), but pehaphs you could coat one diaphragm with graphite and the other with your standard coating and see which one first deflects a compass insofar as you approach the polarized diaphragm?

That does not answer what is the optimum noble metal or the correlated optimum number of moles of such noble metal but it is something to start...

Cheers!


----------



## 100VoltTube

Maybe because they use much thinner diaphragms, they need to stretch them more


----------



## chinsettawong (Jul 29, 2018)

About the coating material, I know what I use isn't the best, but it does serve the purpose.  I fixed a few pairs of Stax headphones by simply coating one of the diaphragms with the new coating, and the headphones come back to sound balance with good bass.  So, I don't think it's the coating material.  I often check the tightness of the diaphragm by knocking the spacer which has the diaphragm glued on against a table and hear the sound.  Stax's sounds much sharper than mine. 

Recently, I have been making my diaphragms using the 1.5 micron Mylar, but still I can't achieve the same tightness as Stax.  If I do, the bass is much less.

The thing I raise up this question is that there is certainly an advantage in the high tightness as Stax's.  As we have often heard of the term "Stax's fart", it actually happens when there is a quick change in pressure within the cup when the headphones are worn on the head.  The diaphragm hits one of the stators and bounces back.  On mine, the diaphragm would hit the stator and just stick there.  I need to unplug the headphones and discharge the bias so that the diaphragm bounces back.


----------



## edform (Jul 18, 2018)

chinsettawong said:


> About the coating material, I know what I use isn't the best, but it does serve the purpose.  I fixed a few pairs of Stax headphones by simply coating of one the diaphragms with the new coating, and the headphones come back to sound balance with good bass.  So, I don't think it's the coating material.  I often check the tightness of the diaphragm by knocking the spacer which has the diaphragm glued on against a table and hear the sound.  Stax's sounds much sharper than mine.



Are you sure that you are not being fooled by the fact that your stack is glassfibre board while the Stax stack is metal? I would expect them to sound a lot different when the edge is tapped on a hard surface.

Have you actually tested the resonant frequencies of the respective diaphragms?

Ed Form


----------



## chinsettawong

The stators on Stax SR007 are made of double sided plate through holes PCB same like mine.  I don't have the equipment to test the resonant frequencies, unfortunately.  

But here is a link where my phones have been tested against the SR009: https://www.innerfidelity.com/content/extraordinary-diy-electrostatic-headphones-chinsettawong


----------



## edform (Jul 18, 2018)

chinsettawong said:


> The stators on Stax SR007 are made of double sided plate through holes PCB same like mine.  I don't have the equipment to test the resonant frequencies, unfortunately.
> 
> But here is a link where my phones have been tested against the SR009: https://www.innerfidelity.com/content/extraordinary-diy-electrostatic-headphones-chinsettawong



Sorry, I was somehow confused and assumed the comparison was SR009 which, if I remember correctly is the nearest Stax equivalent to you devices - and which, of course has a metal stack construction. Looking back over your original post I see that you clearly said 007, so my fault for making assumptions.

You can measure the self-resonance of the diaphragm by placing a loudspeaker close to it and sweeping it across the frequency range where the resonance lies - a tiny spot of light on the diaphragm will visibly blur when the diaphragm excursion increases around its resonance. Sweep up and down once or twice and you'll easily determine the frequency of maximum movement. If you have the diaphragm on its own and your speaker is small and near the diaphragm, you may even be able to detect a little peak in the impedance of the loudspeaker .

Ed Form


----------



## J-Pak

I did some searching and I couldn't find if Sennheiser ever mentioned what the HE-1 stators are made of. Does it look like they're PCB?


----------



## chinsettawong

Can’t really tell from the picture.  But the old Orpheus has gold sputtered on glass as stators.  So, I think Sennheiser has a better technic when it comes to making stators.


----------



## J-Pak

chinsettawong said:


> Can’t really tell from the picture.  But the old Orpheus has gold sputtered on glass as stators.  So, I think Sennheiser has a better technic when it comes to making stators.



The reason I was wondering is if they were using glass stators I would have imagined they made this very public, as it was in pretty heavily advertised by them in HE90 promotional/review material.


----------



## jgazal

> The Making Of $53K Headphones
> 
> (...)
> 
> ...


----------



## chinsettawong

IMO, the different tensioning of the diaphragm and the diaphragm thicknesses make more difference in sound than the difference in stator designs.  But Sennheiser does have its very unique and expensive way of making the stators.


----------



## chinsettawong (Jul 31, 2018)

During these past few days, I've been having the pleasure of listening to the wonderful Stax SR-Omega.






Before sending them back to the owner, I need to take a picture with my very own Omega.


----------



## Garuspik

*chinsettawong ,h*ave you ever experimented with inverted ESL designs with low-resistant membranes?


----------



## chinsettawong

Hi Garuspik,

No, I have not.  In fact I have thought about it for quite sometime but haven't got the chance to try it yet.  Maybe on one of these days, I will.


----------



## Garuspik

I'd love to see new players in ESL league. And you seems the only person who can brake Stax hegemony


----------



## tigon_ridge (Aug 3, 2018)

@Chinsesttawong Wooow. I remember frequenting this thread in 2011 when it was still young, and you'd just built your 2nd pair of electrostats--You're still at it! I'm really impressed by your craftsmanship, diligence, and love for the hobby. It seems you're still using mylar. I wonder what kind of material Stax uses. They probably have a lot of tricks up their sleeves. Keep at it, Sir. I haven't read through all the pages, so I'll ask: has anyone gotten a chance to listen to your creations, and given their impressions? Are you still designing and building your own amps to power them?


----------



## chinsettawong (Aug 3, 2018)

Hi tigon_ridge,

Welcome back!  Yes, I'm still around and quite active here.  I guess I haven't found other more fun projects yet.  Over the years, I've made too many headphones that I could count - some good, some fail.  Many people have listened to my headphones in many occasions.  Some think they sound good and some think they sound just so, so.  But nobody so  far think that they sound bad.  

I have built many amplifiers to go with my headphones as well.  I have built many KG amps such as KGSSHV, KGSSHV Carbon, KGST, Grounded Grid, and T2.  I wish I could design my own circuit and build one.  Unfortunately, my understanding of electronics is limited.  I still have a few more KG amps that I will build and the SRX Plus by JimL too.

Making headphones is fun.  You should try it too.

Wachara C.


----------



## chinsettawong

I'll be sending my Orpheus clone to @purk soon.  Hopefully he can give a brief review of the sound after he has listened.


----------



## purk

chinsettawong said:


> I'll be sending my Orpheus clone to @purk soon.  Hopefully he can give a brief review of the sound after he has listened.


Looking toward to listening to them again brother.  Your DIY phones are all wonderful.  I think my favorite is your Stax Omega Clone out of GG amplifier.


----------



## 100VoltTube

HI,
When you spray-paint the stators, do you paint the entire thing, or do you use a spacer to cover the outside part?
Also, what's the order of applying the coating to the diaphragm and gluing it to the spacer? Which side of the diaphragm gets coated? or does it matter?
Sorry if any of these questions have already been answered.


----------



## chinsettawong

Hi 100VoltTube,

Before I spray paint the copper on the stator, I etch out the unneeded copper first.  Then, I put the spacer on top of the stator and spray.  The paint should cover only the copper part on the stator.

About the diaphragm gluing and coating, I glue the spacer to the diaphragm before I coat.  I only coat on one side of the diaphragm and that is the side opposite to the side being glued.  That way when you put the other spacer together, it acts as a bias ring passing the electricity to the diaphragm.  

Wachara C.


----------



## 100VoltTube

Thanks a lot!
So the spacer you solder to is the one without the diaphragm?


----------



## chinsettawong

Yes, that's correct.


----------



## quintile

Hi,

I have been a long time lurker here and occasionally piped up. I have recently got back into electrostatic phones,
though my target is repairing old headphones rather than building new ones - sorry if this makes me a second class citizen.

The headphones I am working on are micro seiki ms2's - these are definitely influenced by the stax design,
if not actually manufactured by stax. The where originally built with an chemically etched diaphragms but the
material was not stable and degrades over time (crumbles to dust).

The diaphragms are small (55mm) but the headphones are nicely made and quite straightforward to disassemble.

I have successfully repaired some in the past but am finding it very difficult to repeat my results.
I am using 2uM mylar doped with a little tecknik anti-static workbench cleaner fluid. This is a combination
which seems to work well. When I glue the diaphragm in the conductive support ring it has a
resonance of about 250Hz (this feels high but I always use the same tension).

sometimes when I do this I get an LF response that extends to about 50-60Hz, not great but adequate. 
sometimes when I do it the rolloff is closer to 200Hz - which is of little use.

does anyone have any feeling for what effects the LF response from electrostatic headphones? i.e.
how does diaphragm weight, diaphragm conductivity, and tension interact to control the LF response.

I have been digging through Ronald Wagner's and Roger Sanders books but they relate to speakers rather
than headphones and don't seem to have any real answers (that I have found yet).

Thanks for any help,

-Steve


----------



## bruma

Hi Steve,
these ms2's tension the diaphragma, they clamp the diaphragm with a groove and a ridge in the holder. You have to glue it without any tension, just without wrinkles.
Atb, Markus



quintile said:


> Hi,
> 
> ...
> 
> ...


----------



## quintile

yep, I have seen this. 
The diaphragms I made last night I fitted the other way round so I was relying on the tension I put on the diaphragm and the spigot in the stator surround
was not used to tension the diaphragm.

I will try doing as you say.

fundamentally this implies that increased tension on the diaphragm rolls off the LF response of the driver at a higher frequency.
I didn't think this was the case - I didn't think it was that simple, but i am happy to try again.

Thanks for your input.

-Steve


----------



## bruma

quintile said:


> yep, I have seen this.
> The diaphragms I made last night I fitted the other way round so I was relying on the tension I put on the diaphragm and the spigot in the stator surround
> was not used to tension the diaphragm.
> 
> ...


I did try it the same way once and was disapointed too - it seems that the clamping of the membrane is important for the sound. and another hint: if the mylar is too thin this mechanism does not work as it should in these phones. I like it best with 6uM Mylar.
Atb, Markus


----------



## chinsettawong

Hi quintile,

Can you show us some pictures?  I really have no idea of what you're discussing about.

Wachara C.


----------



## bruma (Sep 20, 2018)

chinsettawong said:


> Hi quintile,
> 
> Can you show us some pictures?  I really have no idea of what you're discussing about.
> 
> Wachara C.



hi Wachara, these are the parts that we discuss:
(one picture in the original state, one restored)


----------



## chinsettawong

I can't see any pictures.


----------



## bruma

chinsettawong said:


> I can't see any pictures.


yes, sorry, I forgot to save


----------



## chinsettawong

Have you already fixed it?  I think the diaphragm doesn't have enough tension though.  How do you like the sound?


----------



## statfi

Muamp said:


> All this and MUCH more is in the free book, by Frank Verwaal, the URL has been mentioned many times in this thread, but I cannot remember what it is without looking back.....


Thanks to Muamp "and the crew".  The link on his page is http://home.kpn.nl/verwa255/esl/ESL_English_2011.pdf


----------



## bruma

chinsettawong said:


> Have you already fixed it?  I think the diaphragm doesn't have enough tension though.  How do you like the sound?


Yes I fixed these some time ago. The result is very good. The tension is done with the ridge/rim clamping of the holder and that is what I wanted to tell before. The MS2 are very special to restore.


----------



## chinsettawong

bruma said:


> Yes I fixed these some time ago. The result is very good. The tension is done with the ridge/rim clamping of the holder and that is what I wanted to tell before. The MS2 are very special to restore.


I don’t quite understand how you tension the diaphragm.  Did you not tension it to the right tension before you glue it to the spacer ring?


----------



## bruma

chinsettawong said:


> I don’t quite understand how you tension the diaphragm.  Did you not tension it to the right tension before you glue it to the spacer ring?


Yes, no tensoin before mounting, just without wrinkles but without tension - the construction does the tensioning itself.


----------



## federicopol

Hello gents, i planned to build some diy headphones for a long time, a couple of yeras ago i written some posts on this thread but other projects caused the heaphones to go in the backburner.

Some times ago i milled some stators but the lack of 0.5mm fr4 from my vendor put another halt to the project.

Today i decided to proceed and finish the headphones still lacking the fr4 and not having my cnc anymore how can i made the spacer? 

I decided to redesign the driver assembly making it simple (pcb stators apart but fortunately for this pair i have the old ones) to be built with simpler tools.

My stators are 95mm diameter FR4 circles with an active area of 74mm.

The finished headphones will not have a beautiful but difficult to make wood case but a simpler wooden disk with a protective grill glued on the inside.

The earpads (i'll cut them on measure and sew them on the sewing machine) will have the double function of earpads and cover/protect the driver assembly.
They will be glued on the disk/case.

The headphone viewed from the back or the front will be a 6 mm wooden disk and a big chunky earpad.

For the spacer i decided to use signage vinyl: i glued togheter 7 vinyl layers (0,5mm) cutted them on an hobby vinyl cutter and glued them on the stators.

I did 8 layers for the dust protectors, ear side.

I cutted the vinyl on a vinyl cutter but because my stators are round is simple to cut circular shapes with a rotary cutter compass.

The mylar diapagram will be glued on the vinyl, i'll use some small and thin (0'1mm) copper tabs to connect them to the cable.

Tonight i tried to tension the mylar and glueing it to the stator but i used the wrong glue so i have to wait tomorrow to buy a neoprene contact one.

I'll also redo the spacers because the wrong glue left residues that are hard to remove.

I think the vinyl spacer ( IF that work) could reduce the barrier of entry in the realm of diy electrostatic headpones: 
Order some FR4 stators from a PCB factory in China, cut the spacers with a compass cutter and if a simple enough case can be made you can have an headphone without all the CNC tools.




Now a photo of the work in progress:


----------



## Phthalo

This thread is incredible, I created a head-fi account just to be a part of it. Wachara and everyone else who contributes here, thank you so much for sharing your knowledge with the world, and for 8 years no less. 

Anyway, I'm planning on building my own electrostatic headphones and am currently designing the stators using inkscape as suggested by Azrael3000 (thank you for the how-to guide, it's wonderful for a beginner like me). But I have no prior experience with inkscape and I'm having problems. I want to put holes in concentric circles, but when I try to use the "scatter" function to do this, I get two sets of holes going around the circular path like this:
	

	
	
		
		

		
		
	


	




 Does anyone know how to fix this? I can't find an answer online.

Thank you for your help


----------



## chinsettawong

federicopol said:


> Hello gents, i planned to build some diy headphones for a long time, a couple of yeras ago i written some posts on this thread but other projects caused the heaphones to go in the backburner.
> 
> Some times ago i milled some stators but the lack of 0.5mm fr4 from my vendor put another halt to the project.
> 
> ...



Your stators look really good.  By the way, you can buy the 0.5 mm FR4 on ebay easily.   Please try.

Vinyl spacers should work too, but you need to glue it on the stator becasue it’s not rigid enough.  I personally don’t like it.

Wachara C.


----------



## federicopol

Thanks Wachara, the vinyl is glued on this pair, next one i'll consider the FR4.

By the way some updates: 

I used a different tensioning system than the ones used on the forum.

I work with sewing and embroidery machines by trade and embroidery machines uses tensioned frames of different shapes and measures so i used embroidery frames to tension the mylar.
That way the tensioning is really easy: i tensioned two diapagrams in a couple of minutes: once you find the right tension on the hoop screw you could repeat it with no problem. I also checked the free air resonance of the drivers (because i used two different frames) and the driver are matched (146hz).

I add photos of my tensioning jig.


 
First i position the inner hoop then the mylar, then a bigger inner hoop solely to help me keep the mylar wrinkle free, then i press the big outer hoop in place. 



 

Check if there are wrinkles in the mylar. Check the "sound"/freeair resonance. Glue.

I hope to have some free time tomorrow to continue the building!


----------



## quintile

i use embroidery rings too, though i use home diy ones made of bamboo.

i also use the resonant frequency to set the tension. i suggest you record the resonance of the mylar in the ring, and in the headphone support rings ince you have glued them in place. this means you have very repeatable results so when you change things you can understand what is happening

-Steve


----------



## Torac

federicopol said:


> Thanks Wachara, the vinyl is glued on this pair, next one i'll consider the FR4.
> 
> By the way some updates:
> 
> ...



Do you think you could make a video showing how this is done? Still slightly confused on all the steps but it looks like it would be really easy to repeat.


----------



## federicopol

Steve, thank you for the suggestion on double measuring. 

I'll do that for sure.

What frequency do you usually aim?

I can do the video tomorrow. 

The method is pretty easy. Basically you close the mylar between the two frame parts. If you search on youtube "industrial embroidery machine hooping" you can find the same tecnique but with fabric instead of mylar between the hoop parts.

For measure i hold the framed mylar in front of my speaker while they play different frequencies. (I use a bass test youtube video that shows the frequency on screen).


----------



## quintile

our frequencies will probably be different as my diaphrams are small (about 30mm) and i use 2 micron mylar - i am repairing old 1970s micro seiki headphones.

i will dig out the numbers.

i measure the frequency using an iPhone app “spectrum” from black cat. if you play with its settings you can get it to integrate energy in the spectrum. i use the phone close to the diaphram and rap the outer ring which makes it resonate and i can read off the frequency. 
no more accurate as your method, but good fir lazy people like me.


----------



## chinsettawong

federicopol said:


> Thanks Wachara, the vinyl is glued on this pair, next one i'll consider the FR4.
> 
> By the way some updates:
> 
> ...



That's interesting stretching technic.  Thanks for sharing the idea.


----------



## statfi

I use 009.  Can someone give me a detailed explanation of what happens when they fart?  Is that the diaphragm, or the protective envelope, or what?
Am I correct that farts are not bad for the cans.
Do the various DIY cans also do this?


----------



## chinsettawong (Oct 4, 2018)

The “fart” is actually the sound of the diaphragm hitting one of the stators.  Since the diaphragm is sitting in the middle of the two stators with only 0.5 mm of clearance on each side, any sudden change in pressure in the headphone’s enclosure can push the diaphragm to hit one of the stators.  If the tension is high enough, after hitting the stator, the diaphragm bounces back to the middle where it should be.  If the diaphragm tension isn’t strong enough, the diaphragm can stuck on the stator and would only bounce back when you discharge it.

As far as I have experienced, Stax headphones’ diaphragms are tension high enough and the diaphragms bounce back.  This phenomenon is quite common no matter they’re DIY or commercial headphones and it should not do any harm.


----------



## statfi

chinsettawong said:


> The “fart” is actually the sound of the diaphragm hitting one of the stators.  Since the diaphragm is sitting in the middle of the two stators with only 0.5 mm of clearance on each side, any sudden change in pressure in the headphone’s enclosure can push the diaphragm to hit one of the stators.  If the tension is high enough, after hitting the stator, the diaphragm bounces back to the middle where it should be.  If the diaphragm tension isn’t strong enough, the diaphragm can stuck on the stator and would only bounce back when you discharge it.
> 
> As far as I have experienced, Stax headphones’ diaphragms are tension high enough and the diaphragms bounce back.  This phenomenon is quite common no matter they’re DIY or commercial headphones and it should not do any harm.


Thanks!
I am working my way through this great thread from the beginning.  Most impressive, chinsettawong.
But, in the meantime: The SR-009 has polymer enveloping the stators, inside the protective screens.  Are you also enveloping the transducer in protective, acoustically (almost) transparent polymer?  If so, what material and how thick?  If not, why not?  I had imagined it was necessary to prevent arcing.


----------



## chinsettawong

Yes, it's very important to have protective screens protecting the driver from dust that might go into the driver.  I'm not sure what material it is that Stax uses.  But for us, DIYers, we normally use the same material as our diaphragm material.  That's Mylar.  The most popular thicknesses are 3 microns and below.  Please read through the thread and you'll find all the answers that you might have.


----------



## statfi

chinsettawong said:


> ...Please read through the thread and you'll find all the answers that you might have.


Thx!  Just after I posted the query, I hit your relevant previous post.  I will read on.


----------



## statfi

The simplicity of F=Eq, the fundamental equation for electrostatic headphones, is a thing of beauty.  E is the signal voltage between the stators divided by their distance, and Q is the charge on the diaphragm and F is the force moving the diaphragm.  However, some of the beautiful simplicity fades away *if the Q is not fixed in time and space* wrt. the diaphragm.  So the question is:

Does anyone know how much the charge on the diaphragms moves around laterally on the diaphragm as the musical voltage is applied to move the diaphragms axially, either from an empirical or theoretical point of view?


----------



## chinsettawong

The charge on the diaphragm should remain constant at all times, IMO.


----------



## statfi

chinsettawong said:


> The charge on the diaphragm should remain constant at all times, IMO.


Exactly.  *Should*.  But does it?


----------



## chinsettawong

I’m sure it does.  

That’s the whole point of coating the diaphragm with high resistance coating.


----------



## statfi

I am going to be away from the www for a while.  Is there a way to download the content of this thread so I can read it without being connected?


----------



## WallofHooligans

Heyo head-fiers in this thread. I could use some info that I haven't seen anywhere in this thread.
Specifically I'm looking for a way to build a custom self biasing adapter. I understand how to do that, but I don't understand how to choose a transformer for the job. I know that the design uses a 1:60 ratio between the primary and secondary, as well as a voltage cascade to multiply the voltage further. I don't understand the values I should be looking for or building. I don't understand how to choose a trafo that would be okay being plugged into a 15-60watt amplifier for example. 
I've poked around inside a few adapters and found the lack of documentation as to the specs of the transformers concerning. As an example, what would I be looking for if I wanted to replace the transformers in a stax srd 6/7SB? Any rules of thumb to know?


----------



## federicopol (Oct 21, 2018)

Hello everyone, i'm here for some help, if possible: long story short: i finished my phones but they have a problem:

The efficiency seems really low: the volume even cranking my amplifier (the stax base model) at max the volume is very low and i notice distorsion when there are highly dynamic passages.

I think there could be two causes but i'm unsure of my line of thinking:

1- bad coating product: the product i'm using (floor cleaner) could be less than ideal.

2- cable: i'm using cat5 cable because that is what i have around. Only one strand per pole. I think the cable could be undersized for the application.

I don't know what else to think, i'm tending towards the cable but i am not sure... Could someone more experienced chime in and give me some advice? Thank you.

By the way here is a photo of the finished headband/earpads. Really minimal but really comfortable and light even with the driver mounted in.


----------



## quintile

i would expect the coating.
measuring it is hard, as most multimeters dont read upnto 1Gohm.

from memory (i am on holiday) you are liiking for about 1gohm measured between two coins dropoed on the conductive surface if the diaphram.

cat5 cable is thick enough (the current is very low), the capacitance of the twisted pairs, and the insulation resistance is probably not up to 600v. probably ok for now but long term you should find somthing better.

-Steve


----------



## bui501-tech

quintile said:


> i would expect the coating.
> measuring it is hard, as most multimeters dont read upnto 1Gohm.
> 
> from memory (i am on holiday) you are liiking for about 1gohm measured between two coins dropoed on the conductive surface if the diaphram.
> ...


Steve has a good point re. the capacitance of the cat5 cable.  there's a reason why Stax and Koss and Sennheiser all use flat cables with parallel conductors for their electrostatic headphones.  Cat5 cable has twisted pairs that are all intertwined with each other inside the sheathing.  
If you're experimenting/starting out, I'd at least try with flat ribbon cable rather than cat5 to at least eliminate one likely issue.
If you want to go better than the flat ribbon (computer connection type) cable, Koss sells extension cables for their electrostatic headphones for $20 for a 10-foot piece -- I just cut off the ends and use the actual cable.  Very flexible and relatively durable -- and they were designed for electrostatic headphones.


----------



## federicopol

Thank you very much for your answers.

I can't buy koss cable: i'm in the eu probably the shipping is gonna kill the convenience...

For now i'm going to buy some computer flat cable next week and find a multimeter that can read high resistance.so i can verify the coating.

Thanks


----------



## chinsettawong

Hi,

I would like to know exactly what spacer thickness you are using as it’s one of the most important factors that affect the efficiency.  Most of us here use 0.5 mm.  

Wachara C.


----------



## federicopol

I use 0.5mm.


----------



## chinsettawong

federicopol said:


> I use 0.5mm.



I see.  Then I think it’s the problem of your coating.  Try some other coating materials.  It’s very unlikely that the cable has a problem.


----------



## WallofHooligans

I'm sorry, I think I must have asked too broad a question about the transformers. Has anyone recreated a small self biasing adapter? Something like the e.7 from the koss esp7. I think I understand that the zener gate will protect the circuit from overvoltage, but I've read that small trafos have clipping issues with the audio signal.


----------



## -JFK-

Hi  
Where did you find this Koss cable? 
Thanks


----------



## bui501-tech

You have to call Koss via the number posted on their website and request to order an extension cable for their ESP950 headphones.


----------



## janosch simon

hey all now my playback is finished containing a soekris 1021 dac and a picoreplayer with the iancanada dop to dsd decoder makes it native decode dsd up to dsd128 




this setup feeds the schiit freya over balanced xlr cablr and then balanced into http://www.high-amp.de/html/hybrid-amp_eng.html i have at the moment v6 but the boards for v7 are also here   but not finished. 

 
today was first listening and i love the setup  highs and mids are perfect only bass is meh :/ guess v3 i will go with a round desing at the moment the stator and membran are oval 60x90mm 
also my earpads are from brainwave and a soft fabric guess leather wood keep the bass better`

here are some question:
- how you cast latly coat? my licron can  seems damage its sprays not a fine dust more some blobs  also i find it not so regular and smooth applied. how do you guys coat your mylar?
- any of you build a portable es hp dac amp?  i know there is one from kingsound and also stax but 400 and 800€ i would like to build an streamer dac amp thingy  
- my missing bass could that be only the size of my panel? the tension of the mylar? the coating? 

thx and cheers janosch


----------



## bui501-tech

janosch simon said:


> hey all now my playback is finished containing a soekris 1021 dac and a picoreplayer with the iancanada dop to dsd decoder makes it native decode dsd up to dsd128
> 
> this setup feeds the schiit freya over balanced xlr cablr and then balanced into http://www.high-amp.de/html/hybrid-amp_eng.html i have at the moment v6 but the boards for v7 are also here   but not finished.
> today was first listening and i love the setup  highs and mids are perfect only bass is meh :/ guess v3 i will go with a round desing at the moment the stator and membran are oval 60x90mm
> ...



I use ACL’s staticide aerosol spray, and it also comes out in big droplets on the Mylar. I have to use a lint free tissue to gently spread the coating as evenly as possible, let it dry, then reapply and spread again to ensure complete coverage. The result after drying is a light coating, but I’m sure it’s not 100 percent even—just 100 percent coverage of the Mylar diaphragm with a very light coating of the staticide I’m using.


----------



## janosch simon

hey bui sounds good will try this with my licron  spreading it with a lint free tissu is a good idea 

cheers janosch


----------



## chinsettawong

I put a few drops of Staticide 6300 and wipe it evenly on the diaphragm using a lint free cloth.  That's how I have been doing it.


----------



## chinsettawong

janosch simon said:


> hey all now my playback is finished containing a soekris 1021 dac and a picoreplayer with the iancanada dop to dsd decoder makes it native decode dsd up to dsd128
> 
> this setup feeds the schiit freya over balanced xlr cablr and then balanced into http://www.high-amp.de/html/hybrid-amp_eng.html i have at the moment v6 but the boards for v7 are also here   but not finished.
> today was first listening and i love the setup  highs and mids are perfect only bass is meh :/ guess v3 i will go with a round desing at the moment the stator and membran are oval 60x90mm
> ...



I like your amp.  Can you tell us more about it?


----------



## janosch simon

chinsettawong said:


> I like your amp.  Can you tell us more about it?



sure what you want to know  its a relative hard diy project cause its not so much documented 
it consists of a linear power supply and separate tube heater circuit and the 2 amp boards for right and left chanel its an hybrid onewith fets and tubes, v6 which i build used uses EL84 tubes and V7 uses 6SN7 tubes  i have the boards at home and might try v7 too the rest of the amp is the same 

cheers janosch


----------



## Torac

Does anyone here know where I may get my hands on 0.5mm pcb, I have scoured the internet to try and find some however I can't find a single trace of them.


----------



## chinsettawong (Nov 12, 2018)

Try “0.5 mm copper clad PCB” on eBay.  The seller is PCB Depot.


----------



## bui501-tech

Here's a link to the listing mentioned by chinsettawong:  
https://www.ebay.com/itm/FR4-Copper...-Board-Material/120802756087?var=420050924082


----------



## Torac (Nov 13, 2018)

Thank you both, I did spend at least 15 minutes looking on eBay, I'm guessing it didn't come up because it prefered listings based in my country. The shipping is a bit extreme but worth it for the correct thickness. Thanks again.


----------



## piotrkundu

chinsettawong, I've been following you project for a week and there are tons of information. Are you considering doing a full post on how builds these headphones with plans, instructions etc?
That would be really nice, because over the years you have tried a lot of different experiments and it would be sad if that research was "lost". Also all the failed experiments are really interesting to, so people don't fall for the same traps again.


----------



## jgazal

piotrkundu said:


> chinsettawong, I've been following you project for a week and there are tons of information. Are you considering doing a full post on how builds these headphones with plans, instructions etc?
> That would be really nice, because over the years you have tried a lot of different experiments and it would be sad if that research was "lost". Also all the failed experiments are really interesting to, so people don't fall for the same traps again.



In the meantime, try this:



Azrael3000 said:


> As promised we made a guide on how to build your electrostatic headphones without needing to read close to 200 pages of forum posts.
> You can find our very first version here: https://github.com/Azrael3000/headphone-guide or read the pdf directly: https://github.com/Azrael3000/headphone-guide/raw/master/guide.pdf
> 
> This work is under a CC license, so everybody can copy, modify and redistribute this document (with some minor constraints). If you have comments on how to improve it feel free to let us know either on the dedicated forum thread: https://www.head-fi.org/threads/electrostatic-headphone-construction-guide.877412/ or on Github.
> ...


----------



## Azrael3000

Thanks for recommending our guide. We have recently found time again to get back to our prototype and tried the bike tire method to tension the diaphragm. It worked absolutely fantastic and I hope to update the guide soon.

As usual, if you use our guide and if you have any comments please share them. While I might not seem very active, I'm lurking


----------



## piotrkundu

Good read, thanks guys (Azrael3000 + Jgazal).


----------



## legopart

Where can I buy "mylar dust COVER" ?


----------



## chinsettawong

I use the same kind of Mylar that I make the diaphragm for the dust cover.  I buy it from Ebay: https://www.ebay.com/itm/Electrosta...h=item2849e0b724:g:XBoAAOSwU9xUQPIj:rk:1:pf:0


----------



## legopart (Dec 4, 2018)

chinsettawong said:


> I use the same kind of Mylar that I make the diaphragm for the dust cover.  I buy it from Ebay: https://www.ebay.com/itm/Electrosta...h=item2849e0b724:g:XBoAAOSwU9xUQPIj:rk:1:pf:0


What about this option for example, the thickness not the same
but it write that it have 40m and something about "+ Elvamide 60g"
what is Elvamide 60g, is it something important ?
I need to repair my Stax lambda

do dust cover damage the sound?

another data that i found





which thin acceptable to which  bias voltage ?

Last questions about DIY:
if I want to make some DIY buy I not having any option to drill perfect holes inside the copper plate,
can I use this net, stretch it on the cut copper plate and put it on the front and on the back of the membrane?





additionally I searching for some mesh fiber that will cover the back speaker part

I want to buy some copper and plastic (ABS) plates and cut it to the right size, unfortunately I having only hand/electric basic working  tools
I though to buy though to buy the materials from here
they having also brass material
https://www.ebay.com/itm/1pc-Copper...xp2yke1ZV-7c22-fwQ:rk:1:pf:0&var=431974963353






What is the standard size for electrostatic headphones? I though to create some cans that bigger then my head to receive more membrane efficiency.

one more question, which glue better to use?

again, Thanks for help!


----------



## Muamp (Dec 5, 2018)

Hi Legopart,

With regards to the Mylar, the 40m is referring to the length of Mylar on the roll and the 60g Elvamide is referring to 60 grams of Elvamide, if you wish to use Elvamide to provide the coating. I strongly recommend that you do not use Elvamide (refer to an earlier post of mine highlighting the problems with Elvamide).

I personally use 2um thickness Mylar, others use different thicknesses...

The copper mesh looks excellent! But you will need to tension the mesh to make it very rigid.
HiFiman Shengre La uses a mesh stator and it sounds excellent.

David.

PS - you have many questions,  I guess others will give some more input.


----------



## legopart

Lot of thanks!

the remain questions:
1- what is "Elvamide"?
2- do dust cover effects the  sound quality?
3- which material can used as back side protector (like the thin fabric on the back on stax)?
4- how much voltage can hold, for example 3nm, can it hold 230v or 560v ?
5- which plate better, brass or copper ?
6- I though to create giant membrane as possible to offer from it much sound as I can (cause I decide the material and sizes), I will custom the pads if needed.
what can you recommend me about it?, I think that bigger is better, what size is acceptable?
7- what glue to use?

thanks.


----------



## Muamp

Elvamide is nothing more than Nylon pellets. Small pieces of nylon that are intended to be disoloved in ethanol by heating. When cooled, the resulting solution is applied to the Mylar to provide the conductive coating. The conductive coating is achieved by the Elvamide coating absorbing moisture from the air. This is an old method of coating and is out dated by so many modern alternatives such as Licron Crystal spray or alternatively any water based anti-static spray.

Dust covers are an essential part of a panel in an electrostatic headphone since the distance between the stators and the membrane is so small, typically 0.5mm. A gap this small will whistle when the charge on the diaphragm attracts dust and enters the panel producing a short circuit between the stator and diaphragm.

You only need a dust protector on one side, normally the ear side, where the positive polarity stator is facing the conductive side of the Mylar. 

Questions 4 and 5 do not make sense. The applied bias voltage is applied to the diaphragm at the potential you decide and any conductive material can be used to apply the bias.

The bigger the panel, the more the air movement. If it becomes too big, then they are not really headphones.....  but also, the larger they become, other aspects need to be considered such as possibly increasing the distance between the stators and diaphragm to accommodate the greater size of panel....

Glue to use is a big question, different builders use many different glues and methods, many of which have been heavily discussed in this thread already.

David.


----------



## legopart (Dec 4, 2018)

additional questions about the answares:
1- do I have to clean the diaphragm with "Licron Crystal spray"/"anti-static spray", or it would be fine to use it without any addition?
do I required on old vintage headphones to take care of them?
Can you send me a link to one product that you recommend?

2- can I coat the stator with "Acrylic lacquer insulation" (I think that it's done on motors) to protect it from shorting with the membrane ?

3- why the positive side is on the top? the membrane charged positively with the bias voltage,  if the positive signal  will come on the top of the membrane it will push it backward, so you will get reversed signal polarity (like switching the polarity on regular headphone driver )

4- the high voltage won't damage the diaphragm ?
how the voltage of 560v affect 230v headphones?

5- brass material for the stator is it worst?

6- how to calculate the distance between the stators and diaphragm  if I want to create bigger headphones or to create a speaker (tweeter) with it?
I though about the total size, something like 11*13cm for the total size that I can afford on my head and feel comfort with it

7- about the glue, Can you send me a link to one product that you recommend?

again Thanks.


----------



## bui501-tech (Dec 4, 2018)

I second David's comments on Elvamide...  I've tried using the elvamide included with the mylar in the ebay listing for my coating, and after a week of multiple attempts using lab-quality equipment to heat and mix the solution for the coating, I gave up and just went back to Staticide 6500 spray.  The elvamide would not work at all for me and cost me loads of time and money in parts that went into the garbage.  Not sure if it was because elvamide is just not a good candidate in general for electrostatic headphone coating or if the stuff included with the 3-micron mylar from eBay was just not good quality.

I use 1.4 micron mylar from this website:  http://www.homefly.com/products.asp?id=31&pg=1   (They are more expensive than the eBay version, but I've found them to be very consistent and of high quality for my own use.)
I use the 3 micron mylar from the above eBay listing for the dust covers as I don't want to waste the more expensive 1.4 micron mylar on dust covers.

My 90mm drivers with the 1.4 micron mylar, Staticide 6500 coating, and 3 micron dust covers are good and loud enough to use as speakers in a small room (more than enough to blow out my ear drums with mounted as headphones).  I'm using a KGSS Carbon for the amp.  The stators are .8mm single-sided FR4 (pc board materials), and spacers are .5mm single-sided FR4.  Holes on the spacers are 1mm in diameter.  (Chinsettawong, I perfected the speakers you saw at my house -- these have smaller 90mm drivers, but didn't have problems with the connectors cutting in and out like my first version did.)





I plan to go to the thicker mylar for larger drivers -- Chinsettawong made headphones with larger drivers than my 90mm drivers with the 3 micron mylar, and they sound out-of-this-world awesome!!!  The very best headphones I've ever heard anywhere -- DIY and commercially made.


----------



## legopart

can you recommend another brand or chines brand  for this spray?


----------



## bui501-tech

Chinsettawong is the expert on that.  He's experimented with more coatings than any of us here in this forum.  Earlier in the thread, he was successfully using floor cleaners (available locally in Thailand).  Makes sense as some of the floor cleaners have anti-static properties to repel dust.


----------



## chinsettawong

@legopart There are many electrostatic cleaners that work well in the market.  Unfortunately we can't test all of them.  I think you should try to find what you have in your area and let us know what works and what doesn't.  That way we can learn from each other.


----------



## chinsettawong

bui501-tech said:


> I second David's comments on Elvamide...  I've tried using the elvamide included with the mylar in the ebay listing for my coating, and after a week of multiple attempts using lab-quality equipment to heat and mix the solution for the coating, I gave up and just went back to Staticide 6500 spray.  The elvamide would not work at all for me and cost me loads of time and money in parts that went into the garbage.  Not sure if it was because elvamide is just not a good candidate in general for electrostatic headphone coating or if the stuff included with the 3-micron mylar from eBay was just not good quality.
> 
> I use 1.4 micron mylar from this website:  http://www.homefly.com/products.asp?id=31&pg=1   (They are more expensive than the eBay version, but I've found them to be very consistent and of high quality for my own use.)
> I use the 3 micron mylar from the above eBay listing for the dust covers as I don't want to waste the more expensive 1.4 micron mylar on dust covers.
> ...




Thank you so much for your kind words.  My active diaphragm diameter is 80mm.  And that's probably the largest that I will go with 0.5 mm spacers.  

Thank you also for the link.  I see that they sell the 2 micron aluminized Mylar.  I actually have been searching for something like this for a long time.  One of these days I'll try to make a pair of planar magnetic headphones.  That Mylar will certainly be the most suitable one.


----------



## legopart (Dec 5, 2018)

Can it work without the spray?
this one good?






Ok I understand now, this material will protect the item from the dust,
I can test it on dusty area only the membrane part and see if it going dirt.



Can you answer me the other questions:

2- can I coat the stator with "Acrylic lacquer insulation" (I think that it's done on motors) to protect it from shorting with the membrane ?

3- why the positive side is on the top? the membrane charged positively with the bias voltage, if the positive signal will come on the top of the membrane it will push it backward, so you will get reversed signal polarity (like switching the polarity on regular headphone driver )

4- the high voltage won't damage the diaphragm ?
how the voltage of 560v affect 230v headphones?

5- brass material for the stator is it worst?

6- how to calculate the distance between the stators and diaphragm if I want to create bigger headphones or to create a speaker (tweeter) with it?
I though about the total size, something like 11*13cm for the total size that I can afford on my head and feel comfort with it

7- about the glue, Can you send me a link to one product that you recommend?




chinsettawong said:


> Thank you so much for your kind words.  My active diaphragm diameter is 80mm.  And that's probably the largest that I will go with 0.5 mm spacers.
> 
> Thank you also for the link.  I see that they sell the 2 micron aluminized Mylar.  I actually have been searching for something like this for a long time.  One of these days I'll try to make a pair of planar magnetic headphones.  That Mylar will certainly be the most suitable one.


8- what the different  between Planer magnetic, Electrostatic , and Electret headphones?


----------



## Muamp (Dec 5, 2018)

No, the anti-static spray does not protect it from dust, the dust shield protects it from dust. The anti-static spray provides a coating on the diaphragm to hold the charge, the bias voltage. The panel will not work without a coating or a coating that has dried up since there has to be a bias voltage.

The stator with positive polarity doesn’t have to be on top (ear side) this is just a system many DIY constructors and professional builders choose. This way the dust shield is between the ear and the panel!

You can have any bias voltage you choose, 230v, 580v, 1200v....

I suggest you read Frank Verwaal’s free book on electrostatic speaker design (mentioned many times in this thread). It will help you get a better understanding, plus giving it a go with trial and error teaches you a lot, plus being fun.

David.


----------



## legopart

Ok thanks,

last questions:

1- which spray can you reccomend fot this job?

2- what do you think about my idea to cover the stator with " lacquer insulation" (my idea)?

3- which glue can you recommend ?

4- can I make, Planer magnetic, Electrostatic , and Electret, from the same material ?

5- About the stator positivist, I think that I the first who gonna put the polarity right, and use some carbon thin filter on the top of the driver (cause on the dynamic type I newer do such thing)

6- why Electrostatic driver cover all the area  in front of the ear and not allowed some open spaces, like for example on this hedaphones
and why this type always having an open back?











 7- I plan to use the Beyerdynamic DT880pro cans (after moding it) to put inside 85mm electrostatic driver. cause I like this headphones alot!





Please help me with this issues and the else I will read by myself. Thanks.


----------



## chinsettawong

@legopart I recommend that you gradully read through this thread.  You will learn a lot.   Almost all of your questions are already answered here many times.

For stator insulation, it’s not a must to have. Stax doesn’t have any insulations on the SR007 stators.  I’m sure that the lacquer insulation you mentioned would work just fine.

I use and recommend rubber glue for gluing the diaphragms.

The electrostatic, planar magnetic, and electret are three differnt technologies.  No, you can’t use the same material for all of them.  

You can bias the diaphragm with either positive or negative voltage.  It doesn’t matter.  I have tried both and couldn’t tell the difference in sound.

Open back electrostatic headphones simply sound better than closed back.  Try it for yourself.  

Since this is a DIY thread, we are not professional builders.  We all learn from our experiences.  Many questions that you ask have no exact right or wrong answers.  If you are really interested in building, I suggest that you just do it.  It’s simply better and easier learning by doing.


----------



## legopart

on this thread recommended this  type of spray "*Static Guard Spray*"
I found one from here:
https://www.amazon.com/gp/product/B006M1AOWU/ref=ox_sc_act_title_1_1_1?smid=A1R62X9XZ8492L&psc=1

and something different  on ebay:
https://www.ebay.com/itm/Lot-of-3-S...e=STRK:MEBIDX:IT&_trksid=p2060353.m1438.l2649

which one the users here meant  ?
Is it the same spray?


----------



## Ulfar4

I do not know where are you from, but when I was looking for coating, I ended up with the Antistatik 100 spray.


----------



## legopart (Dec 8, 2018)

I will check,
but is this one is good enoth?




4 bottle for$44.26


----------



## mattmatt

Hello everyone, 

I kind of wrecked my SRM-252s driver unit. The adaptor/transformer for it uses 100v and I accidentally plugged it to 220v, the adaptor/transformer is now broken but I have a spare replacement. The driver unit turns on(green LED light) but no sound is coming out of my headphones. Any idea what may be the problem or what I should check out? Bias voltage perhaps? If so, how would I take measurements and inspections? 

Thanks!


----------



## legopart

on full size forums   there a thread about stax products... this thread for DIY homemade headphones.

take it to some lab to fix it




check the fuse first.
must of chances that you burn some transistor or chip
first check the bias voltage




if you plug it first check if the Bias voltage is ok (voltmeter) between bias and the chasy


----------



## mattmatt

legopart said:


> on full size forums   there a thread about stax products... this thread for DIY homemade headphones.
> 
> take it to some lab to fix it
> 
> ...


Thanks for the reply. 

You mean between bias terminat and the ground?


----------



## mattmatt

The DC Voltage it between the bias terminal and the ground is around 10.5 volts only.


----------



## legopart (Dec 9, 2018)

I really sorry, I dont know how to test.
you'r bias is 560v  (pro stax)...


Question:
Is this connector will fits to stax amp?
https://www.ebay.com/itm/5-Pin-Cont...h=item2116c2a7e7:g:NUAAAOSwgmJX1xzC:rk:7:pf:0


----------



## legopart

Ulfar4 said:


> I do not know where are you from, but when I was looking for coating, I ended up with the Antistatik 100 spray.


This one not available anywhere  for me
something else?

and is this plug will fits to Stax amp?
https://www.ebay.com/itm/5-Pin-Cont...h=item2116c2a7e7:g:NUAAAOSwgmJX1xzC:rk:7:pf:0


----------



## mattmatt

Regular screen cleaner with antistatic worked for me when I restored my Stax.

Look for someting like that from PC/Computer Hardware stores.


----------



## legopart (Dec 10, 2018)

mattmatt said:


> Regular screen cleaner with antistatic worked for me when I restored my Stax.
> 
> Look for someting like that from PC/Computer Hardware stores.


do you replaced the membrane ?

I need to restore my stax too.
I destroyed my Stax totally before desided that I want to restore them and make some DIY





so


----------



## lkos98

Hello everybody. I have read this thread for more than a year already. Thank you all for all the information. I have made my first ESH in the far 1990's with a hand drill PCB and aluminium foil. Even though it was of a very bad quality, it still sounded great then. After so many years I was inspired by this thread to make ESH again. This time I made my DIY CNC first. I made 4 prototypes and probably I will show some pictures when I will be allowed to. My approach is a bit different although the concept is the same. So far I'm pretty happy with the phones, but I need to make a proper amp and improve some things.


----------



## lkos98

I would like to ask a question as well, since I did not find it anywhere in the thread - my apologies if it was already discussed. 
Has anyone checked/measured the cross-talk between channels? It seems it highly depends on the resistors, that are in series with the bias voltage - mainly because of the cable capacitance. The wires of the cable actually transfer the high voltage audio signal to the bias wire. The resistor in the bias supply prevents grounding of this AC signal and it adds/modulates the membrane bias voltage. I have tested with resistor and I can hear a lot of the audio from the right to the left channel although the balance was completely set to the right. Once the resistor is removed or I put a capacitor to ground on the bias wire, channels are completely separated (cross-talk could not be heard). I also noticed a bit of roll off of the treble once the resistor is there. I thought may be my membranes have low coating resistance, but this is not the case, as my multimeter can measure up to 50Mom and I was unable to measure the resistance with the coin method, even when put 0.5 mm from each other. I think this is for the same reason - part of the AC voltages goes to the membranes with 180 deg shift relatively to the stators especially in high frequencies. 

If anyone has this experience, please share. I know removing this resistor is not very safe - I already got few shakes, but I don't see any other option so far.


----------



## Ulfar4

I dont know your bias supply circuit, but what about adding this?


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## lkos98

Thank you, yes, mine is something like that, but..... 
Sorry, I was wrong when I said "remove" the resistor, I meant bypass or shortening it. I'm referring to the 5Meg resistor at the output in your schematics. Imagine that you apply AC signal at the output - this signal will travel all the way to the phones, since it's coupled to the ground via 5Meg resistor. And we don't want any audio signal on our bias wire, right?
For me there are few options here:
1. Put this resistor (mine is 1M) as close tot the phone cup as possible - even inside, I have tried this as well, but then I got rolled off trebles.
2. Put a coupling capacitor (what I did) to ground, after the 5Meg resistor - As you can imagine this is quite dangerous, if you touch anywhere the bias wire. Even after switching off the energizer, the live voltage stays there for hours.  Otherwise this solution works so far for me - the bigger the capacitor the better, but about 100nF is quite enough. 
3. The best - and I think this is what Sennheiser  did in their latest 50 000+ phones - MOSFET amp is integrated in the cup - thus the cable capacitance/cross talk is completely eliminated. Still a dangerous high voltage is running through the wires though.


----------



## chinsettawong

What is the problem you're hearing exactly?  If you hear any roll off,  it could be that your amplifier isn't powerful enough.  I wouldn't take off the the 5M ohm resistor.  You never know when the accident might happen.  And when it does, at least that small resistor can save your life.


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## legopart

I not understand so much on electricity.
but I first time saw a Fuse with 30mA on some vintage Transformer for headphones
I though to Use it If I going to mod the bias voltage 









I saw fuses Inside this holders

I think that connect this type of fuse will protect you.
Can some one confirm my idea?


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## Ulfar4

But you want to limit current as much as possible for bias. 30mA is too much. I would not recommend removing 5M resistor.


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## lkos98

Hi Chinsettawong, First off, let me say I admire your work - very, very nice job with all your projects. 
I'm running on toroidal transformers, which handle pretty well up to 25-30Khz, I don't know if this is causing the issue. By the way my ears are not they used to be - I barely hear up to 13 000, so if I hear a treble roll-off, it means it's significant. 
My active area is 84mm, 4um thermal printer ribbon (looks a lot like mylar), anti-static coating, 0.5 mm spacers, 1mm stator - all copper clad laminate.   
Anyway I just asked a question, if anybody experienced this issue with cross-talk between left and right channels, which with me disappears once this resistor is bypassed (or in fact the bias is AC coupled to the ground). And I just shared my experience with this as a roll-off of highs, if I don't bypass it.
Otherwise you are absolutely right, bypassing it is dangerous, that's why I have a 1Mom in series, but coupled with a small capacitor to ground, after it, so the shock is very short, when the capacitor discharges through your body, yet still not pleasant, but not lethal for sure. I'm also very careful to isolate bias wires well and not to touch them when disassembling the phones.
If nobody has experienced this cross-talk (and roll-off), it definitely means the problem is with me only and I will have to look further to fix it. 
Thank you


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## lkos98

Thanks all for replies. 
@ legopart, 30mA can still kill you, safe value is about 10-15mA. ( https://www.quora.com/What-is-the-maximum-voltage-a-human-can-withstand ) and I agree with ulfar4, the 5Meg resistor is there because of that. And I'm not sure, but I don't think the fuse will burn fast enough, if burn at all, to save you.


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## chinsettawong

In my experience, the toroidal transformers are not so good for this.  The transformers themselve can have high capacitance and cause the roll off at high frequencies too.  Since I only use my headphones with dedicated amps, I don’t have the problem you have.  You might want to try better transformers.  I still do not recommend taking off the 5 Meg ohm series resistor.  I also don’t recommend putting a capacitor after this current limit resistor.


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## chinsettawong

@legopart Please learn more about electricity.  It can be very dangerous playing with high voltage.  Please be very careful and do not take any risk.


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## chinsettawong

@lkos98 Your stator and spacer designs seem interesting.  Please share us some photos.


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## lkos98

Thanks Wachara, I will share, when I take some pictures. 
As per the bias voltage - yes I agree, but remember the AC audio outputs are also very high voltages (5-600V PtP) and as far as I know the current of the output stage is about 10mA. They are not protected by any resistor (or no more than few kOms, so they can be very dangerous too.
The toroidal transformers are not good enough I agree, but I managed to blow my MOSFET amp, just because I forgot to protect Gate Source with a zener diode. The toroidals are just for testing now, until I rebuild my amp. Toroidals have a very bad distortion around 30Hz and bellow because the core saturates bellow 40 or so. 
Still with the amp I was able to hear the cross-talk very much, but I didn't know then where to look for it.


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## quintile

if you are getting crosstalk or hf loss then you need to look elsewhere. removing the large resistor in series with the bias should not help - if it does then you have problems elsewhere.

the stator voltages peak at about 500-600v but their mean voltage is much much lower -remember loudness is logarithmic to voltage.

the diaphram bias voltage is constant and, without the series resistor, potentially leathal. DO NOT REMOVE IT. and als do not add a bigger capacitor after the series resistor. the charge on this just gives you another source of a high current pulse.

if you are not scared (you should be) the concider what hsppens if you overdrive the headphones and the diaphram touches one of the stators - significant current - melted diaphrams.

i suggest you look st your diaphram coating’s resistance which maybe too low or too high.

please be careful,

-Steve


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## lkos98 (Dec 14, 2018)

Here are some pics. Pretty standard frame design. I just use connector pins soldered to the stator/spacer so I can disassemble/assemble it easy without unsoldering/soldering wires.
I also run both headphones in parallel from the same toroidals. I tested to disconnect one and to see if there's any difference, but I could not find one.
The ovals are a bit smaller 94 x 68 mm , while the circle ones are 84mm in diameter. Needles to say circle give much better bass (sometimes it's even too much), but a bit softer highs, while the oval seem better FR balanced, but with weaker bass. The ovals are also a bit quieter, because of the 0.7mm spacers.


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## legopart

chinsettawong said:


> @legopart Please learn more about electricity.  It can be very dangerous playing with high voltage.  Please be very careful and do not take any risk.


Thanks!
I need to Decrease Stax SRM-1 Voltage from 230v to 180v to connect specific headphones (Beyerdynamic Et1000).
How can I do so ?


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## lkos98

@quintile 
Thank you for your concern, you are right, but I have taken some precautions: 
1. My bias voltage is not very high - 360V and the capacitor is relatively small, discharging it is very fast. I did not remove the resistor - it is just shorted to ground on the output side with the capacitor. It can't recharge the capacitor, during load (my fingers  ).
2. The diaphragm is of a good resistance - I can leave it for 2 hours, deenergized and I can still here the music
3. The stator is varnished (this is the way I etch the unneeded copper) and touching the membrane does nothing, except it might get sucked. 

If nobody have experienced this cross-talk, I really need to look where is it coming from. The cable I have is definitely not of a good quality, as you see it's separate wires joined if few places. it's capacity is about 80-100pF. while the headphones on their own are less than 20pF. May be it is coming from the cable or from high impedance of the transformers at high frequencies. I don't know, I just can tell that AC grounding the bias is removing all of the cross-talk.


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## chinsettawong

I do not really understand what you mean by cross talk.  Can you elaborate?

By the way, I can’t see the pictures you posted.


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## lkos98

Yeah, I can't see them as well, I will try to post again.
Cross-talk between left and right channel - lets put a mono source to our amp - driving both left and right channels. Then we adjust the balance of the amp completely to the left (or right). We are supposed to hear only left channel and nothing in the right. In my case a big portion of the left channel goes to the right, so if you put on your head just the right cup you can hear it. As far as I remember in FM radio, there used to be such a parameter cross-talk which was measured in dBs - how much left and right channels are talking between each other.


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## chinsettawong

You need to build yourself a stereo system.    With that, all the problems are solved.


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## legopart

Wow great headphones and system.
Do you test them on Stax amp?


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## chinsettawong

@lkos98 Very nice headphones.  With a good amplifier, they should sound wonderful.


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## lkos98 (Dec 14, 2018)

Thank you very much for the kind words, but as I am a bit of a perfectionist I don't like few things. Headbands - both are not very stable because of the aluminium holders, and the spring (metal sheet from a children's tiara) is a bit weak. Plywood for the casing, although very light, is also not the best solution, I think a harder and heavier wood would be better. May be with the next revision....
I will appreciate your advise - oak, cherry, pine? I made one of my prototypes from bamboo - kitchen cutting board and I think it was very good, but the active area was too small and they got almost no bass.
By the way I remember now - "channel separation" - the other term for cross-talk, if I'm not mistaken.

@legopart , Thanks, if I had Stax amp I wouldn't bother with making my own. Where I live is imposible to find a Stax amp, and ordering it from anywhere will cost me a delivery more than the amp itself.


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## chinsettawong

@lkos98, Headphones with wood case will be very nice indeed.  I use our local teak wood and I really like them.  I have no experience with oak, cherry, or pine.  It's better that you can try them all and let us know what you like best.  

Why don't you try to DIY an amp?


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## lkos98

@chinsettawong. Well I, I can try the bamboo, what I have at the moment. It's hard, flat and dry (seem better for isolation in humid areas). I always make my amps and any other electronics DIY. Where is the fun in buying it? . But it's really difficult to find here parts. Orders from AliExpress take at least 2 months and you never know if it will come at all. eBay don't deliver here.
BTW, I remember you mentioned once, your CNC bed is not flat enough for milling PCB
 I'm using autolevel plugins, the boards come out pretty nice.


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## chinsettawong

Wow, where do you live?

I haven’t touched my CNC for almost 2 years.


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## lkos98

@chinsettawong 
Lesotho, just working here. In my country of birth, I can find almost everything, but it's difficult to predict all the components and parts needed and bring them once in a year , That's why almost everything is DIY and adapted from whatever found in local shops. 
If you are not using your CNC, how do you make new phones? 3D printing for the cups, headband, connectors, etc. ok, but stators and spacers? 

A problem for me is also the mylar, I can't order from ebay and the only one I have access to is about 4um thin, 10cm wide thermal printer ribbon, so there is no way to use any kind of stretching jig. They sell here 11um wrapping kitchen foil, but I think this is too thick for ESH. 
Let me share here my stretching method. I hope it's not too boring. May be someone else can use something similar.    
I wipe a glass table with wet cloth, stick the film to the table, and remove all bubbles (like to put a protective cover on a phone). Then I put glue (Pattex adhesive) on the spacers, wait 2-3 mins to dry and press it with piece of plywood and wood clamp. So far nothing special, but as you can imagine all membranes have different stretching. Someone in this forum proposed to measure free resonance frequency and that's what I'm doing for each diaphragm. I tap the membrane against a microphone attached to a fr. analyzer (this can be done also with a smart phone and analyzer app). Then I adjust the resonance by heating the membrane with a hair dryer until all are with equal resonances. This is extremely difficult, because at first after heating, the resonance goes pretty high, then slowly goes down while cooling and it takes about 5 mins to reach the target frequency - for my 4um ribbon, it's around 140-150 hrz for 0.5mm spacer. I guess for a 2-3 um mylar it should be few tens lower. Then I spray antistatic on a cloth (microfiber) and wipe the membrane as even as possible. I can tell the resonance doesn't change after applying the coating, nor after assembling the whole headphone. The main problem here is that once you exceed the target frequency you can't go down. I have tried several methods to lower the frequency, all resulted with wrinkles or loose membrane, which will then either stuck to the stator or make hiss noises. My ribbon also has different absorption for the coating on it's sides. One side coating is good (phones are much louder) and on the other - almost none, despite applying it several times. I hope this is not the same with the mylar you are using. It's very frustrating if I swap the sides, I have to redo the whole process.


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## chinsettawong

Wow.  I have been to South Africa for a business trip for 3 days and that’s the only place in Africa continent that I have been to. It’s the first time I learn about Lesotho.  

Actually, I think 4 micron is alright.  You won’t hear much difference from using thinner Mylar.  But if you need, I can send some to you.  

You’ll be surprised that the kitchen wrap plastic sounds very good too.  Try it.

As for my CNC, I haven’t used it at all.  I’ve been too busy at work and haven't made any new headphones for a long time.  I also make the gerber files for my stators and spacers, and when I need them, I hire a professional PCB maker to make them for me.  They can do a much better job than I can too.  Actually, I’m getting too lazy nowadays.


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## lkos98

Thank you for your kind proposal, but I sending here is a bi risky  Things tend to disappear in the post. Anyway I have ordered mylar from ebay to my country of birth and when I go there for leave, I'll bring it here.
Kitchen wrap - I was always wondering - is there a relation ship between thickness and high frequencies? I mean the heavier the membrane is, the worse would treble be. Is this correct? What is your experience?


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## chinsettawong

Well, the thickness of the diaphragm does of cause affect the frequencies response.  It is known that the thickness of 6 microns or lower gives good FR.  Anyway, the kitchen wrap can be stretched a lot, and by doing that, the thickness becomes less than its original 11 microns.  I’ve try it when I use thicker spacers.  It sounds very nice.  The problem with it is that it is quite temperature sensitive.  Wearing the headphones in a warm room tends to change the tension of the diaphragm somewhat and collapses the diaphragm to one side.  But with thick spacers (0.8-1MM), it’s fine.  It also gives very good bass too.  Try it!


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## legopart

If the membrane have to absorb electric charge.
Maybe I can use some alominium foil for It





Somebody tried?


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## chinsettawong

legopart said:


> If the membrane have to absorb electric charge.
> Maybe I can use some alominium foil for It
> 
> 
> ...



Please.  Please be careful.  Please don’t play with high voltage and something that you do not really understand.  It’s very dangerous.


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## chinsettawong

Today, I'm listening using my older generation of Omega clone.  I actually put it aside for many years and almost forgot about it.  Surprisingly, it still sounds very nice!


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## legopart (Dec 16, 2018)

Again I ask,
How to decrease the Bias voltage (externally)?
which resistor to use?


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## chinsettawong

To decrease the bias voltage you have to make change from the internal not the external.


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## legopart

chinsettawong said:


> To decrease the bias voltage you have to make change from the internal not the external.


I want to connect old headphones with Bias of 180v to 230v amp.
I can buy and build any electronic board with any elements


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## chinsettawong

The bias voltages of 180V and 230V are only 50V apart.  I’m sure you can just plug in your headphones with no problem.

By the way, what amp is it and what headphones are those?


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## legopart

chinsettawong said:


> The bias voltages of 180V and 230V are only 50V apart.  I’m sure you can just plug in your headphones with no problem.
> 
> By the way, what amp is it and what headphones are those?


Stax Srm-1
and the headphones is Beyerdynamic Et1000


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## bruma

legopart said:


> Stax Srm-1
> and the headphones is Beyerdynamic Et1000



I use the ET1000 with a Stax Amp and it works fine. In fact it is better than the original Beyerdynamic N1000.


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## legopart (Dec 16, 2018)

bruma said:


> I use the ET1000 with a Stax Amp and it works fine. In fact it is better than the original Beyerdynamic N1000.


But will it have some future issues/ impacts  with higher voltage  then It set first?


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## legopart

About  the DIY.
I ordered instead ready pcb one sided plated board with copper 
like here https://www.ebay.com/itm/FR4-Copper...Na4TOtgBhDcV5nLJLA:rk:4:pf:0&var=423514493478

I bough some* "Glass Fiber" boards 
https://www.ebay.com/itm/Glass-Fibe...var=512414829651&_trksid=p2060353.m2749.l2648



*
And some "Copper Cu Metal Sheet Foil"
https://www.ebay.com/itm/99-9-Pure-..._trksid=p2060353.m2749.l2648&autorefresh=true
*





*And now I asking myself, can I glue or cut this things to the right size?,
I need 86mm round shape


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## bruma

legopart said:


> But will it have some future issues/ impacts  with higher voltage  then It set first?



no issues at all, works flawlessly for years


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## lkos98

@legopart 
Interesting approach with copper foil. With 0.1mm thickness  u may get a sturdy stators, but I'm not sure how you can glue it to the FR4, so it's flat enough. And then drilling and etching will be more difficult of course. 
As for the bias - you can adjust it with a high Ohm resistor divider (5M / 50M  will lower your voltage with about 1/10, but 230 is low enough, so I don't really think you have to lower it more.


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## lkos98

@chinsettawong 
These phones are beautiful. What metal did you use for holding the cups (sorry, don't really know the therm)? Mines are 2.5 mm aluminium rods for welding. They are too soft, not elastic at all. Sometimes one side comes out of the hole and cup almost falls.


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## legopart (Dec 17, 2018)

lkos98 said:


> @legopart
> Interesting approach with copper foil. With 0.1mm thickness  u may get a sturdy stators, but I'm not sure how you can glue it to the FR4, so it's flat enough. And then drilling and etching will be more difficult of course.
> As for the bias - you can adjust it with a high Ohm resistor divider (5M / 50M  will lower your voltage with about 1/10, but 230 is low enough, so I don't really think you have to lower it more.


The problem that I decided to make a round hollow shape from all the parts
and glue on them the (the membrane) or the copper mesh for the stator
https://www.ebay.com/itm/Copper-Mesh-Coarse-Dense-Gauze-Mesh-10-20-40-60-80-100-200-width-3-to-20/302402072612?ssPageName=STRK:MEBIDX:IT&var=601234156899&_trksid=p2060353.m2749.l2649






Cause I not having any CNC cutting machine


It's too hard job with too much layers


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## chinsettawong

lkos98 said:


> @chinsettawong
> These phones are beautiful. What metal did you use for holding the cups (sorry, don't really know the therm)? Mines are 2.5 mm aluminium rods for welding. They are too soft, not elastic at all. Sometimes one side comes out of the hole and cup almost falls.



The whole headband is actually from my old headphones.  I think the material is stainless steel wire.


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## lkos98

I see, thank you. I have some 3mm steel rod, but it's too heavy and difficult to bend. I will try to find some 2-2.5mm.


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## bui501-tech (Dec 18, 2018)

lkos98 said:


> I see, thank you. I have some 3mm steel rod, but it's too heavy and difficult to bend. I will try to find some 2-2.5mm.



*I found some replacement AKG headbands from this company that sells online:
https://www.fullcompass.com/prod/198139-akg-2040m02100-outer-headband-for-k240-and-k240-mkii*

They also sell the leatherette bands that go with the steel parts, but the leatherette bands have the “AKG” logo on them.  The steel headbands are pre-shaped and of good quality for a good price...It takes the hassle out of having to make a template or frame to bend  hard steel wire stock into the right shape.


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## lkos98

@bui501-tech 
Thank you very much! I may consider it. I have made a template already for the wire cup holders (anyone knows the right therm for this?  )  with my CNC on a MDF piece. As for the headband I'm using a children's tiara, made of 6 X 0.5mm spring steel, which is not bad at all, and an artificial leather ribbon mounted bellow it.
My earpads are also for AKG ordered from Aliexpress: https://www.aliexpress.com/item/Bla...986.html?spm=a2g0s.9042311.0.0.27424c4dKTAfF9, they are 105mm, which is perfect for my cup and although not original, pretty comfortable and they seal good . Only problem is in hot weather, my ears start to sweat a lot, but I tried different ear pads and it's always the same, when you want a good seal. In fact my project was a bit wrong - I build the cup size, according to the ear-pad size. The stator and spacer size were reflected as well. It should have been the other way around - active area size, then stator, spacer, then cup and last - the ear-pad.


----------



## bui501-tech

lkos98 said:


> @bui501-tech
> Thank you very much! I may consider it. I have made a template already for the wire cup holders (anyone knows the right therm for this?  )  with my CNC on a MDF piece. As for the headband I'm using a children's tiara, made of 6 X 0.5mm spring steel, which is not bad at all, and an artificial leather ribbon mounted bellow it.
> My earpads are also for AKG ordered from Aliexpress: https://www.aliexpress.com/item/Bla...986.html?spm=a2g0s.9042311.0.0.27424c4dKTAfF9, they are 105mm, which is perfect for my cup and although not original, pretty comfortable and they seal good . Only problem is in hot weather, my ears start to sweat a lot, but I tried different ear pads and it's always the same, when you want a good seal. In fact my project was a bit wrong - I build the cup size, according to the ear-pad size. The stator and spacer size were reflected as well. It should have been the other way around - active area size, then stator, spacer, then cup and last - the ear-pad.



That’s what I did with the first set of drivers I made: I designed the drivers’ size around the ear pads I could buy online.  Not everyone has somebody who can custom make real leather earpads to their exact specs like Chinsettawong does :-D


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## chinsettawong

bui501-tech said:


> That’s what I did with the first set of drivers I made: I designed the drivers’ size around the ear pads I could buy online.  Not everyone has somebody who can custom make real leather earpads to their exact specs like Chinsettawong does :-D


I have some good helpers.


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## lkos98

Well, this is how a project is supposed to be done, but I do not agree a 100% on this rule. Sometimes you have to work with what you have and what you can find. No point of creating something and realize, that you don't have the last part or it's extremely costly, or impossible to find. 
@bui501-tech , thanks for the link for headband, but... - US shipping only


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## chinsettawong (Dec 19, 2018)

You need to see my very early headphones. Everything is made from easy to get parts.  My ear pads are made from insulation foam.    To me, that’s the real joy of DIYing.


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## lkos98

Exactly, this is the joy. At first I also made ear pads from foam and some kind of a rubber foam, what they put under the big pallets not to scratch the floor. 
I have a question - how do you compare the ovals to the circle, which are with the approximate same active area? I can only compare my ovals with my circle, but ovals got a thicker spacer and more stretched membrane, so the differences are to be expected. I also don't have any Stax to compare mine like you do. From all the headphones I have, there is one old open air Koss, which was still my favorite, but now these sound far batter. That's the problem with ESH, as you once said - you will never listen to anything else.


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## chinsettawong

I like both of my oval and round headphones.  I think that they are equally good.  The tensions of the diaphragm make more difference in sound than the shape of the driver.  You'll need to experiment with different tensions to see what you like most.  Anyway, the active area also makes a whole lot of difference in sound stage.  Personally, I like big active area.  I would advise that you make the biggest active area as you possibly can.  You'll love the sound stage and the dynamic that come with it.


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## lkos98 (Dec 20, 2018)

Thanks and yes - all you said is true, My rounds are with 84mm - 5541 mm2, the ellipse are 68x94  - 5020 mm2. (equal to 80mm round). Despite the small difference in size round ones sound much more bass-ier.
But tension is also different and this could lead to a weaker bass as well. I can't really understand how you guys manage to stretch to 100 Hz free air resonance with 0.5mm spacers. I cannot make it lower than 140, may be because my mylar is different material and is 4um thick.
Anyway I would like to share an excel file here, which I made for calculations of area (cirlce and ellipse - for other shapes you can put your own formula), filling holes ratio, capacity and impedance of the stators. Please note I made it for myself and it could be quite confusing, because I was too lazy to put descriptions in all fields. Just to let you know - left site is empty, because I put there exported cells of the drills - so I can count all the holes easy. On the right site there is an approximate calculation how much time it will take to drill the holes on a CNC.
Use it as you like.

Hmm, sorry seems I don't know how to put a file, I have uploaded it, but it does not appear in the post.


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## legopart

Do anyone tried?
https://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=Hostaphan&_sacat=0


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## Ulfar4

Have you looked at the thickness? The smallest is 0.01 mm, which is 10 μm. This could work, but better is something around 3 μm.
I suggest you to read whole thread and Roger sanders Electrostatic Loudspeaker Design Cookbook (can be found on google). This could answer most of you questions.


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## legopart

Oh, thanks, always forget that mm and μm is not the same.

Secondary I started to read.
I decide not to build the amp, I going to use my stax amp for this DIY headphones.
I only have to decide the distances of the elements and how to coat the diaphragm and how to replace it right if it blown .
I think to use some plastic screws to tight between the diaphragm and other elements, or cut enough space between the conductive plates and use some normal screws.





I don't want to wast lots  of materials or try to un-glue  each part because one mistake.


----------



## Ulfar4

I am working on my housing for drivers with ear pads and headband. Headband is from Sony MDR7506 and earpads are some 100mm type from ebay. I only need to add some foam to headband for increasing comfort.


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## legopart

looks good!
really quality work!


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## chinsettawong

Ulfar4 said:


> I am working on my housing for drivers with ear pads and headband. Headband is from Sony MDR7506 and earpads are some 100mm type from ebay. I only need to add some foam to headband for increasing comfort.


Very nice!


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## lkos98

Pretty! Are these housings made on 3D printer?


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## chinsettawong

Bought myself a present.  Merry Christmas everyone!


----------



## Ulfar4

lkos98 said:


> Pretty! Are these housings made on 3D printer?


Yes, it is from 3D printer (ABS material).


chinsettawong:
Nice, how it sounds compared to other amps?


----------



## chinsettawong

The Stax amp sounds very nice.  It’s small and portable. I like it.  

Comparing it to my other KG amps, I feel that it is not so much inferior.  It drives my Omega clone easily.  At 11 o’clock, it’s loud enough.


----------



## AngelWing

Happy New Year Wachara, you have gained another follower in me.. Great work.


----------



## chinsettawong

Happy New Year @AngelWing!  Looking forward to seeing your creations soon.


----------



## AngelWing

Hi Wachara, I have gone through almost 150 pages of this thread, And although my basic concepts are clear the size and dimensions are getting diverse.
So the question is, which Headphone Driver Size gave you best result?
I am right now making a dremel based diy CNC (Just started), I already own a 3d printer, but lack knowledge in CNC, what milling bit you use for your CNC?
Also I think you said KGSSHV is really good amp. Is there any better and easier to make SS amp than this?


----------



## chinsettawong

Both of my Omega and Orpheus clones are very good.  You can follow either of those designs.  Beside the shape, the diaphragm tension is very critical in making good sound.  You have to practice to get just the right tension.  I can't really tell you how much is enough.  You'll need to experiment with it. 

I'm not sure if a dremel is powerful enough for the job.  It's probably OK to drill and cut the FR4, but for cutting wood, I'm not sure.  Anyway, try it and let us know how it goes.

Yes, I still recommend you to build a KGSSHV.  Please go with the latest version which is KGSSHV Carbon.  It's a step above the earlier KGSSHV version.  It's also known to be the best DIY SS amp design so far.


----------



## bui501-tech

AngelWing said:


> Hi Wachara, I have gone through almost 150 pages of this thread, And although my basic concepts are clear the size and dimensions are getting diverse.
> So the question is, which Headphone Driver Size gave you best result?
> I am right now making a dremel based diy CNC (Just started), I already own a 3d printer, but lack knowledge in CNC, what milling bit you use for your CNC?
> Also I think you said KGSSHV is really good amp. Is there any better and easier to make SS amp than this?



I bought an old Stax amp just to get started with DIY headphones when I stumbled upon Chinsettawong’s blog... I built a KGSSHV after that because the old Stax was noisy as anything!  The KGSSHV was great but I was really glad I built the KGSSHV Carbon: more power, cleaner sounds at high volume, my DIY drivers sound louder and cleaner with the newer KGSSHV Carbon... all to say that you should listen to Chinsettawong’s advice. He’s got so much experience with both amps and headphones.


----------



## chinsettawong

bui501-tech said:


> I bought an old Stax amp just to get started with DIY headphones when I stumbled upon Chinsettawong’s blog... I built a KGSSHV after that because the old Stax was noisy as anything!  The KGSSHV was great but I was really glad I built the KGSSHV Carbon: more power, cleaner sounds at high volume, my DIY drivers sound louder and cleaner with the newer KGSSHV Carbon... all to say that you should listen to Chinsettawong’s advice. He’s got so much experience with both amps and headphones.



Happy New Year to you, Vinh.  We should get together again when you are back in Bangkok.  Looking forward to listening to your DIY headphones again.


----------



## AngelWing

Thanks for the advice Wachara, I am making this CNC (converting my 3d printer) just to drill FR4 board only. For headphone I am going to use 3d Printer with ABS Plastic. 
But first I will make AMP. Time to look into KGHSSV Carbon..


----------



## MrSlim

Although I have to agree that the KGHSSV Carbon is likely close to or is top of the heap for Electrostatic amplifiers, you might consider something a bit simpler for a first pass at building an Electro amp.  Check out the CFA electrostatic amp thread on the forum where the Stax Mafia hang out (not sure if it is OK to link to them here, pm me if you need more direction).  It is a much simpler build, and only needs the GRHV to supply it (vs a GRHV and a GRLV for the KGHSSV Carbon) (although I think Kerry designed a hybrid PS board that contains both the HV and LV circuitry).   Great bang for the buck from what people are saying.


----------



## AngelWing

Hi Mr Slim thanks for the info, I am pretty comfortable with electronics and circuitry (have designed many circuits some of them high voltages too). I would still take proper precautions due to high voltages required.
I will directly try KGHSSV Carbon. 
Is there any write-up about it anywhere or just build threads which I have to follow ?


----------



## chinsettawong

AngelWing said:


> Hi Mr Slim thanks for the info, I am pretty comfortable with electronics and circuitry (have designed many circuits some of them high voltages too). I would still take proper precautions due to high voltages required.
> I will directly try KGHSSV Carbon.
> Is there any write-up about it anywhere or just build threads which I have to follow ?



The build thread is the only source of the information.


----------



## legopart (Jan 2, 2019)

First DIY for Stax plug






I dont know If I going to build the all amp for the electrostatic headphones.


----------



## bui501-tech

chinsettawong said:


> Happy New Year to you, Vinh.  We should get together again when you are back in Bangkok.  Looking forward to listening to your DIY headphones again.


Happy New Year, Wachara! I just got back in Thailand, but cannot stay for as long as I thought. Spent too much time skiing over Christmas with my kids.... I’m leaving again Sunday. I should be back for Songran break, and since the kids get off school for only a week then, there will be more time for DIY :-D


----------



## Ulfar4

Hi, I have progress with my drivers, for long time i was fighting with coating, it seems that antistatic 100 spray is unstable on its own. I found some screen cleaner at home AND mixed it with antistatic 100. now it seems working properly. So I am curios how long it will work.
Specification:
- 1mm double sided FR4 with vias and 2mm diameter holes
- 0.6mm FR4 spacers
- 3um Mylar from ebay
- dust covers are made from spacers and wrinkled mylar





I must say that I really enjoy the sound and it is lot of fun with this, although I am working on this for almost 1 year.


----------



## lkos98

Looks good. What is your active area/diameter? How does it sound without housing (ear sealing)?
For me antistatic 100 is working fine. I spray it on cloth, that is used for eyeglass cleaning and then wipe the diaphragm with it. Only problem I noticed is that if the membrane touched the stator, the spot there becomes dark on the stator (I guess it's the lacquer, because it can be cleaned easy). Probably the coating also vaporizes on that spot. Still I haven't re-coat my diaphragms for more than a month already and I couldn't hear any difference.


----------



## Ulfar4

Active area is 70mm. Like there is no bass, but I'm not good with the sound description because I've never heard anything better, it's very good for me.
Maybe it was something else, but when I put the driver in the housing and listened for while, distortion became more and more audible and when I put them back on the desk it returns to normal state after some time.


----------



## bui501-tech

Ulfar4 said:


> Active area is 70mm. Like there is no bass, but I'm not good with the sound description because I've never heard anything better, it's very good for me.
> Maybe it was something else, but when I put the driver in the housing and listened for while, distortion became more and more audible and when I put them back on the desk it returns to normal state after some time.


Are you using the clips to hold the layers outside the housing like in your photo, and just several screws to hold them inside the housing? Just curious... I’ve found that the FR4 parts can flex unless you have the sandwhich of parts held together securely in enough places.


----------



## legopart

I starts to read the book about electrostatic headphones.
can someone explain me how works the electret one ?, I heard this type of headphones and always Interested how do they works?


----------



## Torac

legopart said:


> I starts to read the book about electrostatic headphones.
> can someone explain me how works the electret one ?, I heard this type of headphones and always Interested how do they works?



The diaphragm is pre biased, in an oven I think, then when playing music you only need to send voltage to the stators like a regular electrostatic.


----------



## lkos98

[/QUOTE]="Ulfar4, post: 14697991, member: 493966"]Active area is 70mm. Like there is no bass, but I'm not good with the sound description because I've never heard anything better, it's very good for me.
Maybe it was something else, but when I put the driver in the housing and listened for while, distortion became more and more audible and when I put them back on the desk it returns to normal state after some time.[/QUOTE]
I agree with bui501-tech, fr4 tends to bend, which could make the tension uneven. It also depends what kind of distortion you hear - slapping of membrane, wrinkles on the membrane? Heat and moisture also builds up in housing, causing much less resistance of the coating - in my opinion and feeling, ESH become much louder and distortion increases as well, especially in the middle fr. range (voices, sax, etc.). Not sure if this is true, I have never measure it.


----------



## Ulfar4

bui501-tech said:


> Are you using the clips to hold the layers outside the housing like in your photo, and just several screws to hold them inside the housing? Just curious... I’ve found that the FR4 parts can flex unless you have the sandwhich of parts held together securely in enough places.



When it is in the housing, there are four screws that holds driver together. The nuts pushing all parts towards to housing. I've posted my housing at the previous page. There is foto with driver in housing







lkos98 said:


> I agree with bui501-tech, fr4 tends to bend, which could make the tension uneven. It also depends what kind of distortion you hear - slapping of membrane, wrinkles on the membrane? Heat and moisture also builds up in housing, causing much less resistance of the coating - in my opinion and feeling, ESH become much louder and distortion increases as well, especially in the middle fr. range (voices, sax, etc.). Not sure if this is true, I have never measure it.



I had bending problems when I received the first batch of stators from the PCB manufacturer, they were not flat.
I do not know how to describe distortion but it was always only bass region where the distortion was.
Other thing is, that I did not have a dust cover on the driver, so maybe it was because of moisture when I had it on my head.


----------



## lkos98 (Jan 5, 2019)

Ulfar4 said:


> When it is in the housing, there are four screws that holds driver together. The nuts pushing all parts towards to housing. I've posted my housing at the previous page. There is foto with driver in housing
> 
> 
> 
> ...



Your rings are wide enough, so even with 4 screws it should not bend. The only reason for distortion in bass I could imagine is if the tension is not enough and membranes touch the stators in high volume.


----------



## lkos98

Today I got some time and decided to disassemble my last (and favorite) ESH, because I have some little left/right unbalance. As you see my design is a bit different although the principle is the same. For some reason nobody is doing this or at least I could not find anything build in practice (just an article in tubecad and a patent). I would like to hear your opinions, I'm sure many people will jump on me, I'm ready to defend it.  .


----------



## chinsettawong

Interesting design.  Are you using two diaphragms and one stator?  Please tell us more about how the driver works.  Do you feed the music signal to your stator or your diaphragms?


----------



## lkos98

Driving diaphragms with audio signal has been done, but it requires a low resistance membranes (aluminium foil) and high resistance stator. It's called inverted ESL. I'm using fully inverted ESL - one stator and 2 diaphragms, which are high resistance coated. Diaphragms are biased +360 and -360 V. Stator is a double sided copper, at 0V DC and is driven both sides with audio signal 220V AC. This is completely equal to 2 stators/1 diaphragm, except that you need double audio voltage in order to get 600V p2p. Linearity is the same, since both diaphragms are driven at the same time and mathematically they can be replaced with one driven from both sides. Actually they help each other to move in unison, since the air is trapped between them. Cons here are:
1. Double audio voltage - can't use and normal ESH amplifier without modding it or listen to a low level.
2. 4 equally tension-ed diaphragms - for me it's a big problem since I tension all separately. 
3. Shielded cables for biases (it's a long and complicated story, remember my issue with channel separation?)
4. Need for thinner mylar - 3um are effectively around 4-5um - considering they move in unison and air is trapped between them (this is why I didn't want to use 11um kitchen foil )

Advantages - as I see them in my personal opinion.
1. Extremely low drivers capacitance (in fact only cable capacitance is in the game). I think this is a good point to experiment with big ESL pannels
2. No need for dust/sweat covers (diaphragms are coated against the stator and air between them is sealed). But protective grills are very desirable. 
3. Spacers on which the myler is glued can be as thick as you wish - I use 1.6mm FR4 
4. Just 1 stator to drill per cup 
5. Most people say that single output amp is easier to build. 
Not sure I mentioned all, some of the pros and cons can be justified either way, according to person preferences. For example - membranes are always attracted to each other and to the stator - for me they are relatively more stable, but need a bit more tension. On the other hand they can be pressurized in advance with some inert gas so they are flat, or even a bit swollen,  but I don't think this can be done DIY. 
I like how they sound, can't really tell a difference between both designs, may be a bit bassier (because of the effectively thicker membrane), which for me is great - I love bass. And yet again, I can't compare them to any high quality headphones, I just know they sound far better than anything else I own.


----------



## chinsettawong

Very interesting.  Thanks for sharing your design.  About the bass, you should try different diaphragm tensions.  It's not that easy to get a spot on tension.  But, once you can achieve it, you can hear very, very deep bass.


----------



## chinsettawong

By the way, what spacer thickness between the stator and the diaphragm do you use?  Why do you bias the diaphragm to only +/-350V?  Have you tried a higher bias voltage? 

How do you tension your diaphragm?


----------



## lkos98

chinsettawong said:


> Very interesting.  Thanks for sharing your design.  About the bass, you should try different diaphragm tensions.  It's not that easy to get a spot on tension.  But, once you can achieve it, you can hear very, very deep bass.


Oh yes, I have tried so many tensions (I read almost the whole threat ). I have wasted may be 30 membranes already until I reached around 140 Hrz free air resonance and +- 360V bias (only for these 84mm drivers). Any lower than 140 or higher than 360 slaps the membrane to the stator. With these setting I have measured the FR and it's amazingly flat from 30 up to about 700 Hrz. I'm still using toroidal transformers, which can't go lower than 30 - they saturate and the output signal is almost a square wave. Even so, the bass is very deep - I can feel the pressure in my ears without actually hearing it.


----------



## lkos98

chinsettawong said:


> By the way, what spacer thickness between the stator and the diaphragm do you use?  Why do you bias the diaphragm to only +/-350V?  Have you tried a higher bias voltage?
> 
> How do you tension your diaphragm?


Well +-360 is actually 720 (between the 2 membranes) - way above 580V that you use. Yes it's only 360 /per membrane -stator, but unfortunately is not attracted only by the stator, but also by the other membrane. With normal design the membrane is attracted from both stators, so it's in kind of equilibrium. So we can say the membrane is at 0.5 mm from both stators. With me both membranes are actually closer - may be 0.45?, so the electrostatic force is higher.  
I have tried with +-600V in the beginning, with no success, unless I increase the spacer to 0.8mm and apply more tension. The voltage between membranes became 1200V! with only 1+ 2 x 0.8 - 2.6 mm distance. You have to increase the tension a lot to make it stable, but then my precious bass is gone and all sort of sparking noises are there. With such high voltage there are many problems - resistors in the bias supply, cable (flat ribbon cable is rated to 300V btw), wooden housing, etc. I had sparks between membrane and wooden frame in many occasions, a 10 Mohm resistor in the bias supply was leaking current, etc. Once I lower it to 360, everything was back to normal. 
I explained once my tension method, I don't want to bother everyone again, simply put I put the film (thermal printer ribbon film about 4um) on a flat glass and remove bubbles, then I glue the spacers and then adjust the tension with hair dryer, by measuring the free resonance frequency until I reach about 140 Hrz.


----------



## chinsettawong

Thanks for the explanation.  About how you tension your diaphragm, I think you can have a much better tensioning result using a mechanical tension - either using weights or inner tire method like I do.  Hot air can’t give enough tension to the diaphragm.  

Anyway, that’s just my opinion.  Your driver is interesting and I know that it must sound excellent.  Keep us posted with your progress.


----------



## bui501-tech

lkos98 said:


> Driving diaphragms with audio signal has been done...



I really like your design—something a little different from most of the other working designs here... looks great!


----------



## legopart

Really great jobs on the last page!, likes it a lot!

How can I cut round right shape ?


----------



## lkos98

@chinsettawong Thank you. I must find some time (and proper elements) to build my amp at last, then I can post some FR plots. As for the tension, my mylar is only 100mm wide, so it's impossible to stretch it mechanically. I agree, heating is not very good - it stretches uneven and is very difficult to make all of them equal, but it's the only option I have, until I get my ordered 2um mylar. 
@bui501-tech Thank you. I went for this design, because I wanted to make something different and because of the 2 main advantages (IMHO) - low capacitance and "the no need" for dust cover. And the main reason of course - doing something with your own hands - so much fun.  
@legopart  Thanks for the nice words. I cut all parts, including housing on my DIY CNC router. It can be made by hand as well, but it's will be extremely difficult, and time consuming. Accuracy is also very important, that can't be done by hand. So to answer your question - 3D printer or CNC, but I think all will agree the shape is not so important, may be just for aesthetic point of view. You can see in this thread a lot of people doing their phones with rectangular shape.      
I got the idea long time ago, but the real inspiration came from this thread, Chinsettawong, great thread indeed.


----------



## chinsettawong

I bought a Chinese 100W laser cutter for my own New Year gift.  It's so easy to cut acrylics.  This is going to be a lot of fun.


----------



## lkos98

@chinsettawong 
You make yourself a lot of gifts 
Are you going to use this as a spacer? Acrylic 0.5 mm?


----------



## chinsettawong

Unfortunately, I can't find any 0.5 mm acrylic yet.  I'm just testing to see how well it cuts.  

Actually, I'm planning to build a pair of electrostatic loudspeakers using the acrylic as the stators.  I've bought some conductive paint which I will paint it on the stators to make them conductive.  With this laser cutter, this task becomes so easy.


----------



## lkos98

That's nice, although it's not in the topic of this thread, I'm very interested in this, please keep us updated on the sizes, distance, etc. Thank you


----------



## VandyMan (Jan 9, 2019)

Is there any place I can download DXF or Gerber files for a stator (so I can order some from PCBWay)? Long term, I'll create my own, but thought it would be easier to get started and learn with a proven design.


----------



## lkos98

Hi VandyMan, 
I'm not sure you can find such thing for download. And it depends on the design itself. Mine for example, doesn't have through holes for holding everything together. And I have only a gcode for CNC.
A limited edition of Eagle software is free and relatively easy to use and can export gerber.


----------



## VandyMan

A friend of mine who does a lot of DIY projects has offered to help me create the files, so I'm all set. However, if anyone does have Gerber or DXF files for stators that they would be willing to share, I'd still be interested in getting them in order to get ideas and avoid mistakes.


----------



## bui501-tech

VandyMan said:


> A friend of mine who does a lot of DIY projects has offered to help me create the files, so I'm all set. However, if anyone does have Gerber or DXF files for stators that they would be willing to share, I'd still be interested in getting them in order to get ideas and avoid mistakes.



Check your PM.


----------



## ts8051

chinsettawong said:


> Thanks Jtwrace and Headdie for your kind compliments.  I'm making them for fun, and I can assure you that the sound isn't bad at all.  To raise your appetite, here are a few pictures of my latest pair.  They are not yet finished though.
> 
> 
> 
> ...




Hello,
Please let me know about the thickness of the stators.


----------



## ts8051

chinsettawong said:


> Hi,
> 
> I'm more than willing to share with you my project.
> 
> ...



Hello again,
Do you use 1mm thickness for stators double sided or single sided ?


----------



## Ulfar4

I put drivers in housing. Oh, It is awesome. But after some time, left side become distorted in bass range. I still do not know why, but when I do recoating, it is ok, and then there is a distortion again. Also, the volume decreases with increasing distortion. Right side work like charm.


----------



## chinsettawong

ts8051 said:


> Hello again,
> Do you use 1mm thickness for stators double sided or single sided ?



When I made them with my CNC machine, I used 1 mm single sided.


----------



## chinsettawong

VandyMan said:


> A friend of mine who does a lot of DIY projects has offered to help me create the files, so I'm all set. However, if anyone does have Gerber or DXF files for stators that they would be willing to share, I'd still be interested in getting them in order to get ideas and avoid mistakes.



PM me your email.


----------



## lkos98

Ulfar4 said:


> I put drivers in housing. Oh, It is awesome. But after some time, left side become distorted in bass range. I still do not know why, but when I do recoating, it is ok, and then there is a distortion again. Also, the volume decreases with increasing distortion. Right side work like charm.


IMO you have a membrane stuck to one of the stators. When you recoat, you actually disassemble/reassemble and at the beginning it's fine. Then after some time membrane slaps again. Try switching off the bias only during listening and if the membrane is not stuck to the stator permanently the sound will come back normal while the bias is still not discharged completely.


----------



## legopart

Which method using Stax or another Electrostatic Headphones company to make the membrane chargeable ?


----------



## legopart

Which cables to use for Electrostatic headphones?


----------



## Ulfar4

lkos98 said:


> IMO you have a membrane stuck to one of the stators. When you recoat, you actually disassemble/reassemble and at the beginning it's fine. Then after some time membrane slaps again. Try switching off the bias only during listening and if the membrane is not stuck to the stator permanently the sound will come back normal while the bias is still not discharged completely.



Thanks, you were right, membrane was stucked to stator. I had bend stator. I changed stators in left drivers and now it is working properly.


----------



## lkos98

Ulfar4 said:


> Thanks, you were right, membrane was stucked to stator. I had bend stator. I changed stators in left drivers and now it is working properly.


Glad you found it, because after I wrote the response, it came to me there was an easier method to check, just blow air first to one side than to the other and if the membrane is sucked, you might hear a noise like a ripping off a scotch tape. Unfortunately I had this also few times. I guess stator/s bend with temperature (or moisture), mostly created by our heads.  
I think Chinsettawong proposed some time ago to put a small drop of silicon in the middle of the stators, I have never tried this. May be he can share his experience, doesn't it loose some bass? (part of the membrane stops moving).


----------



## legopart

I test now the anti-static spray on the membrane and it really got some resistance (something like 1000-2000ohm).
is it too much low?

I planing to use 2core rca cable for each driver with this diagram





it can be something like this, But with bigger cables


----------



## chinsettawong (Jan 16, 2019)

legopart said:


> I test now the anti-static spray on the membrane and it really got some resistance (something like 1000-2000ohm).
> is it too much low?
> 
> I planing to use 2core rca cable for each driver with this diagram
> ...



You need 3 insulated wires per side.  That is 6 insulated wires for the headphones.  Good flat and flexible ribbon cables can do the job.  I use extension cables from Koss.  They are not expensive and are made for electrostatic headphones.


----------



## legopart

chinsettawong said:


> You need 3 insulated wires per side.  That is 6 insulated wires for the headphones.  Good flat and flexible ribbon cables can do the job.  I use extension cables from Koss.  They are not expensive and are made for electrostatic headphones.







In this case only one cable is not have double  insulation but it still insulated from the outside, it called shielded wire.
The shield wire used on my Et1000 as Bias cable (with same structure).
I decide to change it on my build model a little bit and set the -- minus  as shielded one and the internal cable will use Red cable for ++Plus and Back for Bias voltage.
I think that it safety enough, regular headphones not having any issue to use one isolation layer, Stax headphones using only one layer for each of 3 wires for each side.
I know the electronics roll that the modern electricity cable must have dual insulation, but we still talks only about headphones and wiring for it.





another questions about the anty-static spray:
- Why the resistance is gone after the spray dries ? what to do to keep this resistance ?
- If I having some vintage headphones, do they need new re-coating on the diaphragm to work better (like old Stax old one)?


----------



## lkos98

legopart said:


> In this case only one cable is not have double  insulation but it still insulated from the outside, it called shielded wire.
> The shield wire used on my Et1000 as Bias cable (with same structure).
> I decide to change it on my build model a little bit and set the -- minus  as shielded one and the internal cable will use Red cable for ++Plus and Back for Bias voltage.
> I think that it safety enough, regular headphones not having any issue to use one isolation layer, Stax headphones using only one layer for each of 3 wires for each side.
> ...


Hi Legopart, if you can, don't use the shielded cables, they are heavier and have higher capacitance. And using shield as a signal or bias wire is not a good idea. It will work for sure, but you may get some noises and hums.  Also please check the specifications for the insulation of the cable - it should be no less, than the bias voltage, otherwise you risk leakages between cables.
The flat ribbon cables are better with capacitance and easy to work with. I used 10 wires flat ribbon cable, skipping every second wire (not connected) , so you increase the insulation and decrease the capacitance at the same time. A standard stereo audio cable (like it looks from your picture) will also work, but I don't think the isolation voltage is more than 2-300 V.  
The resistance of 1Mohm for a membrane is low, I don't know how you measure it, but of course once it's dry, you can't get reading anymore unless you have a special high resistance Ohm-meter. Don't worry - even you can't measure it, it is there - probably around 100 MOhm or more, which cannot be measured with a standard multi-meter.


----------



## legopart

thanks!
I will check about the insulation leakage, for 580v +

another question:
Do old vintage headphones like Stax need re-coating for sound better ? do someone tried to restore old headphones with re-coating the membrane ?


----------



## chinsettawong

Recoating the diaphragms doesn’t make them sound better. You only do it when there is trouble with imbalance and etc.


----------



## chinsettawong (Jan 18, 2019)

I almost forgot that I had a pair of baby Orpheus - HE60.  To my ears, they sound just so, so.


----------



## Tjj226 Angel

chinsettawong said:


> I almost forgot that I had a pair of baby Orpheus - HE60.  To my ears, they sound just so, so.



That is very interesting. 

I have always considered the HE-60s to be my end game headphones. 

I have been dragging my feet for a couple years now to build some electrostatic headphones. My HE-500s broke, and we just moved into an apartment with walls that are thinner than paper. So now is as good as time as any I suppose. 

I hate to ask you such a broad question, but in your opinion, which designs have you done that sound better than the HE-60s? I have always liked the HE-60s for their bass and warmer tone. If you have produced something better, I would be REALLY interested in copying and iterating on it.


----------



## chinsettawong

To my ears, HE60 is too bright.  It also lacks deep bass.  

Either round or oval shape headphones like my design can be made to sound better.  The most critical thing is to tension the diaphragms to just the right tension.  But it's not easy.  It'll take a lot of practice, but it's well worth the effort.


----------



## Ulfar4 (Jan 19, 2019)

Today I finished repair of Lambda Nova Basic headphones. I had to do new case holders, change two dust covers and glue the drivers to the housing.





There is 3D model of Stax Lambda Case Holder for solidworks and drawing with dimensions.
https://drive.google.com/drive/folders/1J_dmJ29zJgSko5dflM5sCi2kIXiqYN3Y?usp=sharing


----------



## legopart

Ulfar4 said:


> Today I finished repair of Lambda Nova Basic headphones. I had to do new case holders, change two dust covers and glue the drivers to the housing.
> 
> 
> 
> ...


How much force do you use for the dust membrane ?

I need to repair on mine the membrane too on one side 
maybe I will buy a glue spray ...


----------



## Ulfar4

legopart said:


> How much force do you use for the dust membrane ?
> 
> I need to repair on mine the membrane too on one side
> maybe I will buy a glue spray ...


Just a little. I am doing it on table with tape.


----------



## legopart (Jan 19, 2019)

I fail to restore: Stax Lambda Normal (Normal bias)
I put a new membrane on each driver.
1- I done not quality work with fast qlue.
2- I disappointed from the stars

The sound is so quite and after 3/4 of the volume it scratching.  
maybe connect it to pro bias like stax Lambda pro


I can afford another one {after having the Pro one}


----------



## legopart

How much time do you let the glue and the spray dry?
how much spray to put ?


----------



## chinsettawong

Spray glue is not very strong IMO.


----------



## janosch simon

Hey all  my first measurment with my recently bought miniDSP Ears measurehead  
i also plan on measuring impulse response and found a way to measure this with arta but its awkward :/ any of you measure your headphones? if so which soft and hardware?

my setup is as follows:
miniDSP ears connected to my windows 10 workstation.
with REW i made an offline measurement file (https://www.roomeqwizard.com/help/help_en-GB/html/offlinemeasurements.html) that i play then via my mediastreamer dac (soekris DAM1021) into my alpha centauri V06 eshp amp and then into my V001 Headphones see attached image 




jep my seal sucks as i can confirm very bad bass  but now with the minidsp EARS i can make lot of test for example mylar tension differnt coatings and so on 

here is a image of my headphones with the minidsp ears measure rig:


----------



## ts8051

chinsettawong said:


> Hi Fred,
> 
> Your designs look really nice.  I think the prices you got were quite reasonable too.
> 
> ...



Hello,
Please do you know the diameter of holes and spacing also ?

Theologos Sarafidis


----------



## chinsettawong

ts8051 said:


> Hello,
> Please do you know the diameter of holes and spacing also ?
> 
> Theologos Sarafidis



No, I don't.  They look like 1 mm in diameter, but I can be wrong.


----------



## chinsettawong

janosch simon said:


> Hey all  my first measurment with my recently bought miniDSP Ears measurehead
> i also plan on measuring impulse response and found a way to measure this with arta but its awkward :/ any of you measure your headphones? if so which soft and hardware?
> 
> my setup is as follows:
> ...



From the measurement, I think the tension on your diaphragm is too high.  You don't seem to get any low bass.  

Your measuring rig is interesting though.


----------



## lkos98

This has just a little connection with the scope of this thread (it's made from the left-over - the circle in the middle of the spacer), but I could not resist. One can think of doing something more useful with all these scraps that are left.


----------



## chinsettawong

lkos98 said:


> This has just a little connection with the scope of this thread (it's made from the left-over - the circle in the middle of the spacer), but I could not resist. One can think of doing something more useful with all these scraps that are left.


Nice!


----------



## janosch simon (Jan 26, 2019)

chinsettawong said:


> From the measurement, I think the tension on your diaphragm is too high.  You don't seem to get any low bass.
> 
> Your measuring rig is interesting though.



 
thx chinsettawong  here the latest measurment i just changed the hanger now its much better sealed me like  bass is now noticeable better but next time i will try your tip with the tension  

cheers janosch


----------



## chinsettawong

Here is my Omega clone’s measurement graph for your reference.


----------



## janosch simon

nice thx  do you know what that "compensated curve" is all about? mine are with the HEQ calibration file of the miniDSP ears hmm perhabs i should try the .raw calibration file? 

cheers janosch


----------



## chinsettawong

janosch simon said:


> nice thx  do you know what that "compensated curve" is all about? mine are with the HEQ calibration file of the miniDSP ears hmm perhabs i should try the .raw calibration file?
> 
> cheers janosch



I have no idea.

This one is Stax SR009’s


----------



## lkos98

janosch simon said:


> nice thx  do you know what that "compensated curve" is all about? mine are with the HEQ calibration file of the miniDSP ears hmm perhabs i should try the .raw calibration file?
> 
> cheers janosch


I think this explains it: https://www.innerfidelity.com/content/headphone-measurement-proceedures-frequency-response


----------



## janosch simon

nice ikos98 now it makes sence so i guess minidsp HEQ is the HRTF they designed so i will stick with that  would be soooo cool of more ESHP diy have an miniDSP ears head so we can compare and discuss even more )


----------



## qu1en

Do you do a closed or open back on your ESLs? i thought ESL had to be open back. I noticed you mentioned that you get a better bass response with a tight closed back seal, is that right?


----------



## legopart

Muamp said:


> Elvamide is nothing more than Nylon pellets. Small pieces of nylon that are intended to be disoloved in ethanol by heating. When cooled, the resulting solution is applied to the Mylar to provide the conductive coating. The conductive coating is achieved by the Elvamide coating absorbing moisture from the air. This is an old method of coating and is out dated by so many modern alternatives such as Licron Crystal spray or alternatively any water based anti-static spray.
> 
> Dust covers are an essential part of a panel in an electrostatic headphone since the distance between the stators and the membrane is so small, typically 0.5mm. A gap this small will whistle when the charge on the diaphragm attracts dust and enters the panel producing a short circuit between the stator and diaphragm.
> 
> ...


Need another spray.
I got no successes.

Do I have to coat the both sides of the mylar ?

or the membrane starched bad or the coating bad done,
maybe 230v bias is too low
The sound is too low


----------



## qu1en

legopart said:


> Need another spray.
> I got no successes.
> 
> Do I have to coat the both sides of the mylar ?
> ...




I started with -700V bias, now I’m using -1400V and it is noticably louder and satisfactory. Audio is about +/-250V... I think i need a -1400V bias with +\-500V audio to get it to very satisfying loudness!! I have heard Stax ised -560 or -700V bias.. may be OK if the audio is at 500V or so.. but more bias means more force.


----------



## chinsettawong

Come on guys.  You should at least understand the principle of electrostatic speakers.  The bias voltage depends very much on your spacer thickness.  The thicker the spacer you use,  the higher bias voltage you need also.  Stax Omega series use around 0.45 or 0.5 mm spacers and with the bias voltage of 580v, they are a good match.


----------



## janosch simon

dohhhh indeed bro  my alpha centauri v6 has also bias of 580 and its perfectly fine with 0.5 spacer my new design will be a 100mm driver yay but my anycubic photon cant print the housing to big DD


----------



## legopart

Can you explain me again how to coat with  Elvamide ?

I still got low sound with high distortion on high volume.
do I have to stretch the diaphragm more ?


----------



## qu1en

Are you sure it’s not the amp? can you share your amp schematic? i can share mine if you need


----------



## chinsettawong

How do you stretch your diaphragm?  What kind of glue do you use?


----------



## legopart

chinsettawong said:


> How do you stretch your diaphragm?  What kind of glue do you use?





qu1en said:


> Are you sure it’s not the amp? can you share your amp schematic? i can share mine if you need


The amp is Stax Srm1 mk2, I tested it on regular headphones.
I trying to fix the Stax Lambda Normal (Its going bad)
I don't know how I going to make my version of headphones (I bought all the materials)



chinsettawong said:


> How do you stretch your diaphragm?  What kind of glue do you use?


The glue is "B7000"

I stretched It on top of hollow box  with regular tape from 4 sides.


----------



## chinsettawong

I’m not sure if your glue is strong enough to hold the tension of the diaphragm.  You also might not have stretched your diaphragm strong enough.  Stretching a diaphragm to the right tension isn’t easy.


----------



## legopart

chinsettawong said:


> I’m not sure if your glue is strong enough to hold the tension of the diaphragm.  You also might not have stretched your diaphragm strong enough.  Stretching a diaphragm to the right tension isn’t easy.


Ok, I will find another method to stretch.
about the glue, I don't know which one will work.

how about the dust filter?, do I have to stretch it too ?

Do I have to squash the diaphragm before ?, or try to take straight piece?


----------



## chinsettawong

You should really go through the old threads.  All of your questions have been answered here many, many times.

I have also recommended you to use contact cement for gluing the diaphragm before.  It's the most suitable kind of glue I have found so far.

There is no way that you can stretch the diaphragm strong enough without using any kind of stretcher.  Expect to do, redo, and redo the diaphragms, because they are really difficult to be made just right.

No tension should be put on the dust cover.  We crumble the Mylar before making it into the dust cover.


----------



## legopart (Feb 4, 2019)

chinsettawong said:


> You should really go through the old threads.  All of your questions have been answered here many, many times.
> 
> I have also recommended you to use contact cement for gluing the diaphragm before.  It's the most suitable kind of glue I have found so far.
> 
> ...


About dust cover, why not to put the same stretch on it?
only when it stretch it sound, do it?

The most important question:
Can I glue the diaphragm only from one side and after the glue is dried, cut it sides and apply the second plate ?

Which glue do you use?
*I can read this thread again but all the answers mixed


----------



## federicopol

Finally finished them... 
Third time i rebuild them: this time is the last one i hope, now they sound well and i am finally happy of them.

Thank to all the people that shared info here! 

80mm active area 0.5mm spacers.

Shells are 3d printed, headband is (was) a coathanger.


----------



## qu1en

federicopol said:


> Finally finished them...
> Third time i rebuild them: this time is the last one i hope, now they sound well and i am finally happy of them.
> 
> Thank to all the people that shared info here!
> ...



What kind of coating did you use? Graphite?
To what impedance?
What were your lessons learned?


----------



## federicopol

qu1en said:


> What kind of coating did you use? Graphite?
> To what impedance?
> What were your lessons learned?



The problems i had were caused by the wrong coating and a badly designed connection between the mylar and the bias cable, the fact that i decided the driver sandwitch had to be glued amplified the problem (or the troubleshooting difficulties).

I changed the coating, redesigned the connection and now the driver are easily disassembled because they are hold togheter removable by metal clips.

The coating is antistatic fluid, i can't measure impendance because my multimeter doesn't go high enough.


----------



## lkos98

They look very nice, did you make the ear pads by yourself and what did you put inside the leather?


----------



## bui501-tech

federicopol said:


> Finally finished them...
> Third time i rebuild them: this time is the last one i hope, now they sound well and i am finally happy of them.
> 
> Thank to all the people that shared info here!
> ...


That looks beautiful!


----------



## federicopol

lkos98 said:


> They look very nice, did you make the ear pads by yourself and what did you put inside the leather?



Yep i sew the earpads myself. The black mesh material has Left and Right machine embroidered on a speaker grille material, the earpads are leather the inside is made of different strata of Legacy brand l-ff78f1 a flexible foam made for quilting (there are  equal alternatives of pellon brand or other quilting products brands).

The bottom rear of the ear part has more foam inside than the rest. You can't see that while not on head but while on head that part compress less aiding the seal. 



bui501-tech said:


> That looks beautiful!



Thanks!


----------



## chinsettawong

@janosch simon Ok, I've bought the MiniDSP Ears.  Now I need to learn how to make the measurements.


----------



## janosch simon

yeahhhh nice so we can compare veryyyy good mate   i used rew   cant wait to see your results


----------



## qu1en

what is the model of that equipment and how much does something like that cost?


----------



## qu1en

Here is my progress so far building the headphones and stators:


----------



## chinsettawong

qu1en said:


> Here is my progress so far building the headphones and stators:




Nice video!  What is your spacer's thickness?  It looks to be pretty thick.  Is it 1 mm?  What amp are you making?

For thick spacers, using a heat gun to shrink the diaphragm is OK.  But if you go down in thickness, you'll need a lot more tension on the diaphragm and heat shrinking won't be sufficient.

Keep us posted with your progress.


----------



## chinsettawong

qu1en said:


> what is the model of that equipment and how much does something like that cost?



I bought it from here: https://www.minidsp.com/products/acoustic-measurement/ears-headphone-jig


----------



## qu1en (Feb 12, 2019)

chinsettawong said:


> Nice video!  What is your spacer's thickness?  It looks to be pretty thick.  Is it 1 mm?  What amp are you making?
> 
> For thick spacers, using a heat gun to shrink the diaphragm is OK.  But if you go down in thickness, you'll need a lot more tension on the diaphragm and heat shrinking won't be sufficient.
> 
> Keep us posted with your progress.



Thanks - this is great info.
Spacer thickness is PCB width so 1.6mm.... i have on order a 0.6mm version.. still experimenting. I did not know that heat shrunk may be too loose.. Will find out if I have arcing with the 0.6mm version.. The amp is a modified version of what your original post was. Instead of using an xformer for the bias I am using a voltage doubler off a 310V tap referenced to GND. Using a negative bias since ive been told the negative ions are healthier (haven’t researched it much). For output tube I’m using a 12at7.. Also added some negative feedback so for a 0.55V amplitude input the output will have max swing. attached are some prelim pics of the amp


----------



## qu1en (Feb 26, 2019)

Just got done with the first prototype build and it sounds good. I had an issue with buzz on my amp and so I put in a humdinger (two 500ohm resistors in series across the heater the tie that center tap to GND so the heater to cathode now has a reference). Buzz is caused by heater to cathode leakage current. Then there is a very slight low and calm 60Hz  hum now caused by battery ripple. Not noticeable when playing music. I can make it 100% quiet by placing a bigger output cap but there is simply no room in the chassis.... Not concerned though. Hope this helps anyone with hum or buzz issues.


----------



## chinsettawong

Have you changed your spacers to thinner ones yet?  Are you sure that the noise isn’t from the phones?


----------



## qu1en

chinsettawong said:


> Have you changed your spacers to thinner ones yet?  Are you sure that the noise isn’t from the phones?



Yup they are 0.4mm now with -700V bias. Buzz was def caused by heater to cathode leakage - fixed with a humdinger like I discribed. Buzz is always heater cathode leakage. Hum is different. The very quiet hum can be completely removed with larger output caps on the +B but like is said my chassis is too small. But it doesn’t bother me because it is so quiet anyway. I have a 6.8k grid stop resistors on the input so I never have issues with noise pickup on the input. I adjusted the cathode bias to make sure they are both as  balanced as possible at the center point (0V) to get max output swing. Loudness is excellent. I can post my schematic once I get it updated.


----------



## chinsettawong

With 0.4mm and -700V bias voltage, your diaphragm tension must be very high.  How did you tension your diaphragms?


----------



## qu1en (Feb 20, 2019)

How do you tension yours? Any pics? I may need to learn how


----------



## chinsettawong

It's amazing that you can hand stretch and heat shrink your diaphragm to the right tension.  I use inner tire stretcher which I have posted pictures many, many times on this thread.  Please check.


----------



## qu1en (Feb 26, 2019)

Thanks man - i'm working on reading the thread.. on page 47... It's pretty interesting.
Maybe I can see how much force it will take to displace the diaphragm.
Just an idea -but maybe I can make a solid state driver with FETs that have very high headroom maybe +/-400V... and put in some active filter and create a bass boost... or a baxendall equalizer...
May be cheating but it may work also for deeper bass.


----------



## bui501-tech

It's so great and inspiring to hear the different methods and materials that all the DIYers on this forum use to design and build their working electrostatic headphones.

I've experimented with different materials for the membrane prior to settling on the more "traditional" mylar that chinsettawong uses.  shrinkwrap, model airplane membrane, etc -- none of them would work.  I've never heard of the heat-shrinkable mylar you're using.  q1en, would you mind sharing the source (vendor) for the heat-shrinkable mylar if you can get the info from your friend who provided you your mylar?


----------



## 100VoltTube (Feb 24, 2019)

I finally finished my headphones today. I'm listening to them now. They sound pretty great, but have very little bass. I'm assuming that the tension is just too high. Would heating up the diaphragms reduce the tension?
Also, the dust covers crinkle whenever I move my head. They're 3um mylar the was crumpled up. Is this normal?

Edit: actually, the lack of bass was because of series resistors in the transformer box. Time to save up to make a proper electrostatic amp.


----------



## qu1en

100VoltTube said:


> I finally finished my headphones today. I'm listening to them now. They sound pretty great, but have very little bass. I'm assuming that the tension is just too high. Would heating up the diaphragms reduce the tension?
> Also, the dust covers crinkle whenever I move my head. They're 3um mylar the was crumpled up. Is this normal?
> 
> Edit: actually, the lack of bass was because of series resistors in the transformer box. Time to save up to make a proper electrostatic amp.



Ok good. I was going to say, headphones should be fine and check your amp but I thought you said you use a STAX amp. Is the transformer the power transformer or does it use an audio transformer? If it's a power xformer then you can probably increase the capacitance to get the proper cutoff. What is up with your dust cover? Can you send a pic? Why do you want a crinkly thing on your headphones? lol


----------



## chinsettawong

100VoltTube said:


> I finally finished my headphones today. I'm listening to them now. They sound pretty great, but have very little bass. I'm assuming that the tension is just too high. Would heating up the diaphragms reduce the tension?
> Also, the dust covers crinkle whenever I move my head. They're 3um mylar the was crumpled up. Is this normal?
> 
> Edit: actually, the lack of bass was because of series resistors in the transformer box. Time to save up to make a proper electrostatic amp.



To tension the diaphragms to just the right tension takes a lot of practice and patience.  If you have used some kind of mechanical tension to stretch your diaphragm, using a heat gun to go over the diaphragm does actually reduce the tension down a little.  The dust cover shouldn't make any strange noise when you move your head.  Is it too loose?

I am not sure why you think that the lack of bass is from the series resistors inside the transformer box.  Are they the resistors connecting between the inputs and the transformers?  A lot of times, these series resistors are there to protect the amplifier when it's driving the headphones at very high and low frequencies.  If your amplifier can drive low impedance loads well, you can take out those resistors.  

Can you post some pictures?


----------



## qu1en

Has anyone done any subjective or objective testing to see the impact of using a graphite coating vs a anti- static spray? I get that theoretically it’s difficult to get a uniform graphite application unless you go down into very low impedences but wondering if anyone can tell the difference by listening to it.


----------



## lkos98

I have done both, not with graphite, but with black in coating. I was using thermal printing ribbon and the black color seemed to have the same resistance as of the graphite - about 80-100Kom with the coin method. The whole membrane resistance was of a bout 6-800 kom, which is definitely not enough. I can't remember everything, but I can summarize:
1. The sound levels were much higher (I would say about twice) with the same other parameters (area, spacer distance)
2. A big problem with stability - hence increased tension - hence lower bass
3. Sharp or crispy trebles
4. Distortion at mids can be heard. 
I could not measure the distortion with values, but the peak in 2nd & 3rd harmonics (of 1kHz signal) were obvious. As far as I know human ear cannot detect less than 1-2% distortion (depending on the frequency - for high frequencies it becomes even 5-6%), so it means lower resistance coating is adding a lot of distortion. This is normal - low resistance is not constant charge, the charge is moving across the membrane and therefor it's attracted in some points more that others. This is causing a non-uniform membrane movement - one of the biggest source of distortion in dynamic speakers.


----------



## qu1en

lkos98 said:


> I have done both, not with graphite, but with black in coating. I was using thermal printing ribbon and the black color seemed to have the same resistance as of the graphite - about 80-100Kom with the coin method. The whole membrane resistance was of a bout 6-800 kom, which is definitely not enough. I can't remember everything, but I can summarize:
> 1. The sound levels were much higher (I would say about twice) with the same other parameters (area, spacer distance)
> 2. A big problem with stability - hence increased tension - hence lower bass
> 3. Sharp or crispy trebles
> ...



What would you say is an optimal impedence? I’ve heard anywhere from 2Meg to 3k with the advantage of 3k being that uniformity is easier (less variation).  I heard spray is roughly 2Meg but you mentioned anywhere from 600k-800k is too high. I think we should put together a list of knowledge, with a list for known facts and thought opinions. For example:

Fact:
1) Tention too high = Less bass. 
2) Tentiont too low = risk of the diaphragm touching one side. 

Would you agree?


----------



## lkos98

I wish it was that simple . All these parameters depend on a lot of things. For example - tension depends on the active area, bias voltage, spacer thickness, etc. Chinsettawong explained many times that you have to experiment a lot of times with tension to get it just right. IMHO with measuring the free air resonance frequency of the membrane, it is easier to set the tension, but then again - with area of 80mm diameter, the frequency will be lower than with 74mm with the same tension or different membrane thickness.  
What I'm trying to say - for example:
1. Spacer thickness - 0.5mm
2. Bias voltage - 580V
3. Tension - ??? - first, what is the thickness of the membrane itself, second how do you measure it?, third - what is the active area, forth - what coating you use (with what resistance)?  
Now you see, some will use 0.5 spacer, others 0.4 or 06 and all these "rule of thumb" parameters will change.  
All this was discussed in the forum many times, tension, impedance, coating etc. and it's not easy to make a simple list of values, because they very much depend on everything else.
As for the impedance - 6-800kohm as I said, is not enough - meaning too low, It should go above 20-30Mohm up to the Gohm range. The higher the better, but without exceeding the leakage resistance of the cables, mountings and so on, because then you will wait for hours to charge the membrane if charged at all.


----------



## chinsettawong

I have been playing with the miniDSP for a little while and I've made some measurements of my Orpheus Clone and Stax Omega MK1 for comparison.  Here are some results:












To my ears, the Omega MK1 is a little better on the deep bass, and I think the graph shows exactly just that.


----------



## lkos98

chinsettawong said:


> I have been playing with the miniDSP for a little while and I've made some measurements of my Orpheus Clone and Stax Omega MK1 for comparison.  Here are some results:
> 
> To my ears, the Omega MK1 is a little better on the deep bass, and I think the graph shows exactly just that.



Interesting! seems MiniDSP is not good with bass measurements or not sealing properly. Comparing the graphs to Tyll's measurements (if these are the same phones you sent to him), it seems they are quite different, not only with the bass response (almost flat with Tyll's), but also mid and high resonances. Otherwise above 50Hrz , the FR is very impressive.


----------



## chinsettawong

Yea, not sure how Tyll did his measurements.  But, these are the readings I’ve got so far.  I have tried the measurements many, many times.  And the graphs are pretty consistent.  I will measure Stax SR009 and 007 MK2 and see how the graphs look.


----------



## qu1en

So I put in an order for the minidsp ears... can’t wait until they arrive.

I want to try and compare graphite to anti-static gel. Has anyone had issues with the longevity of anit static? I feel like it is not intended to make a permanent coating.

Is it something like this: https://www.walmart.com/ip/Anti-Sta...MIwbSKzJbl4AIVgY3ICh0iuwoCEAQYAiABEgI1TfD_BwE


Also, as far as the cable goes, i enjoy a simple 6 wire harness with some braiding... anyone know if using a koss cable truly makes a difference? i feel like the capacitance won’t be much different, this is audio not RF. It shouldn’t have to be constant along the cable, just total capacitance is what matters.. anyway I could be wrong.


----------



## chinsettawong

qu1en said:


> So I put in an order for the minidsp ears... can’t wait until they arrive.
> 
> I want to try and compare graphite to anti-static gel. Has anyone had issues with the longevity of anit static? I feel like it is not intended to make a permanent coating.
> 
> Is it something like this: https://www.walmart.com/ip/Anti-Sta...MIwbSKzJbl4AIVgY3ICh0iuwoCEAQYAiABEgI1TfD_BwE



Since you're in the US, get a good coating such as Licron Crystal.  It has been proven by many people that it works well.


----------



## qu1en

chinsettawong said:


> Since you're in the US, get a good coating such as Licron Crystal.  It has been proven by many people that it works well.


Thanks - different sources say different results about their successes with different types of coatings so it’s hard to determine what will work best for me. Your suggestion makes me feel more confident about spending the extra cash on licron... 

I am going to experiment with different tentions to get my SRF down to closer to 150Hz or 75Hz.. at 300Hz (too tight?) on my first prototype but haven’t measured it on my second prototype...

Since I don’t have Licron yet and don’t want to do a ton of iterations of test, does Licron vs Graphite impact the bass at all???? or is it just the overall gain and lower distortion??? 

My thinking is bass is impacted mostly by tention and enclosure seal and not so much the coating (coating is not frequency dependent).. would you agree?


----------



## lkos98

qu1en said:


> Thanks - different sources say different results about their successes with different types of coatings so it’s hard to determine what will work best for me. Your suggestion makes me feel more confident about spending the extra cash on licron...
> 
> I am going to experiment with different tentions to get my SRF down to closer to 150Hz or 75Hz.. at 300Hz (too tight?) on my first prototype but haven’t measured it on my second prototype...
> 
> ...



That is correct, unless you apply a very thick layer or heavy coating, which would increase the weight of the membrane and lower the resonance. You would lose highs as well.


----------



## ts8051

MuZo2 said:


> Search for Electrostatic Speaker Membrane Dupont Mylar C 3um 40M, its shipped from Taiwan.



Hello,
Please, if somebody knows where in Europe can i find Mylar Membrane 2 micron.


----------



## qu1en

Can someone recommend me a good CNC router? I want to make my earcups out of wood. It is about 1.7 inches deep and about 3.5 inches in diameter with a few layers and some angles, is it possible? Can i just load a STEP file and it will carve it out for me? I want to buy a commercially available one with good software ( I don’t want to build my own router ). Thanks.


----------



## Torac

qu1en said:


> Can someone recommend me a good CNC router? I want to make my earcups out of wood. It is about 1.7 inches deep and about 3.5 inches in diameter with a few layers and some angles, is it possible? Can i just load a STEP file and it will carve it out for me? I want to buy a commercially available one with good software ( I don’t want to build my own router ). Thanks.



I have just started building the mpcnc myself and hope to start making my own headphones too. I want to try milling aluminium cups for mine.


----------



## Torac

I'm trying to source the materials to make my diaphragm tensioner, I have obtained a 12" inner bike tube but can't seem to find a suitable ring to wrap it around. Some on here have used cardboard tubes but I can't find any that look thick enough that I would trust them with the pressure and not just bend. Has anyone got suggestions/sources for what they used, I would much appreciate it


----------



## bui501-tech

EssentialEDM said:


> I'm trying to source the materials to make my diaphragm tensioner, I have obtained a 12" inner bike tube but can't seem to find a suitable ring to wrap it around. Some on here have used cardboard tubes but I can't find any that look thick enough that I would trust them with the pressure and not just bend. Has anyone got suggestions/sources for what they used, I would much appreciate it



I’ve had great luck/repeatability using a small diameter inner tube (about 10 or 12”, can’t remember which) around the outside of an aluminum circular cake pan. The cake pans were about $8usd for 2 on amazon.  The cake pan was large enough that I had to stretch the inner tube around it (i.e. was not loose when the tube was deflated).

Chinsettawong made me a nice rectangular wooden frame that I’m now also using.  unlike the round cake pans, the rectangular frame allows me to use the corners of the stretched membranes.


----------



## Torac

bui501-tech said:


> I’ve had great luck/repeatability using a small diameter inner tube (about 10 or 12”, can’t remember which) around the outside of an aluminum circular cake pan. The cake pans were about $8usd for 2 on amazon.  The cake pan was large enough that I had to stretch the inner tube around it (i.e. was not loose when the tube was deflated).
> 
> Chinsettawong made me a nice rectangular wooden frame that I’m now also using.  unlike the round cake pans, the rectangular frame allows me to use the corners of the stretched membranes.



I hadn't even thought about using cake pans, thank you


----------



## chinsettawong

You need to be more creative.


----------



## lkos98

I would like to ask about measuring stretching. Some people use a scale to stretch, some use free air resonance, some use weights. These that measure the frequency (for me it's easiest) - anybody with this experience - do you measure the frequency of the whole stretched membrane as it is on the stretching rig or you measure it on the spacer frame glued and cut? People say between 90-120 Hz, but I'm completely unable to go bellow 140 Hz resonance of the spacer itself without getting instability with 84mm inside diameter and lower than 580V bias. 
If you measure the whole, 90 Hz stretching makes sense.Sorry if this was answered already, I tried to find it and couldn't get a reliable response.


----------



## bui501-tech

lkos98 said:


> I would like to ask about measuring stretching. Some people use a scale to stretch, some use free air resonance, some use weights. These that measure the frequency (for me it's easiest) - anybody with this experience - do you measure the frequency of the whole stretched membrane as it is on the stretching rig or you measure it on the spacer frame glued and cut? People say between 90-120 Hz, but I'm completely unable to go bellow 140 Hz resonance of the spacer itself without getting instability with 84mm inside diameter and lower than 580V bias.
> If you measure the whole, 90 Hz stretching makes sense.Sorry if this was answered already, I tried to find it and couldn't get a reliable response.



Since I didn't/don't have the equipment to measure the frequency response of my DIY setup at home, this is what I did to arrive at a repeatable process for stretching the mylar membrane:
- I made enough copies of the spacer rings to try multiple iterations of the membrane at different tensions;
- When it came time to stretch the membrane (using an inner tube stretched around a 7" aluminum cake pan), I attached the membrane to the contraption using cellophane tape around the edges, making sure that the membrane had no creases but was just in its natural state with no extra tension (inner tube was completely/totally deflated).
- I then pumped up the inner tube -- I used the same small, portable bicycle pump every time, and I counted and wrote down the exact number of pumps for each interation.
- I then glued several spacers to the membrane -- marking the spacer with the tension (# of pumps) using a permanent marker to write on the spacer part.
- Next, I cut out the spacer-membrane combos from the membrane stock using a soldering iron.  (WORKS better with mylar than using an exacto knife)
- Repeated the above with varying # of pumps (i.e., varying tensions) -- all with good written records.
- Coated the stretched membranes now glued to the spacers.
- After the coating has had 24 hours to dry, I tested out each combination and picked out the tension # (# of pumps) that resulted in the best sounding drivers to my ears.
- I've been able to consistently make good sounding drivers (good repeat-ability) following the above steps...  in my early days, this process allowed me to adjust for the membrane collapsing to one side (tension too low) and for the lack of bass (tension too high) -- all by varying the number of pumps I use with my small bicycle pump...  And ultimately, since my goal was to make the best sounding drivers I could make with what I had available, the process was good enough for me.


----------



## lkos98

At last I made my amp so the measurements followed. I was impressed that with such simple amp the phones could go up to 50kHz before they started rolling off (not that anyone can hear that, I can not hear above 13kHz anyway). The measurement rig was also not very properly done - a cheap microphone used for auto-level calibration for a receiver mounted on MDF piece. The mic long cable and amp got so much noise and hum, that I couldn't measure the THD reliably. On top of that the TV was on and the environment was quite noisy as well (as you know ES headphones cant attenuate surround noise). And as last - I'm using USB oscilloscope with integrated generator, sweeper, spectrum analyzer and a bunch of other goodies and for the price, it's pretty good, but far from professional.  Still I'm happy with the results. 
Pictures - Amp, Power supply, Logarithmic FR 5Hz - 30Khz Left & Right


----------



## legopart

Can someone please send me the schematics of Normal and Pro bias from 230v-AC 10A 50Hz gain?


----------



## lkos98

legopart said:


> Can someone please send me the schematics of Normal and Pro bias from 230v-AC 10A 50Hz gain?


I don't understand really your question. What is 230v-AC 10A? 10 amperes? This is 2,3 kW. Is it an oven you want to power with this?
if you want to build yourself a bias for headphones, you can make with transformer and simple voltage multiplier, but you need a very small current there - in fact 100 micro A is more than enough. 
But be very careful, this is extremely dangerous, it could be lethal. If you don't understand much of electricity I would suggest buy this from somewhere, or read all related information first.
A simple regulated from 300-1200V bias supply can be bought from here:
https://www.aliexpress.com/wholesal...0328233513&SearchText=DC+boost+5V+to+1200V+DC
or ebay, amazon etc. 

you just need to power it with a 5V DC supply, like phone charger. It's pretty noisy, but does the job.


----------



## legopart

I need some thing that convert  230v-AC 10A to 230v or 560v with several mA (less then 20mA) for the bias voltage.
I can use the 5v DC from the phone charger instead of 230v-AC 10A line.


----------



## Ulfar4

lego part:
I think you really don't understand how this things works, it can be very dangerous for you if something happens. Playing with this is not fun.


----------



## legopart (Mar 30, 2019)

Ulfar4 said:


> lego part:
> I think you really don't understand how this things works, it can be very dangerous for you if something happens. Playing with this is not fun.


Even the experts took some risk.
I having all the measuring tools to test is my work done good.

First I want to transfer Stax Srd7/sb to Srd7 mk2
I just need the information what the size that required for the Diodes and the Zener one and the voltage for the capacitors and the Watts for the resistors





I have the Srd7/sb (self biased from the left chanel to 230v) abd Srd4 (without the bias voltage)


----------



## Muamp (Mar 30, 2019)

Hi Legopart,

You need to listen to the advice from Ulfar4!  230V un-isolated mains IS very dangerous. The circuits from the SRD-7 would NOT pass the safety regulations of today. If you wish to use mains for your bias then you would need to use a mains isolation transformer. The circuit of this SRD-7 as is, is only protected by a 300mA fuse, far more than enough to kill or provide a serious shock.The C-D voltage multiplier circuit is what Stax relied on in limiting the current, not acceptable in todays world.

The bias voltage required is only in the order of nano Amps or even down to pico Amps, so small that if you were to touch it, the resistance of the body wound sink the voltage and it would be harmless, at worst you would feel a small tingle sensation.


----------



## legopart (Mar 30, 2019)

Muamp said:


> Hi Legopart,
> 
> You need to listen to the advice from Ulfar4!  230V un-isolated mains IS very dangerous. The circuits from the SRD-7 would NOT pass the safety regulations of today. If you wish to use mains for your bias then you would need to use a mains isolation transformer. The circuit of this SRD-7 as is, is only protected by a 300mA fuse, far more than enough to kill or provide a serious shock.The C-D voltage multiplier circuit is what Stax relied on in limiting the current, not acceptable in todays world.
> 
> The bias voltage required is only in the order of nano Amps or even down to pico Amps, so small that if you were to touch it, the resistance of the body wound sink the voltage and it would be harmless, at worst you would feel a small tingle sensation.


So do you suggest not to mess with the SRD-7  ?
Or can I buy some ready board and use it for the bias?
I renewed the solder on each of my vintage amps, as the Stax Srm-1 pro, I re-solder all the connection and test all of the Capacitors and they fine. But I still plan to recap it.
And set-off the DC voltage by this guide for SRM-1 https://www.head-fi.org/threads/stax-srm-1-mk2-re-cap.648596/

I really interested in DIY projects, and I still try to re-film/ Strech the diaphragm on some broken Stax  headphones, and I want to create some electrostatic driver by myself.


I asked if it possible to create the bias voltage for SRD-7. if not then I guess that it useless for me.
I bought the SRM-1 because I found SRD-7/sb not quality enough with delays, and I found it as bad idea to buy another SRD-7 mk2 pro because it rare and have high price


----------



## Muamp

Hi Legopart,

This is a web page    http://muamp.com/uAmp-energiser.html    that I wrote a while back. The info' has has been published on Head-Fi by me in the past. At the bottom of the web page, it shows two different ccts for bias from the mains, I prefer the second one as it has fewer components, although the first one allows you to adjust the bias voltage to what ever you want by changing the potential divider resistors to different values . Both have mains isolation transformers but still need you to be electrically competent.


----------



## legopart (Mar 30, 2019)

Muamp said:


> Hi Legopart,
> 
> This is a web page    http://muamp.com/uAmp-energiser.html    that I wrote a while back. The info' has has been published on Head-Fi by me in the past. At the bottom of the web page, it shows two different ccts for bias from the mains, I prefer the second one as it has fewer components, although the first one allows you to adjust the bias voltage to what ever you want by changing the potential divider resistors to different values . Both have mains isolation transformers but still need you to be electrically competent.


http://muamp.com/images/MuampPhotos/uAmp-energiser/BiasII.JPG
about the last one,
 What the size of the elements that requires?
- What diodes  (IN4007 1A 1000V) and capacitors (uF and Voltage) to use?
- How much Watt acceptance use for the Resistors ?


----------



## bui501-tech

legopart said:


> So do you suggest not to mess with the SRD-7  ?
> Or can I buy some ready board and use it for the bias?



When I decided to go into this hobby, I started out by purchasing an old Stax SRM-1 MK-2 that I modified using procedures that have been well documented online to be able to drive pro-bias (580v boas) headphones. The version I have can drive pro-bias from one jack and the normal (230v) bias from the 2nd jack.  It was noisy as hell compared to modern designs, but it was reliable and it got me started with DIY electrostatic headphones.

I’ve since moved on and built several Kevin Gilmore-designed amps, but I still have the original Stax SRM-1 mk-2 I used at the beginning to test and drive my early diy drivers.  
(Legopart, PM me if you’re interested in purchasing the srm-mk2.  I’m currently using it as my electrostatic headphone amp for my home computer when I’m working at my desk.)


----------



## lkos98

legopart said:


> So do you suggest not to mess with the SRD-7  ?
> Or can I buy some ready board and use it for the bias?
> I renewed the solder on each of my vintage amps, as the Stax Srm-1 pro, I re-solder all the connection and test all of the Capacitors and they fine. But I still plan to recap it.
> And set-off the DC voltage by this guide for SRM-1 https://www.head-fi.org/threads/stax-srm-1-mk2-re-cap.648596/
> ...



I'm not familiar with SRD-7, but it appears it runs on audio transformers only and the bias is created from the mains with multiplier. It's a non-isolated multiplier, which is never a good idea as  ulfar4 and muamp said. Otherwise it should be quite easy to connect a separate bias to this - the principle is the same for all types of energizers - the gnd of the bias goes to the middle point of the audio transformers (or the ground point of an amplifier) and the positive (or negative) bias wire is connected to the 2.2Mohm resistor (as per the posted by you schematic). But the bias voltage must be ISOLATED! 
This is exactly how I ran my ESHs for a long time - audio transformers and separate bias. Very uncomfortable - heavy amplifier and on top, heavy energizer + a lot of wires. On the other hand it's very safe and reliable - no amp oscillations, no high voltage power supply (except for the bias), accepts heavy loads, etc.


----------



## legopart

What do you mean by ISOLATED bias?


----------



## lkos98 (Mar 31, 2019)

legopart said:


> What do you mean by ISOLATED bias?


I'm not sure how exactly is it called, but it means it has to be isolated from the mains power socket. Meaning there should be insulation transformer usually 220x220 VAC, so there is no electrical connection between the bias circuit and your power socket.
Explanation is simple - your power socket has Live and Neutral. When you plug into the socket, you never know which is which and you may get LIVE connected to your schematics GND. Since this is usually a common ground you may get electrocuted (not even mentioning the damage to that it can do to your equipment).  For example you connect your phone as audio source with a 3.5mm jack socket - L,R and GND - hence your phone chassis is now connected to the LIVE from the mains. You don't want to hold with your hand the LIVE from the mains?
https://www.quora.com/Where-and-why-are-isolation-transformers-used


----------



## Ulfar4 (Apr 19, 2019)

I have some update for my phone. I printed fully new enclosure for drivers, because I found out that the previous were little bended. For this I buy 3d printer for myself, so i can print anything anytime, which is great.







Now it is playing great more than month and half. So I am happy that I achieved this. I think that I will not modificate this headphones anymore. But I will create new one with larger diameter active area and print enclosure with PETG instead of PLA material.


----------



## chinsettawong

Ulfar4 said:


> I have some update for my phone. I printed fully new enclosure for drivers, because I found out that the previous were little bended. For this I buy 3d printer for myself, so i can print anything anytime, which is great.
> 
> 
> 
> ...



Very nice!  Congratulations!  Look forward to seeing your new headphones.


----------



## legopart

do I have to spray the membrane from the both sides?


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## chinsettawong

You only need to coat one side of the diaphragm.


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## legopart (Apr 25, 2019)

My last try to reglue and strach the membrane on broken STAX LAMBDA Normal





dast filters





I use some wood fram and glue the the membrane with streching it.











Unfutualy, after all tryies and unglueing its destroys and deform the shap of the parts (and the distance between the plates) so the work done very badly
Unfutualy the cable is for normal bias , and this headphones works better with pro
I unfutuatly think that the membrane touching one of the plates and it makes this headphones to function as electret, even without the bias voltage (I will try it.)
on normal bias they having some distortion on the high volume but on pro bias they not having any distortion.

they sound somehow, I think that they not so bad.

hop to build some electrostatic headphones by myself in the futur.


----------



## chinsettawong

What glue did you use for gluing the diaphragms?  What glue did you use for gluing the pieces of the driver together?


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## legopart (Apr 25, 2019)

Something like this one https://www.ebay.com/itm/50ML-Yello...054674?hash=item5b3c619f52:g:eL8AAOSwtYxZgsBq
I bough several years ago some "speakers glue"


For other parts I used B7000 the known glue https://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=B7000&_sacat=0


----------



## Ulfar4

legopart: I think that your glues is not strong enough for mylar.


----------



## legopart

Ulfar4 said:


> legopart: I think that your glues is not strong enough for mylar.


please inform me which glue to use next time ?


----------



## Ulfar4

legopart: I am using Pattex chemoprene extreme


----------



## chinsettawong

For gluing other parts, I would use something that can be taken off easily if I would make the repair again.  I would use something like silicone sealant or hot melt glue.  When gluing, don’t use so many clamps.  I think your clamps are too strong, and they actually bend the structure.


----------



## quintile

Hi.

Re: glues

i have had success with UHU POR glue. i find it a bit too thick and dilute by mixing it with Naptha (cigarette lighter fluid).

-Steve


----------



## lkos98

Here's my brand new DIY stretching rig. 8 screws are used for stretching and 4 for guiding the two rings to one another. This is the my attempt a 2um mylar stretched to 41 Hz free air resonance. Based on Helmholtz formula, this should transfer to about 125 Hz for the diameter of my spacers, if my calculations are correct. Otherwise will have to re-do, but in any case it will give me a starting point for calculations.
I was unable to find a proper ring to tighten the mylar to the frame, so I used a wire as a temporary solution. If anyone knows where I can find such ring - something like hose clamps with 30cm diameter, please let me know.


----------



## bui501-tech

lkos98 said:


> Here's my brand new DIY stretching rig. 8 screws are used for stretching and 4 for guiding the two rings to one another. This is the my attempt a 2um mylar stretched to 41 Hz free air resonance. Based on Helmholtz formula, this should transfer to about 125 Hz for the diameter of my spacers, if my calculations are correct. Otherwise will have to re-do, but in any case it will give me a starting point for calculations.
> I was unable to find a proper ring to tighten the mylar to the frame, so I used a wire as a temporary solution. If anyone knows where I can find such ring - something like hose clamps with 30cm diameter, please let me know.


 that’s cool and very creative! it also looks a lot like a embroidery hoop.... why don’t you look into buying a pre-made embroidery hoop? They are cheap, come in lots of different sizes, are easily available in just about every country, and are designed to hold tightly and stretch fine fabric for embroidery work.


----------



## legopart

30cm diameter,
is it some speaker?


----------



## lkos98

bui501-tech said:


> that’s cool and very creative! it also looks a lot like a embroidery hoop.... why don’t you look into buying a pre-made embroidery hoop? They are cheap, come in lots of different sizes, are easily available in just about every country, and are designed to hold tightly and stretch fine fabric for embroidery work.


Thank you this is a good idea. It's going to be very difficult to adjust the tension once the rings are locked, but I guess this can be modified as well to fit our needs.
@legopart  No, it's for headphones and it's 30 cm, so I can glue 4 spacers together with the exact same tension.


----------



## legopart

bui501-tech said:


> that’s cool and very creative! it also looks a lot like a embroidery hoop.... why don’t you look into buying a pre-made embroidery hoop? They are cheap, come in lots of different sizes, are easily available in just about every country, and are designed to hold tightly and stretch fine fabric for embroidery work.


do you heve any progress ?


----------



## legopart

I read about parasitic capacitence and about the importance to ground the plug after each usage






though to build some female plug that will make the shortage between the connections inside the connector the prevent this and store the headphones quitly.





do you have some suggestion for such female covering for the plug to disscharge the headphones ?


----------



## chinsettawong

legopart said:


> I read about parasitic capacitence and about the importance to ground the plug after each usage
> 
> 
> 
> ...



If you want to, you can discharge the headphones by simply touching the pins with your finger as shown in the picture.  But even if you don't touch them, the charge will gradually drain out by itself.  But why do you worry about this?


----------



## legopart

chinsettawong said:


> If you want to, you can discharge the headphones by simply touching the pins with your finger as shown in the picture.  But even if you don't touch them, the charge will gradually drain out by itself.  But why do you worry about this?


I want to create some female cap for the passive storage, to cover the headphones when they not in use.
though to short the connections or add some resistors








or something like this





10 or 100 ohm resistors (?)


----------



## lkos98

legopart said:


> do you heve any progress ?


I guess this is a question for me. Well, calculations did not match as expected - with 41 Hz resonance on the tension rig, the ellipse 94x68 (active area) mm gave 135Hz, which was  close enough, but then with 43 Hz on the rig, my second pair with circle 84mm, went up to 200Hz. After that, the ellipse (already mounted) went to 175 and circle to 215. This is quite confusing, I don't see any relationship. I suspect my free air resonance measurements were not correct. I will make a new set of membranes with about 35-36 Hz on the rig, to see what's wrong. But firstly I need to fix my mic that I use for measurements - the 50Hz noise is so big, that messes up with the whole spectrum. 
As for the charge of the phones, Chinsettawong is right - why do you need to discharge them? Just leave them and they will discharge slowly. If you wish to carry them somewhere - touch the pins to the amp cover (if it's metal) and it will discharge immediately.


----------



## lkos98

legopart said:


> I want to create some female cap for the passive storage, to cover the headphones when they not in use.
> though to short the connections or add some resistors
> 
> 
> ...


Any from 1k to 100k ohm will discharge them fast enough.


----------



## lkos98

lkos98 said:


> Any from 1k to 100k ohm will discharge them fast enough.


This was a stupid answer, sorry. If the female plug is not grounded, there's no point of doing this - it will just equalize the charge between membrane and stators. In fact you just need to connect a lets say 100k ohm from the bias pin to some ground.


----------



## legopart (May 14, 2019)

lkos98 said:


> This was a stupid answer, sorry. If the female plug is not grounded, there's no point of doing this - it will just equalize the charge between membrane and stators. In fact you just need to connect a lets say 100k ohm from the bias pin to some ground.


If I just short it all, the charge will be equal or even disable it self.
If I will put any resistor it will use the charge for heating.









I remembering something about zener diodes or another element that Stax using inside theire headphones, I dont know what it can prevent.
(cant find any Stax driver images)


----------



## lkos98

legopart said:


> If I just short it all, the charge will be equal or even disable it self.
> If I will put any resistor it will use the charge for heating.
> 
> 
> ...


Charge for heating of what? The charge is over a capacitor of about 120pF at max. On top of it, the membrane itself is a resistor of more than 100 Mohm. How much heat you will create with a 120pF and 100 Mohm? The zener diodes (my guess) are just a protection - not to allow voltage between stators or stator/membrane to become more than the zener breakout voltage.


----------



## bruma

legopart said:


> If I just short it all, the charge will be equal or even disable it self.
> If I will put any resistor it will use the charge for heating.
> 
> 
> ...


these drivers look like the old Beyerdynamic 880DT with the protection circuit. it makes sense in pro-use with musicians in dynamic drivers.


----------



## legopart

bruma said:


> these drivers look like the old Beyerdynamic 880DT with the protection circuit. it makes sense in pro-use with musicians in dynamic drivers.


I saw the same things on Stax headphones.
somehow I planning to renew them or put some on my other headphones, dynamic and electrostatic.
which zener diodes/diodes to use?

do you have any idea about how to build the female cap/cover for the connection to protect the heaphones from parasitic capacitence?
*or othe issues when you store them after usage.

I can make lot of female connectors from 2 *  XLR 3PINS connectors.

thanks.


----------



## bruma

legopart said:


> I saw the same things on Stax headphones.
> somehow I planning to renew them or put some on my other headphones, dynamic and electrostatic.
> which zener diodes/diodes to use?
> 
> ...



the Quad ESL uses the clampboard as shown in this picture to protect the treble panel.


----------



## lkos98

legopart said:


> I saw the same things on Stax headphones.
> somehow I planning to renew them or put some on my other headphones, dynamic and electrostatic.
> which zener diodes/diodes to use?
> 
> ...


As I understand you want to protect the headphones from your body electrostatic charge - is this correct? In such case just discharge yourself, by touching the metal cover of your amp, or the floor, or the wall. 
On the connector you plan to build you can connect all the pins together and solder a 1M ohm resistor from this common point to some grounding point in your home. This will discharge the phones safely after you unplug them from the amp and plug them to this connector.
Zenner diodes for electrostatic phones should be at least of 650V each (depending on the max peak to peak voltage your amp can provide + at least 20%), otherwise your amp might burn them on max volume. I would not advise to put such zenners - if they blow making short, your amp may blow as well and they will do more harm than good.  
Still I think all this is not necessary for headphones.


----------



## legopart

What about the idea to store my headphones with shorted connections?
could it help to something?
could it make some damage?


----------



## chinsettawong

Since you talk about this, the original Stax Omega has two resistors connecting to the stators too.






They are then connected to the grill.






But the grill is floated.  Why do they do that?


----------



## lkos98

@legopart 
I think you can store them like that, I can't think of any damage. The bias voltage will transfer to stators and eventually will discharge after some time.
@chinsettawong 
Do you know what is the resistance of these? And sorry, I have no idea how these phones look like and from the picture I can't see how they are connected. Each stator to a resistor, then both resistors to each other and then to one grill, or each to a separate grill? And another question - in stax amps - are there couplng capacitors at the outputs - meaning both stators are at 0V with no input signal?
In such case they may serve as grill grounding, since the differential outputs of the amp are out of phase and then the grill will be always at 0V. This way you save additional GND cable from the amp to the grill for protection. 
Again, I'm just guessing.


----------



## legopart

Looks like 10M ohm 10%


----------



## lkos98

legopart said:


> Looks like 10M ohm 10%


Yeah you are right, well done checking the colors. So in case both are connected to each other and then to the floating grill, I support my guess, it's for setting the grill at 0V and also when you touch it, it will not introduce hum or noise, because it will transfer the signal to both stators with the same polarity.


----------



## legopart

Why can't I use Pro bias on Normal biased headphones?


----------



## chinsettawong

legopart said:


> Why can't I use Pro bias on Normal biased headphones?



The pro bias is set with 580V whereas the normal bias voltage is at 230V.


----------



## legopart (May 24, 2019)

chinsettawong said:


> The pro bias is set with 580V whereas the normal bias voltage is at 230V.


What the diferent do it makes on the membrane ?
If I made my DIY headpohnes or using some know one.
the voltage only charhe the membrane.
The membrane made of hard to condactive materials (high resistent material).
How high, too much high voltage can make some damage to it?

The membrane is passive element  (not a coil or resistor) that influenced from it charge, better charge --> sound better ?


----------



## chinsettawong

legopart said:


> What the diferent do it makes on the membrane ?
> If I made my DIY headpohnes or using some know one.
> the voltage only charhe the membrane.
> The membrane made of hard to condactive materials (high resistent material).
> ...



It's only easier if you try it yourself.  

Well, what is your DIY headphone spacer's thickness?  You should know that the thickness and the bias voltage go hand in hand.  The pro bias is good for the spacer thickness of around 0.45-0.5 mm and the normal bias spacer thickness is much less.  If you were to use the pro bias with normal bias headphones, a few things can happen.  The diaphragms can become unstable.  They might make noises or could collapse to one of the stators.  If not, the sound will sound very loud.  And if you are not careful and turn the volume up too much, you can put a burnt hole on the diaphragm.


----------



## Ulfar4

Ulfar4 said:


> I have some update for my phone. I printed fully new enclosure for drivers, because I found out that the previous were little bended. For this I buy 3d printer for myself, so i can print anything anytime, which is great.
> 
> 
> 
> ...



So the coating still working without problems and since then they are my daily headphones. I also have Stax Lambda Nova, but I really don't like the sound too much. They are too bright and they have much less bass in comparison with my stats.

Anyway, I just started to work on new version of headphones. These will probably have 84mm active area. So there is 15mm difference with previous one.
I bought STAX SRE-725 and I will make from this cable for headphones.





Now I am choosing pads, do someone use these from ebay? They are Genuine Leather Sheepskin Ear Pads Cushion 





They have opening dimension 70x50mm. But I also found similar pads but with circle opening with 65mm diameter. Which one is better in your opinion?


----------



## lkos98 (Jun 5, 2019)

Ulfar4 said:


> So the coating still working without problems and since then they are my daily headphones. I also have Stax Lambda Nova, but I really don't like the sound too much. They are too bright and they have much less bass in comparison with my stats.
> 
> Anyway, I just started to work on new version of headphones. These will probably have 84mm active area. So there is 15mm difference with previous one.
> I bought STAX SRE-725 and I will make from this cable for headphones.
> ...


I'm using the circle with 110mm out diameter - replacement for AKG550 - https://www.aliexpress.com/item/Bla...986.html?spm=a2g0s.9042311.0.0.27424c4dSUNMUZ They are very comfortable, but do not have different thickness front/back (flat cylinder). I think they have pretty good seal and can't tell any issue (considering they are pretty cheap), except for a very nasty dip at 3Khz, which I'm not sure is coming from them or from my plywood cans resonance. If you could please give the link of yours, I will appreciate. Thanks.


----------



## legopart

Antistatic spray not works at all.


----------



## chinsettawong

legopart said:


> Antistatic spray not works at all.



Which brand?  Pictures?  How do you apply it?


----------



## legopart

chinsettawong said:


> Which brand?  Pictures?  How do you apply it?


Spray through the Stator and waiting 1 day.
I have one broken pair of Stax lambda Normal  that I tried to refoam.
Now I understood that the Normal biased Stax used 1mm diaphragm and distance of 0.5mm or less.
I tryied even to to run it (after refoaming) with Pro bias, and it sound even worst.

all the regluing proces make it worst.
I sure that the diaphragm thight good enoght.
I just not success to fix this speaker.


----------



## chinsettawong

legopart said:


> Spray through the Stator and waiting 1 day.
> I have one broken pair of Stax lambda Normal  that I tried to refoam.
> Now I understood that the Normal biased Stax used 1mm diaphragm and distance of 0.5mm or less.
> I tryied even to to run it (after refoaming) with Pro bias, and it sound even worst.
> ...


You should know that fixing this kind of headphones is not easy.  I do not understand what you meant by refoaming.  The 1 mm diaphragm is also not possible.

Can you share us some pictures?  I really want to see what you have done and what you’re trying to do.


----------



## legopart

I share it in the past





after one side is blown, I tried to replace theme both with 2mm from ebay





I dont know what else I can do with this pair.
I spent lots of money on it, unfurtualy it will never be again Stax Lambda normal.

after all glueing and unglue, it even harder to do something with it.
I can't even imagin what other driver can fits to it.

I tried to speak to the front of this phone and it resonate.
So It has to do it job ?


----------



## chinsettawong

How do you stretch your diaphragms?  I think you must have used 2 microns Mylar and not 2 mm.

It’s not so easy as you think to fix these drivers.  You have to be very careful on every step and you should not give up so easily.  If you have read this thread, you should have known that many of us take a long time to master the technic.  It’s not easy.

By the way, what glue do you use?


----------



## cherylyn

legopart said:


> I share it in the past
> 
> 
> 
> ...



Holy crap! That's a lot of clamps.


----------



## WallofHooligans

@legopart damn, rest in pieces lambda boi. Actually I'd like to try repairing a set of these, did you want to sell your dead one?
What kind of glue are the spacers covered in?


----------



## legopart

WallofHooligans said:


> @legopart damn, rest in pieces lambda boi. Actually I'd like to try repairing a set of these, did you want to sell your dead one?
> What kind of glue are the spacers covered in?



all kind of =D

The last one:
https://www.ebay.com/itm/50ML-Yello...bber-Dust-Cap-Edge-Sealer-Bottle/391855054674


----------



## Ulfar4

lkos98 said:


> I'm using the circle with 110mm out diameter - replacement for AKG550 - https://www.aliexpress.com/item/Bla...986.html?spm=a2g0s.9042311.0.0.27424c4dSUNMUZ They are very comfortable, but do not have different thickness front/back (flat cylinder). I think they have pretty good seal and can't tell any issue (considering they are pretty cheap), except for a very nasty dip at 3Khz, which I'm not sure is coming from them or from my plywood cans resonance. If you could please give the link of yours, I will appreciate. Thanks.



I am using these:
https://www.ebay.com/itm/100mm-Repl...hash=item2827096ca5:m:mSDUHXqo5FL200NsPbGFaiA

I also tried another one, they are similar looking to yours. But I prefer the thick one.
There is picture of these two pads.


----------



## legopart (Jun 18, 2019)

I found some sheep skin pads here:
https://www.aliexpress.com/af/HEADPHONES-PAD-SHEEPSKIN.html

Never tried one becoase the price of the premium one.

still planning to read the manual in my free time.
Why someone used a heat gun on his electrostatic speakers?

I found this video about speaker making


Speakers having more then 3500V bias voltage.


----------



## lkos98

Ulfar4 said:


> I am using these:
> https://www.ebay.com/itm/100mm-Repl...hash=item2827096ca5:m:mSDUHXqo5FL200NsPbGFaiA
> 
> I also tried another one, they are similar looking to yours. But I prefer the thick one.
> There is picture of these two pads.


Yeah thanks, these look good. I just hope they will fit to my wooden cans - about 105 mm


----------



## legopart

chinsettawong said:


> It's only easier if you try it yourself.
> 
> Well, what is your DIY headphone spacer's thickness?  You should know that the thickness and the bias voltage go hand in hand.  The pro bias is good for the spacer thickness of around 0.45-0.5 mm and the normal bias spacer thickness is much less.  If you were to use the pro bias with normal bias headphones, a few things can happen.  The diaphragms can become unstable.  They might make noises or could collapse to one of the stators.  If not, the sound will sound very loud.  And if you are not careful and turn the volume up too much, you can put a burnt hole on the diaphragm.


0.5mm ITS NOT SEEN POSSIBLE!
if the membrane will touch the stator then It wount sound or will sound scracchie.
0.5mm is too small for the distance


----------



## WallofHooligans

legopart said:


> 0.5mm ITS NOT SEEN POSSIBLE!
> if the membrane will touch the stator then It wount sound or will sound scracchie.
> 0.5mm is too small for the distance


Listen to Chinsettawong- he is not only magnitudes more experienced at this stuff than you are, he's also looking out for your best interests. I gotta suggest that you stop and read more of the information here- there's a wealth of knowledge here, at your fingertips and you're obviously not using it.


----------



## bui501-tech

legopart, you doubt the master craftsman who started this thread? I’ve been copying his design to make my own headphone drivers that I’m using as room speakers... all with excruciating detail and clarity and loud enough to easily blow out my eardrums... all with 0.5mm spacers.


----------



## legopart

Planned to buy this glues but the descriptions says:
Not for (pp, pe) polypropylene, polyethylene
https://www.ebay.com/itm/PATTEX-Contact-Adhesive-Glue-Leather-Shoes-Rubber-Felt-Nylon-30g-50g-125g/152779424328
https://www.ebay.com/itm/UHU-All-Pu...e-Wood-Metal-Glass-Crystal-Clear/173548991899

I found it really difficult to glue the membrane


----------



## lkos98

legopart said:


> Planned to buy this glues but the descriptions says:
> Not for (pp, pe) polypropylene, polyethylene
> https://www.ebay.com/itm/PATTEX-Contact-Adhesive-Glue-Leather-Shoes-Rubber-Felt-Nylon-30g-50g-125g/152779424328
> https://www.ebay.com/itm/UHU-All-Pu...e-Wood-Metal-Glass-Crystal-Clear/173548991899
> ...



The glues were commented here also many, many times, let me share my experience. 
I use universal contact adhesive (they also call it contact cement glue), but not for shoes, although I think it should work fine. With the UHU I have had no success - may be I'm not using it properly. 
It is very important to apply the glue, then wait few mins until it gets almost dry, but still a bit sticky. Then press firmly for about 30 mins (the longer the better) and then you can leave it in open air (membrane still stretched though) for another 2 hours. The membrane acts like a sealer and glue cannot vapor fast. This is why many glues (silicone sealant for example) don't work - they cannot dry. 
Sometimes I glue them at the evening, press for about 30 mins, then leave over night. If you don't allow the glue to dry in the beginning, you can wait for few days and it might still not be glued (imagine the glue is still in the tube - it can take a year for it to dry out). 
I think the important thing here is not to allow the membrane to slip against the flat surface of the spacer (not to become loose). If you try to rip it off, it goes out relatively easy.


----------



## quintile

i have had good success with uhu por, not standard uhu but the polystyrene glue “por”

you can also dilute it with a little naptha (cigarette lighter fluid) so you can paint it on.

just my experience.

-Steve


----------



## lkos98

quintile said:


> i have had good success with uhu por, not standard uhu but the polystyrene glue “por”
> 
> you can also dilute it with a little naptha (cigarette lighter fluid) so you can paint it on.
> 
> ...



This is great, I always wanted to use a diluted glue. Universal adhesive is easy to dilute with thinner, but then it dries before I can apply it to the whole spacer.  
Thanks


----------



## legopart

lkos98 said:


> The glues were commented here also many, many times, let me share my experience.
> I use universal contact adhesive (they also call it contact cement glue), but not for shoes, although I think it should work fine. With the UHU I have had no success - may be I'm not using it properly.
> It is very important to apply the glue, then wait few mins until it gets almost dry, but still a bit sticky. Then press firmly for about 30 mins (the longer the better) and then you can leave it in open air (membrane still stretched though) for another 2 hours. The membrane acts like a sealer and glue cannot vapor fast. This is why many glues (silicone sealant for example) don't work - they cannot dry.
> Sometimes I glue them at the evening, press for about 30 mins, then leave over night. If you don't allow the glue to dry in the beginning, you can wait for few days and it might still not be glued (imagine the glue is still in the tube - it can take a year for it to dry out).
> I think the important thing here is not to allow the membrane to slip against the flat surface of the spacer (not to become loose). If you try to rip it off, it goes out relatively easy.





quintile said:


> i have had good success with uhu por, not standard uhu but the polystyrene glue “por”
> 
> you can also dilute it with a little naptha (cigarette lighter fluid) so you can paint it on.
> 
> ...


Can you incluade some images or links for this items (cant find them. or understand how they looks)? 
" universal contact adhesive (they also call it contact cement glue)"
"little naptha (cigarette lighter fluid) little naptha (cigarette lighter fluid) "

thanks


----------



## qu1en

You should use contact cement.
You apply to both surfaces you’re trying to bond together, wait 15 min to dry/become tacky. Then make contact with both surfaces and press together for 10 min or so and it will never come apart. Don’t use “shoe glue” that stuff doesn’t even work on shoes. I use contact cement by weldwood. Here is an example: 
DAP 107 Contact Cement https://www.amazon.com/dp/B000M2SKNU/ref=cm_sw_r_cp_api_i_vVQhDb3N5N2ST


----------



## Ulfar4

After a few months, I had an imbalance on my phones, so I decided to reacoat them. But I run out of lcd cleaner which I was using.
I tried floor cleaner and It is working very nice.


----------



## legopart

Ulfar4 said:


> After a few months, I had an imbalance on my phones, so I decided to reacoat them. But I run out of lcd cleaner which I was using.
> I tried floor cleaner and It is working very nice.


Which headphones?

I start to realize that the antistaic spray unglueing the membrane from the stator and cover it with glue, dust and other another unwanted surface.


----------



## Ulfar4

legopart said:


> Which headphones?



I posted picture on page before.


----------



## chinsettawong

Ulfar4 said:


> After a few months, I had an imbalance on my phones, so I decided to reacoat them. But I run out of lcd cleaner which I was using.
> I tried floor cleaner and It is working very nice.



That's a nice find.


----------



## legopart

The membrane from eBay sounds bad!


----------



## chinsettawong

legopart said:


> The membrane from eBay sounds bad!



What is it with you?  I use rubber glue, antistatic spray, 0.5 mm spacers, and Mylar from eBay and my headphones sound wonderful.  

Please don’t generalize something like this if it’s only your own opinion.  If you have something better, please share.


----------



## legopart

chinsettawong said:


> What is it with you?  I use rubber glue, antistatic spray, 0.5 mm spacers, and Mylar from eBay and my headphones sound wonderful.
> 
> Please don’t generalize something like this if it’s only your own opinion.  If you have something better, please share.


what bias do you use?


----------



## legopart (Jul 13, 2019)

how can I make the bias voltage lower? can I use some resistor?
how can I make the serial diodes protector by myself ?
how the amp will react for short between bias and one of the +/- channels? how It will act to short between + and - ? do I hear it or the the amp will stop function ?


----------



## legopart (Jul 15, 2019)

What you recommend to do to fix old speakers that I trying to restore.
Qued esl 57
makes a lot of scratches noise on middle and high volumes.
though about:
1- check the bias voltage
2- check the electricity
3- recoat the diphrgm with antistatic spray
4- Try to open it and Strach the diaphragm better, or put another one.
may glade for any suggest where to start
thanks for any help =D


----------



## chinsettawong

You should go and ask the experts here: https://www.diyaudio.com/forums/planars-and-exotics/


----------



## WallofHooligans

legopart said:


> What you recommend to do to fix old speakers that I trying to restore.
> Qued esl 57
> makes a lot of scratches noise on middle and high volumes.
> though about:
> ...


Whoa. Uhhhhh Do us a favor and be really careful with that stuff- 1 because these are nice rare speakers and 2 because they are biased with speaker voltages which are quite high and dangerous.
I would honestly suggest that you start smaller and work your way up. Find success in easier projects then move up to something like this.


----------



## XLR8

legopart said:


> What you recommend to do to fix old speakers that I trying to restore.
> Qued esl 57
> makes a lot of scratches noise on middle and high volumes.
> though about:
> ...


Look for any obvious holes and patch with scotch tape. 
Aside from that, if it's voltage related and again the voltages are dangerous with quad electrostats, then unless you have someone local who does refurbishments, then it's time to get rid of them sadly.


----------



## legopart (Jul 16, 2019)

XLR8 said:


> Look for any obvious holes and patch with scotch tape.
> Aside from that, if it's voltage related and again the voltages are dangerous with quad electrostats, then unless you have someone local who does refurbishments, then it's time to get rid of them sadly.


In the most bad case I can strech another cheap membrane for all of 6 speakers (Buy I dont know how to measure the streching force).
I can even glue the old membrane while streching it.
and I can try to remove one of dust membranes/filters and spray the original membrane, If they only dried from the first coating.

I not have any measure tools to measure the bias voltage of 6000v (the regular voltmeter works up to 1000v)
I dont know where to measure the bias





  < the red part is covered by wax cube
I can test each capacitor and each diode.
I sure that they fine.
this data is from the company restoring book https://www.quadesl.com/origRefs/quad_book.pdf

And thank!, I'll be very carefull!

as I know screching sound may causes by:
- bad streching of the membrane or damaged membrane
- bad bias voltage

as chinsettawongone suggested, I will post the message in speakers furom too.


----------



## WallofHooligans

legopart said:


> In the most bad case I can strech another cheap membrane for all of 6 speakers (Buy I dont know how to measure the streching force).
> I can even glue the old membrane while streching it.
> and I can try to remove one of dust membranes/filters and spray the original membrane, If they only dried from the first coating.
> 
> ...


Okay, but seriously do be careful. These sorts of voltage multipliers "cockroft walton multipliers" are quite simple, but the actual parts themselves can't be measured in circuit if I remember correctly. Look for burnt diodes, they will be discolored and harder to read. Make sure all the capacitors are intact, no cracks. If the old membrane is loose, it will probably look loose. Under a light you should check the edges, see if the diaphragm is still taut. Check the center of the diaphragm by blowing on it gently. If it moves a lot it's probably too loose. I wouldn't patch any holes with tape as the above user suggested, but I would check for holes. You can definitely replace full diaphragms, but you will have to think of a clever way to mount the plastic in order to pre-stretch it.


----------



## qu1en

legopart said:


> In the most bad case I can strech another cheap membrane for all of 6 speakers (Buy I dont know how to measure the streching force).
> I can even glue the old membrane while streching it.
> and I can try to remove one of dust membranes/filters and spray the original membrane, If they only dried from the first coating.
> 
> ...




I would do the easy stuff first. It looks dirty so try and clean it without damaging anything. Listen to the type of crackling you’re hearing. Check for bad capacitors etc.. I can’t imagine a bad bias is causing crackling. If there is no bias it will be very quiet or not work at all. It is also unlikely to be the voltage at the stators but you can measure it with a scope with a very low volume. Does the crackling change with different volumes? Is it possible to inspect the diaphram by removing the stators? how does it look? just don’t do anything complicated until you are confident something is the issue first. Start with the easy stuff first, and make as many observations as possible.


----------



## legopart (Jul 16, 2019)

qu1en said:


> I would do the easy stuff first. It looks dirty so try and clean it without damaging anything. Listen to the type of crackling you’re hearing. Check for bad capacitors etc.. I can’t imagine a bad bias is causing crackling. If there is no bias it will be very quiet or not work at all. It is also unlikely to be the voltage at the stators but you can measure it with a scope with a very low volume. Does the crackling change with different volumes? Is it possible to inspect the diaphram by removing the stators? how does it look? just don’t do anything complicated until you are confident something is the issue first. Start with the easy stuff first, and make as many observations as possible.


To reveal the diaphragm I have to remove the element first and then to cut the dust filter from the corners

This sopeaker have 2 very heavy tranformers with all the electric elements (one for the speakers bass/tweeter and one for the bias) the speakers too heavy because of them, I want to remove them from the speakers and connect each element separate with longer wires, out side of the speaker.

I plan to test the option to connect each speaker element with a portable amp and Stax Srd-4  energizer (I think that its rate is 1:25).
the bias still use the original transformer of 6000v.
^ I must to chek if this option is actual becoas Stax Srd-4 using better transformer.

I will afford on this speakers some thing like several hours a day or a week. can't fix or check them by once.
Because of it I have to seperate all the transformers and the  elements.


----------



## legopart (Jul 16, 2019)

---
Sorry mistake the bias is function good, after it charges the diaphrasm several minutes, and I unplug it, the speaker still function the same.

Yes as I wrote, one of them function the same with/without the bias voltage (external power)

Another new about it.
I accidently removed the power plug from bias supply...
and what I discovered?
they sounding the same with cracking noises, and with the same volume.

I can explain this only as: something goes wrong with the bias functionality 

The bias connection not affect the sound == there is some problem with bias producing
​two explains:
-maybe I not dischaged from the last connection
-maybe the transformer/bias circuit not function

the second one function without screch noises up to high volumes
the first with the bias problems function bad on the middle volumes


----------



## chinsettawong

Quad 57 isn’t that easy to fix.  The stators are riveted together.  If you want to remove them, you’ll need to use a drill press to drill all the rivets out.  And then you’ll need to check if the stator surface is damaged.  The stators are first coated with conductive paint and followed by insulation paints.  If you need to remake the diaphragm, you’ll need to know what tension you need to get to first.  You can buy a diaphragm repair kit from eraudio.com.  They’ll tell you exactly what tension you need to achieve.  Overall, it’ll take quite a lot of time to fix.  And you need to do a lot of studies before you start fixing it.  Don’t forget that you’re playing with extremely high and lethal voltage.  Be very careful!


----------



## legopart

chinsettawong said:


> Quad 57 isn’t that easy to fix.  The stators are riveted together.  If you want to remove them, you’ll need to use a drill press to drill all the rivets out.  And then you’ll need to check if the stator surface is damaged.  The stators are first coated with conductive paint and followed by insulation paints.  If you need to remake the diaphragm, you’ll need to know what tension you need to get to first.  You can buy a diaphragm repair kit from eraudio.com.  They’ll tell you exactly what tension you need to achieve.  Overall, it’ll take quite a lot of time to fix.  And you need to do a lot of studies before you start fixing it.  Don’t forget that you’re playing with extremely high and lethal voltage.  Be very careful!


Do you have some guide to make some straching machine or where can I buy one ?
I hope not to touch the paint on the stators, do I have to buy it too ?


----------



## bui501-tech

Why don’t you read through he threads in this forum just like everyone else has and like the other members have suggested half a dozen times before already?


----------



## legopart (Jul 16, 2019)

bui501-tech said:


> Why don’t you read through he threads in this forum just like everyone else has and like the other members have suggested half a dozen times before already?


I tried but I can't find what I searching for inside this 200+ pages
lots of people here show the final product and I cant understand from it how to do it by myself


----------



## legopart (Jul 16, 2019)

chinsettawong said:


> Quad 57 isn’t that easy to fix.  The stators are riveted together.  If you want to remove them, you’ll need to use a drill press to drill all the rivets out.  And then you’ll need to check if the stator surface is damaged.  The stators are first coated with conductive paint and followed by insulation paints.  If you need to remake the diaphragm, you’ll need to know what tension you need to get to first.  You can buy a diaphragm repair kit from eraudio.com.  They’ll tell you exactly what tension you need to achieve.  Overall, it’ll take quite a lot of time to fix.  And you need to do a lot of studies before you start fixing it.  Don’t forget that you’re playing with extremely high and lethal voltage.  Be very careful!


 eraudio.com not function anymore.
I thought from the guide that I read about the conductive paint use inly for the part where I connect the membrane and  the bias.
so the stators made of plastic too, and they just coated with condactive paint that protected with isulation paint.

new I can understend why the bass panels on the front side covered by black/blue paint.
to isulate the electric charge from the user. (if I right)





this condactive paint for example is fine: ?
https://www.ebay.com/itm/Conductive-Carbon-Paint-3ea-30-grams-SPRAY-FORMULA/280448195257?epid=1955725924

cant find isulated paint (one of the bass plate front without it.)

drill is not a problem.

I still hope that the problem is from some electric elements.
I cant belive that speakers membrane that stored uselessly many years will unstrach.
for example, stax headphones works fine after all this years.

If I will open the plates, I plan to try and keep the membrane and try to restrech it and glue it again.

someone suggested to try shrink the membrane with heat-gun (shrink gun).

I still need some suggestion for the condactive and isulate paint.
And some suggestion how to regulate the straching of the membrane.

thanks for help!


----------



## quintile

usually the problem with the old quad ESLs is the diaphragm is damaged by them being overdriven.

i would buy or make a high voltage probe and check the EHT voltage. if that is ok check the stator drive voltages. opening the panels should be the last resort.

there is a huge amount written on the net about repairing ESLs, most of it sensible but there are some rather silky ideas about (this is always true on the net).

i suggest you read widely from many different sources on esl57 repair before attempting any serious disassembly.

-Steve


----------



## WallofHooligans

I really have a bad feeling about what's happening here. 

On the note of tensioning a diaphragm, I think a heat gun would be a bad idea. Assuming that the plastic is even slack and could be reformed with heat, you would probably be better off putting it in an oven with carefully selected temperatures, and only if the frame is able to withstand that heat without warping. I really think you need to slow down and read more before you go full hog on it. Like you would never take apart your car's engine if you didn't know how to reassemble it. The bit about exchanging the transformers for stax voltages makes it clear that you don't know what you're doing. You're messing with stuff that you shouldn't until you know more.


----------



## chinsettawong

Here is the link to eraudio: http://www.eraudio.com.au/ESL_Repair_Kits/esl_repair_kits.html


----------



## legopart (Jul 20, 2019)

Thanks, I read alot about the electrostating speakers/headphones, after having one pair of Q57, I understand now about what he talked.
I cant find any "conductive coating" for cheap price.
I want to try this material https://www.ebay.com/itm/DecoArt-Americana-Chalky-Finish-Paint-8oz-Carbon/232227805278
even if I sure that its not it purpuse, and maybe it described as Carbon only becoase it black color.
Or this one
https://www.aliexpress.com/item/32719764648.htmhttps://www.aliexpress.com/item/32719764648.html
or this pen https://www.aliexpress.com/item/32920339916.html



chinsettawong said:


> Here is the link to eraudio: http://www.eraudio.com.au/ESL_Repair_Kits/esl_repair_kits.html


the price of this set that you suggest is too high, and without some streching mechanism and with limited materail.

I read some about the streching mechanism and found my method is not so good






I though a lot how to restore the original membrane, but It seen unpossible.
At this point I do it without any seccess. the only method that I found usefull, is to strech it with tape on a table.

I tough about this membrand if I will replace on mine
https://www.ebay.com/itm/Electrostatic-Speaker-Membrane-Dupont-Mylar-C-12um-20M/182167831875

Cant understand this guy on 20:00, which material he used, look wrong to cover the membrane with conductive material.


----------



## qu1en

1. Does anyone have issues sometimes with rattling during deep bass caused by the sweat guard?

2. Has anyone compared their sensitivity to the stax? I notice the stax is probably twice as sensative as my own. I’m using 0.6mm and stax uses 0.5mm but I wonder if the larger contributing factor is how penatrable their stators are? (almost mesh like)...


----------



## legopart

How do you measure the gap distance?
I always hearing high distortions on high volumes.
Up to middle it sound great!


----------



## wrinex

legopart said:


> Cant understand this guy on 20:00, which material he used, look wrong to cover the membrane with conductive material.




I might be able to translate  since i am that guy.   but i am unsure of witch part you did not get 

Ill try to explain.  i used a carbon Black tatoo ink, and the reason is that it has allot of carbon black percentage, besides some filler material of which i dont know what it is. i do know it is water soluble. carbon black is a conductor and has very very tiny particles, this makes it suitable to make a coating that is medium high resistance up to really high resistance. when dried it is really thin, problem is getting a consistent coating, also the reason i rather not use it if i can. but it is a bit of hit and miss so far.

"it looks wrong to cover the material with conductive material" 
Well since the whole goal is to charge the foil statically, this works with about everything that conducts, but higher resistance coatings perform better in the low end since the charge does not migrate as much as with low resistance coatings.  so on a low resistance  coating the charge when low frequency are played tend to move to the point that is closest to one of the stators (with high frequencies there is hardly any movement  thus not much of a problem). in a high resistance coating this effect is not as strong. creating an more even static foil. and thus less distortion. 

i hope that helps, if not just ask, although im no expert in ESL's or EST's you can always try


----------



## wrinex

OOh hee *chinsettawong long time no seen on DiYAudio  *


----------



## chinsettawong

wrinex said:


> OOh hee *chinsettawong long time no seen on DiYAudio  *


 Sorry!  I haven’t been doing anything on the ESL in a long time.  Actually I do go back and browse the forum from time to time.  It’s nice to see you here.  Please hang out here for a while and give us some ideas and advices.


----------



## Amberlamps

Cool thread!

After reading a few pages of this thread, now I want to make a pair of electrostatic headphones, but sadly, no cigar 

Cool nonetheless


----------



## chinsettawong

Amberlamps said:


> Cool thread!
> 
> After reading a few pages of this thread, now I want to make a pair of electrostatic headphones, but sadly, no cigar



Why?


----------



## qu1en

My latest setup:


----------



## Amberlamps

chinsettawong said:


> Why?



Sadly I'm not in a position to make something cool like that, although I would like to, but this thread is cool.


----------



## wrinex

Amberlamps said:


> Sadly I'm not in a position to make something cool like that, although I would like to, but this thread is cool.



im pretty sure everyone can  you dont need a cnc to make one !


----------



## Amberlamps

wrinex said:


> im pretty sure everyone can  you dont need a cnc to make one !



Pretty sure I can't.

Pushing a button is easy, hence me typing, but I don't have the dexterity to build headphones,

I won't post a pic, but google images "rheumatoid arthritis and hands".


----------



## wrinex (Aug 8, 2019)

Amberlamps said:


> Pretty sure I can't.
> 
> Pushing a button is easy, hence me typing, but I don't have the dexterity to build headphones,
> 
> I won't post a pic, but google images "rheumatoid arthritis and hands".




Oh im sorry i never thought actually about not actually being able. im sorry must keep that in mind ! usually people just say stuff like that since they never worked with it etc.  in my opinion allot of people can make much more then they think but i can imagine if it its just physically not possible that might sound rather stupid.. , if all thats true , and you are able to make a cup and maybe some of the other parts i would be happy to send you some of my planar magnetic drivers if i feel they are decent enough. so you can build the stuff your own that you are able to manage.  but only if it is not a bad joke ! everyone should have the opportunity to build something you like yourself !.

i know its not an esl, but i first have to finish one project for a change before i start the next one (although i already made a fast driver EST recorded a  week ago i am trying to restrain myself)

Greetings Joppe


----------



## Amberlamps

wrinex said:


> Oh im sorry i never thought actually about not actually being able. im sorry must keep that in mind ! usually people just say stuff like that since they never worked with it etc.  in my opinion allot of people can make much more then they think but i can imagine if it its just physically not possible that might sound rather stupid.. , if all thats true , and you are able to make a cup and maybe some of the other parts i would be happy to send you some of my planar magnetic drivers if i feel they are decent enough. so you can build the stuff your own that you are able to manage.  but only if it is not a bad joke ! everyone should have the opportunity to build something you like yourself !.
> 
> i know its not an esl, but i first have to finish one project for a change before i start the next one (although i already made a fast driver EST recorded a  week ago i am trying to restrain myself)
> 
> Greetings Joppe



It's all cool, no need to apologise 

I can do alot of things, my hands are not 100% wrecked, but they are well on the road to being wrecked. it's just a matter of when and not if.

I could probably build a pair, but it would take ages and hurt alot in the process, as once I really start working with my hands, within 5 - 10 minutes they are all swollen, stiff and sore.  What I wouldn't be able to is things like wiring, soldering etc, the last time I tried to use my soldering station ended in disaster. Anything that needs precision hand movement is dodgy nowadays. Don't get me wrong, my hands are not useless, but for delicate or small things, we don't get along nowadays.

Thank you for your kind offer to send drivers etc, it's very much appreciated, it really is, but I know I would make a complete mess of building them.

However;

It would be cool to hear your home made planars, if your ever in or going to be in the UK, if you want, take your home made planars and pop in by my pad, I will get to hear your planars and if you haven't already, you can get to listen to my Chord MScaler and Chord Hugo TT 2. Your planars will sound good on TT2, as it has alot of power behind it to drive even the hardest to drive planars on the market.

It's all cool though


----------



## wrinex

Well if i ever am in the UK (wish i would) we defintely could arange something !, to bad did not have a vacation for the last 5 yeas but who knows  haha


----------



## qu1en

Tried to post this pic earlier.. let's try again. Let me know what you think. I used a nylon cover for the dust guard. Seems to work pretty well and doesn't take away from the sound. Amplifier is my own design, and solid state.


----------



## wrinex

qu1en said:


> Tried to post this pic earlier.. let's try again. Let me know what you think. I used a nylon cover for the dust guard. Seems to work pretty well and doesn't take away from the sound. Amplifier is my own design, and solid state.


i walays wondered how much dust is an isue , for esl it is mentioned often to although i had 30+ old panels in many shape and forms and actually never seen dus to  be honest   look nice trough


----------



## chinsettawong

qu1en said:


> Tried to post this pic earlier.. let's try again. Let me know what you think. I used a nylon cover for the dust guard. Seems to work pretty well and doesn't take away from the sound. Amplifier is my own design, and solid state.


The headphones and the amp look really nice.  Would you share your amp design?


----------



## chinsettawong

wrinex said:


> i walays wondered how much dust is an isue , for esl it is mentioned often to although i had 30+ old panels in many shape and forms and actually never seen dus to  be honest   look nice trough



Actually dust in the driver is a big issue with electrostatic headphones, the phones can sound rather annoying when you hear those static sounds.  I highly recommend that the stators be coated with insulation paint.  This could very well solve the noise issue even if there is dust inside the driver.  By the way, the dust cover also serves as a protective layer against sweat.  In hot summer days, you don’t want to have your sweat inside the driver and short everything.  It can be very dangerous too.


----------



## qu1en

chinsettawong said:


> The headphones and the amp look really nice.  Would you share your amp design?



Sure man. I have PcBs too. If you msg me your email address I can send you the schematic and BOM..


----------



## chinsettawong

qu1en said:


> Sure man. I have PcBs too. If you msg me your email address I can send you the schematic and BOM..



Thanks for the offer.

If it's not too much trouble, I would prefer that you share your design here so that we all can learn together.


----------



## legopart

chinsettawong said:


> Actually dust in the driver is a big issue with electrostatic headphones, the phones can sound rather annoying when you hear those static sounds.  I highly recommend that the stators be coated with insulation paint.  This could very well solve the noise issue even if there is dust inside the driver.  By the way, the dust cover also serves as a protective layer against sweat.  In hot summer days, you don’t want to have your sweat inside the driver and short everything.  It can be very dangerous too.


Without dust covers even conditioner could make enoth humidity for distortions


----------



## legopart (Aug 10, 2019)

I bough some used Stax sr-202, That I have now to restore, the drivers falls inside + the headband not soo good + the ear pad dried and pretty hard.

I glue the driver back in place.
I accidently touch the back side of the driver becoase I dont know that there is a phassive filter, old lambda not having this one on his back.

What the element on the bias connector that they put there:
I short it becaus the I not like the sound of this headphones.



here where I touch, I dont know how protect the dust filter In future.





And how to replace the headband and make the pads softer?


----------



## legopart

@wrinex
I need your help to fix my quad esl57
https://www.diyaudio.com/forums/planars-and-exotics/341092-fix-quad-esl-57-a.html#post5874554

first, I having an issue to understand how to create the protection boards ( arc clamping boards), where can I order the zener-diodes/diodes?

I still can't understend how to coat the membrane of the electrostic headphones
even when I found some explanation, I still cant find this matterial.
for example
I just couldn't understand how this material looks like.
10ml organsol+4ml soup (contain Sodium Laoral Sulphate) ?
what is organsol?
what is Sodium Laoral Sulphate?


----------



## chinsettawong

legopart said:


> @wrinex
> I need your help to fix my quad esl57
> https://www.diyaudio.com/forums/planars-and-exotics/341092-fix-quad-esl-57-a.html#post5874554
> 
> ...



@legopart, please consider asking questions about fixing your ESL at diyaudio as there are far more experts over there.


----------



## qu1en (Aug 17, 2019)

Hi Guys,
I attached (uploaded) my schematic design.
It uses the 272BX transformer.
It works pretty well.. I have the Stax SMR1/MK2 amp and strangely it seems quite similar.
The STAX amp also uses high power 25k resistors as the load, but they use transistors and I use FETs.
My design is much more simple.

https://imgur.com/a/kEamkLj

Edit: When I try and edit this post it shows that there is an attached file.. but once posted, I don't see a file where I can click and open... Any help is appreciated.


----------



## chinsettawong

qu1en said:


> Hi Guys,
> I attached (uploaded) my schematic design.
> It uses the 272BX transformer.
> It works pretty well.. I have the Stax SMR1/MK2 amp and strangely it seems quite similar.
> ...



Really like to see your design.  It's simpler to put your file somewhere else and post a link here.  That goes for all the pictures if you will post too.


----------



## qu1en

chinsettawong said:


> Really like to see your design.  It's simpler to put your file somewhere else and post a link here.  That goes for all the pictures if you will post too.



I just edited my original post and put up an imagur of the schematic and setup. Let me know if it works.


----------



## wrinex (Aug 17, 2019)

legopart said:


> @wrinex
> I need your help to fix my quad esl57
> https://www.diyaudio.com/forums/planars-and-exotics/341092-fix-quad-esl-57-a.html#post5874554
> first, I having an issue to understand how to create the protection boards ( arc clamping boards), where can I order the zener-diodes/diodes?
> ...



Never done 57s as well i dont know the components you mention.  They are i guess 57 (only) related. I know they used a weird coating  and 2 different types of foil. But cant help you there. Indeed ask the fellow diyaudio members. But most of all use the search butten over there or just google. It has been done many times i  believe.


----------



## Torac

qu1en said:


> Hi Guys,
> I attached (uploaded) my schematic design.
> It uses the 272BX transformer.
> It works pretty well.. I have the Stax SMR1/MK2 amp and strangely it seems quite similar.
> ...



I would love to build my own energiser, I currently have just a srm-252s for testing my stats. Would it be possible to get a PCB like you mentioned before and a BOM? I would greatly appreciate it.


----------



## qu1en

EssentialEDM said:


> I would love to build my own energiser, I currently have just a srm-252s for testing my stats. Would it be possible to get a PCB like you mentioned before and a BOM? I would greatly appreciate it.



Sure man, just PM me your email and I can send you all the info.


----------



## afgmjkl

Hello,
I have 007 which have tiny holes in the membrane, so am planning to renew it.
But I don't know how to separate rings that sandwich the diaphragm.
Any ideas?


----------



## chinsettawong

If it’s only a tiny hole, don’t worry about it.  Renewing a new membrane isn’t that easy.


----------



## afgmjkl

chinsettawong said:


> If it’s only a tiny hole, don’t worry about it.  Renewing a new membrane isn’t that easy.


Thanks for the advice.
If I remove the dusts and left channel keeps making buzzing noise, I am going to renew a membrane.


----------



## chinsettawong

The noise can only come from something like dust inside the driver.  Even if you change the diaphragm, you might still have the problem.  You need to patiently check the stators and diaphragm and clean everything extremely thoroughly.  It’s not easy, but it’s achievable.


----------



## legopart (Aug 30, 2019)

@wrinex do you reccomend the method of using speaker under the membrane to set the right tension?
if I can scale the tension
what the tension (in Grams) that I have to use on headphone diaphragm?

* I carved dipper hole inside Stax lambda normal so it have now 0.5mm depth.
* I accidently destroyed my sr-202 try to recoat them with antystatic spray and its melt the black color that coated on the stators 

Can I acchive the same quality as branded original headphones from streching a diaphragm by myself?


----------



## legopart

afgmjkl said:


> Thanks for the advice.
> If I remove the dusts and left channel keeps making buzzing noise, I am going to renew a membrane.


possible that the air conditioner or some humidity pass between the stators, you have to keep the headphones on dry place.

I have this issue on some old headphones too and I plan:
- add some mineral wool on the back of them
- add some resistor on the bias connector to protect it from too high charging, read that resistor can keep the driver from distortions (I think  10Mohm or even more)
*protecting from overcharching spead
*the last one is if the membrane over charged becoase the coating


----------



## wrinex

legopart said:


> @wrinex do you reccomend the method of using speaker under the membrane to set the right tension?
> if I can scale the tension
> what the tension (in Grams) that I have to use on headphone diaphragm?
> 
> ...



hmm well i am no expert at all with ESL headphones, or even esl's  i used the speaker method on bigger panels. i think it might be hard to pull off on headphones. maybe the weight thing might be the easiest method for a headphone.

not sure what anitstatic you sued and what material is on the stators... 


may


----------



## chinsettawong (Sep 7, 2019)

Yesterday was a very special day for me.  I got to meet a young entrepreneur from India, Aumkar of Kaldas Research.  He came to Thailand to meet me and to give me a pair of his electrostatic headphones.  Using this opportunity, I set up a mini meeting with my local head-fi friends.  We had a lot of fun listening to his headphones and many other.





































By the way, his headphones sounded absolutely fantastic.  Congratulations, Aumkar!


----------



## Tachikoma

afgmjkl said:


> Thanks for the advice.
> If I remove the dusts and left channel keeps making buzzing noise, I am going to renew a membrane.



Try this: play a series of ultrasonic tones using Foobar2000's tone generator (25 khz, 30 khz, 40 khz) for 10 seconds each. You'll need to set the tone/sweep sample rate to 96khz in Advanced settings.

This won't help with major dust issues (you'll need to wet clean the stators with alcohol, at least), but it might get a pesky dust particle off without resorting to driver surgery. Seemed to work for me at least.


----------



## afgmjkl

Thank you everyone.
I removed dusts and renew dust cover with 2 micron mylar, and the problem seems to be solved.
I tried 1.5um Toray PET film as dust cover but that doesn't work. (can't insulate from humidity and causes noise)


----------



## wrinex (Sep 12, 2019)

i still wonder why dustr is such a problem.. it never is with tweeters with 1mm spacings and  far higher biases in the regions of 3Kv........ headphones..... few hundred


adding dustcovers just like quad did moves the upper ferquencies exactly the same way it does as using thicker foil . i once made tweeters with multiple membranes and doubling them, perfectly folows the use of 2 as thick foil


----------



## chinsettawong

wrinex said:


> i still wonder why dustr is such a problem.. it never is with tweeters with 1mm spacings and  far higher biases in the regions of 3Kv........ headphones..... few hundred
> 
> 
> adding dustcovers just like quad did moves the upper ferquencies exactly the same way it does as using thicker foil . i once made tweeters with multiple membranes and doubling them, perfectly folows the use of 2 as thick foil



Do you know that some headphones’ stators aren’t insulated.  Any dust goes in between the stators and diaphragm can actually cause noise.  

I don’t really notice the degradation of sound with the dust cover on though.


----------



## legopart

maybe the plates isolated.
quad 57 treble (squacker + tweeter) using 0.5mm  and 1.5kV

the must DIY makers proffer to put the dust filter on headphones
after squashing it like this,
claimed that else it will damage some frequencies

on quad 57 guide it says to put it normally without stretching and some suggest to use some heat-shrink membrane and heat it.


squash like this








I think that humidity makes more sound distortion then dust, you will hear it without any sound from the headphone, the dust cover or some felt layers the only that can protect from it.


if it shorted (on headphones) you will hear really distorted low sound, on speakers I read that if you forget to put the resistor, all the diodes will blow (so DIY headphones to).


----------



## chinsettawong

legopart said:


> maybe the plates isolated.
> quad 57 treble (squacker + tweeter) using 0.5mm  and 1.5kV
> 
> the must DIY makers proffer to put the dust filter on headphones
> ...



Are you sure that the treble panel on Quad 57 has only 0.5 mm gap?  I don’t think you can bias 1.5KV with that small gap.


----------



## legopart (Sep 13, 2019)

chinsettawong said:


> Are you sure that the treble panel on Quad 57 has only 0.5 mm gap?  I don’t think you can bias 1.5KV with that small gap.


Yes 0.5mm
I have to restore my pair.
*one tweeter having some born parts that I have to fix, working on it now.
the restoring guide describe the distance to 0.5mm.
I tested to prove this, the distance under the border tapes (will not! remove, they important for the distance)
My metal ruler thickness is +-0.5mm so its 0.5mm
don't know the reason for 1.5Kv for 0.5mm maybe because the size (I still not checked this chapters in the book)




the plate separate by crossover to 3 boards 2 squacker (low tweeter) and 1 tweeter, 1.5kV bias, the size is something like 33*66cm.


----------



## wrinex

yeah resonance of the dust cover in combination of the foil resonance creates a new combined resoanance so it should be stretched very lightly.  at the same time the dust covers thickness adds up to the membrane thickness.  so a 3 micron membrane with 2  3 mincron dust covers behaves more like a 9 micron membrane.


----------



## wrinex (Sep 13, 2019)

chinsettawong said:


> Are you sure that the treble panel on Quad 57 has only 0.5 mm gap?  I don’t think you can bias 1.5KV with that small gap.



breakdown of air is around 3 Kv a mm

I think it was a little thicker spacing but, one must not forget that the pcb stator itself has the copper on the outside, so it is 0.5 + thickness of the stator almost. wich makes it possible to use 1.5kv  since 1.5 would be the breakdown voltage of the 0.5 gap but there is  an extra 0.5-1mm from the stator.  if they etched the holes on teh stators it is actually even more, since the breakdown voltage of pcb is much higher then air.  By etching the holes the  path from copper to foil is even slightly higher then 0.5mm + 1mm+ the edge of the hole where the copper is etched away. total of 1.5-1.6mm  witch would give you a breakdown voltage of 4Kv.   another thin  to keep in mind i believe is you should add the voltage swing of the trannie to. so 1.5Kv bias + the opposite voltage swing on the stator for instance for a headphone max 0.5 Kv or something ?  so total of 2kv.   i add this value because the stator when pulling on the foil has a opposite charge of the foil bias. it makes it  want to jump faster.

and lastly the stuff is coated, wich increases breakdown voltage to. but as you can see in the stator when this paint fails once.... it will keep failing until everyting gets destroyed. although these panels look a bit like the had a bit more  troubles then breakdown voltage only  overdrivven or the foil came lose.  most likely overdrivven since it looks more like the stators arced from one to another witch has far more destructive amperage behind the spark 


just my 2 cents


----------



## chinsettawong

I really, really like to see you guys actually try biasing that kind of voltage with the driver having only 0.5 mm spacer.  Try it and let us know if it’s actually OK.

I actually give the information of what I have leaned over years of making electrostatic headphones here.  Nothing that I put here is something that I haven’t tried.  If you don’t like to use the dust cover, that’s fine.  It’s all up to you.


----------



## quintile

wrinex said:


> yeah resonance of the dust cover in combination of the foil resonance creates a new combined resoanance so it should be stretched very lightly.  at the same time the dust covers thickness adds up to the membrane thickness.  so a 3 micron membrane with 2  3 mincron dust covers behaves more like a 9 micron membrane.



i don’t buy this.

the resonance of the dust cover will be at very low frequency (relatively speaking) as it will be under almost zero tension - it is still crinkled. finger in the air guess, 30hz?

the diaphragm will have a resonance of more like 100 to 500hz depending on material, size and coating.

given the self damping if the crinkled plastic dust coveri would expect this to have a very low Q resonance.

the two frequencies will be far enough apart and differ enough in Q to have very little effect on each other.

could you do some response measurements with and without dust covers?

-Steve


----------



## wrinex (Sep 13, 2019)

quintile said:


> i don’t buy this.
> 
> the resonance of the dust cover will be at very low frequency (relatively speaking) as it will be under almost zero tension - it is still crinkled. finger in the air guess, 30hz?
> 
> ...




if the main membrane resonance is indeed 100 or 500 hz  i am absolutely wrong !! but i cant think of a panel having such high resonance if it has to do fullrange (i thought it was about a headphone). for a tweeter it does not matter indeed since cover has lower res then the frequency the thing is gone produce.  only thickness counts in that case.

here a measurement of a stacked ESL  adding more membranes, witch is almost the same as adding additional dust covers except they are not active. so the increase in output as seen here is not present of course  you can see as well resonance is going up. but im not to sure yet if this is related since these are active.


----------



## wrinex (Sep 13, 2019)

chinsettawong said:


> I really, really like to see you guys actually try biasing that kind of voltage with the driver having only 0.5 mm spacer.  Try it and let us know if it’s actually OK.
> 
> I actually give the information of what I have leaned over years of making electrostatic headphones here.  Nothing that I put here is something that I haven’t tried.  If you don’t like to use the dust cover, that’s fine.  It’s all up to you.



problem is mostly we are comparing apples with pears..   a headphone has a really low resonance compared to a tweeter like this. the tweeter would not even function without allot tension at high bias voltages since the slightest imperfection in terms of equilibrium would make the foil stick to one of the stators witch result in instant arcing. (because the surface area is much larger it is easy to move the foil close to one stator)   As example i got a few mid/top panels from solo sound here that use 1.2 mm stators made from PCB with a normal laquar on the copper side, copper side outwards.

They have a resonance of 350-400hz, and have a spacing of 1 mm stator to membrane. + the 1.2 mm of the pcb(stator) itself so actually 2.2 mm.  there bias is a whopping 5Kv+. and step up ratio120!   they are only 10x15 cm in size but 4 of them almost give 88-90dB efficiency @ 1 meter, so yes it is possible but it depends on the purpose.. an reliability is an issue when you push it this far as they did. although most panels failed 15 years later... still rather good.


----------



## chinsettawong

I have done a few pairs of ESL myself, and I know very well that making ES loudspeakers and ES headphones is very different.  For one thing, the drivers of the headphones are positioned right next to your ears.  Even a slightest noise can be annoying.  The dust cover is there not only to protect the dust.  It also serves as a protective seal against humidity and the possible sweat going inside the drivers.  You can try making a pair of headphones and see it for yourself.

Please, can we get back to only headphones discussion here?


----------



## qu1en

I have had issues with resonance with the sweat guard if i dont make it loose enough. I have to be quite purposeful about keeping it loose. Even though the SRF is around 20-30Hz, during deep bass you can hear it rattle, kind of like a buzz if there is even a little bit of tention.


----------



## legopart

Discovered that all the glues are useless, I can break the bound easily.




afgmjkl said:


> Hello,
> I have 007 which have tiny holes in the membrane, so am planning to renew it.
> But I don't know how to separate rings that sandwich the diaphragm.
> Any ideas?


This why I learned by hard way not mess with Stax,
After the disassembly you remain with lots of boards that cant stick together again, not remaining the issue of stretching+coating.


----------



## afgmjkl

legopart said:


> Discovered that all the glues are useless, I can break the bound easily.
> 
> 
> 
> ...



Recent models like 007 are assembled by screws not the glue.


----------



## chinsettawong

afgmjkl said:


> Recent models like 007 are assembled by screws not the glue.



Have you already fixed your diaphragm?  If the hole is only a tiny one, you don't need to renew it.  Use it as it is, and it should be OK.


----------



## afgmjkl (Sep 16, 2019)

chinsettawong said:


> Have you already fixed your diaphragm?  If the hole is only a tiny one, you don't need to renew it.  Use it as it is, and it should be OK.



There are 0.5mm split and one tiny hole on the diaphragm.
I've removed dusts and solve noise issue, but recently found that it has treble dip around 1.4kHz.
I'm going to recoat the diaphragm but I hear same dip on other headphones, so my left ear may cause this problem.


----------



## legopart (Sep 17, 2019)

afgmjkl said:


> There are 0.5mm split and one tiny hole on the diaphragm.
> I've removed dusts and solve noise issue, but recently found that it has treble dip around 1.4kHz.
> I'm going to recoat the diaphragm but I hear same dip on other headphones, so my left ear may cause this problem.


Try to re-screw little bit and tight again (don't break the screws)  the connectors maybe you created some dis-balance  or glue the corners with regular  thin selotape only to see if it helps.

do the screchie noises comes after several time of listening or immediately ?


----------



## legopart

Finish to restore Sr-202, the old signature back even with 2micron membrane, and I hate it!!!
glue it little bent, not 1:1 on the stators holes 
I just so clumsy and unprofessional.

Life less sound! bad and dry ear-pads.
some said it because the low quality cable that having high capacitance on purpose, to make the sound less warm.
(some said that this is the same drivers that installed in sr404 and sr-sigma-404 )
this is the most low level of Stax I ever heard!

I have the Stax Lambda Pro, that having life full sound.
This is my reference headphones (and untouchable for any mods)

I can't do nothing to fix the Sr-202.
Still preper to fix my first electrostatic headphones that broken after I tried to clean them.
The Sr-Lambda Normal.
I carved before gluing it together 0.5mm hole for the stators.
Don't know how it capable and safe (1mm or less air distance between the stator and the bias), but after I will install/glue the membrane and hop to restore,
I still not have any specific Pro cable for them and the price for new one is too high.
can dissasamble the Sr-202 cable for any experiment.


----------



## afgmjkl

legopart said:


> Try to re-screw little bit and tight again (don't break the screws)  the connectors maybe you created some dis-balance  or glue the corners with regular  thin selotape only to see if it helps.
> 
> do the screchie noises comes after several time of listening or immediately ?


 
I bought defective unit so I hear noises immediately.


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## legopart (Sep 18, 2019)

afgmjkl said:


> I bought defective unit so I hear noises immediately.


Used?

but, really this headphones built from 2 metal plates and nylon layer
what could be the difficult one from another?

electrical distortion? Yes its a great problem with build and insulation.
Dynamic drivers may have even more distortion, dust could be the reason too.

maybe the burned holes made some material parts wider ... so it touching the plates.

I don't want to recommend you to disassemble it, but if you going to do so take some picture of it.
again, disassemble the electrostatic headphones/speaker for the first times most can cause to dysfunction of the headphone .


Look I really don't aspect from 30Hz squire wave to change something...
http://onlinetonegenerator.com/


----------



## legopart (Sep 18, 2019)

Found the sr-202 now having some electrical noises/distortion after I tap on/hit it a bit from the side.
at this point I cant even open or change anything with them after they glued.

with Normal bias its works without randomal distortions.
think to dissasamble it again, this time to paint the the stators.
the same thing with the other lambda.
the squicking noise on Pro mode (580v) making me really angry and dissapointed

Additional problem: I need some new pads for sr-202, and Stax pads cost too much so I don't want to buy it. what to do?


----------



## Tjj226 Angel

Quick question for you guys. 

I would like to make some completely inverted electrostatic headphones like Ikos98 did here https://www.head-fi.org/threads/my-diy-electrostatic-headphones.498292/page-212

I was looking on ebay for mylar, and I found a listing for both 2um mylar and some Elvamide. https://www.ebay.com/itm/Electrosta...191878?hash=item2a69f37f06:g:gR0AAOSw6EhUQNa9

I know Elvamide can be used for restoring electrostatic speakers, but does it work just as well for headphones? There seems to be a ton of options for chemically treating membranes, but is there any particular one that the community seems to favor that might be better than elvamide?


----------



## Torac (Sep 18, 2019)

Tjj226 Angel said:


> Quick question for you guys.
> 
> I would like to make some completely inverted electrostatic headphones like Ikos98 did here https://www.head-fi.org/threads/my-diy-electrostatic-headphones.498292/page-212
> 
> ...



Elvamide is difficult to coat equally and well, most people seem to use antistatic screen cleaner as it is cheap and easy to coat with.


----------



## legopart (Sep 18, 2019)

EssentialEDM said:


> Elvamide is difficult to coat equally and well, most people seem to use antistatic screen cleaner as it is cheap and easy to coat with.


The seller on ebay promised to send me some guide to my email, and do so.
I ordered the 2um+Elvamide and don't know what to do with it.
the 2um from ebay actually good, and worth the price.
do someone know where can I get some less thickness?

Important message about anti-static spray that sold, it contains acetone (acetyl) that destroying the previous coating totaly, the electret coating too, destroying the glue connections that holding the membrane and destroying any color insulation.
this spray destroyed my sr-202 because the stators was covered by insulation color that just melted and touch the membrane.


----------



## qu1en

legopart said:


> The seller on ebay promised to send me some guide to my email, and do so.
> I ordered the 2um+Elvamide and don't know what to do with it.
> the 2um from ebay actually good, and worth the price.
> do someone know where can I get some less thickness?
> ...



You should try Lycron. It's just a permanent spray. It does not contain acetone and won't melt your headphones.
Elvamide is more work, for no additional benefit. Also be careful when working with all these chemicals. Wear a respirator when using it.
2um is very thin. I can't imagine any thinner than 2um would be difficult to handle it easily. I use 3um.

On a completely different note: Earlier I saw a comment to the effect that there was a rumor that additional capacitance is added to the harness to make it more warm. This cannot be true. Additional capacitance will introduce of slew and distortion to the high frequencies and will sound extremely harsh. This is kind of a rediculous claim. If a warmer sound is required, there are many other methods to achieve this (equalizers, circuit LPF, tension changes etc..)


----------



## Tjj226 Angel

EssentialEDM said:


> Elvamide is difficult to coat equally and well, most people seem to use antistatic screen cleaner as it is cheap and easy to coat with.



Awesome, thanks for the quick reply. Now its time to go mock up the design in cad : )


----------



## legopart (Sep 19, 2019)

What will happened if I will put twice the amount of coating on the membrane from seller recommendation (for quad esl 57)?
do the sound will become dipper or the headphones will be more sensitive?

although I think at this point that almost all of the distortion is gone, I still think that the regular coating is not enough or the tension it too high or the membrane too thick (have to use some wider) or not quality enough.

I still cant understand how to work with this program + the fact that I not use it long time.
but this two headphones tested on the same setting, environment and time:
Red - stax sr-202 that I fixed
Green - Stax sr-lambda pro original (from 80s ?)




Its really not easy part to disassemble all the glued parts 
(yes, I put too much strong glue again)


----------



## wrinex

legopart said:


> What will happened if I will put twice the amount of coating on the membrane from seller recommendation (for quad esl 57)?
> do the sound will become dipper or the headphones will be more sensitive?
> 
> although I think at this point that almost all of the distortion is gone, I still think that the regular coating is not enough or the tension it too high or the membrane too thick (have to use some wider) or not quality enough.
> ...




you need a method to replicate, either use the weight method (placing a weight onto the original until you hit the stator and use that as reference for your new foil) or the method i used with a speaker and REW in this video. 

 but for such small things i think the weight might be the easiest way to go


----------



## lkos98

Tjj226 Angel said:


> Quick question for you guys.
> 
> I would like to make some completely inverted electrostatic headphones like Ikos98 did here https://www.head-fi.org/threads/my-diy-electrostatic-headphones.498292/page-212
> 
> ...




Thanks for trying my design. I hope you will find it good. I'm still trying to improve mine, tested with different tension, different amps, etc. I still think this design have 2 big advantages - extremely low capacitance and no need for dust cover. I also want to try now to blow some air between membranes in order to keep them a bit bulge, hence away from the stator. In such case the spacers can be made thinner -  may be 0.3-0.2 mm, which should increase the sensitivity as well. Problem is how to put the air (could be also some inert gas), between membranes and then keep the pressure there infinitely. Must create some kind of a valve - any ideas would be appreciated.    
I'm using 2u mylar, and antistatic 100, have no idea about Elvamide, but there were a lot of discussions on it on this thread, I have tried floor cleaner as well - works fine, but I guess it's with a higher resistance, because the phones are less sensitive and you need to increase the volume, where it starts clipping.   
I was busy lately with building amps - created 3 of them - class A and class AB, and spent too much time on trying a class D, Unfortunately, it appeared class d is very efficient for 50 - 100W amp with supply voltage up to 100V, but not for electrostats with 600V rail, because with this voltage and SW frequency of 200kHz, the switching losses are about 2-3 W, which makes it very inefficient for 1-2 W headphone amp.


----------



## lkos98

legopart said:


> The seller on ebay promised to send me some guide to my email, and do so.
> I ordered the 2um+Elvamide and don't know what to do with it.
> the 2um from ebay actually good, and worth the price.
> do someone know where can I get some less thickness?
> ...



I don't know what antistatic spray you have, I have never had any issues with antistatic 100. It definitely contains alcohol, but not acetone. I have never seen any effect on the glue or any plastic part.
What I don't like is that it is a spray - it makes it difficult to apply evenly to the membrane, and it doesn't feel cheap to me, actually it's quite expensive (comparing it to a floor cleaner for example )


----------



## legopart

lkos98 said:


> Thanks for trying my design. I hope you will find it good. I'm still trying to improve mine, tested with different tension, different amps, etc. I still think this design have 2 big advantages - extremely low capacitance and no need for dust cover. I also want to try now to blow some air between membranes in order to keep them a bit bulge, hence away from the stator. In such case the spacers can be made thinner -  may be 0.3-0.2 mm, which should increase the sensitivity as well. Problem is how to put the air (could be also some inert gas), between membranes and then keep the pressure there infinitely. Must create some kind of a valve - any ideas would be appreciated.
> I'm using 2u mylar, and antistatic 100, have no idea about Elvamide, but there were a lot of discussions on it on this thread, I have tried floor cleaner as well - works fine, but I guess it's with a higher resistance, because the phones are less sensitive and you need to increase the volume, where it starts clipping.
> I was busy lately with building amps - created 3 of them - class A and class AB, and spent too much time on trying a class D, Unfortunately, it appeared class d is very efficient for 50 - 100W amp with supply voltage up to 100V, but not for electrostats with 600V rail, because with this voltage and SW frequency of 200kHz, the switching losses are about 2-3 W, which makes it very inefficient for 1-2 W headphone amp.


0.3 space is too small for 580v, any mistake or high volume will lead to shorts and distortion.

Some trying looser membrane and 1.0mm with 1000v bias.
dont know about it safetiness. electricity could make arcing.


about my sr-202, Its sounds good but with air-conditioner function in my room its stops to function! (the dust filters not helped)


----------



## lkos98

legopart said:


> 0.3 space is too small for 580v, any mistake or high volume will lead to shorts and distortion.
> 
> Some trying looser membrane and 1.0mm with 1000v bias.
> dont know about it safetiness. electricity could make arcing.
> ...



Well if you have read about my design it's different. First of all I dont use 580, but +-360V on 2 membranes. Secondly, if there is trapped air between membranes under slight pressure it would not allow them to slap to the stator. And third ( I was also very surprised):
"The electric field needed to arc across the minimal-voltage gap is much greater than what is necessary to arc a gap of one metre. For a 7.5 μm gap the arc voltage is 327 V, which is 43 MV/m. This is about 13 times greater than the field strength for the 1-metre gap. The phenomenon is well verified experimentally and is referred to as the Paschen minimum." 
So even if we consider the "normal" 3.4MV per meter, for 0.3mm it will require about 1000V to arc.


----------



## legopart

4,300,000V to 1000mm (over air*?*) --> 4,300V to 1mm --> 430V to 0.1mm
* 1290V to 0.3mm
* 2150V to 0.5mm
^ So you have to keep this distance from human and the stator and one stator and the bias (even on high sound volumes that moving high the membrane) ?

another question that interesting me is: what the voltage that can reach the stators ?, the audio output?


----------



## wrinex (Sep 20, 2019)

Atistatic 100 isnot permanent. An based or moisture.  Not the mosr r


lkos98 said:


> Well if you have read about my design it's different. First of all I dont use 580, but +-360V on 2 membranes. Secondly, if there is trapped air between membranes under slight pressure it would not allow them to slap to the stator. And third ( I was also very surprised):
> "The electric field needed to arc across the minimal-voltage gap is much greater than what is necessary to arc a gap of one metre. For a 7.5 μm gap the arc voltage is 327 V, which is 43 MV/m. This is about 13 times greater than the field strength for the 1-metre gap. The phenomenon is well verified experimentally and is referred to as the Paschen minimum."
> So even if we consider the "normal" 3.4MV per meter, for 0.3mm it will require about 1000V to arc.




+360 on 2 mebranes ? is this like stacked ?  2 complete esls sandwiched 4 stators 2 membranes ?  since you can get away with 3 stators if you reverse the polarity of the bias on the second foil. i did that in a 2 3 and 4 stacked esl tweeter. every doubling gains 6dB . rather much, and was actually my next project  to make an esl headphones that works rather different and is more efficient and could work with less beefy transformers , witch could make it cheaper and or smaller


----------



## wrinex (Sep 20, 2019)

legopart said:


> 4,300,000V to 1000mm (over air*?*) --> 4,300V to 1mm --> 430V to 0.1mm
> * 1290V to 0.3mm
> * 2150V to 0.5mm
> ^ So you have to keep this distance from human and the stator and one stator and the bias (even on high sound volumes that moving high the membrane) ?
> ...




hmm i beleive 3.3Kv for 1 mm is most common. 2150 would make 4300 volt. also dont forget potential difference i think ? like stators 500 ? then minus the 500 from the max bias so for a 3.3Kv a gap that corresponds to a distance of a gap that wont arc at 3.8 Kvolt.


still with high excursion the thing might still be able to arc to the bias.


----------



## lkos98

wrinex said:


> Atistatic 100 isnot permanent. An based or moisture.  Not the mosr r
> 
> 
> 
> +360 on 2 mebranes ? is this like stacked ?  2 complete esls sandwiched 4 stators 2 membranes ?  since you can get away with 3 stators if you reverse the polarity of the bias on the second foil. i did that in a 2 3 and 4 stacked esl tweeter. every doubling gains 6dB . rather much, and was actually my next project  to make an esl headphones that works rather different and is more efficient and could work with less beefy transformers , witch could make it cheaper and or smaller



Nope, I'm using fully inverted design - 2 membranes and 1 stator in the middle. Membranes are biased with positive and negative voltage. The stator is double sided pcb and is connected to single output amp. Since the air between the membranes is trapped, they move in unison, helping each other. In fact this is push-pull version of open baffle design. The distance between the membranes is about 2mm (2x 0.5mm spacers + 1mm stator), much lower than the lowest quarter wave length, so there are no resonances in the audible spectrum. If I could also pressurize the air in between, so the membranes are not sucked to each other, it would be perfect. The stator plates are isolated and membrane coating is against the stator, which makes it possible to skip completely the dust cover. Also the capacitance is extremely low, because the amp sees only the stator (and the cables of course). Sensitivity is not +3dB bigger, than a normal 2 stators 1 membrane, because membranes move behind each other together, not next to each other. 
I have posted some pictures and some IMO pros and cons some time ago here. Next I want is to compare normal against my design in practice, but can't find time to make new phones with the exact same dimensions and new differential output amp. 
I would expect may be just a bit better bass, because effective membrane thickness is about twice of the single membrane. Also push-pull design lowers exactly twice the equivalent air volume of a single speaker, which is not significant in this case, because it's an open air design. At the same time, may be a bit better even HDs, but definitely worse noise and CMRR, because of the single output amp.


----------



## wrinex (Sep 20, 2019)

lkos98 said:


> Nope, I'm using fully inverted design - 2 membranes and 1 stator in the middle. Membranes are biased with positive and negative voltage. The stator is double sided pcb and is connected to single output amp. Since the air between the membranes is trapped, they move in unison, helping each other. In fact this is push-pull version of open baffle design. The distance between the membranes is about 2mm (2x 0.5mm spacers + 1mm stator), much lower than the lowest quarter wave length, so there are no resonances in the audible spectrum. If I could also pressurize the air in between, so the membranes are not sucked to each other, it would be perfect. The stator plates are isolated and membrane coating is against the stator, which makes it possible to skip completely the dust cover. Also the capacitance is extremely low, because the amp sees only the stator (and the cables of course). Sensitivity is not +3dB bigger, than a normal 2 stators 1 membrane, because membranes move behind each other together, not next to each other.
> I have posted some pictures and some IMO pros and cons some time ago here. Next I want is to compare normal against my design in practice, but can't find time to make new phones with the exact same dimensions and new differential output amp.
> I would expect may be just a bit better bass, because effective membrane thickness is about twice of the single membrane. Also push-pull design lowers exactly twice the equivalent air volume of a single speaker, which is not significant in this case, because it's an open air design. At the same time, may be a bit better even HDs, but definitely worse noise and CMRR, because of the single output amp.




interesting ! but it is not a complete push pull. i mean forces are not pushing and pulling on one of the foils. its more like two single ended ones helping each other.  so the one stator acts like the foil would in a inverted  esl (but then in single ended mode).  in a normal inverted you would gain around 6 dB (since you got 2 stators)  if the same transformer was used in both setups. in your case the force acting ont he foil is half that so -6 but since you doubled the foils it gains in theory 6db. so as efficient as a normal inverted esl with 2 stators.  with the downside of having a higher resonance then a single foil would have.  still a nice and fun thing to try ! nice you go of the knows path ! i love that stuff

what i meant with not true push pull besides the air trapped in between helping the next foil.  is that if the foil moves further away from the stator its not in an even field anymore, i know the other foil does compensate for it since it has the reversed problem, but im not sure how well it does compared to a normal esl.

one last thing distortion in a inverted esl is always higher even with 2 stators. never a free lunch  and a single ended one even higher. you already know that im pretty sure, so im looking forward to the tests !

stacked esl , 3 stators and 2 foils does ressemble the same as  anormal esl with the benefit of increasing ouput by 6dB, xmax remains the same so only efficiency goes up and resonance does as well.  and thickness of foil used can be multiplied by 2 (as for top end drop off)


----------



## lkos98

wrinex said:


> interesting ! but it is not a complete push pull. i mean forces are not pushing and pulling on one of the foils. its more like two single ended ones helping each other.  so the one stator acts like the foil would in a inverted  esl (but then in single ended mode).  in a normal inverted you would gain around 6 dB (since you got 2 stators)  if the same transformer was used in both setups. in your case the force acting ont he foil is half that so -6 but since you doubled the foils it gains in theory 6db. so as efficient as a normal inverted esl with 2 stators.  with the downside of having a higher resonance then a single foil would have.  still a nice and fun thing to try ! nice you go of the knows path ! i love that stuff
> 
> what i meant with not true push pull besides the air trapped in between helping the next foil.  is that if the foil moves further away from the stator its not in an even field anymore, i know the other foil does compensate for it since it has the reversed problem, but im not sure how well it does compared to a normal esl.
> 
> ...



Thanks for nice words. 
You are right - it's not true push-pull, but very close to it. When I first thought of it, I was imaging the normal membrane in the middle of 2 stators (normal design). In fact my first ESH DIY phones were normal design. Anyway, when the membrane moves to one stator forces are different - the pull force becomes higher and higher, while the push force gets lower, the closer to the stator is the membrane. Now lets imagine membrane is stationary and stators move (we can ignore the coating resistance and holes). Same forces apply here and they act the same way (considering air between the membranes does not compress/expand much during the movement) - the closer to the membrane - the higher the force and vice-versa. So in fact both normal and fully inverted designs are not true push-pull. There is one more force in inverted design and it's between the membranes, because of the opposite charges. Since stator in between acts like a shield, the distance is big enough (2mm), and it's a constant force, I think it can be ignored too. This force have a negative and positive effect on the design - the membranes are constantly sucked to the stator, and bulged, but at the same time they are stable. Issue here is that the middle of the membranes is closer and excursion is limited. That's why I had to lower the bias to + - 360, I was completely unable to energize with 580Vs without all sort of crackling, squeaking and buzzing noises. A pressurized air between membranes will do a perfect gob, membranes will be flat and away from the stator. I'm open for suggestions. 
BTW - inspiration came from Linkwitz lab site, he explained very well how a dual speaker in a tube can be replaced with a single one and vice versa. Dual speaker setup got the advantage of canceling some of the harmonics, because the non-linearity of the speaker cones are not completely equal, but the volume of the air in between should be as less as possible.


----------



## Tjj226 Angel

lkos98 said:


> Thanks for trying my design. I hope you will find it good. I'm still trying to improve mine, tested with different tension, different amps, etc. I still think this design have 2 big advantages - extremely low capacitance and no need for dust cover. I also want to try now to blow some air between membranes in order to keep them a bit bulge, hence away from the stator. In such case the spacers can be made thinner -  may be 0.3-0.2 mm, which should increase the sensitivity as well. Problem is how to put the air (could be also some inert gas), between membranes and then keep the pressure there infinitely. Must create some kind of a valve - any ideas would be appreciated.
> I'm using 2u mylar, and antistatic 100, have no idea about Elvamide, but there were a lot of discussions on it on this thread, I have tried floor cleaner as well - works fine, but I guess it's with a higher resistance, because the phones are less sensitive and you need to increase the volume, where it starts clipping.
> I was busy lately with building amps - created 3 of them - class A and class AB, and spent too much time on trying a class D, Unfortunately, it appeared class d is very efficient for 50 - 100W amp with supply voltage up to 100V, but not for electrostats with 600V rail, because with this voltage and SW frequency of 200kHz, the switching losses are about 2-3 W, which makes it very inefficient for 1-2 W headphone amp.



Thank you for sharing it. I have been looking for a design that allows for more of a direct path between the membrane and your ear. This not only solved that issue, but a few others too. 

I mainly design tube amps, so I will probably build something similar to whats on the tube cad page. I would keep the membrane that is close to the ear at ground potential, directly couple the stator to the tube plate, and then keep the outside stator at twice the voltage of B+. With a single ended class A design, I could also potentially see the second order harmonics of the amp and the headphones cancel out, but we will see what happens. 

I have also been thinking about trapping some other type of air in between the driver. What I have thought of is building the driver inside a vacuum chamber. Build a half decent chamber with a glove to let you stick your hand inside. Suck out all the air. And then let in something like nitrogen. Then you should be able to use the glove to assemble the drive. If the glue up is decent, it should keep everything air tight. 

The other thing I thought about is using copper mesh for the stator instead of a PCB. The individual wires are rounded and should be more acoustically transparent compared to the pcb.


----------



## legopart

wow, I tried to understand you all and just cant.
you build something like that.
but each membrane is the audio signal (the stator is bias?)






interesting case, maybe you have to stretch the back membrane more.
can't understand the issue and how its working.


----------



## wrinex (Sep 20, 2019)

lkos98 said:


> Thanks for nice words.
> You are right - it's not true push-pull, but very close to it. When I first thought of it, I was imaging the normal membrane in the middle of 2 stators (normal design). In fact my first ESH DIY phones were normal design. Anyway, when the membrane moves to one stator forces are different - the pull force becomes higher and higher, while the push force gets lower, the closer to the stator is the membrane. Now lets imagine membrane is stationary and stators move (we can ignore the coating resistance and holes). Same forces apply here and they act the same way (considering air between the membranes does not compress/expand much during the movement) - the closer to the membrane - the higher the force and vice-versa. So in fact both normal and fully inverted designs are not true push-pull. There is one more force in inverted design and it's between the membranes, because of the opposite charges. Since stator in between acts like a shield, the distance is big enough (2mm), and it's a constant force, I think it can be ignored too. This force have a negative and positive effect on the design - the membranes are constantly sucked to the stator, and bulged, but at the same time they are stable. Issue here is that the middle of the membranes is closer and excursion is limited. That's why I had to lower the bias to + - 360, I was completely unable to energize with 580Vs without all sort of crackling, squeaking and buzzing noises. A pressurized air between membranes will do a perfect gob, membranes will be flat and away from the stator. I'm open for suggestions.
> BTW - inspiration came from Linkwitz lab site, he explained very well how a dual speaker in a tube can be replaced with a single one and vice versa. Dual speaker setup got the advantage of canceling some of the harmonics, because the non-linearity of the speaker cones are not completely equal, but the volume of the air in between should be as less as possible.




well in push pull i believe the increasing forces because the foil is getting closer to the stator are i believe the same (but reversed) on the other side. the forces become les and less. wich makes it an ideal push pull. (one loses controll the other oen gains control in proportion) (if you would work with 100% acuracy, wich noone does so it usually prefers one stator) as for presure, if you want to go all wild get SF6 gas, its used in switches for high voltage etc since it has a higher breakdown voltage.  a normal inverted design ahs only one foil so if the bias would eb equal on both stators it would be in perfect equilibrium to... never happens but theory. one problem i see with the bulging is resonance  it will increase since it will be on more tension then one foil alone. i had the same problem with stacked esl's.

btw yeah the linkwitz stuff is good, but if i remember correct he used woofers and then reversed one and then put one out of phase, so mechanical distortion because of the way it is build cancels each other to some extend   that might workd for single ended esl's as well.  what you make is sort of a combination of inverted and single ended esl. inverted usually means audio on the foil bias on stators. since the bias differential can be 2 as high because oen being -2Kv  and other stators +2Kv (difference of 4Kv) you can get away with half the stepup ratio for your transformer. single ended means one stator one foil (withc has rather high distortion down low). , what you made is more 2 times a single ended ESL, but with the benefit that one foil helping the other in the direction it loses controll  funny stuff


----------



## qu1en

Tjj226 Angel said:


> Thank you for sharing it. I have been looking for a design that allows for more of a direct path between the membrane and your ear. This not only solved that issue, but a few others too.
> 
> I mainly design tube amps, so I will probably build something similar to whats on the tube cad page. I would keep the membrane that is close to the ear at ground potential, directly couple the stator to the tube plate, and then keep the outside stator at twice the voltage of B+. With a single ended class A design, I could also potentially see the second order harmonics of the amp and the headphones cancel out, but we will see what happens.
> 
> ...




Does anyone want to talk tube amps with me? I built the tube amp from tube cad that was shared by OP on the first page. But I realized that is not a good design and doesn't have nearly enough output drive strength to deal with the 150pF capacitance. If you play a 20kHz sine wave and measure the output with the headphones connected you can see a lot of slew and distortion. You can also hear it as harsh high's. It looked cool though. 

Here is a KG design that is all triode and uses feedback which will also improve the output impedence but it does not simulate well.
https://headwizememorial.wordpress....ps-for-electrostatic-and-electret-headphones/

Do you guys mind sharing your designs or simulations for a tube design? I like to keep it as small and simple as possible but with enough drive to handle the capacitance. I have posted a MOSFET version of an amp earlier but am looking to do a tube design.


----------



## chinsettawong (Sep 20, 2019)

Have you checked out KG's other amp designs?

I personally like KGST.  Using 6S4A tubes, it's a small and simple amp.  Try to search for it on the other site.


----------



## Tjj226 Angel

qu1en said:


> Does anyone want to talk tube amps with me? I built the tube amp from tube cad that was shared by OP on the first page. But I realized that is not a good design and doesn't have nearly enough output drive strength to deal with the 150pF capacitance. If you play a 20kHz sine wave and measure the output with the headphones connected you can see a lot of slew and distortion. You can also hear it as harsh high's. It looked cool though.
> 
> Here is a KG design that is all triode and uses feedback which will also improve the output impedence but it does not simulate well.
> https://headwizememorial.wordpress....ps-for-electrostatic-and-electret-headphones/
> ...



Im wondering how easy/difficult it would be to mod the amp you already have to use 5687s as the output tube. I would also use gyrators as the tube load rather than resistors. Plate resistors and tubes do drift in value over time. A gyrator will help stabilize the tube plate voltage over time.


----------



## Ulfar4

qu1en said:


> Does anyone want to talk tube amps with me? I built the tube amp from tube cad that was shared by OP on the first page. But I realized that is not a good design and doesn't have nearly enough output drive strength to deal with the 150pF capacitance. If you play a 20kHz sine wave and measure the output with the headphones connected you can see a lot of slew and distortion. You can also hear it as harsh high's. It looked cool though.
> 
> Here is a KG design that is all triode and uses feedback which will also improve the output impedence but it does not simulate well.
> https://headwizememorial.wordpress....ps-for-electrostatic-and-electret-headphones/
> ...



You can look on SRX amplifier. It has one pair of tubes more but it solves the problems you mentioned. On internet, there is JimL SRX+ version. And if you want, I have LTspice simulation for SRX with CCS at ouput (Combination of SRX and SRX+).
There is original SRX: http://www.bonavolta.ch/hobby/en/audio/hdgsta.htm


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## lkos98

@Tjj226 Angel - I have also tried that one - +600 to outer membrane, 300 - stator, coming out of the amp (without decoupling cap) and 0 to inner membrane (this should also answer Legopart's question). I could not notice any difference and in theory, there should not be. What I don't like is that you are limited to bias voltage - if you decide to increase it to lets say 700V, the stator remains on 300 and membranes are unevenly charged relatively to the stator. The other issue is with the outer membrane polarized at 600V. When moving, it acts as an electret microphone and will start inducing parasitic voltage in wires and back to the bias and may be even to the amp, while the inner at gnd would not do that. With +- biases they both move and the voltages cancel out - same as single, against differential input/output. This is partially solved with a bypass capacitor to gnd AFTER the series MOhms resistor in the bias circuit (best is to put another one after the cable - inside the phone cups), but this means bias voltage is not safe for touching anymore. Even with +- biases I put a relatively small bypassing capacitor, everybody blamed me it's dangerous - and I agreed, until I saw a schematic of a Stax amplifier with a 100nF capacitor bypassing the bias voltage. If they put it, why can't we? 
@wrinex - Hmm, yes and sorry, but can't agree on all. The design is as you say 2 single side esl stacked back to back with the benefit of membranes helping each other. But this is very significant benefit, membranes are so close to each other and air in between is almost 0 volume (assuming 20-30KHz bandwidth), so they are in fact stuck to each other and act like a single one (twice thicker though). So, as I tried to explain - it does not differ much from a normal design. If we speak about 200-300 KHz, than I agree, the 2mm distance is already too big and there will be non-linearity involved.  
In the true push-pull IMO, both forces are equal - this is how a dynamic push-pull speakers work, the force does not decrease or increase when closer or further to the end (it's decreasing because of the sinusoidal signal and coil getting out of the magnetic field, not because it's closer to something).  While in esl when membrane moves closer to the one of the stators, the pull force is much higher than the push force from the other stator, because of the F = K[q1 x q2]/D^2. The force is a quadratic function of the distance, which is probably the main disadvantage of ESLs - distortion in high excursions. The differential design of the ESLs is compensating for this quadratic function in lower excursions, where the force is still nearly linear. 
You are correct about Linkwitz design - yes he puts a speakers in specific configuration to cancel out the harmonics formed by the shape of the membrane - cone. ESL (headphones, should not have this, since membrane is flat and moving (ideally) the whole surface. But there are always some differences between the 2 membranes - stretching, non uniform thickness, non -uniform coating, etc., which at some frequencies will cancel out, in other will add to each other  
Ohh, sorry I got carried away, but it's really a very interesting matter for me. I hope I did not bother everyone with this. I'm sure someone with better knowledge in mathematics and physics will approve or completely deny what I just wrote here. I will be happy to hear, because it's the way we learn. Thanks again to Chinesattawong for creating this wonderful thread.


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## Ulfar4 (Sep 21, 2019)

Today I finally finished my single ended solid state amp after long time. HW is combination of mosfet and opamp ( simmilar to qu1en, but with 650V power supply and caps at outputs).


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## legopart

lkos98 said:


> @Tjj226 Angel - I have also tried that one - +600 to outer membrane, 300 - stator, coming out of the amp (without decoupling cap) and 0 to inner membrane (this should also answer Legopart's question). I could not notice any difference and in theory, there should not be. What I don't like is that you are limited to bias voltage - if you decide to increase it to lets say 700V, the stator remains on 300 and membranes are unevenly charged relatively to the stator. The other issue is with the outer membrane polarized at 600V. When moving, it acts as an electret microphone and will start inducing parasitic voltage in wires and back to the bias and may be even to the amp, while the inner at gnd would not do that. With +- biases they both move and the voltages cancel out - same as single, against differential input/output. This is partially solved with a bypass capacitor to gnd AFTER the series MOhms resistor in the bias circuit (best is to put another one after the cable - inside the phone cups), but this means bias voltage is not safe for touching anymore. Even with +- biases I put a relatively small bypassing capacitor, everybody blamed me it's dangerous - and I agreed, until I saw a schematic of a Stax amplifier with a 100nF capacitor bypassing the bias voltage. If they put it, why can't we?
> @wrinex - Hmm, yes and sorry, but can't agree on all. The design is as you say 2 single side esl stacked back to back with the benefit of membranes helping each other. But this is very significant benefit, membranes are so close to each other and air in between is almost 0 volume (assuming 20-30KHz bandwidth), so they are in fact stuck to each other and act like a single one (twice thicker though). So, as I tried to explain - it does not differ much from a normal design. If we speak about 200-300 KHz, than I agree, the 2mm distance is already too big and there will be non-linearity involved.
> In the true push-pull IMO, both forces are equal - this is how a dynamic push-pull speakers work, the force does not decrease or increase when closer or further to the end (it's decreasing because of the sinusoidal signal and coil getting out of the magnetic field, not because it's closer to something).  While in esl when membrane moves closer to the one of the stators, the pull force is much higher than the push force from the other stator, because of the F = K[q1 x q2]/D^2. The force is a quadratic function of the distance, which is probably the main disadvantage of ESLs - distortion in high excursions. The differential design of the ESLs is compensating for this quadratic function in lower excursions, where the force is still nearly linear.
> You are correct about Linkwitz design - yes he puts a speakers in specific configuration to cancel out the harmonics formed by the shape of the membrane - cone. ESL (headphones, should not have this, since membrane is flat and moving (ideally) the whole surface. But there are always some differences between the 2 membranes - stretching, non uniform thickness, non -uniform coating, etc., which at some frequencies will cancel out, in other will add to each other
> Ohh, sorry I got carried away, but it's really a very interesting matter for me. I hope I did not bother everyone with this. I'm sure someone with better knowledge in mathematics and physics will approve or completely deny what I just wrote here. I will be happy to hear, because it's the way we learn. Thanks again to Chinesattawong for creating this wonderful thread.


My brain stopped to function when I start to read about you'r\this method.
still couldn't fully understand how reqular ES-headphones function, this modes sound too too difficult for me.


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## Tjj226 Angel

legopart said:


> My brain stopped to function when I start to read about you'r\this method.
> still couldn't fully understand how reqular ES-headphones function, this modes sound too too difficult for me.




It's really not that hard. You have 2 membranes and 1 stator just like your drawing a post or two ago.

In a normal headphones you have 2 stators and a membrane. The membrane is charged with high voltage and the signal is applied BETWEEN 2 STATORS (crucial key element). One stator gets the positive half of the analog signal, the other half gets the negative half of the analog signal. In this situation the amplifier HAS TO BE A PUSH PULL AMPLIFIER.

As the signal is applied to the stators, the voltage potential starts to change. As your signal voltage swings from positive to negative your membrane will be attracted to one stator and repelled by the opposite stator. In this situation, one stator is helping the other. Again lending to the idea that this headphone design is indented for push pull operation.

In the case we are discussing, the design of the driver becomes "inverted". The best hint I can give you is that the inversion of push pull is single ended. In a "normal" stax headphone, you had 1 bias voltage and you had to split the audio signal into 2 signals. In our case we have to split the bias voltage into two voltages. 1 positive and 1 negative. However the audio signal is just the normal audio signal.

The membranes are in the place of the stators and 1 side is charged with positive high voltage and the other is charged with negative high voltage. Ideally this means that the stator in the middle is in a null zone where no force is being applied. Finally you apply your signal to the stator that is in the middle. As the signal swings positive and negative, your TWO membranes are attracted and repelled from the stator IN TANDOM. Ideally this action forms sort of an acoustic spring and will help linearize the performance of the driver, but I am sure there is probably a butt load more 2nd order harmonic distortion compared to the "regular" method.

What Ikos98 are talking about with our ground potential membrane thing is this. We have 3 separate elements. We have a membrane that is close to the ear, a stator, and a 2nd membrane on the outside of the driver. The voltages are -360v, 0, and positive 360v respectively. Ideally, we would like to keep the elements of the driver that are close to your ear at ground potential so that they don't shock you. So we want the membrane that is normally at -360v to be at 0v. We can do this, but it means all the other voltages have to move up by the same amount.

So the stator now has to be at 360v and the outside membrane is at 720v. Now since the stator is where we apply our music signal and since it is now at a high voltage, this allows us to directly coupled a high voltage tube output to the stator without any DC blocking caps or other crap in the way.

Another fun thing to point out is that since the driver design is going to generate second order harmonics, I suggest using a single stage tube amp in order to create 2nd order harmonics and try to get the distortion to cancel out.


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## legopart (Sep 21, 2019)

ok, you made me smarter a bit.
(still could understand only half of things)







my knowledge still too small to suggest something.


The only thing I know that when the electrical force become physical, the physical force is really hard to control, like the movement of the membrane.
maybe

tubes works the same but without moving elements.
tubes = triode == 3 plate design
I know that ESH works like a capacitor but each voltage have to return to is negative side
for example +100v +10v
have always return to get some opportunity to return to -110v
this why you got the +110v that moved on.










*


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## Tjj226 Angel

legopart said:


> ok, you made me smarter a bit.
> (still could understand only half of things)
> 
> 
> ...




Lets not focus on vacuum tubes because they work to form a circuit in a very particular way. 

Electrostatic headphones, speakers, or otherwise do no work like a capacitor. In fact we actually REALLY REALLY REALLY want to avoid ANY sort of capacitance at all. No matter how much we want to avoid it, it sadly is present in all electrostatic devices. It is even present in the design I am talking about doing, however it ideally is handled outside of the audio path. 

There also shouldn't be ANY flow of electrons from positive to negative. If there were, you would see big sparks and it would ruin your headphones. 

Here is where I think you are getting tripped up. The BIAS voltage that we use to charge the headphones is DC voltage. The thing we use to create an opposing charge is AC (our audio signal). Once you understand the individual rolls of the DC and AC VOLTAGE (not current since there hardly any to speak of to begin with), I think you will get a better understanding of what is going on with a normal stax headphone. Once you get that concept down pat, then the design I am working on should come easily to you. I think you are almost there too, so it shouldn't be hard.


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## lkos98

@legopart  Tjj gave a nice and simple explanation of the basic electrostatic principal involved in ESL. The regular design is in fact a capacitor with a charged object moving between the plates when we apply an AC signal to them. With my design I replace the capacitor plates with moving charged objects (membranes) and leave just one stationary plate in the middle. 
@Tjj226 Angel  What I wanted to do with class D single ended amp was exactly this - to create some sort of non-linear/quadratic signal from the input signal in order to cancel the 2nd order. Unfortunately my simple oscilloscope/spectrum analyzer and generator are not accurate enough to measure properly less than 0.5 % THD+N. In fact sometimes I got THD+N at the output, less than at the input.  
BTW - the method of assembling in a vacuum camera seems very interesting, if you try it, please share the results. I was thinking of assembling in a very cold place and then the air inside should warm up and expand  
I DON'T glue the membranes to the spacers (they are thin and bend under stretching force). I glue them to an outside frames - 1.5mm PCB (in fact same shape as spacers, but can be made as thick as you wish). Then I just place the spacers in between stator and these frames and tie all together with screws ( through the cups) This allows me to assemble/disassemble at any time and replace the spacers or membranes with different ones. On the negative side - the membranes are not completely sealed it's just the spacer flat surface pressed against membrane foil. Cannot put sealer there either, because I need membrane to be in electrical contact with the copper of the spacer. Needles to say - mechanically this design has advantage of simplicity, humidity and dust prove. 
I have to warn you though if you decide to do it this way - there are issues like atmospheric pressure and constant pulling force against the stator - over time membranes got sucked closer to the stator and if atmospheric pressure rises they got sucked even further. Since they are almost sealed, sucking back air inside is hard and they remain bulged. I need some method of blowing air (better some other gas as you proposed) in between, keep it sealed as much as possible, but retaining the electrical contact at the same time. I do not like to apply the coating outside, because all of the pros are gone, leaving just the cons. BTW - this design also allows me to switch to a regular 2 stator - 1 membrane at any time. Just need to create one more stator and glue the membrane to one of the spacers. A dust covers can be glued to the outside frames. And a differential output amp, which I'm too lazy to build  .


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## legopart (Sep 22, 2019)

vacuum will shrink the membranes one to another and will not allows them to move at all, you will get too much air pressure out side of the membrane (pressure will make lots of tension on the membrane)
the reason is that the air outside will push the membranes outside to complete the vacuum.
on the back moving it used as vacuum
For making some temporary vacuum you can use some empty syringe, just let enough hole for it.





The second option  is to use some cheap pomp that you reverse it rubber  inside and it will act reversely


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## lkos98

I decided to replace my spacers with a bit thinner ones (instead of 0.65 to 0.55mm) so I disassembled the phones and took some pictures. I also made some measurements with my poor setup.
What surprised me a lot, the expected 2-nd harmonics were not there as much as I thought. If I increased the volume until the amp starts distorting, the odd harmonics showed up, but not the even ones. Very strange. I really can't explain this, - may be it is the terrible microphone or poor setup? As you could see, the THD of the source are higher than that of the output. What do you think?

@legopart 
Vacuum will do nothing to the membranes, because the whole setup is in vacuum, the pressure on both sides of the membrane is equal (if I understood correctly what Tjj226 wants to do). We want opposite to a vacuum, a bit of higher than atmospheric pressure between membranes, so they are slightly blown, as much as when the constant bias is applied to the membranes, they become flat.


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## Tjj226 Angel

lkos98 said:


> @legopart  Tjj gave a nice and simple explanation of the basic electrostatic principal involved in ESL. The regular design is in fact a capacitor with a charged object moving between the plates when we apply an AC signal to them. With my design I replace the capacitor plates with moving charged objects (membranes) and leave just one stationary plate in the middle.
> @Tjj226 Angel  What I wanted to do with class D single ended amp was exactly this - to create some sort of non-linear/quadratic signal from the input signal in order to cancel the 2nd order. Unfortunately my simple oscilloscope/spectrum analyzer and generator are not accurate enough to measure properly less than 0.5 % THD+N. In fact sometimes I got THD+N at the output, less than at the input.
> BTW - the method of assembling in a vacuum camera seems very interesting, if you try it, please share the results. I was thinking of assembling in a very cold place and then the air inside should warm up and expand
> I DON'T glue the membranes to the spacers (they are thin and bend under stretching force). I glue them to an outside frames - 1.5mm PCB (in fact same shape as spacers, but can be made as thick as you wish). Then I just place the spacers in between stator and these frames and tie all together with screws ( through the cups) This allows me to assemble/disassemble at any time and replace the spacers or membranes with different ones. On the negative side - the membranes are not completely sealed it's just the spacer flat surface pressed against membrane foil. Cannot put sealer there either, because I need membrane to be in electrical contact with the copper of the spacer. Needles to say - mechanically this design has advantage of simplicity, humidity and dust prove.
> I have to warn you though if you decide to do it this way - there are issues like atmospheric pressure and constant pulling force against the stator - over time membranes got sucked closer to the stator and if atmospheric pressure rises they got sucked even further. Since they are almost sealed, sucking back air inside is hard and they remain bulged. I need some method of blowing air (better some other gas as you proposed) in between, keep it sealed as much as possible, but retaining the electrical contact at the same time. I do not like to apply the coating outside, because all of the pros are gone, leaving just the cons. BTW - this design also allows me to switch to a regular 2 stator - 1 membrane at any time. Just need to create one more stator and glue the membrane to one of the spacers. A dust covers can be glued to the outside frames. And a differential output amp, which I'm too lazy to build  .



I want to reiterate something here. Any ESL headphone is built like a capacitor. Even a single sided ESL design has a membrane acting as a plate and a stator acting as the second plate, with air acting as a dielectric.

However the way in which an ESL device produces sound has nothing to do with a capacitor. There is a charge on the membrane and the alternating voltage simply works to push or pull the membrane. No real current is flowing and we are not effecting the charge on the opposite plate (at least significantly) enough to change the mechanical operation of the device. 

HOWEVER!!!!!!!!!! Capacitance WILL effect the sonic performance of the device. It does form a filter and if you do not properly drive the capacitance you can end up with high frequency roll off. 

------------------------

Anywho. 

I did not realize that you haven't fully sealed your driver. I would suggest you try a drive that is completely glued together. While air is a compressible gas, the forces we are dealing with are quite small. If the air were fully sealed in the driver I doubt the driver would be able to compress air all that well and you should see at least a flatter driver. 

Alternatively you could go the other direction and put a vent in the driver. This would act like a port, and you could tune the port to a really low frequency to put it out of the audio band. Or you could try to use it to reinforce bass 

If the port is tuned right, the membranes should still be aiding one and other, but now you wont have to think about atmospheric pressure differentials from day to day.


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## lkos98 (Sep 22, 2019)

Tjj226 Angel said:


> I want to reiterate something here. Any ESL headphone is built like a capacitor. Even a single sided ESL design has a membrane acting as a plate and a stator acting as the second plate, with air acting as a dielectric.
> 
> However the way in which an ESL device produces sound has nothing to do with a capacitor. There is a charge on the membrane and the alternating voltage simply works to push or pull the membrane. No real current is flowing and we are not effecting the charge on the opposite plate (at least significantly) enough to change the mechanical operation of the device.
> 
> ...



Yeah, that's correct, at first when I assemble, the membranes are probably flat (I don't think I can see how flat they are) and unable to compress the air much, but with time (and help of Atm pressure), slowly but surely air escapes and although I still can't see the buldge, I can tell by the increase in sensitivity and the instability. I also know this, because sometimes I use a small trick to blow them back - I put positive voltage on both membranes and stator and leave it over night.  I use free air resonance for stretching and I know that for my 84mm active area bellow 110 Hrz they can become unstable for may be 2-3 weeks, while with 160 Hrz they are stable for may be forever. With 160 Hrz though they sound a bit harsh and the bass is not that deep. I'm still struggling to make them about 130-140 Hrz, which I think would be the correct stretching.
As for the sealing - I really have no idea how to seal them and at the same time to keep the electrical contact. Sealing between stator and spacers is easy although it will increase the spacing, but where and how to put sealant between copper laminate and coated membrane?


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## legopart (Sep 22, 2019)

about the stators:
If I making one pair, do it suggested to make less holes size in it, or make giant holes as possible.
giant holes will decrease the capacitance. but how it will control the sound?


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## lkos98

legopart said:


> about the testators:
> If I making one pair, do it suggested to make less holes size in it, or make giant holes as possible.
> giant holes will decrease the capacitance. but how it will control the sound?



As far as I remember the rule of thumb is at about 1.5-2 times the thickness of the stator and NO more. The smaller - the better, but it means thinner stator. Thinner stator is though not hard enough and could start vibrating. There is no free lunch


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## legopart (Sep 22, 2019)

I have some material with 3mm holes diametar and something like 1.4mm solid conductive distance between the holes,
can it be good enough for a stator?

math: 1.4+3 = 4.4 staor area
conductive area: 1.4
holes area 3.0

4.4:1.4= 3.15 total_area:conductive_area
3.0:1.4=2.12 holes_area:conductive_area
4.4:3.0=1.45 total_area:holes_area

which ratio to look on?


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## lkos98

@legopart 
I didn't really understand this. Easiest - take the total area of the material and count how many holes. Area of material S= A x B, Area of holes S1 = n x Pi x D / 4 . Space ratio = S1/S and ideally should be as high as possible for transparency, and lower as possible for sensitivity and stiffness. Some people use - 0.3, some - 0.4 some 0.5. I usually try to stay a bit bellow, but close to 0.4. 
Not sure anyone can tell you what should be the exact ratio. If you have some stators from some model try to calculate the ratio and use it. Please share it here as well, I'm also interested what are manufactures using.


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## chinsettawong

Frankly, don't worry too much about the diameter of holes on the stators.  To my ears, stators with bigger holes sound more open and I quite like it.  In the past, I've always used 2 mm or 2.5 mm holes with 1 mm stators and 0.5 mm spacers.  They sound great together.  And many people have tried and liked my headphones.  If you wan to use 3 mm holes, I say go for it.  After all, we're doing it for fun.  If you like or don't like it, please share your finding.


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## lkos98 (Sep 23, 2019)

I agree, I have also tried 2 and 1.4 mm  holes on 1mm pcb. I don't think 3mm would sound worse, despite the "rule". Important though is to follow some rules on the ratio, Going bellow 30%, might not sound good, although I was thinking of drilling just one or few big holes in the middle (something like a port that Tjj226 propposed) with a total ratio of 10 to 20 % and see what will happen. This will probably create distortion, because at this points the ES force on the membrane is 0.


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## legopart

lkos98 said:


> I agree, I have also tried 2 and 1.4 mm  holes on 1mm pcb. I don't think 3mm would sound worse, despite the "rule". Important though is to follow some rules on the ratio, Going bellow 30%, might not sound good, although I was thinking of drilling just one or few big holes in the middle (something like a port that Tjj226 propposed) with a total ratio of 10 to 20 % and see what will happen. This will probably create distortion, because at this points the ES force on the membrane is 0.


So maybe drill this holes on  the outer.
Like planar types
that all the passive area moves because the active one







or the old style that the membrane holded from the frame + from the center





though about the option, what  not connect the membrane to bias from center.


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## chinsettawong

@legopart, I really don’t know what you’re trying to explain.


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## legopart

I plan to connect the bias to the center/middle of the membrane
and not from the corners


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## chinsettawong

legopart said:


> I plan to connect the bias to the center/middle of the membrane
> and not from the corners



What are you trying to achieve?  What do you expect from doing that?


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## -JFK-

legopart said:


> I plan to connect the bias to the center/middle of the membrane
> and not from the corners


What is for?


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## legopart

I think that it is easier to connect the center in 1 point instead to connect all the membrane from the corner to the bias
you will loose all the base but still you not going to spend so much materials for frame bias


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## chinsettawong

legopart said:


> I think that it is easier to connect the center in 1 point instead to connect all the membrane from the corner to the bias
> you will loose all the base but still you not going to spend so much materials for frame bias



I'm very confused with your theory.  How are you going to connect the bias to the diaphragm in the middle of it?  Are you just trying to save some money for doing this?  Actually if you attach a bias wire or ring in the middle, wouldn't it make the bass worse since it needs to be fixed somehow?  Are you going to drill a big hole in the middle of the stator so that you can put the bias in the middle of the diaphragm?


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## legopart (Sep 25, 2019)

chinsettawong said:


> I'm very confused with your theory.  How are you going to connect the bias to the diaphragm in the middle of it?  Are you just trying to save some money for doing this?  Actually if you attach a bias wire or ring in the middle, wouldn't it make the bass worse since it needs to be fixed somehow?  Are you going to drill a big hole in the middle of the stator so that you can put the bias in the middle of the diaphragm?


You not have to think how to attach the frame to the bias





on regular version you doing something like this


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## chinsettawong

When you put a spacer right in the middle of the driver, you're actually limiting the area which the diaphragm can vibrate - the lesser the area, the lesser the bass.  So, how can you improve the bass?


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## legopart (Sep 25, 2019)

chinsettawong said:


> When you put a spacer right in the middle of the driver, you're actually limiting the area which the diaphragm can vibrate - the lesser the area, the lesser the bass.  So, how can you improve the bass?


yes, put the spacer on middle will limit the membrane active area to half,
you will got something like half active membrane,
but now you can increase the dimension of all the drive (no frame for bias) => the frame is the active membrane place.
it means:
- cheaper building
- more space used and not wasted for bias
- more safetiness, you can isolate the middle part by 2mm from each side in one point
- no surrounding of high distortion voltage
- better stability for bigger/giant membrane,  you can make double size membrane
- less resonance from too big membrane.


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## chinsettawong

Try it!


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## legopart (Sep 25, 2019)

My plan is ... to wait until tomorrow when its dry and then throw it... 
it's looks bad  and it definitely will not work.
I think that with this try I will quit from ESH-DIY, sorry.


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## chinsettawong

legopart said:


> My plan is ... to wait until tomorrow when its dry and then throw it...
> it's looks bad  and it definitely will not work.
> I think that with this try I will quit from ESH-DIY, sorry.



That’s definitely not how to make the headphones.


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## janosch simon

chinsettawong said:


> That’s definitely not how to make the headphones.


no clue what he is trying


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## Muamp (Sep 25, 2019)

Wonderful photos Legopart.
Made me and some guys in the office laugh. Superb!
Keep these photos coming and DON’T stop.


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## legopart (Sep 25, 2019)

first attempt always fail, and it really looking ridiculously. 

Not like to wait.
I cut it from the film, check the continuity  and then solder it.
I made it too flexible + overstretch it.
done it too clumsy.
2-4 hours of work+ 16 hours of waiting

it sound too low and too scretchie
I gonna throw it and just learn from this trying.
it gonna be hard to make ESH without working tools and knowledge.









got to find some easier DIY, or get lots of more knowledge and ability


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## Muamp (Sep 25, 2019)

Having just watched your video,.... is that really the sound coming from your DIY ESHS’s ?
If so, not only am I surprised, but quite impressed.
Mmmm, I should hold before I laugh or mock and instead be amazed.


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## chinsettawong

My traveling set.


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## legopart

@


chinsettawong said:


> My traveling set.


The amp yes.
the headphones no so.
Looks like MB Peerless PMB1000 D=


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## legopart

Muamp said:


> Having just watched your video,.... is that really the sound coming from your DIY ESHS’s ?
> If so, not only am I surprised, but quite impressed.
> Mmmm, I should hold before I laugh or mock and instead be amazed.


Next time I will do it more accurate, less flexible and set the bias on the corner and not on the middle.


found something iteresting about ESH with bias of 1350v
but still can't understand how do they built.

I have the problem to understand things, 
Tyll is the best!!!
@Tyll Hertsens


----------



## legopart

chinsettawong said:


> My traveling set.


Do the bigger sizes improves the quality of the sound/music ?


----------



## lkos98

legopart said:


> Do the bigger sizes improves the quality of the sound/music ?


Of course it does. Bigger active area - more air volume - more bass (and louder). I have 74mm - 4300mm^2, 94x68 - 4430mm^2 - ellipse and 84mm - 5540mm^2 - circle. You can hear the difference between circle 74 and ellipse 68x94 in bass response, although the area is almost the same, but with 84 circle there is huge difference in bass. Planning to try now 70X100 ellipse, to see how it would perform. Area is the same as with 84 circle, but I have the feeling bass is better with ellipse. 
There is some roll off of trebles with bigger phones, but it's not that significant (at least it's not for me, I can't hear anything above 12-13 kHz anymore ) as the with the bass.


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## legopart (Sep 30, 2019)

elops of circle 74 o
when you using 68x94 is feels like 94 o, round circle instead of 74
reminded me some dynamic speaker





But still, with bias of 580v you can have space only of 0.5mm
so you on small driver you can stretch the membrane less and achieve it full movement
on bigger drivers with with spacer of 0.5mm you have to stretch the membrane to stop it from moving and hit the spacer and make any distortion.
so... theoretically  for same bias (and same ear canal area of 1cm and spacer 0.5mm)  you almost archive the same sound



lkos98 said:


> There is some roll off of trebles with bigger phones, but it's not that significant (at least it's not for me, I can't hear anything above 12-13 kHz anymore ) as the with the bass.


add some tweeter as 2way system


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## lkos98 (Sep 30, 2019)

legopart said:


> elops of circle 74 o
> when you using 68x94 is feels like 94 o, round circle instead of 74
> reminded me some dynamic speaker
> 
> ...



On stretching I agree, you can stretch less and that's what I do, but still the bass is much lower. I believe, because stretching although has some effect on the bass, it's not that much, as the sealing to the ear, I have made measurements with microphone, which pretty much demonstrated this, I think many others did that as well. .
As for the ellipse, well, 68x94 is definitely not like 94 circle, As per area calculation it should be 74 circle, but may be in practice, it's a bit bigger, in the way it sounds. The ones that you showed are not ellipse, but rectangular with round corners, those got bigger area that ellipse, with the same long and short diameters. My first prototype was with that shape. 
Adding twitter for me is a waste of time and resources. and is complicated - you need a separate path (plus crossover??) for it, it will "eat" out of your active area - hence lower bass. I think you will not gain anything, after all membrane is almost as light as air, moving it with 20kHz shouldn't be an issue.

Hmm, I don't really know, when and how I got so wrong. 68x94 ellipse is exactly 80mm circle. So that's why my ellipse sounded with better bass than the 74, but with less than 84.


----------



## quintile

non circular is interesting on speakers, it distributes the breakup modes from radial resonances so you get a broader but less intense breakup.

ESLs have such light diaphragms and simple (well controlled) mechanics that it might not make much difference - but its hard to know. 

elipses might work very well. i would be very interested to see the low-ish frequency response graphs (50-400hz) if you build them.

-Steve


----------



## lkos98

quintile said:


> non circular is interesting on speakers, it distributes the breakup modes from radial resonances so you get a broader but less intense breakup.
> 
> ESLs have such light diaphragms and simple (well controlled) mechanics that it might not make much difference - but its hard to know.
> 
> ...



Here you go:
The top one is circle 84mm, lower - 68x94 ellipse. Setup is not good, ambient was noisy and I had to apply some pressure on the phones to create good seal, but for comparison it works. 
As expected circle has better bass and is a bit louder (bigger area), otherwise I don't see much differences.


----------



## quintile

very impressive results, i have never measured such a flat low frequency response. i usually see a peak around 70-100 hz, which i assumed was the diaphragm breakup.

did you check the fundamental resonance of your diaphragm? i use it to confirm i have the tension i expected.

i do agree though, the responses dont look different enough to be meaningful.

also, how are you measuring the rssponse, the minidsp dummy head?


----------



## qu1en (Oct 1, 2019)

Doesn't look that good to me honestly. Here's mine measured using the DSP EARS. Left and Right measurement. Response is very flat (within 3dB SPL between 20Hz and 1kHz). Difficult part is to perfectly match the L and R with sensitivity and this one is very well matched and the sound stage will be excellent. Bass response is insanely good. Clarity and speed is what you'd expect from Estats. I use round stators.


----------



## chinsettawong

qu1en said:


> Doesn't look that good to me honestly. Here's mine measured using the DSP EARS. Left and Right measurement. Response is very flat (within 3dB SPL between 20Hz and 1kHz). Difficult part is to perfectly match the L and R with sensitivity and this one is very well matched and the sound stage will be excellent. Bass response is insanely good. Clarity and speed is what you'd expect from Estats. I use round stators.



That's very impressive FR.  Very, very nice!


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## lkos98

@quintile  The free air resonance is around 160-170Hz for the circle and as far as I remember around 150-160 for the ellipse. 
@qu1en  Very impressive FR indeed, I like your 1K-8K curve, I always got a high peaks and lows there.
Yes, the above FRs are terrible, I think this is because of the very bad setup. I don't have the DSP ears, I was using a autolevel mic, and I just put it on the table inside the phone cup. I did these in a hurry, just to compare ellipse with circle, because they were made at the same conditions. 
Here is my old measurement with the circles It showed less than 3dB in 10Hz, and in 10-1K flatness. And yes - the bass is incredible.


----------



## lkos98

quintile said:


> very impressive results, i have never measured such a flat low frequency response. i usually see a peak around 70-100 hz, which i assumed was the diaphragm breakup.
> 
> did you check the fundamental resonance of your diaphragm? i use it to confirm i have the tension i expected.
> 
> ...



Could you please let me know what is the fundamental you need to get the expected tension? What area size and membrane thickness? 
I tension on a 30 cm rig, measure the resonance there and then try to calculate the resonance of the spacer only (relatively to the area). I never got a proper results so far, I guess my calculations are either wrong or there are other factors involved, because the resonance of the rig could be anywhere between 30 and 90, but spacer resonance is completely unrelated to this.


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## legopart (Oct 5, 2019)

Begin to read something interesting that I want to share about "Adhesion Promoter"
It says that any surface having his potential to contact with glue and hold to it.
materials like plastic, Mylar, polythene  having low value of this strength and if you want to glue between them you have use some first applying of adhesive promoter that will cause this bound
https://coatings.specialchem.com/selection-guide/select-adhesion-promoters-for-coatings
https://adhesives.specialchem.com/selection-guide/adhesion-promoters-adhesives-sealants

this is one of the reasons why glued materials cant hold together, even if the strongest glue is applied


----------



## chinsettawong

legopart said:


> Begin to read something interesting that I want to share about "Adhesion Promoter"
> It says that any surface having his potential to contact with glue and hold to it.
> materials like plastic, Mylar, polythene  having low value of this strength and if you want to glue between them you have use some first applying of adhesive promoter that will cause this bound
> https://coatings.specialchem.com/selection-guide/select-adhesion-promoters-for-coatings
> ...



I and many of us here don’t have any problem with gluing the diaphragm to a stator.  I think that I have told you many, many times that you should use rubber glue (contact cement).


----------



## Tjj226 Angel

legopart said:


> Begin to read something interesting that I want to share about "Adhesion Promoter"
> It says that any surface having his potential to contact with glue and hold to it.
> materials like plastic, Mylar, polythene  having low value of this strength and if you want to glue between them you have use some first applying of adhesive promoter that will cause this bound
> https://coatings.specialchem.com/selection-guide/select-adhesion-promoters-for-coatings
> ...



You didn't read the article carefully. Here is the key part you either missed or didn't fully understand. 

"Without the adhesion promoter, the properties of the applied coating may not be sufficient to meet the final performance requirements."

Our performance requirements are almost non existent. The diaphragm tension is the only stress we put on the glue joint, and its only a couple pounds of stress. 

If we were in a situation where the glue joint had to withstand massive stress, or the glue joint had to be over engineered due to safety concerns, then a adhesion promoter would be required. 

But in our case, I wouldn't be surprised if someone could get elmers glue to work with enough time and motivation.


----------



## chinsettawong

I’m making another Orpheus clone.  This one will have thin ear pads.  I think it sounds really nice.


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## legopart (Oct 9, 2019)

Astonishing great!!


About Orpheus, you can find that even on the public versions such HD650 they using some tilted build to the air caps.
and like to use valuer/hybrid pads






About the plugged area
some use some shrinking tube for DIY,
companies using some special plastic design, that I cant find.







Really interesting model!
plus very interesting DIY headband!
What the dimension of this driver ?

and please send some sound measurements.


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## lkos98 (Oct 12, 2019)

@chinsettawong    Very nice! Why did you decide for a thinner pads? Experimenting, better sound? Also with thinner pads your ear may touch the grill or sweat screen?

I would like to ask what program you guys use to create the holes for stators? The program I use, fills the area with offset points, which is very nice, but the distances for X and Y are equal, and distribution of holes is not completely even (like it should be, if every 3 holes form an equilateral triangle). It is not a big deal, I doubt somebody can hear the difference, but still out of curiosity - what do you use?


----------



## Muamp

Hi Ikos98,

I use a Python script called “grill13.py”.
It requires Python version 2.7 or older to run.... it will not run on the latest v3.6....
Just install the python interpreter on any Windows PC or already on Linux boxes.
Google search “grill13.py”, or I can email it to you.

This python program can design ANY array of holes you require, very easy to use and generates g code.
Also you can take the coordinates from the g code and put them into openSCAD to generate a DXF file.


----------



## lkos98

Muamp said:


> Hi Ikos98,
> 
> I use a Python script called “grill13.py”.
> It requires Python version 2.7 or older to run.... it will not run on the latest v3.6....
> ...



Thanks very much Muamp, but I'm not such an advanced user. I run exactly 2.7 python with bCNC for my DIY CNC, but as a simple user I need GUI. I have no idea how and where to put this add on grill13.py. 
Thanks anyway, I will search and try to use that somehow.


----------



## Muamp

Hi Ikos98,

If you already have Python 2.7 then just download grill13.py and run it. It does have a graphical user interface.
It even draws you an image of the array you will generate.
When you have grill13.py just bring up a python CLI window (from the folder which Python is installed) and type “grill13.py” in the Python cmd window, and it’s GUI will run like any Windows graphical application.
The g code is copy - pasted to a text file to import or view in Notepad...
You will really like this program and the unlimited power it provides - you can then design unlimited variations of stators.


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## Muamp (Oct 12, 2019)

Hi Ikos98,

https://github.com/LinuxCNC/simple-gcode-generators/tree/master/grill

Hopefully this link (best one of many for this code) even shows the GUI screen images you will see when running grill13.py.

Also, this website shows you many other useful pieces of Python code for various uses!


----------



## lkos98

Muamp said:


> Hi Ikos98,
> 
> https://github.com/LinuxCNC/simple-gcode-generators/tree/master/grill
> 
> ...


Thanks again Muamp. I will definitely try it. So far I'm using cambam, which is pretty nice and easy program and can draw objects and create g-code, but of course it has limitations.


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## lkos98

This is my new work - this time I will try with normal (stator-membrane-stator) with ellipse. This can also be easily transferred to my usual full inverted membrane-stator-membrane design.
I want to see if there will be any difference between this and the same area circle, and also between normal and inverted designs. 

 

 @Muamp  - This is still the old not equilateral interleaving holes, since first pair of stators were already drilled, before you sent me this nice link.


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## legopart

How do you gonna glue or wiring this ?


----------



## lkos98

legopart said:


> How do you gonna glue or wiring this ?


I'm not gluing anything except the membrane to one of the spacers/rings. As for the wiring, I solder pins to the small holes on the top and when I assemble everything the three pins form a single row 5mm distance connector, which I make also DIY. 
All is then assembled inside 2 cups which are stick to each other with 8 screws. Please see p.233 - there is a good view of the connector and assembly there.
I like this design, because it makes it very easy to disassemble and repair or replace any of the components.


----------



## chinsettawong

@lkos98   Actually, the ear pads on the original Orpheus are a lot thinner than the ones I have on my old Orpheus clone.  For this pair, I try to make the ear pads similar to those on the original.  

About drawing holes, my method isn’t that good.  I simply copy and paste them rolls by rolls and delete the excess.  Muamp’s method is much better.

By the way, I don’t see anything wrong with your holes orientation.  Your stators and spacers look really nice.  Are you using 0.5mm spacer?


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## legopart

How do you apply the stretch on the membrane ?


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## lkos98 (Oct 13, 2019)

chinsettawong said:


> @lkos98   Actually, the ear pads on the original Orpheus are a lot thinner than the ones I have on my old Orpheus clone.  For this pair, I try to make the ear pads similar to those on the original.
> 
> About drawing holes, my method isn’t that good.  I simply copy and paste them rolls by rolls and delete the excess.  Muamp’s method is much better.
> 
> By the way, I don’t see anything wrong with your holes orientation.  Your stators and spacers look really nice.  Are you using 0.5mm spacer?



That's interesting, I thought they also use thicker pads, especially at the back side of the ears.
I would like to see some measurements of those as well, and if you can share what you like better - thinner or thicker pads.

Thanks, it's not that it's wrong, it's not wrong with square distribution of holes too. To achieve max stiffness and transparency of the stator, the holes should be interleaved on the way that each 3 neighbor points form a perfect equilateral triangle, So each 2 Y rows should be  sqrt(3)/2 multiplied by the distance between points. For example if the distance between points is 2.5, the distance between Y rows should be 2.165. All programs I tried so far, make this 2.5mm, which although is pretty close, is not perfect  .
My spacers are actually 0.6. I have 0.5 as well, but the material is not FR4, but some kind of plastic - difficult to glue properly and it tends to bend and even break.


----------



## lkos98

legopart said:


> How do you apply the stretch on the membrane ?


As everybody else, stretch it on a rig and then glue it to a spacer.


----------



## legopart

lkos98 said:


> As everybody else, stretch it on a rig and then glue it to a spacer.


Can you send some example or picture how to do so?


----------



## lkos98

legopart said:


> Can you send some example or picture how to do so?


I have posted pictures of my stretching rig and of the design. And there are tons of pictures and info about this here.


----------



## chinsettawong

legopart said:


> Can you send some example or picture how to do so?



You should really read the old posts.  I have posted how I stretch the Mylar many times already.


----------



## legopart

chinsettawong said:


> You should really read the old posts.  I have posted how I stretch the Mylar many times already.


I searched a lot and not satisfied from the information.


----------



## lkos98

I showed my stretching jig on p.222. https://www.head-fi.org/threads/my-diy-electrostatic-headphones.498292/page-222#post-14930358
Once stretched, you put glue to the spacers, wait for it to dry and then put them onto the stretched membrane. As simple as that.  
By the way stretching was probably the most discussed topic here, so just search for "stretching" in this thread only and you will find a lot of information.


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## legopart (Oct 14, 2019)

Why any headphones applying followed by distortions?
even after the sound off and the headphones still connected, I still can hear some screchie sounds?

I trying to fix both lambda but without the dust filters, I just check if it works


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## Muamp (Oct 14, 2019)

Probably dust between the stators and membrane.
You just wrote you left the dust shield off, The high voltages attract dust....
Switch off and unplug headphones, then gently blow into the stators to hopefully remove any dust.
It will keep happening if you don’t put the dust shields back after a thorough clean.


----------



## Ulfar4

Legopart: All informations was written so many times in this thread. You just need to search.


----------



## legopart

Muamp said:


> Probably dust between the stators and membrane.
> You just wrote you left the dust shield off, The high voltages attract dust....
> Switch off and unplug headphones, then gently blow into the stators to hopefully remove any dust.
> It will keep happening if you don’t put the dust shields back after a thorough clean.


but, how can I test the headphones first before applying the dust filters ?


----------



## qu1en

legopart said:


> but, how can I test the headphones first before applying the dust filters ?



I like to tention my diaphgram pretty loose, so a lot of times what can happen is if you put them on and adjust them while biased, the diaphram will get stuck to one of the stators. To fix this, while it is on my head, i unplug it, and touch all of the pins (on the headphone side of course) together with my thumb. This will unstick the diaphram and you can hear it unstick (kind of sounds like your ears are popping). Then just plug it back in and it is fine. Could this be what is happening to you? When you place the headphones on your head is it already biased, therefore getting stuck? You can fix this by tentioning it more, but you will lose bass. Not sure if anyone else has this same issue but I think I have read it on this forum before.


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## legopart (Oct 14, 2019)

I decide too, to low the tension to the minimum, but coat the surface with dielectric  lacquer and it still seems like useless.  

this kind of noise that starts when I pluged the headphones and sound parallel to to music.




@Muamp thanks for help, I will do it more accurate and close the headphones right before first active them


----------



## chinsettawong

I've mentioned it many times that the most difficult process in making the electrostatic headphones is to stretch the diaphragm to the just right tension.  If it's too loose, you'll have the problem of the diaphragm collapsing to one side.  If it's too tight, you won't have good bass.  I often have to make many pairs of diaphragms before I feel that I really have the right tension.  It's really not easy.  

@legopart  You should really do more research.


----------



## legopart

chinsettawong said:


> I've mentioned it many times that the most difficult process in making the electrostatic headphones is to stretch the diaphragm to the just right tension.  If it's too loose, you'll have the problem of the diaphragm collapsing to one side.  If it's too tight, you won't have good bass.  I often have to make many pairs of diaphragms before I feel that I really have the right tension.  It's really not easy.
> 
> @legopart  You should really do more research.


I done lot of research, but:
- Its hard to remember and apply it all
- Things not always works
- There is no actual roll about the stretching
- Coating amount changing the driver characteristic too (stronger one sided or dual sided) and must of reasons that the membrane stick to the stator is because over-coating


----------



## chinsettawong

I really don’t know how to help you.

Many people here follow my advice and actually successfully built some very nice headphones.  I think you need to really believe what people here told you and just follow the advice and just do it.  Once you’ve managed to make a successful pair then you’ll know exactly how things work.

Some of your questions are just too strange to answer.  For example,  “Coating amount changing the driver characteristic too (stronger one sided or dual sided) and must of reasons that the membrane stick to the stator is because over-coating”. What are you trying to say?  Do you not believe that coating on one side works?  There is no relationship between coating and the diaphragm collapsing to one side.  Please try to understand it.


----------



## legopart (Oct 15, 2019)

chinsettawong said:


> I really don’t know how to help you.
> 
> Many people here follow my advice and actually successfully built some very nice headphones.  I think you need to really believe what people here told you and just follow the advice and just do it.  Once you’ve managed to make a successful pair then you’ll know exactly how things work.
> 
> Some of your questions are just too strange to answer.  For example,  “Coating amount changing the driver characteristic too (stronger one sided or dual sided) and must of reasons that the membrane stick to the stator is because over-coating”. What are you trying to say?  Do you not believe that coating on one side works?  There is no relationship between coating and the diaphragm collapsing to one side.  Please try to understand it.


Ok, my mistake!
on ESL some using high resistors (20M OHM or more)  for the bias to try overcome arcing problems

I promise you that I read on the past lots of pages here,
I will read it all again.

thanks for help.


----------



## qu1en

legopart said:


> Ok, my mistake!
> on ESL some using high resistors (20kOHM or more)  for the bias to try overcome arcing problems
> 
> I promise you that I read on the past lots of pages here,
> ...



I think you should focus on one thing at a time. Get a known working energizer (like a STAX) and just focus on the headphones only.  This way if you have an issue, you will know it is the headphones and not the energizer. Otherwise you will just drive yourself mad. 
Once you get your headphones working, then maybe you can design your own energizer. I use a 20 Meg in series with my bias, but even if it was not there, it will not arc. 
Please look at the photos of OP and others have posted on here on the stators and diaphragms. If it doesn't look almost exactly like their photos (tight clean diaphragm, flat and clean stators, no bends in the spacers, no wrinkles in the diaphragm whatsoever) it will work.
Some of the photos you posted looked quite bad. The black material you used for your stators, I couldn't make sense of what it was. The stators had like three or four holes in it and the holes looked like they had burrs. Not sure how you expect to get any airflow or sound through them. 
They looked nothing like the stators and rings that everyone else has posted. I think the tension of the diaphragm is the least of your problems. You really need to get the stators and rings very clean and precise. Then tension the diaphragm so that there are no wrinkles at all. Finally, you should try and copy these designs and get it working before trying new ideas.


----------



## legopart

Acctually I talked about the attempt to restore the Stax Lambda headphones.




legopart said:


> Finish to restore Sr-202, the old signature back even with 2micron membrane, and I hate it!!!
> glue it little bent, not 1:1 on the stators holes
> I just so clumsy and unprofessional.
> 
> ...



and less about the fail version of my headphones...
I actually not having any CNC so I cant really create things on level that the members here can.
thanks for the explaining, I found by myself too lots of issues and I will try to avoid them next time.



legopart said:


> My plan is ... to wait until tomorrow when its dry and then throw it...
> it's looks bad  and it definitely will not work.
> I think that with this try I will quit from ESH-DIY, sorry.





legopart said:


> first attempt always fail, and it really looking ridiculously.
> 
> Not like to wait.
> I cut it from the film, check the continuity  and then solder it.
> ...


----------



## qu1en

legopart said:


> Acctually I talked about the attempt to restore the Stax Lambda headphones.
> 
> 
> 
> ...



Fixing a Stax headphone is probably difficult. I won't even attempt it because i'm sure I'll just ruin it.
If you don't have a CNC machine with the correct material and thickness, or use FR4 and design PCBs to the proper thickness then you really don't have a chance.
If you try and manually cut and drill holes it won't work. The pics you provide shows that nothing is completely flat.
You're talking about 0.5mm which is so small that even a poorly drilled hole, or flexed stator could exceed that thickness.
This should be obvious honestly, you're dealing with very tight tolerances so everything has to be flat and clean.


----------



## legopart (Oct 15, 2019)

qu1en said:


> Fixing a Stax headphone is probably difficult. I won't even attempt it because i'm sure I'll just ruin it.
> If you don't have a CNC machine with the correct material and thickness, or use FR4 and design PCBs to the proper thickness then you really don't have a chance.
> If you try and manually cut and drill holes it won't work. The pics you provide shows that nothing is completely flat.
> You're talking about 0.5mm which is so small that even a poorly drilled hole, or flexed stator could exceed that thickness.
> This should be obvious honestly, you're dealing with very tight tolerances so everything has to be flat and clean.


Yes, as you said,
I having only ordered material with 0.5mm thickness.
not having CNC, only drill and some Round cutters, I can cut only round shapes.
I have some dremel addition that turns it into router





Still no skills or accuracy, nothings cant promise that even after gluing I will not glue the membrane to the stator 


although I having lots of ideas how to overcome the the absence of CNC and even the skills to use it, and still to create some ESH .
if it will success (or even if not), I will share it here.


----------



## qu1en

legopart said:


> Yes, as you said,
> I having only ordered material with 0.5mm thickness.
> not having CNC, only drill and some Round cutters, I can cut only round shapes.
> I have some dremel addition that turns it into router
> ...



"I having only ordered material with 0.5mm thickness"
This will work for the spacers (ring) but will not work for the stators. 0.5mm is far too thin for stators because it will bend easily. I use 1.6mm thickness for the stators with copper on one side.


----------



## legopart (Oct 15, 2019)

Muamp said:


> Probably dust between the stators and membrane.
> You just wrote you left the dust shield off, The high voltages attract dust....
> Switch off and unplug headphones, then gently blow into the stators to hopefully remove any dust.
> It will keep happening if you don’t put the dust shields back after a thorough clean.


Great ideas.
I really applied it and it fixed the problems of the white noise,
unfortunately I find some unglued part of the stator on the Stax Lambda, at this point tried the cement glue to overcome this.

last attempt to fix my Sr-202 ends with this graph after finish assemble them (using high tension membrane.)




Still not good enough for me, not enough bass.
plan to reassemble them.

At this point I plan to finished to assemble the  Stax Lambda Normal, that I extend the distance between the membrane and the stator to 0.5 (so now it Pro biased.).
applied the membrane with low tension.
After fully assembly, I will share the results and the fraph


Spoiler: -











*Update, one side still got lots of distortion 

The only working side sound good, but the measurements not the best
*the second I decided not to test 


Spoiler: only right










ok, made the second driver function, somehow





*The results not so good, and even the fact that I tight the membrane together it still looks not the same.



qu1en said:


> "I having only ordered material with 0.5mm thickness"
> This will work for the spacers (ring) but will not work for the stators. 0.5mm is far too thin for stators because it will bend easily. I use 1.6mm thickness for the stators with copper on one side.


Yes... its one of my mistakes.
thanks.


----------



## lkos98

Well at least it's a progress. By the way it doesn't look too bad, are you sure the phones were sealed good to the measuring device (whatever it is)?  The peak in 100 - 120 HZ looks a lot like a free air resonance. 
CNC (or 3D printer) is very, very useful (actually I made my CNC, just because I wanted to make ES headphones), but still you can make them with the dremel, sanding the burrs (I also do a lot of sanding after CNC drill and cut), filing the edges, etc., so you get flat stators. Drilling 2-3000 holes by hand (estimating at least 500 per stator) is not very pleasant (my CNC makes 4 stators for about 3 hours and I barely stand waiting for it to finish). 
The 0.5mm PCB is a problem, but there is solution there as well - glue with epoxy 2 or 3 of the PCBs (before drilling )  pressing them very hard between flat surface MDF or similar, and here you are - 1-1.5 mm with pretty good stiffness. There's also another option - create a gerber file for the stators and sent it to a PCB manufacturer (won't give any name, not to sound as advertisement) and they will do the job for you. Not sure you can do the same for the spacers - don't think they work with 0.5 mm PCB. 
The possibilities are countless and that's what makes this so much fun. 
In any case - do a lot of reading, and searching and ..... reading. And as said - focus on one thing - don't jump from one cloud to another. Just go on and at some point it will bring you a lot of satisfaction.


----------



## Tachikoma (Oct 29, 2019)

*I know this is a bit off-topic from the current discussion, but I'm not sure where else I should put this.

I've been trying to recoat my SR007 over the past few days, and I have finally worked out a procedure that seems to produce decent results.
1. Mix floor cleaner in a 1:4 ratio with water (1 part floor cleaner, 4 parts water). Diluting the floor cleaner increases the resistivity of the coating, and thus, the loudness of the driver. I _think_ its a little more stable this way too.
2. Clean the membranes prior to coating, then dry with air (I use a rubber dust blower... which is a rather laborious process).
3. Use a soft sponge to apply the coating - I use liberal amounts of coating here, and only on one side.
4. Dry with air, again.
5. Buff the coating until its clear-ish (to "homogenize" the coating across the membrane and remove excess coating) - I used a soft cloth made of synthetic fiber (read: sports jersey) to do this. 

Note: Maybe don't bother buffing the membrane if its a vintage model, the membrane is a little too easy to damage.

The coating seems to stabilize after ~24 hours. The loudness/balance of the drivers may change slightly over this period of time.

This procedure is basically identical to Chinsettawong's procedure, which he posted somewhere in this thread. The only difference is that the floor cleaner is diluted rather than concentrated.

Coatings I've tried before this: Staticide 6300, various screen cleaners, soap, and undiluted floor cleaner. My experience with (undiluted) Staticide 6300 is rather negative, because the balance changed randomly after a while, but maybe its because I didn't buff the membrane after applying the coating. Its also damn near impossible to remove the Staticide 6300 layer once it has settled.


----------



## chinsettawong

It’s glad to know that other floor cleaners also work.  I’m not so sure about your comment about having higher resistivity and the loudness is higher though.  Anyway, thanks for sharing.


----------



## Hi-Fi-Apricity

What's a good CNC people here recommend for working on the stators and wooden enclosures? Particularly for someone that's new to CNC machining. Thankyou


----------



## Tachikoma

chinsettawong said:


> It’s glad to know that other floor cleaners also work.  I’m not so sure about your comment about having higher resistivity and the loudness is higher though.  Anyway, thanks for sharing.



I started by recoating only one channel (the other channel still had the coating you did for me ), which allowed me to compare the loudness of each coating to a reference. Diluting the coating to increase resistivity is something that has been discussed a fair bit on diyaudio, so I figured that it was worth a try.


----------



## Muamp

@Hi-Fi-Apricity 
cnc 3020 is very popular. I have one and can highly recommend it.
You can buy one from many suppliers on ebay.
Easy to use, high quality and good value for money.


----------



## lkos98

Tachikoma said:


> I started by recoating only one channel (the other channel still had the coating you did for me ), which allowed me to compare the loudness of each coating to a reference. Diluting the coating to increase resistivity is something that has been discussed a fair bit on diyaudio, so I figured that it was worth a try.



Thanks for sharing your experience in coating. 
I agree with Chinsetawong though - when you dilute, the resistance increases as you said, because after it dries completely, there is less conduction substance, but the loudness should decrease, because of the charge losses in membrane, cables, etc. Otherwise with no coating at all, you should have highest loudness . If you have higher loudness with diluted coating, it means the coating is not completely dry, as the water has lower resistivity than the floor cleaner.
I also tried floor cleaner and it's working good, but I don't dilute it, the one I use is quite liquid anyway. For me still anti static 100 gives better loudness.


----------



## chinsettawong

I like to think the diaphragm like a battery.  When you have high resistance on it, it takes longer time to charge up and also longer time to bleed out.  With two different resistances on two different diaphragms, given enough time to charge up, both diaphragms should have the same bias voltage eventually.  That’s why I don’t think one can be louder than the other if nothing else is wrong.


----------



## statfi

chinsettawong said:


> That’s why I don’t think one can be louder than the other if nothing else is wrong.


Might there be a difference in mass that could lead to a difference?


----------



## chinsettawong

Do you mean the mass from the coating?  Wow.  That difference should be very, very little and I don’t think it should make the difference.


----------



## Tachikoma (Oct 23, 2019)

lkos98 said:


> Thanks for sharing your experience in coating.
> I agree with Chinsetawong though - when you dilute, the resistance increases as you said, because after it dries completely, there is less conduction substance, but the loudness should decrease, because of the charge losses in membrane, cables, etc. Otherwise with no coating at all, you should have highest loudness . If you have higher loudness with diluted coating, it means the coating is not completely dry, as the water has lower resistivity than the floor cleaner.
> I also tried floor cleaner and it's working good, but I don't dilute it, the one I use is quite liquid anyway. For me still anti static 100 gives better loudness.



My personal theory is that if the resistivity is too low, the voltage across the membrane will be significantly less than 580V, since V1/R1 = V2/R2 and the ballast resistor itself is 5 mega ohm. It is also known that most voltmeters won't see 580V (more like ~350V with a typical 10 mega ohm voltmeter) when you measure the bias at the output, since their impedance isn't high enough to see all 580V of the bias.

Obviously if resistivity is too high there won't be any sound either, so there is an ideal value somewhere between infinite resistivity and too little resistivity. I think someone mentioned that Stax membranes have a resistivity around 10^9 ohms per square... meter?

I generally find that recoated membranes are less sensitive than those with the original Stax coating. Case in point, I have a pair of headphones where the right channel has the original coating, and the left channel, my floor cleaner coating. I have to decrease the volume on the right channel by 20% to balance the channels, and the balance does not change over time.


----------



## chinsettawong

We might have different experiences, @Tachikoma.

I have fixed a few pairs of headphones which have imbalanced sound.  I only had to recoat one of the diaphragm and the headphones come back to be balanced again.


----------



## VandyMan

I wonder if very small amounts of water are getting trapped between the coating and the membrane throwing everything off. I'm not convinced that all the water would evaporate off.


----------



## lkos98

@chinsettawong That is correct, they should sound equally, if we consider there are no losses at all. Unfortunately there is parasitic resistance between membrane and stator/cup/ring (even surrounding air), between cables etc.  It's extremely high, that's why we are "allowed" to use very high resistance for coating - Gohms. But once the coating resistance becomes closer to this parasitic resistance, the membrane will charge less. Less charge - lower electrostatic force - lower spl.  
@Tachikoma - I'm sorry - I did not fully understand R1 and R2. The voltage on the membrane is a simple voltage divider if you meant this. But membrane itself is not part of this divider, it's not connected to the bias from one side and to the ground at the other. It's in fact a resistor, one end of which is connected to the bias and the other - nowhere - there is no current flowing through it. Yes - if you connect a voltmeter, you actually make a divider 5MOhm - 10Mohm (the voltmeter resistance), but the membrane is connected to the middle point only, so it has no influence at all. Try to connect one side of the membrane to the bias, a voltmeter at the other and ground - you will measure 0V. But if the membrane is aluminium foil and you do the same - then you will measure your 580*10/(10+5) = 386V.  
Anyway the most important thing here - we don't care about the voltage on the membrane, but of it's charge. Bias voltage is there to create this charge. And the charge must be constant. "The Electrostatic loudspeaker cookbook" by Roger Sanders explains all this very well. We don't want low resistance coating, because the electrostatic charge is moving fast to the closest point between membrane and stator and creates uneven charge (hence e-force) across the surface, therefor - distortion. For the voltage, it does not matter low or high resistance - it will be one and the same - the bias voltage everywhere on the membrane.
Otherwise low resistance membrane  sound louder with my experience. I have tried many types - aluminium foil sounds loudest, ink ribbon (100KOhm) - louder, graphite coating less louder and so on. Anti Static 100 sounds definitely louder than floor cleaner with the same phones and bias. I guess this has something to do with the same charge movement - creates higher force at one spot. This concentrated force moves the whole membrane as is the coil in a dynamic speaker - it moves the whole cone.


----------



## Tachikoma (Oct 23, 2019)

Erm, voltage is the difference in charge between two points, so yes, we do care about voltage on the membrane. Why would we bother with the exact numerical value of the bias voltage otherwise?

I know the KSE1500 seems to use aluminium foil, but anyway, I will stand by my observation that diluting the coating actually made the driver louder. I doubt that its because of the residual water content, because the sensitivity has been stable over 3 days already.

Also, coating the drivers with multiple layers of undiluted floor cleaner (coat, dry, then coat again) did not make it any louder, despite the addition of conductive substances to the membrane.

It is possible that resistivity has nothing to do with this (perhaps the uniformity of the coating matters more, or there is a chemistry-related reason as to why my floor cleaner works better when diluted), I can live with my hypothesis being wrong. In any case, I don't think the coating is a straightforward issue at all - the ESL diaphragm coating thread on DIYaudio is 120 pages long for a reason.


----------



## lkos98

@Tachikoma Of course bias voltage matters as it's related to the charge. Higher voltage - higher charge and this charge is moving the membrane. 
I just wanted to simplify things in ideal world. But membrane resistance is of course also part of the voltage divider mention above, there is some current flowing through it as well, because of the parasitic resistance and capacitance. Membrane itself is part of mechanical resonance and so on - it's quite complicated.  
I never wanted to argue about you coating method or your coating material, actually I congratulate you on trying and sharing this with us. I just don't agree with the statement that higher resistance would give a louder sound. For me, your diluted floor cleaner has a lower resistance or for some reason, or may be there is something else involved. 
Anyway it doesn't matter much, what is important here is how you like it. If you are happy with the sound - that's great!


----------



## chinsettawong

@Tachikoma, would you kindly share with us the floor cleaner that you use?  A picture would be nice.


----------



## lkos98 (Oct 24, 2019)

@Tachikoma, Also I would like to ask you if it's not much of a hustle. Can you try the same solution with a distilled water? May be some salts or minerals in the water are mixed (or react) with the cleaner and stay there even after drying. Do you think this could be a reason?
By the way I'm thinking of a method to measure the resistance with a standard voltmeter. I will connect the membrane in one point (may be with a coin) to a high voltage source for example the bias resistor. At the further side connect the voltmeter and measure. With 10GOhm resistance it should give about 500mV ( 500V*10*1e6/(10*1e^9). I know it's not going to be very accurate, but at least it will give us some numbers to work with.


----------



## Tachikoma

Have you seen this? ("Measuring surface resistance of the coating" at the bottom of the page) https://wireesl.weebly.com/conductive-coating.html

The floor cleaner: 
https://imgur.com/exgBEp8
https://imgur.com/kuzE68Q

I have a membrane-based water purifier, but I don't think it can produce proper distilled water. 

If my tap water has a conductivity of 800 uS/cm (https://sensorex.com/blog/2017/07/12/conductivity-monitoring-reverse-osmosis/), its resistivity would be 1250 ohm cm, which gives a resistivity of 125 mega ohms/sq for a 0.1 micron layer of water. I have no idea how that would change as the water evaporates, though.


----------



## VandyMan

Tachikoma said:


> I have a membrane-based water purifier, but I don't think it can produce proper distilled water.




In the US, most supermarkets sell distilled water. I assume that is true elsewhere since people use it for ironing clothes and such.


----------



## legopart

found this materials, that look also good for some DIY
 Have to find how to cut it.

https://www.ebay.com/itm/5mm-Hole-X...-Steel-Perforated-Mesh-Sheet-New/333290549055

https://www.ebay.com/itm/Titanium-M...Holes-plate-expanded-300x200x1mm/301943235658

\


----------



## Muamp

@legopart 
I used perforated steel similar to this on my very first test panel.
It is okay, no way near as good as FR4, but worked fine although cutting it to size is not so easy.
Perforated steel is more suited to large ESL speaker panels.


----------



## lkos98

Tachikoma said:


> Have you seen this? ("Measuring surface resistance of the coating" at the bottom of the page) https://wireesl.weebly.com/conductive-coating.html
> 
> The floor cleaner:
> https://imgur.com/exgBEp8
> ...


Yes, I have seen this, but with 9V battery it would give about 9mv with 10Gohm resistance, which is in the lower range of the standard voltmeters and there will be noise and induced EMF. With 500V we are close to the "natural" for the membrane voltage that we use for biasing. The 9V should work fine for lower resistance of less then 1GOhm.
Thanks for the pictures as well, Mr. Muscle is well known. I may try to coat some leftovers of the mylar I use and see what the measurements will show.
Not sure the water purifier can remove the dissolved salts and minerals, although it's reverse osmosis. For sure it's not producing distilled water.


----------



## legopart (Oct 27, 2019)

Theoretic question,
Will this schematic work to decrees the bias voltage if needed?
I though about it today





*something like R of 150Kohm 600v

can it work?


----------



## lkos98

Yes it should, and by varying R4 and R3 you can regulate the bias But it's not that simple. The total resistance of R4+R3 should be such as not to load the bias which is usually made with voltage multiplier, that can't hold a high load. So 600V/150k = 4mA, which is too much, not talking about that the resistors must be of 2.5W and more. You should make this with at least 2-3MOhm total resistance.


----------



## lkos98 (Oct 27, 2019)

Yesterday I measured different coating resistance. I put some coating and measured with 2 coins separated 5mm from each other and applied 300V to one and measured on the other.
Floor cleaner not diluted - 4.2V - 7GOhm, Floor cleaner diluted about 1:1 - 3.3 - 9GOhm, and Antistatic 100 - 5.8V - 5GOhm.
The results were not consistent, for example Antistatic 100 gave a very high and unstable resistance at one side of the mylar and normal at the other, unlike the floor cleaner which was more or less the same on both sides. Diluted (with tap water) floor cleaner also gave similar results on both sides.
As expected - diluted floor cleaner was with higher resistance. No coating could not be measured at all.
What I liked about the floor cleaner - it was giving pretty stable readings - especially the diluted one - so I may try it next time on my phones - thanks for the hint Tachikoma.


----------



## Ulfar4

Ikos98:
This correspond to my experience. For me, the anti static 100 was very unstable so I switched to floor cleaner. Now it is few months and it is working well.


----------



## chinsettawong

@lkos98, what brand of floor cleaner do you use?  

Thanks guys for your infos.  These infos will be very useful for the newbies


----------



## lkos98

chinsettawong said:


> @lkos98, what brand of floor cleaner do you use?
> 
> Thanks guys for your infos.  These infos will be very useful for the newbies



I used what I have at home - Cobra tile cleaner. I guess most of the floor cleaners would give similar results, except maybe for carpet cleaner, which I think has some anti-static components inside. The essence they put (mine got apple) may also affect, but not much I think.  
Please note, these measurements are not accurate and should not be used for reference, because:
1. The coated area was not exactly the same for the three coatings. 
2. The distance between coins was not exactly the same - I used a simple ruler. 
3. The coating might not be evenly applied. 
4. The resistance is not only the short line between the coins - it includes all the resistances around coins added in parallel (that's why it's given usually as Ohm/square). 

To make a relatively accurate measurement, it should be done I think, on the membrane glued to the spacer and cut, so the coated area is always the same. The voltage should be applied to the spacer ring as we do with the bias and the measurement taken from a coin placed at the center. 
The bias resistor is not of a big importance (unless you use low resistance coating - in such case it must be included in the calculations), because it's value is low compared to the membrane resistance. I'm not sure, but the position of the coin exactly in the center should not affect the measurement much (all resistors between the coin circumference and ring are in parallel).


----------



## legopart (Oct 27, 2019)

Can someone take some measurements for coating density and response audio graph?


----------



## legopart

Is it good to store ESH with SILICA GEL ?





I heard that it can protect electronics when it storage for long time.
but I heard that too dry area could damage the electrostatic headphones and make them loss the coating on the membrane.

What do you think about that?


----------



## Tachikoma

lkos98 said:


> Yesterday I measured different coating resistance. I put some coating and measured with 2 coins separated 5mm from each other and applied 300V to one and measured on the other.
> Floor cleaner not diluted - 4.2V - 7GOhm, Floor cleaner diluted about 1:1 - 3.3 - 9GOhm, and Antistatic 100 - 5.8V - 5GOhm.
> The results were not consistent, for example Antistatic 100 gave a very high and unstable resistance at one side of the mylar and normal at the other, unlike the floor cleaner which was more or less the same on both sides. Diluted (with tap water) floor cleaner also gave similar results on both sides.
> As expected - diluted floor cleaner was with higher resistance. No coating could not be measured at all.
> What I liked about the floor cleaner - it was giving pretty stable readings - especially the diluted one - so I may try it next time on my phones - thanks for the hint Tachikoma.



Have you opened up a pair of Stax headphones to measure the resistance on their coatings?  Would not recommend this unless you don't mind the damage.

I just recoated another pair of headphones, this time using a 1:4 dilution (1 part floor cleaner to 4 parts water). The 1:4 coating seems to be a significant improvement over 1:1 - I finally have a balanced pair of headphones. I only recoated the left channel without touching the stock Stax coating on the right channel to make this comparison.


----------



## lkos98

@Tachikoma 
Well, if I had one, I might have tried  . In any case I'm trying to make my own, not to repair a broken one.   
So what is your opinion - the coating of your Stax has wiped away or they just use a higher resistance coating? Why don't you measure it, compare with the 1:4 solution and share the results? I'm sure most people in this thread would like to know what would be a "recommended" resistance to use.


----------



## quintile

honestly, in my experience the resistivity of the diaphragm makes little difference. the requirements are (imho).

the resistance must be low enough to allow the diaphram to charge up in a reasonable time (a few seconds)

it must be low enough such that the diaphragm remains charged (i.e. the resistance must be significantly lower than the leakage resistance to the stators.

finally the resistance must be high enough to prevent the charge migrating across the surface as the diaphragm moves. 

this last one is very important, charge migration makes the driver very non-linear, read harmonic distortion.

imagine the diaphragm being driven by 1 hz, it will dome towards one stator and then the other. as the middle of the diaphragm in now nearer the stator the electric field to the stator is higher and the charge will move to the middle of the diaphragm; this would mean the field across the gap would vary based on displacement. only the very low conductivity of the coating stops this happening.

-Steve


----------



## statfi

quintile said:


> finally the resistance must be high enough to prevent the charge migrating across the surface as the diaphragm moves.
> 
> -Steve



That seems like it might be quite important.  Does anyone have even a ball-park equation for motion of the charge?


----------



## lkos98

quintile said:


> honestly, in my experience the resistivity of the diaphragm makes little difference. the requirements are (imho).
> 
> the resistance must be low enough to allow the diaphram to charge up in a reasonable time (a few seconds)
> 
> ...


Exactly, that's why I put recommended in quotes. If one knows the leakage resistance, he would then assume a resistance of lets say 100-1000 times lower than that, is good. It would be high enough for prevention of charge migration and at the same time low enough for the leakage. 
But how to measure the leakage? So - how much low is low enough and how much high is high enough? People say somewhere between 10MOhm and 100GOhm. This is a huge difference. What I'm trying to do by measuring, is to get these limits closer, so I can try different coatings (and solutions) - if they can give similar resistance and are stable enough.


----------



## Tachikoma

lkos98 said:


> @Tachikoma
> Well, if I had one, I might have tried  . In any case I'm trying to make my own, not to repair a broken one.
> So what is your opinion - the coating of your Stax has wiped away or they just use a higher resistance coating? Why don't you measure it, compare with the 1:4 solution and share the results? I'm sure most people in this thread would like to know what would be a "recommended" resistance to use.



I deliberately recoated a membrane that was working fine, which was rather silly of me. 

I have a few damaged membranes that I could try measuring... if I can be bothered to try >__< I would only be able to do it with a 9V battery instead of a 300V supply. 

I suspect that the relationship between "loudness" and coating resistance is not necessarily a unimodal plot.


----------



## lkos98 (Oct 31, 2019)

@Tachikoma
9V may work if you put the coins very close to each other (less than 1mm ?).
Otherwise as a high voltage supply you can use the bias voltage of your amp/energizer. Just run a wire from it to the first coin ( or spacer ring). To measure the bias voltage itself you need to know the bias resistor and your voltmeter resistance values and just calculate. You can also connect the voltmeter BEFORE the bias resistor and measure it straight (just make sure the voltmeter is specified for at least 600V and of course be careful ).
Although I'm not sure if the membrane is damaged, what is the coating condition and if there is any sense to measure it.
The relationship I think is definitely not unimodal. I'm just guessing it's non linear, but of some P = V^2 / R kind. So when the resistance is very high, change does not affect the loudness much. And when the resistance is close to infinity (non coated membrane) the power is 0.


----------



## qu1en

Anyone know the dimensions of the active area of the diaphragm of stax headphones? (the common stax Lambdas that look like cheese graters).


----------



## Ulfar4

I looked on my lambdas and it is 90x45mm, but it has rounded corners so it will be less.


----------



## Ulfar4

Anyway I started working on my new phones.


----------



## lkos98

@Ulfar4  Impressive design! The holes are that big, or it's just for the drawing?


----------



## Ulfar4

lkos98 said:


> @Ulfar4  Impressive design! The holes are that big, or it's just for the drawing?


Thanks. It is only for drawing. In real, it will have 2mm holes.


----------



## legopart

Can I replace the dust covers with some material ?

will it improve the bass and the treble if I gonna stretch the diaphragm stronger from the vertical ?


----------



## chinsettawong

You don’t want the dust cover to change the sound.  Don’t put tension on it.


----------



## legopart

chinsettawong said:


> You don’t want the dust cover to change the sound.  Don’t put tension on it.


Stax up to Lambda Pro using some mesh material on the back plate instead of the dust filter.

the second quastion is about the membrane between the stators, if I gonna to apply another tension on each corner will it improve the bass and the treble ?


----------



## chinsettawong (Nov 16, 2019)

legopart said:


> Stax up to Lambda Pro using some mesh material on the back plate instead of the dust filter.
> 
> the second quastion is about the membrane between the stators, if I gonna to apply another tension on each corner will it improve the bass and the treble ?



You should really try and make a pair and see what you can achieve.  What you are asking is very strange and I don’t think any of us here has tried it.  The tension of the diaphragm affects the bass response directly. But I don’t think that stretching the diaphragm in one direction more than the other direction will make any improvement or difference.  You better try it and report back.


----------



## Tachikoma (Nov 28, 2019)

@lkos98 mentioned this a few months ago:
https://www.aliexpress.com/item/327...hweb0_0,searchweb201602_10,searchweb201603_53

If I were to use this as a bias supply for a transformer-based amplification system, would it be necessary to add a ballast resistor in series with the output? (My gut feeling is that the answer is yes...)

Maybe this is a dumb question, but what goes to the GND part of the output? Is it the center tap of the transformers?


----------



## quintile

please do not remove the large valu resistor in series with the bias supply, i has only one use, and that is to preserve your life!

the current flow from the bias supply is picoamps (unless you have some leakage due to dust or condensation in which case it might be some microamps.) having a large series resistor is not a problem.

i would also worry a little about the radiated RFI and power supply induced noise from a cheap smps. 

an old valve amp mains transformer will always be simpler and may well work better.

-Steve


----------



## Tachikoma (Nov 28, 2019)

quintile said:


> please do not remove the large valu resistor in series with the bias supply, i has only one use, and that is to preserve your life!
> 
> the current flow from the bias supply is picoamps (unless you have some leakage due to dust or condensation in which case it might be some microamps.) having a large series resistor is not a problem.
> 
> ...



I'm not modifying an existing Stax bias supply, the idea is to repurpose one of these "DC booster" boards from aliexpress (which do not have a large value resistor in series with the output) as a bias supply. They seem safer than bias supplies that run off mains AC at least, since they run off a 5V-12V input.


----------



## lkos98

Tachikoma said:


> I'm not modifying an existing Stax bias supply, the idea is to repurpose one of these "DC booster" boards from aliexpress (which do not have a large value resistor in series with the output) as a bias supply. They seem safer than bias supplies that run off mains AC at least, since they run off a 5V-12V input.


I do not agree the resistor is just to preserve our life - the main reason is to make the charge as constant as possible even with a very low resistance coatings. But in most cases the membrane resistance is high enough, so even if you touch it, it will not do any harm to you (unless you touch the wire that supplies the bias to ESL - in this case resistor will save your life). As I mentioned few times - it's equally dangerous to touch stators - they are not protected with a resistor and if the volume is max - there are good 600 up to 1200 V peak to peak there. 
In any case to answer your question - it's better to put a resistor in series. Stax put also a bulk capacitor after the resistor to ground, making this as a low pass filter - this prevents the back current (from the moving in electrostatic field membrane) to affect the bias voltage. So if you touch the membrane the capacitor will discharge through you, but the value of the capacitor is small (10nF), so the discharge is so fast, that you might not even feel it. 
This DC-DC converter that I showed is very noisy, so I would advice to do the same - put a large resistor and small capacitor to filter the noise. It is not isolated, so ground point is the same as the 5V supply ground point, so yes, you should connect this to the center tap of the transformer or ground point in your amp. Please bear in mind you can't measure the voltage from this DC-DC - the output current is so small, that the input resistance of the voltmeter overloads it. Also try not to use 1200V - I'm not sure this DC-DC is able even to produce it., without a big ripple at the output.  
Using a valve transformer is always better, but bulky, if you have space - this is the best solution of course.


----------



## quintile

i think the capacitor to ground on the stax is purely to act as a LPF, there is no significant signal modulated current flow from the diaphragm back into the EHT supply; unlike loudspeakers where back EMF is a real problem.

“stiffening” the EHT supply with a cap across the diaphragm also makes no sense as there is again no significant current flow.

even if you had a 1ohm diaphragm the diaphragm itself is insulated, the only current flow is leakage through the air and insulators (or some dust - but that causes squeal).

the diaphragm has (and must have) a constant charge. the only current flow is for the first 2 or 3 seconds as the charge builds up.

-Steve


----------



## lkos98

chinsettawong said:


> You should really try and make a pair and see what you can achieve.  What you are asking is very strange and I don’t think any of us here has tried it.  The tension of the diaphragm affects the bass response directly. But I don’t think that stretching the diaphragm in one direction more than the other direction will make any improvement or difference.  You better try it and report back.


I have actually tried it by accident. I tried to get rid of wrinkles at one side of the membrane (at the edge) using a hair dryer. I removed the wrinkles heating just the edge, which I think created an uneven stretching of the membrane in one direction. I'm not 100% sure, but very positive, that because of this, the FR got a big bump of about 5-6 DB around 100 Hrz - some unpleasant resonance. With the same phones and only different stretching, the FR was flat. 
@legopart 
Lesson learned - never use hair dryer again , better replace the membrane. 
Take a look at this https://en.wikipedia.org/wiki/Vibrations_of_a_circular_membrane- a drum membrane resonance - there are so many modes of vibration, If you stretch it in one direction you can excite a mode, that is very far from the ideal one.


----------



## legopart (Dec 6, 2019)

lkos98 said:


> I have actually tried it by accident. I tried to get rid of wrinkles at one side of the membrane (at the edge) using a hair dryer. I removed the wrinkles heating just the edge, which I think created an uneven stretching of the membrane in one direction. I'm not 100% sure, but very positive, that because of this, the FR got a big bump of about 5-6 DB around 100 Hrz - some unpleasant resonance. With the same phones and only different stretching, the FR was flat.
> @legopart
> Lesson learned - never use hair dryer again , better replace the membrane.
> Take a look at this https://en.wikipedia.org/wiki/Vibrations_of_a_circular_membrane- a drum membrane resonance - there are so many modes of vibration, If you stretch it in one direction you can excite a mode, that is very far from the ideal one.








All the membrane, each micron of it affected in the same time by electric force.
so the membrane not having the option to bump
The stators affect on it at any point any time

speaker dynamic not having stretch shape only because this reasone




known companies using Mylar

but still the measurements shows that on high frequencies its still unstable by the membrane





In the other hand some speakers not shows flat response at all


----------



## legopart

lkos98 said:


> I have actually tried it by accident. I tried to get rid of wrinkles at one side of the membrane (at the edge) using a hair dryer. I removed the wrinkles heating just the edge, which I think created an uneven stretching of the membrane in one direction. I'm not 100% sure, but very positive, that because of this, the FR got a big bump of about 5-6 DB around 100 Hrz - some unpleasant resonance. With the same phones and only different stretching, the FR was flat.
> @legopart
> Lesson learned - never use hair dryer again , better replace the membrane.
> Take a look at this https://en.wikipedia.org/wiki/Vibrations_of_a_circular_membrane- a drum membrane resonance - there are so many modes of vibration, If you stretch it in one direction you can excite a mode, that is very far from the ideal one.


fan not returning the first memory mod,
as wrote on some guide: "it changing the structure of material"
if the membrane not supporting the abilities of stretching by heat, heating just changing it plasticity and destroys it elastic,
even it I sure that the membrane created in manufactury by heat, still after it stretched for ESH heat is not useful


----------



## lkos98

quintile said:


> i think the capacitor to ground on the stax is purely to act as a LPF, there is no significant signal modulated current flow from the diaphragm back into the EHT supply; unlike loudspeakers where back EMF is a real problem.
> 
> “stiffening” the EHT supply with a cap across the diaphragm also makes no sense as there is again no significant current flow.
> 
> ...


Agree, the membrane is the last thing, that you touch - stators are enclosing it. In this case resistor is to prevent you from touch the wires, but this is not the main reason to put it. 
Please take a look at "The Electrostatic loudspeaker design cookbook by Roger Sanders".

As for the bias, I didn't mean to affect the bias at the supply, but the voltage after the resistor in the bias wire. Because of the high value resistor, the amplitude of the voltage created by the membrane movement (acting like a microphone) is quite high as well and since this is the same wire to the other phone it creates a bias swing on the second membrane. I have seen this on oscilloscope - without capacitor part of the signal of left channel goes to the right channel and vise-versa. Capacitor makes the impedance seen from the membrane to the resistor low enough to kill this signal. If you shorten the resistor, the impedance is low enough, but then there is no constant charge, high initial charge current and no protection of course.


----------



## lkos98

@legopart 
Yes, true - force acting on all points of membrane equally (ideally if all points at the same distance), but remember there is force acting in opposite direction, otherwise membrane will slap to the stator even with the smallest force acting on it. This force is created by the tension of the membrane. So if you stretch membrane in one direction and loose it in another, you create a different force at different points. Now the membrane is not moving equally. I guess a mathematical model can be created and analyzed, but it's quite complicated. The ideal movement is for the whole membrane to move equally, but it's never the case. Even with ideal stretching, the center always moves more than the rest and the edges don't move at all. I think this is the reason some phones have a big central whole. Some have a bigger holes in the middle, which become smaller and smaller towards edges in an attempt to flatten the movement of the membrane. 
The heat - you are right, it destroys the elasticity, I wanted to use it just to remove wrinkles, but it seems this makes more damage than good.


----------



## legopart

Cant understand about what


lkos98 said:


> @legopart
> Yes, true - force acting on all points of membrane equally (ideally if all points at the same distance), but remember there is force acting in opposite direction, otherwise membrane will slap to the stator even with the smallest force acting on it. This force is created by the tension of the membrane. So if you stretch membrane in one direction and loose it in another, you create a different force at different points. Now the membrane is not moving equally. I guess a mathematical model can be created and analyzed, but it's quite complicated. The ideal movement is for the whole membrane to move equally, but it's never the case. Even with ideal stretching, the center always moves more than the rest and the edges don't move at all. I think this is the reason some phones have a big central whole. Some have a bigger holes in the middle, which become smaller and smaller towards edges in an attempt to flatten the movement of the membrane.
> The heat - you are right, it destroys the elasticity, I wanted to use it just to remove wrinkles, but it seems this makes more damage than good.


do you mean the hole in the middle of the magnet




Or the hole on the middle of the driver like HD800





Maybe this is the reason why drivers and electrostatic drivers is so small


----------



## lkos98

@legopart 
No I meant the hole/holes in stators of ES headphones.


----------



## Tachikoma (Dec 6, 2019)

lkos98 said:
			
		

> This DC-DC converter that I showed is very noisy, so I would advice to do the same - put a large resistor and small capacitor to filter the noise. It is not isolated, so ground point is the same as the 5V supply ground point, so yes, you should connect this to the center tap of the transformer or ground point in your amp. Please bear in mind you can't measure the voltage from this DC-DC - the output current is so small, that the input resistance of the voltmeter overloads it. Also try not to use 1200V - I'm not sure this DC-DC is able even to produce it., without a big ripple at the output.



So stick a 10 nF capacitor between GND and VCC, and put a ballast resistor in series with the output, got it. How noisy is the DC-DC converter? Can you get acceptable results by feeding it a clean DC supply from an LPS or a battery? I might try a simple 9V battery.

I'll only set it to 580V, in any case.


----------



## lkos98

Tachikoma said:


> So stick a 10 nF capacitor between GND and VCC, and put a ballast resistor in series with the output, got it. How noisy is the DC-DC converter? Can you get acceptable results by feeding it a clean DC supply from an LPS or a battery? I might try a simple 9V battery.
> 
> I'll only set it to 580V, in any case.


If I understood you right - no. First is the resistor, then capacitor to ground and the point between resistor and capacitor is your bias supply. Capacitor from VCC to ground is already in this converter - it is in fact a voltage multiplier, as far as I remember 6 times - one of the reasons, it's so weak - 10Mohm load and voltage drops dramatically. I never tried 9V, I think it was rated for 5V, so I connected a simple phone charger. I used it with my first ES headphones and fairly said it was not that bad, although I did not use the resistor-capacitor filter, which I think should improve the things. Since I did not have ES amp at that time, I was using also step-up transformers. Later with my double bias design, I needed positive and negative high voltages and this converter was of no use anymore.


----------



## ts8051

-JFK- said:


> I'm not at that step, so I can't help you...
> I'm thinking to use 3mm metal rod with cold bending...
> 
> This is my first diaphragm!
> ...



There is no problem with excess of glue because you can use aceton to clear.


----------



## Ulfar4

I am progressing with my new headphones. Driver specs are 80mm active area, 0,55mm spacers and 3um mylar.


----------



## chinsettawong

Ulfar4 said:


> I am progressing with my new headphones. Driver specs are 80mm active area, 0,55mm spacers and 3um mylar.



The driver looks really nice.  How do you like the sound?


----------



## Ulfar4 (Dec 16, 2019)

So far, very promising. In comparison with the previous one with 70mm diameter, it has bigger soundstage and very nice pleasant sound. But I need to experiment more with membrane tension for better bass extension.

Anyway, this part for stators and spacers. It is printed from pet-g material.








And there is bottom side of the driver. It is holding dust cover and earpad.


----------



## chinsettawong

Very nice!  To find the right tension isn’t easy.  Keep trying!

What kind of cable do you use?


----------



## lkos98

@Ulfar4  Beautiful! I think I need to buy 3D printer or DIY.


----------



## Ulfar4

chinsettawong said:


> Very nice!  To find the right tension isn’t easy.  Keep trying!
> 
> What kind of cable do you use?


I am using STAX SRE-725 extension cable. I bought it used for good price. I only needed to make y-split part.



lkos98 said:


> @Ulfar4  Beautiful! I think I need to buy 3D printer or DIY.


Thanks. Yeah, it is very good tool for diy things.


----------



## chinsettawong

It was a great fun meeting with @Tachikoma and his “boss” last Saturday.


----------



## Ulfar4

I finished my headphones, from my previous posts. There are some pictures.


----------



## Tachikoma

chinsettawong said:


> It was a great fun meeting with @Tachikoma and his “boss” last Saturday.



Sorry for taking so long to visit  Your Jecklin style electrostats are truly amazing


----------



## Ulfar4 (Jan 2, 2020)

I decided to try build a measurement rig. I started with buying microphone. I bought POM-2738P-R. Then I soldered simple circuit so I can connect it with my sound card. There is result:

(on the picture, the are headphones with 70mm active area)





I know that paper box is not ideal solution since I am not able to measure low frequency very well. Also the mic is not calibrated but I was surprised that I got some results.

First I measured my lambda nova.There is the large peak between 1kHz and 2kHz, so they have highlighted mids.





Next headphones was my first pair I made. They have round driver with 70mm active area. Mids are not so much presented as they was at lambads.





Finally, there is my latest pair from previous posts. For me they are the best sounding in comparisons with others.





In summary, I can hear some things from graphs and I think it is great help to understanding what is going on. Now I can tune my headphones, and then compare these changes with my ears and graphs. Now I can focus on membrane tension experimenting to achieve best sound.


----------



## legopart

looks excellent!
calibration is very important tool.
also I shure that you using dynamic microphone and not capacitor (?)

Still with to comparing with Lambda its looks excellent


----------



## Ulfar4

legopart: Microphone I mentioned above is electret type.

Anyway, I did not like the paper box for measuring, so I drew up and print new holder for measuring. When I finish this, I will upload 3d models so everyone can print this if someone want.
First prototype:


----------



## legopart (Jan 4, 2020)

Which wire/cable do you use for this headphones?


----------



## Ulfar4 (Jan 12, 2020)

I finished my measurement rig. I have built new amp for microphone so I can use it directly with line input of my sound card.
If anyone want to print this, there are 3D models:
https://www.thingiverse.com/thing:4099146






Here is new measurement of my headphones:


----------



## legopart

WOW!


----------



## ts8051 (Jan 13, 2020)

Ulfar4 said:


> I finished my measurement rig. I have built new amp for microphone so I can use it directly with line input of my sound card.
> If anyone want to print this, there are 3D models:
> https://www.thingiverse.com/thing:4099146
> 
> ...




Hello,
I also made 80mm drivers with similar case. What force you use to tension the membrane? Do you use dust covers?


----------



## Ulfar4

Since I tensioned it with trial and error method, it is hard to tell. Yes, I have them on both sides of driver.


----------



## Hi-Fi-Apricity

I have a question to the fellows here. I have very little CAD experience and I have been using Fusion 360. Fusion 360 does not have a fill pattern tool like solidworks so how does everyone here go about filling the Stator with holes?


----------



## Torac (Jan 14, 2020)

Hi-Fi-Apricity said:


> I have a question to the fellows here. I have very little CAD experience and I have been using Fusion 360. Fusion 360 does not have a fill pattern tool like solidworks so how does everyone here go about filling the Stator with holes?


You can import a premade perforated DXF file onto the face of your stator and use the extrude tool to cut the holes into your stator.
I use this website for the perforated patterns: https://www.accurateperforating.com/resources/patterns
You could also use the pattern tool but I haven't learnt how to use that properly yet so the above method is easier for me


----------



## edform

Hi-Fi-Apricity said:


> I have a question to the fellows here. I have very little CAD experience and I have been using Fusion 360. Fusion 360 does not have a fill pattern tool like solidworks so how does everyone here go about filling the Stator with holes?



I'm not familiar with your particular drawing package, but it will almost certainly have a linear pattern function.

So draw one hole in the right place in a corner then pattern it across horizontally so that it slightly more than fills the width of the object your drawing. Then delete the excess holes, and, if necessary, move the whole pattern to better centre the line of holes across the space. Now pick the whole pattern as the starting point and pattern that vertically until it exceeds the bounds of the object. Finally delete all the excess holes - laborious but you don't really have a choice. It might also be necessary to move the whole pattern vertically until it is evenly balanced in the vertical space, and possibly to remove one or two extra holes or even to draw in a few extra after the move.

Picking the whole 2D array can be a pain since you're never quite sure that you haven't got some other elements of the drawing picked with it, so draw the array on a separate layer and pick by layer which will get it all in one go.

A big word of caution. If your pattern is fine so that the number of holes is large, don't draw it in 3D. Many drawing programs will crash while producing it - something I needed to draw, which was intended for chemical milling from stainless steel foil, and had well in excess of 10,000 holes, crashed Autocad, Solidworks and Spaceclaim and I had to make a separate 2D drawing to produce the artwork needed by the milling company.

Ed Form


----------



## lkos98 (Jan 23, 2020)

@Hi-Fi-Apricity,
Check page 236. I had the same question and Muamp was very helpful. He showed me the python script grill13.py
Check it, if it works for you. I use it to create the toolpath (peck drill) , then import it in Cambam and create drawing from the toolpath. Not sure how it can work with Fusion360.
Just adding - many programs have fill pattern, including Cambam, but all of them create the offset pattern with equal distance between rows and columns, the beauty of grill13 is that it creates exactly 60 deg between any 3 points (equilateral triangle), which is the most effective distribution of the holes.


----------



## Tachikoma (Feb 23, 2020)

lkos98 said:


> If I understood you right - no. First is the resistor, then capacitor to ground and the point between resistor and capacitor is your bias supply. Capacitor from VCC to ground is already in this converter - it is in fact a voltage multiplier, as far as I remember 6 times - one of the reasons, it's so weak - 10Mohm load and voltage drops dramatically. I never tried 9V, I think it was rated for 5V, so I connected a simple phone charger. I used it with my first ES headphones and fairly said it was not that bad, although I did not use the resistor-capacitor filter, which I think should improve the things. Since I did not have ES amp at that time, I was using also step-up transformers. Later with my double bias design, I needed positive and negative high voltages and this converter was of no use anymore.



Hi, I've finally installed the aforementioned bias supply, with the RC filter (4.7M resistor + 10 nF capacitor). It produces 580V from a regulated 5V supply, but I can hear a faint high-frequency whine when no music is playing (plus a high-frequency whine from the board itself). Would anything bad happen if I increased the capacitance of the RC filter from 10 nF to 100 nF?


----------



## qu1en

Tachikoma said:


> Hi, I've finally installed the aforementioned bias supply, with the RC filter (4.7M resistor + 10 nF capacitor). It produces 580V from a regulated 5V supply, but I can hear a faint high-frequency whine when no music is playing (plus a high-frequency whine from the board itself). Would anything bad happen if I increased the capacitance of the RC filter from 10 nF to 100 nF?



Noise on amp is probably the inductor or coil you're using to generate the boost. It's called magnetostriction. Or your capacitors may not be rated for enough voltage. They need to be 1000V+ caps. Can you share your design?

Also guys, I saw some posts on how to make the Stax plug, but can someone send links to where they get the pins from to create the plug (withoug buying DIN plugs and taking them apart). Also how do you get the pins to stay on the housing/plate? Is it potted with a resin, or friction fitted, or glued or what? 

Thanks.


----------



## Marco audio

Hello,
i want to glue 2um mylar diaphragm on fr4 copper side plate.
I Can't find 3M 4693H any where.
But i have this:see picture (Natural Rubber and Hexane).It's a fluid glue.Could it works ? I use or for carbon rims.
Otherwhise, what glue do you use ,please ?
Regards.


----------



## Tachikoma

qu1en said:


> Noise on amp is probably the inductor or coil you're using to generate the boost. It's called magnetostriction. Or your capacitors may not be rated for enough voltage. They need to be 1000V+ caps. Can you share your design?



Its this thing:
https://shopee.com.my/product/35202258/2344718050

Once adjusted to 550-600V with a 5V input supply, the noise is mostly inaudible through the headphones. The physical noise from the board itself isn't too bad either. I guess this is acceptable for a bias supply that cost $6 with shipping.


----------



## lkos98

Tachikoma said:


> Its this thing:
> https://shopee.com.my/product/35202258/2344718050
> 
> Once adjusted to 550-600V with a 5V input supply, the noise is mostly inaudible through the headphones. The physical noise from the board itself isn't too bad either. I guess this is acceptable for a bias supply that cost $6 with shipping.


I replied few days ago, but it doesnt show now. . 
Anyway, 100nF may improve the noise, you can try and check, but I do not recommend leaving the bias with it. 100nF is 10 times bigger than 10nF and it becomes dangerous if you touch - it will discharge through you 10 times slower! 
How do you measure the voltage? This supply is extremely weak (very high output resistance), so once you put your 10Mohm probe, the voltage is not real anymore.


----------



## Tachikoma

lkos98 said:


> I replied few days ago, but it doesnt show now. .
> Anyway, 100nF may improve the noise, you can try and check, but I do not recommend leaving the bias with it. 100nF is 10 times bigger than 10nF and it becomes dangerous if you touch - it will discharge through you 10 times slower!
> How do you measure the voltage? This supply is extremely weak (very high output resistance), so once you put your 10Mohm probe, the voltage is not real anymore.



Hmm, I guess I'll just leave it at 10 nF then, the noise coming through the driver is almost unnoticeable. 

Yes, its not possible to measure the supply directly - I can tell that the voltage is changing since the noise changes when I put the probes on the output. I set the bias voltage by ear, that is, by setting the output to a voltage where the driver is stable, and then lower it slightly.


----------



## qu1en

You could try a couple of experiments like increasing the input supply to 12V to see if it will go away. Using a 20 Meg series resistor for the bias. Try not using a cap after the resistor.


----------



## Tachikoma

qu1en said:


> You could try a couple of experiments like increasing the input supply to 12V to see if it will go away. Using a 20 Meg series resistor for the bias. Try not using a cap after the resistor.



I did try attaching a 9V battery to the supply. The minimum output voltage becomes too high, and the noise is louder if anything.


----------



## lkos98

Tachikoma said:


> I did try attaching a 9V battery to the supply. The minimum output voltage becomes too high, and the noise is louder if anything.


Check the 200V point - this one is measurable (as far as I remember), may be with 9V it will reach 500+. If it is good, just solder a wire there and use it, the ripple and output resistance of this point is much better.


----------



## Ulfar4

Marco audio said:


> Hello,
> i want to glue 2um mylar diaphragm on fr4 copper side plate.
> I Can't find 3M 4693H any where.
> But i have this:see picture (Natural Rubber and Hexane).It's a fluid glue.Could it works ? I use or for carbon rims.
> ...




I think that you should try it and you see if it is good. Personally, I am using Pattex chemopren glue.


----------



## Marco audio

edform said:


> 1. The perforated part of the stator is very thin which is good.
> 2. The edges of the holes in the perforated part have been post-etched, which I think means they have been radiused chemically like the square holes this drawing...
> 
> 
> ...


Hello Head-fiers,
I want to show you my work, this is my first built.



I trie to built my own electrostactic headphones and OTL amplifier in order to learn about ESL.

Stators are steel grids:step is 8mm, square holes are 5.3x5.3mm,thickness is1.5mm.Sand blasted and expoxy painted.

Frames are bakelite with a 0.4mm copper sheet who is glued on them.

Diaphragm area will be 94x71mm.Thickness 2um(Mylar).

Spacer thickness is 0.8mm.Made with fr4 plate (one side coppered).

Any review ?
Regards


----------



## chinsettawong

Marco audio said:


> Hello Head-fiers,
> I want to show you my work, this is my first built.
> 
> I trie to built my own electrostactic headphones and OTL amplifier in order to learn about ESL.
> ...



The parts look nicely done.   Go for it!


----------



## Marco audio

chinsettawong said:


> The parts look nicely done.   Go for it!


Thanks for encouragements Chinsettawong,
I saw your beautifull pieces with wonderment: you're an artist !
I'm building now the spacers.
To follow...


----------



## Marco audio

I want to built the OTL tube amp too(in order to learn).
Due to an order error ,i have 4 6p7s tubes (instead g807 for my plasma speakers).
This tube can handle a 500v anode voltage.
So i wonder if i can use them for the output stage of the amplifier.
A 24Kohm anode resistor and around 550v at entrance.Grid bias -22.5v
Am I wrong ?Could it work ?
Regards


----------



## chinsettawong

Sorry, I can’t help you with the amp design. Maybe someone will shim in later.


----------



## lkos98

@Marco audio 
Wow, 94x71 is equal to a circle 92 mm diameter. You should have amazing bass response. Please share it once you finish the phones.


----------



## Marco audio

lkos98 said:


> @Marco audio
> Wow, 94x71 is equal to a circle 92 mm diameter. You should have amazing bass response. Please share it once you finish the phones.


In fact i have designed my speakers with the step of the grid.
Now  i'm starting to build the spacers with 0,8mm fr4 plate with one side coppered.
Mylar jig is builded.
I Have now 2um mylar film and Licron crystal.
Regards.


----------



## Marco audio

Hello,

Difference between stators load In the same speaker.

There is few differences between the both stators of the same speakers :
-spacers should be lightly different as well as grids sizes .
Conductive coat is on one side of diaphragm.
Theorically it goes loads différence :
how many Ohms could it have ?
please.

Regards.


----------



## Ulfar4

It is not about Ohms, it depends on capacity. You should get about 100pF to 150pF on headphones. When you have bigger active area, capacity will increase.


----------



## Marco audio

Thanks for reply.
You mind a différence of 50pf between both stators of the same speaker or 50pf for the both speakers of the headphones ?
My question was for one speaker and his both stators.


----------



## Ulfar4

It is for one speaker, stator to stator, but I thought about it as complete speaker with cable. Without cable it will be less than the 100pF I mentioned above.


----------



## Marco audio

Ulfar4 said:


> It is for one speaker, stator to stator, but I thought about it as complete speaker with cable. Without cable it will be less than the 100pF I mentioned above.


Thanks a lot !
I understand now why there is an adjustable entrance voltage for each power stage tube on some schematics.
Regards


----------



## Tjj226 Angel

Marco audio said:


> I want to built the OTL tube amp too(in order to learn).
> Due to an order error ,i have 4 6p7s tubes (instead g807 for my plasma speakers).
> This tube can handle a 500v anode voltage.
> So i wonder if i can use them for the output stage of the amplifier.
> ...



If you want an OTL amp, then I highly recommend you triode strap the pentodes. Pentodes have a lot more noise than triodes do, so its not a great idea to use them in an OTL configuration. 

Ideally I would recommend you just spend extra money and get proper low noise triodes. I would go so far as to put a few triodes in parallel to reduce the output noise even further. 

If you are considering a simple OTL push pull amp with a bipolar PSU to directly drive your ESL headphones, then I would go buy a bunch of 6bq7a tubes. They are cheap as dirt, they sound great, and you can afford to parallel a few of them to keep the noise pretty darn low.


----------



## Ulfar4

I am using floor cleaner for coating but I found out that after few months or half of the year approximately, it is starting to go bad and I need to recoat membrane. I am thinking about buying Licron spray. Will this spray do the trick for long term stability? And I am able to purchase LICRON 1756-8S, but I do not know if it is the right type.


----------



## Marco audio

Ulfar4 said:


> I am using floor cleaner for coating but I found out that after few months or half of the year approximately, it is starting to go bad and I need to recoat membrane. I am thinking about buying Licron spray. Will this spray do the trick for long term stability? And I am able to purchase LICRON 1756-8S, but I do not know if it is the right type.


Hello Ulfar4,
Thanks for your reply.
I have readed In post on facebook group that Licron is not so good:
Performances decrease quickly.
Expérimentéd diyers use elvamid and colloïdal graphit.
Oh a propos i have a Pdf from Philippe Higara. Hé use colloïdal graphit and vynil cleaner(near glue for wood?).see p116 or 8/11.
Regards


----------



## Marco audio

PS:The amplifier from Philippe Higara


----------



## Azrael3000

It's been a while since I have been on this thread but for both me and my friend Benny life happened (in many good ways fortunately) and so we did not have time to start with Mk2 of both our headphones and the guide we wrote. I have started to educate myself in electronics and have now reached a stage where I start thinking about an amplifier build for the old and to be built headphones. I don't want to make it too complicated as I'm still learning, so the two options that seem most sensible to me right now are the ES HPA-1 (or 2) from Tubecad or as a solid state alternative the CFA from Kevin Gilmore.
Does anybody here have any experience with these amps in terms of difficulty to build, performance or even a comparison between the two? Obviously tube and solid state are going to be different, so any general recommendations are welcome too or even name dropping of other amps that would be suitable candidates.

Thanks,
Arno


----------



## chinsettawong (May 25, 2020)

Hi Arno,

Nice to hear that you're progressing with your DIY headphones and amps.  I highly recommend any of Dr. Gilmore's amp.  I have not tried CFA yet, but I have a KGSSHV Carbon which sounds fabulous.  Or if you prefer tubes, KG Grounded Grid is basically a tube version of KGSSHV Carbon.  It's very nice too.  I also have a KGST which uses small 6S4A tubes.  It's easy to build and sounds fabulous as well.


----------



## Ulfar4

I would not go for the Tubecad if you want to get out maximum from the headphones. This amplifier have significant roll-off before 20kHz. If you want relatively simple tube amp, you can try SRX+ from JimL.

Anyway, I am just finishing my last project.


----------



## Azrael3000

Thanks gents for the recommendations. It seems Kevin Gilmores website is no longer up and while I tried really hard to find a mirror, I couldn't. It would be a shame to loose all the information that he provided over the years. I suppose I can get the schematics and boards for the KGST from Spritzer or am I missing something?

And on a slightly unrelated note, I stumbled across the two capacitor paradox today, which is an easy read in between if you are not familiar with it.


----------



## chinsettawong

Hi Arno,

All the infos on KG's Amps are still out there.  The link has been updated.  Please check your PM.

Wachara


----------



## Marco audio

Bonjour tout le monde.
Je suis à la recherche de plans cotés des deux prises Stax.
Impossible de les retrouver aujourd'hui.
Les liens de Kévin Gilmore ne fonctionnent plus
Une aide s'il vous plaît.
C


----------



## chinsettawong (Aug 3, 2020)

I have the 3d drawing of the socket.  You can 3D print out using ABS filament:  https://www.tinkercad.com/things/l59XfzK35qP


----------



## Marco audio

[QUOTE = "chinsettawong, message: 15779765, membre: 154445"]
J'ai le dessin 3D de la prise. Vous pouvez imprimer en 3D avec du filament ABS:  https://www.tinkercad.com/things/l59XfzK35qP
[/CITATION]
Thanks A lot !


----------



## Marco audio

chinsettawong said:


> I have the 3d drawing of the socket.  You can 3D print out using ABS filament:  https://www.tinkercad.com/things/l59XfzK35qP


I can't read the drawing with my little phone.Is it possible to have a drawing with measurments please ?
This one is for stax pro headphones,but where can i have the oldest (6 pins),please ?
Otherwise no 3d printer ,but miling,driling and lathe machine.
Regards


----------



## chinsettawong

Sorry, it’s been a long time and I don’t have the measurements anymore.


----------



## Marco audio

[QUOTE = "chinsettawong, message: 15779881, membre: 154445"]
Désolé, cela fait longtemps et je n'ai plus les mesures.
[/CITATION]
Merci dans tous les cas pour votre réponse.
J'essaierai d'utiliser vos fichiers avec un ordinateur plus tard.
Regards


----------



## DrBiehl

Hello everyone. I have been reading the thread over the last couple of weeks and damn, there is a lot of information to take in. I have started to design my own estats after being influenced by chinsettawong's work and that of everyone else that has followed. I have spoken with several members who have been very helpful with general orientation and answering some questions. So over the course of the following months I'll be posting pictures and updates of the process once I am done with my KGST. Thus far, I have ordered 3 micron mylar, staticide 6500, and have started playing around with CAD. My first design is going to be round, as doing everything round is much easier than oval shapes like the orpheus clone. Active area will be 80mm. I'll be posting images shortly. My second project is going to be something like an L700 plus, with oval and quite tall drivers (still figuring out possible dimensions)

As far as cable goes, I am probably going to use the Koss extension but I have a question regarding the wiring to the headphones. Has anyone used mini XLR or MrSpeakers conectors as a possible detachable solution? I remember reading about a MK1 L700 mod a while back, and now that STAX has started going detachable with it's MKII's, I wonder if there is any experience with any of these connectors? Thanks every one for all the information shared.

Best regards


----------



## DrBiehl

This is version 1. Still missing some details, as this is a rough sketch. 
Inner diameter 80mm
Outer diameter 95cm
2mm holes with 1 mm spacing
63% open area. 

The stators I am probably going to have done by pcbway in 1mm double sided FR4. Spacers will be 0.5mm single sided FR4. 
Would there be any benefit in going double sided FR4 for the spacers?

Best regards


----------



## chinsettawong

Hi DrBiehl,
Your design looks good.  I also use single sided FR4 as the spacers.  I don’t see any advantage of using double sided one for the spacers at all.


----------



## DrBiehl (Aug 12, 2020)

Version 2. These are 120x90 ovals. Active area is 105x75mm. Still rough sketches. The idea with this design is to do a sort of big lambda driver into a Stax looking enclosure, akin to the SoCas CanMod for the lambda series. Version 1 will be more like omegas.

I couldn't find any info regarding detachable cables on DIY builds so I'll give it a go and report back. It seems there are some 600V mini XLRs that could do the trick.


----------



## DrBiehl (Aug 19, 2020)

Ended up going for a massive round shape. Active area will be 90mm in diameter, total width of driver is 110. The housing design is done as well. I will be using 110mm AKG pads. This gives the greatest surface area for all of the designs I have tried so far, even more than the 105x75 oval. I am considering using 0.6mm spacers since the driver is actually very wide.


----------



## DrBiehl

Driver housing compared to an M1060 grille for reference.


----------



## chinsettawong

90 mm in diameter is indeed a bit too much for 0.5 mm spacer.  Make them and let us know your result.


----------



## lkos98

I decided to play with in-ear ES headphones. Attached are design and a picture of assembled product. First impressions - very nice sound - I haven't heard so far such sound from in-ear phones. I assume this is because all of the in-ear phones I've heard are closed back, Mids and highs are amazing, unfortunately as expected, bass is a bit weak, but natural. They also need some improvement of the ear pipes and some sort of hook over the ear, because it's almost impossible to keep them in ear without falling. Active area is 22mm, overall diameter is 30.


----------



## chinsettawong

lkos98 said:


> I decided to play with in-ear ES headphones. Attached are design and a picture of assembled product. First impressions - very nice sound - I haven't heard so far such sound from in-ear phones. I assume this is because all of the in-ear phones I've heard are closed back, Mids and highs are amazing, unfortunately as expected, bass is a bit weak, but natural. They also need some improvement of the ear pipes and some sort of hook over the ear, because it's almost impossible to keep them in ear without falling. Active area is 22mm, overall diameter is 30.


Very nice!  Are you using single stator?


----------



## Ulfar4

Indeed, very nice. Maybe the loss from bass is because of long neck for tips? You could try to short it if it is possible. Or there may be improvement if you try connical shape of the neck. Something similar is on the SR003.


----------



## lkos98

Thank you
@chinsettawong  - Yes this is my design as with all my other ES headphones, I'm using single stator with dual membrane - single output amp with dual bias voltage.  
@Ulfar4  - It's not seen in the picture, but the hole of the neck is actually conical, also the cup is with conical surface heading to the hole. I tried to shorten the neck, as you say, but then it doesn't seal good in my ear. But I will definetely experiment with all these, thanks for the suggestions.


----------



## chinsettawong

What is your spacer thickness?  The last time I made mine, I used 0.5 mm spacer and the sound was just too soft.  It was a fun project but I didn’t get to finish it.  By the way, since the driver is so small, you might try to reduce the tension on the diaphragms more, and maybe the bass could improve.


----------



## lkos98

chinsettawong said:


> What is your spacer thickness?  The last time I made mine, I used 0.5 mm spacer and the sound was just too soft.  It was a fun project but I didn’t get to finish it.  By the way, since the driver is so small, you might try to reduce the tension on the diaphragms more, and maybe the bass could improve.


Unfortunately I don't have FR4 less than 0.5mm. I thought of using plastic transparent sheet 0.3mm, but gluing membrane to it would be a big challenge, since with such small rings, I'm not using any supporting holes/screws. All is just stacked between the cups. The other way around (which is one of the major advantages of my design in MHO) is to glue the membrane to the outer spacers (which I do with all my other over the ear phones), then use the FR4 as a spacers and bias supply at the same time, but I can't find 0.2 - 0.3mm single side FR4.  As for the tension - it's pretty low, it does not affect the stability, because with 0.5 mm spacing and 22mm active area, as you said evan with loose tension, membranes cannot touch the stator. Loosing more would not improve the bass - there is just not much sound pressure volume on such small area. 
I'm planing to try to grind the FR4 0.5 mm  on my CNC, with about 0.2 mm and use this for spacers, but I'm not sure my CNC can do that so precise - it will need auto leveling, and very flat surface. 
Overall these are prototypes and they need a lot of improvements.


----------



## chinsettawong

I understand exactly what your problem is.  I was in the same shoe before.


----------



## lkos98

chinsettawong said:


> I understand exactly what your problem is.  I was in the same shoe before.


As you said it's for fun - I doubt these would ever sound as good as a pair of 80-85mm over ear HP. Still I'm surprised how good they sound, I was expecting much less.


----------



## tib8

Hi All, 

I would like to ask for your help:
I have my stators and spacers ready for my first ESL headphone, also the PCB for the corresponding amplifier.
But unfortunately the 3um mylar I have ordered on Ebay has not arrived and I wonder what to do now?
Please let me know alternative sources where I can purchase material for the membrane!
(I'm located in Hungary (EU).)
I'm also interested in:
- what kind of glue (mylar to FR4/copper) would you recommend (which may easily be available here)?
- does anyone have recommendation for relatively cheap cable material, which will be nice to 'wear'?


----------



## DrBiehl

tib8 said:


> Hi All,
> 
> I would like to ask for your help:
> I have my stators and spacers ready for my first ESL headphone, also the PCB for the corresponding amplifier.
> ...



I am in the process of building my first pair as well, so I cannot speak from experience, but I can try and give a summary from what I have read and discussed with other members.

1) any mylar should work, it is recommended by many members here  to experiment with different thickness. I purchased mine from ebay and it has yet to arrive as well.

2) yellow contact cement seems to be the mainstay

3) koss extension cable is the goto, but currently unavailable at the time (phone call last week) Kaldas research has their own pro bias to mini xlr cable for 50 dollars and 2.5m. You could cut off the xlr ends and sodder or make your headphone have mini xlr terminals. I have yet to find a minixlr that can handle 800v peak to peak.

I hope this helps.
Best regards.


----------



## lkos98

Hi, welcome to this nice thread. I will try to give my opinion based on some experience. 
1. Mylar - until you get the order you can try with any type of foil, for example the tiniest wrap kitchen foil - I have seen 11um, may be you can find even tinier. My first ESHP (about 25 years ago) were with aluminium foil , which is definitely not advisable, but still sounds good. Also please check which side of the foil to coat, I have had some cases where one of the sides could not hold the coating, while the other did.
2. Glue - contact cement is most recommended and works best. Since it's a bit thick, I trying to dilute it with lacquer thinner - not always successful. Lately I'm using double sided tape - but bear in mind it adds about 0.1mm to the spacers and is not easy to apply as a ring shape. 
3. Yes - Koss cable seems a very good choice as most of the people here say. Personally I have no experience with it,  I'm using flat ribbon cable - 10 or min 8 wires and using  every second wire. Thus the isolation and high voltage handling is doubled and capacitance is half. Not the best solution, but it works fine and is very light. 
You can experiment with all these and please share your designs.


----------



## chinsettawong

Hi!

The kitchen's Saran wrap can sound pretty good if you can't find the Mylar yet.  However, it's quite heat sensitive.  Using 0.5 mm spacer with Saran wrap might not work well since any change in temperature might loosen it's tension.  I found that even the heat from the body when wearing the headphones can cause the problem.  Using 1 mm spacers with it works well though.


----------



## tib8

Well, I was a bit misunderstood I think: my Mylar order not arrived in 2 months so likely it never will, and the seller does not ship to Hungary anymore, this is why I'm looking for an alternative source.

Anyway, beside asking, I wanted to share an idea: 
While I was looking for components on AliExpress, I have ran into various "Screen Printing Stretchers", which are used to stretch meshes used during printing T-shirts or PCBs, etc.
I was wondering if those could be used to tension membrane? 
This is just one example, there are meany variations:






Also there are items called "Screen printing mesh tension meter" - maybe those could solve the tension reproduction issues I read across this forum.





PS.: I do not think I would use these, but maybe some else here will give a try.
I that case I'm looking forward to get some feedback.


----------



## chinsettawong

Anything is possible.  If you have a chance to try, please try them and let us know the results.


----------



## lkos98

I have done some measurements with my in-ear headphones. Here they are:
@Ulfar4 There is some improvement of the bass bellow 40 Hz with about 2dB, but I don't think I can hear it. Also there is very nasty peak at around 3-4 kHz with 15mm neck, compared to no neck - the peak is still there, but not so significant.
Any thoughts how to improve the response? High frequencies also go too high, I may need to put some light foam in the neck.


----------



## -JFK-

Hi all, 

Long time !
I have finish my CNC and started my new stators.

Made with 7075-T6 aluminium, 2mm thick.
Holes are 3mm with 0.5mm 45° chamfer.

What do you think about it ?


----------



## chinsettawong

-JFK- said:


> Hi all,
> 
> Long time !
> I have finish my CNC and started my new stators.
> ...


Those look really nice!


----------



## lkos98

-JFK- said:


> Hi all,
> 
> Long time !
> I have finish my CNC and started my new stators.
> ...


They look great!. Could you share the active area, and what's the holes/total area ratio? From the picture it looks more than 50%, but this could be because of the chamfer.


----------



## -JFK- (Aug 29, 2020)

lkos98 said:


> They look great!. Could you share the active area, and what's the holes/total area ratio? From the picture it looks more than 50%, but this could be because of the chamfer.


Hi,
The holes/total ratio is, 56.8% (ignoring the chamfer).
The active area is , 105x85mm

I'm working on the amplifier, "DSP, D class, high tension".
It will work in the next 3 months.
So exited to listen it.


----------



## chinsettawong

Are you planning to use 0.5mm spacers?


----------



## -JFK-

chinsettawong said:


> Are you planning to use 0.5mm spacers?


I'm on 0.8mm for now, let's try.


----------



## chinsettawong

-JFK- said:


> I'm on 0.8mm for now, let's try.


0.8 mm will be 👍


----------



## tib8

Here is my first driver. It has 100mm diameter - from that 90mm is active.
I used 0.6mm spacers, but it was too easy to overdrive it (membrane touched the stator), so first I tryed to flip the stators, which surprisingly did not decrease the volume.
Then instead I doubled the spacers to 1.2mm. So now only the amp is overdriven at the highest volumes.

I drive it currently from my normal speaker amp trough a small 2x115V : 2x7.5V transformer. The membrane connected to 650V bias.
The bottleneck is now definitely the transformer so my next step will be to build the direct amplifier. The it will make sense to do some measurements.


----------



## chinsettawong

Nice work!  With 1.2mm spacers, you can increase the bias voltage to over 1KV.  That will increase the loudness more.  However, if you reduce the active diameter down to around 80mm, the spacers of 0.6 will work a whole lot better.


----------



## DrBiehl

Very nice build. My idea is to also do 90mm active area. I was going to use 0.64 spacer but based on your results I am inclined to use 0.8 or even 1mm spacers to prevent the membrane from touching the stators. Let us know how they sound


----------



## tib8 (Oct 16, 2020)

DrBiehl said:


> Very nice build. My idea is to also do 90mm active area. I was going to use 0.64 spacer but based on your results I am inclined to use 0.8 or even 1mm spacers to prevent the membrane from touching the stators. Let us know how they sound



Now the prototype is finished (including the amplifier). And I must say it sounds just as I have expected: crisp clear, transparent highs, enough bass. Accurate transients, blah blah, blah. It is very nice to listen.
Now all my kids wants one, so I have to figure out nicer packaging, and a smaller power supply for the amp.
Also I need to buy a DAC because the sound card in the computer is definitely the new bottleneck.


----------



## chinsettawong

Very nice!  By the way, try not to twist the cables of the headphones together like that because it increases the capacitance of the cable and makes it more difficult for the amplifier to drive the headphones.


----------



## Sky44

Marco audio said:


> Bonjour tout le monde.
> Je suis à la recherche de plans cotés des deux prises Stax.
> Impossible de les retrouver aujourd'hui.
> Les liens de Kévin Gilmore ne fonctionnent plus
> ...


Bonjour,

Avez-vous trouvé les plans ?

Au départ, Stax a utilisé les prises SRC en bakélite d'un fabricant japonais.

Les broches des prises sont celles des XLR 3 broches.

Bien cordialement,

Philippe Hiraga.


----------



## Marco audio

Sky44 said:


> Bonjour,
> 
> Avez-vous trouvé les plans ?
> 
> ...


Hello Philippe,

Thanks for your reply and explanation about xlr pins.
I bought a plug on eBay.It's works well.
Bravo and thanks for your l'audiophile pages about electrostatics stuffs.

Regards

Marc.


----------



## Muamp

Hi Wachara, all,
It has been a long time since I last checked out this thread, even longer since I built my last electrostatic headphone, although I am still very much enjoying listening to my 'stats.
Just spent a bit of time catching up on all the recent comments and designs on the thread, especially the ear bud 'stats! It is amazing there is always a constant stream of people taking up designing and building ESHS. It is fasinating seeing some great designs and new ideas.
David.


----------



## ivanrocks321

Hi Wachara. Got a question for you and was told you might know although its not about estat headphones but my friend Kerry G directed me to this thread to ask around. 

I just got a pair of Peerless PMB 100 they are planarmagetic headphones and I was wondering if anyone including maybe yourself knew the pinout for these, they come with a 5 pin DIN "domino" connector. Was hoping to construct a pig tail to try to use them on some low powered speaker amps.


----------



## chinsettawong

ivanrocks321 said:


> Hi Wachara. Got a question for you and was told you might know although its not about estat headphones but my friend Kerry G directed me to this thread to ask around.
> 
> I just got a pair of Peerless PMB 100 they are planarmagetic headphones and I was wondering if anyone including maybe yourself knew the pinout for these, they come with a 5 pin DIN "domino" connector. Was hoping to construct a pig tail to try to use them on some low powered speaker amps.



I have no idea at all.  Sorry!


----------



## tib8 (Feb 4, 2021)

Just to bring up a new topic: recently I read that one of the electrostatic headphone manufacturers using different method to drive the headphone:
They apply only aprox 140V of signal on the membrane, and put approx 3kV on the stators, this results simpler (single ended, lower voltage) driving electronics.
I decided to give a try for this configuration with the following hack:
DO NOT TRY THIS YOURSELF if you are not expert since HIGH VOLTAGES MAY KILL YOU!
I put the +/- 350V power of my amp on the stators and one side of the symmetric drive signal was connected to the membrane.
The result was exactly what I expected:
- due to the small CD voltage on the stators, it was weak (not loud at all!)
- my membrane has high resistance and this together with its few pF capacity forms a low-pass filter so the high freq was missing
- it had a big background noise (white/brown noise)  - which is likely also due to the high resintance of the membran: we can hear how those few electrons pop on/off the membrane to change its potential...

So from the perfect driver it went back to the quality of the first transistor radios 60 years ago. 

It is likely that using better conducting material as membrane and higher +/- voltage on the stators would solve most of the above problems, but I'm not sure.
(Also a single ended audio signal would be needed...)

What do you think?
Does anybody have more experiences with this configuration?


----------



## lkos98 (Feb 12, 2021)

tib8 said:


> Just to bring up a new topic: recently I read that one of the electrostatic headphone manufacturers using different method to drive the headphone:
> They apply only aprox 140V of signal on the membrane, and put approx 3kV on the stators, this results simpler (single ended, lower voltage) driving electronics.
> I decided to give a try for this configuration with the following hack:
> DO NOT TRY THIS YOURSELF if you are not expert since HIGH VOLTAGES MAY KILL YOU!
> ...



First I want to congratulate you for your enthusiasm to try this method (by the way I think it is called inverted ESL). Very nice!
Your observations are absolutely true, but I think the manufacturers did use different approach setup:
1. The membrane resistance should be very low and the stator resistance - very high - this removes the low-pass filter seen by the amp.
2. With 3kV the bias is high enough so the sound should be loud. Still with such high bias the isolation on stators must be very good - 0.3-0.5 mm - this adds to the spacing
3. Low resistance membrane is heavy, whatever the coating is. So it becomes heavier than air - we all try to avoid this at any cost with the ESLs. In other words - still not good with high frequencies.
4. Forgot to mention - with low resistance membrane - charge is concentrated in the middle - moving is no longer linear - distortion.
My experience with aluminium foil many years ago - please note I used low resistance stators (single side FR4) and low resistance membrane (aluminium foil):
1. I had to replace the output transistors of my amp every now and then, because once the membrane touches the stator it's a short circuit.
2. Because of the aluminum foil the phones got some kind of metallic sound.
3. Very unreliable with high surround humidity.
4. High total capacitance


----------



## tib8

lkos98 said:


> First I want to congratulate you for your enthusiasm to try this method (by the way I think it is called inverted ESL). Very nice!
> Your observations are absolutely true, but I think the manufacturers did use different approach setup:
> 1. The membrane resistance should be very low and the stator resistance - very high - this removes the low-pass filter seen by the amp.
> 2. With 3kV the bias is high enough so the sound should be loud. Still with such high bias the isolation on stators must be very good - 0.3-0.5 mm - this adds to the spacing
> ...



Thank you for your reply! Here are my toughts for your points:
1., 3., 6. The membrane resistance should be low, but not very low: only a few mA has to move in every direction of the membran permitter.
(Lower signal voltage on the membrane decreasing the required current even more!)
So a very thin gold coating for example should be more than enough (I know gold is heavy, but we need only a few nm thickness).
Since I do not have vacuum chamber at home to make such coating, "Emergency Mylar Thermal Blankets" could be a good first try.
It is 12um, which is 3x thicker than ideal, but still close to the target. 
2., 5. Four layer PCB (FR4) could be used with copper only on the middle layers and with no galvanization in the grid holes.
    Biger spacing is not a problem, can be compensated with even higher bias voltage, which is easy to provide (only a few diodes and capacitors needed on AC).
    (This isolation on the inner side will protect the membrane driving transistors too.)
   ((Instead of FR4 an isolated + tensioned wire mesh could also be used, but I have no ide how to make it.))
4. In case of DC signal or low frequency you are right, the charge goes to the middle, but the charge has to come and go in every period, so on higher frequencies they spend more and more time on the way between the middle and the permitter... Should we also consider "skin effect" on higher frequencies?
7. I think humidity is not good for any electrostats anyway.
8. C = epsilon * A / d, I do not see here problem: the capacity is the same as for any normal electrostat. The good isolator may increase epsilon, bot the bigger distance compensates.

I whish I would have lot of free time to try this concept more seriously.


----------



## ts8051

My new Electrostatic Headphones.
Designed my me and 3d printed with PETG. The stators are circular in shape 1.5mm pcb FR4 single sided constructed with my CNC machine. The inner membrane is 2micron tensioned with weigths on a small table.


----------



## chinsettawong

Very nice!  What is the size of the active area?  How thick is your spacer?  What amp do you drive them with?


----------



## Ulfar4

It is nice to see that there is always someone who is building new headphones.

I am using my last pair for about one year I think and I'm still enjoying them very much. There is only one negative about them, I have to recoat them after few months.
Now I printed out mylar stretcher, because my previous method was unrepeatable. And I want to test graphite coating, which could more reliable. I rubbed the graphite and it is working immediately on my test setup, but we will see after some time.


----------



## chinsettawong

Nice!  Let me see more of what you guys made.


----------



## ts8051

chinsettawong said:


> Very nice!  What is the size of the active area?  How thick is your spacer?  What amp do you drive them with?


The active area is 80mm in diameter, the spacer is 0.5mm as in stax and i use the standard stax amplifier.


----------



## lkos98

tib8 said:


> Thank you for your reply! Here are my toughts for your points:
> 1., 3., 6. The membrane resistance should be low, but not very low: only a few mA has to move in every direction of the membran permitter.
> (Lower signal voltage on the membrane decreasing the required current even more!)
> So a very thin gold coating for example should be more than enough (I know gold is heavy, but we need only a few nm thickness).
> ...


Don't get me wrong, I agree with what you said, it's just that for DIY it's very difficult to make light low resistance membrane. (as you mentioned the lighter you could find is 12um, so it's at least 4-5 times (including the gold) heavier than what we use here. High resistance stators shouldn't be so difficult to create - coating on a non-copper FR4.  
Points 5-8 were for my experience with aluminium foil and low resistance stators - which is a terrible combination in my opinion. Capacitance is bigger than normal electrostatic headphones, because now the membrane is in the C equation (high resistance membrane is transparent for the capacitance stator-stator). Humidity was a big problem for me, because of good isolation - when there was a high humidity my ears were shocked with electricity, despite the megaohms resistors I had there.  
By the way as I mentioned few times here, I use a different approach with my ES phones - pretty similar to these "inverted" ones.


----------



## lkos98

@ts8051 
Beautiful. I see you used a light foam for the ear pads, please let me know how it sounds, does it seal good enough?
@Ulfar4 
Great stretching jig. Is this a bicycle tyre?


----------



## Ulfar4

lkos98 said:


> @ts8051
> Beautiful. I see you used a light foam for the ear pads, please let me know how it sounds, does it seal good enough?
> @Ulfar4
> Great stretching jig. Is this a bicycle tyre?



Yes, 14 inch bicycle tire.


----------



## tib8

lkos98 said:


> Don't get me wrong, I agree with what you said, it's just that for DIY it's very difficult to make light low resistance membrane. (as you mentioned the lighter you could find is 12um, so it's at least 4-5 times (including the gold) heavier than what we use here. High resistance stators shouldn't be so difficult to create - coating on a non-copper FR4.
> Points 5-8 were for my experience with aluminium foil and low resistance stators - which is a terrible combination in my opinion. Capacitance is bigger than normal electrostatic headphones, because now the membrane is in the C equation (high resistance membrane is transparent for the capacitance stator-stator). Humidity was a big problem for me, because of good isolation - when there was a high humidity my ears were shocked with electricity, despite the megaohms resistors I had there.
> By the way as I mentioned few times here, I use a different approach with my ES phones - pretty similar to these "inverted" ones.



Thank you for this reply - it has triggered many toughts in me.
I was looking at many of your previous post to find out what was your "inverted" construction exactly. During that I realized that you are (or you were) using a very similar stretching method, which I have discovered lately myself after several trials, and you also use the free air resonance to check membrane tensioning, even the resonance freq is pretty similar, so it is good to see some confirmation that I am on the right track. 

Last weekend I have received high voltage cables for my oscilloscope, so I was able to measure my DIY amplifier finally. I was surprised how big harmoic distorsion components appeared at high volume when the input freq passed over 8-10kHz and they increased rapidly with the frequency. 
I was surprised because the THD in the spice simulation was very low - BUT that simulation runs on 1kHz! So I repeated the THD simulation on 6kHz, 10kHz and 20kHz, and the simulation was in good correlation with the reality. Then I simulated several popular electrostatic amplifier designs from Kevin Gilmore and from STAX, and all of them showed the same behavior, even with smaller signals.
So lucky this is not my design fault, but it is due to the limitations of HW components. I am still thinking how to minimize this effect, but it has to be accepted that some distorsions are present in every amplifiers.

So back to the main topic: all these classic esl amplifers are symmetric, not single ended. And due to this they tend to cancel out the second harmonic distorsion of the signal and the third harmonic is stronger than the second. On the other hand Nelson Pass (an iconic amp designer) said that he made several experiments what kind distorsions the most people like (or accept more than others), and they find out that the second harmonic should be the biggest component and all higher harmonics should be lower than the previous one. (This is not meaning that you intentionally increase distorsion, but it means that you are trying to archtecture the amp in a way that the reamining small distorsions should follow the rule above.) From this the conclusion is that single ended amplifiers should be used. 

So If you don't mind, I will likely try to replicate your completely inverted construction mainly because it can be driven with a single ended amplifier, which I would like to try and compare if it is really better...


----------



## ts8051

quintile said:


> I am interested to hear if anyone tried Neil Pollock's headphone amps from Wireless world in 1979.
> 
> http://www.amateuraudio.fr/images/ww5.pdf
> 
> ...


Hello,
I contructed the Neil Pollock's amplifier before many years and it has a mistake in circuit related to bias high voltage section. It has a potensiometer which after some hours of playing burned because of circuit error. The rest of the circuit plays very well. Note that the type of used transistors are obsolete and cannot be found any more. But as i constructed my headphones with success, i followed the stax prototype for 0.5mm spacing and 580v bias, i used a regular stax energizer.


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## lkos98 (Feb 24, 2021)

tib8 said:


> Thank you for this reply - it has triggered many toughts in me.
> I was looking at many of your previous post to find out what was your "inverted" construction exactly. During that I realized that you are (or you were) using a very similar stretching method, which I have discovered lately myself after several trials, and you also use the free air resonance to check membrane tensioning, even the resonance freq is pretty similar, so it is good to see some confirmation that I am on the right track.
> 
> Last weekend I have received high voltage cables for my oscilloscope, so I was able to measure my DIY amplifier finally. I was surprised how big harmoic distorsion components appeared at high volume when the input freq passed over 8-10kHz and they increased rapidly with the frequency.
> ...


Thanks for the efforts to find and read my posts  I would be also glad if someone else tries the fully inverted ES and to share/compare how they sound. 
Well, I cannot tell my design is better or worse as sound quality.  Since most of amps use negative feedback (except some class A tube amps) the distortion is mainly related to the depth (and type of the components used) of the negative feedback. With ESL amps it can't be too deep, because you have to amplify a small signal to a very large one, but since it's usually with a passive (resistors) components, the distortion is low. 
So in this context differential output should be a bit better, because it needs twice lower amplification (twice deeper neg. feedback). It also cancels the common noise much better. Still I'm surprised you got such high distortion in high frequencies, I did not see this with my DIY amps, but that's maybe because I can't measure them very good (my setup can't measure below 0.4 % THD).
So I think a fully inverted ESH must have a bit worse distortions compared to the classic design and that's not because of the design, but because of the amplifier. Still the distortion of the both amp types can be quite low, so it is insignificant or lets say human ear can't distinguish it. What I like in my design I think I mentioned already, but I will repeat it here risking to bore all of the people here.
1. It can be done without sweat protection - membranes are coated only inside the "sealed" membrane-stator-membrane enclosure.
2. I bit more stable membranes - they are constantly sucked to each other, on negative side - they tend to touch the stator easier and they are bended - hence maybe some small non-linearity when moving.
3. Very low capacitance - theoretically 0, because there is just one stator and the membranes are of a very high resistance. Still the main capacitance of the cable remains, but in fact the amp can see as low as 60-80 pf opposed to the 100-120 of the classic design.
4. I think they have a better bass, but it's just my guess that this is because of the 2 membranes moving in unison.
5. Membranes can be glued to a thick and hard frames, without sacrificing the spacing to the stator.
6. The construction of the phones is relatively simple and can be assembled/disassembled easy.
On the other end you need 2 grills - for both sides, although I don't put one at the ear side - I just make sure the distance is big enough and I handle the phones quite careful. One of my pairs doesn't have even a foam in between, membrane is completely "naked" at my ear - you can imagine how careful you have to be not to touch or rip it.
But yeah, for sure there are some more pros and cons, but I like the design and I like how they sound, and that's most important for me. Currently I'm designing a new ones with a bit different approach - 2 stators in the middle, made with thin 0.5mm FR4 facing copper to each other (saving the isolation coating this way - I hate to do this!) and bend shape like this -  )( , so they can be hard enough as an assembly. This allows me also to make very small holes (1mm or even smaller) diameter. The bend shape would also allow the already bended membranes to move further without touching the stator. The problem here is how to glue the 2 stators only in the middle and I will also have to increase a lot the bias voltages - to compensate for the bigger spacing.


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## lkos98 (Feb 24, 2021)

@tib8
I just noticed I forgot to ask about your stretching jig. I thought mine was good, (at least it's not bas as an idea), but lately I'm not using it, because of the following issues:
1. The wood is not slippery enough and when stretching the membrane gets wrinkles at sides and is unevenly tensioned.
2. The resonant frequency of the my jig is completely unrelated to the resonant frequency of the glued to the frame membrane. There simply is no correlation at all - sometimes my jig shows 30 Hz and one would expect lets say 120 for the glued membrane, but it goes to 150. Then with 35 Hz it should go to 175 or so, but it is 100.
3. I think depending on how much glue is applied, how long you wait for it to dry, in what sequence the frames are glued and pressed, and how hard they are pressed, and what is the ambient temperature/humidity - the tension changes quite a bit.  
4. Maybe due to the uneven tensioning in the jig (or maybe because of the reasons mentioned in p3), the 4 membranes come out with slightly different resonance frequency +-10hz and those with lowest frequency become unstable. 
Please share your design and your experience/results.
Thanks


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## tib8 (Feb 25, 2021)

lkos98 said:


> Thanks for the efforts to find and read my posts  I would be also glad if someone else tries the fully inverted ES and to share/compare how they sound.
> Well, I cannot tell my design is better or worse as sound quality.  Since most of amps use negative feedback (except some class A tube amps) the distortion is mainly related to the depth (and type of the components used) of the negative feedback. With ESL amps it can't be too deep, because you have to amplify a small signal to a very large one, but since it's usually with a passive (resistors) components, the distortion is low.
> So in this context differential output should be a bit better, because it needs twice lower amplification (twice deeper neg. feedback). It also cancels the common noise much better. Still I'm surprised you got such high distortion in high frequencies, I did not see this with my DIY amps, but that's maybe because I can't measure them very good (my setup can't measure below 0.4 % THD).
> So I think a fully inverted ESH must have a bit worse distortions compared to the classic design and that's not because of the design, but because of the amplifier. Still the distortion of the both amp types can be quite low, so it is insignificant or lets say human ear can't distinguish it. What I like in my design I think I mentioned already, but I will repeat it here risking to bore all of the people here.
> ...


I do not have a CNC for FR4 milling, so I simply order nowdays PCBs from China. They are dirty cheap (with the cheapest shipping metod) you can get 5-10 piece 1/2/4 sided PCBs around 10$. They have so good quality that I do not feel the need for a CNC. The only drawback is that you have to wait a month for them to arrive. 

Is this ")(" shape an important part of your design idea? If not, you could try to order 0.6mm 4 layer PCB with copper only on the middle layers (avoiding the grill holes a bit to get rid of the galvanized holes) and use the outer layers only at the signal connector. This would mean only approx 0.6/3 = 0.2mm FR4.
Or 0.6mm 2 layer PCB with only the normal green coating as isolator is likely also good: copper will be even closer to the membrane, but the isolation is weaker.
OR you could combine these two to create a virtually bent shape: the center of the stator could use the middle 2 layers, and the outer lets say 1/3 ring of the stator could use the outer two layers...

About glueing in the center: soldering could be also an option...


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## tib8

lkos98 said:


> @tib8
> I just noticed I forgot to ask about your stretching jig. I thought mine was good, (at least it's not bas as an idea), but lately I'm not using it, because of the following issues:
> 1. The wood is not slippery enough and when stretching the membrane gets wrinkles at sides and is unevenly tensioned.
> 2. The resonant frequency of the my jig is completely unrelated to the resonant frequency of the glued to the frame membrane. There simply is no correlation at all - sometimes my jig shows 30 Hz and one would expect lets say 120 for the glued membrane, but it goes to 150. Then with 35 Hz it should go to 175 or so, but it is 100.
> ...


Well, first I tried the usual bike tier around a wooden frame method, with "only a little", "a little more" and "a lot more" stretching (there is just enough space on the frame for 2 membranes - so better matching was not needed). Then I was using the results for a week. The "lot more" streched version was stable finally: it was not sucked all times to the stators, but the deep were completely missing. The others were relatively good after increasing the spacers from 0.6 to 1.2mm. (D=90mm active area, 580V bias)
Then I wanted to try 1um mylar, but at the first try they were broken on the strecher - so then I tried avoid stretching completely: I cleaned a flat surface, I put the mylar on it and smooth it out as much as possible, and drop the frame with the almost dry contact glue on it.
Of course these were immediately sucked to the stators, so I heated them to shrink a bit and used 1.2mm spacers. This way one of them become useabe. So I made a third one from 2um mylar with the same method - except I simply streched the mylar a bit on the table with my fingers to be smooth just before a helping hand dropped the glued frame on it (then pressed against the table of course) - this time heating was not needed. I reduced also the bias to 325V and finally they got stable.
I use this "asymmetric" pair since then (around two weaks), they go down to 30Hz easily and even with the 1.2mm spacing and the low 325V bias they are loud enough for my normal listening levels. 
As you can see this is far from the wished exact, repetable method.
( I measured the resonance frequency of the ready membranes only beause of curiosity by blowing air on the membrane and running an FFT app on my phone and looking for the first peak. Unfortunately I do not have measurements to this latest pair, but I remember that the better ones were around 140Hz. )
Do you have any advice for improvement?


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## tib8 (Feb 25, 2021)

quintile said:


> I am interested to hear if anyone tried Neil Pollock's headphone amps from Wireless world in 1979.
> 
> http://www.amateuraudio.fr/images/ww5.pdf
> 
> ...


Well, I remembered a design, which is pretty much the same with modern parts:
https://nectarsound.net/wp-content/uploads/2020/09/Nectar1p0_HeadphoneAmp_Rev2_SCHEMATIC.pdf

There is no problem with these (except that the output transistor works agains only a simple resistor so likely it will not effectively use the full range of supply voltage), they can be a good start for the DIY amp hobby. Just be careful with the high voltages!


----------



## ts8051

tib8 said:


> Well, I remembered a design, which is pretty much the same with modern parts:
> https://nectarsound.net/wp-content/uploads/2020/09/Nectar1p0_HeadphoneAmp_Rev2_SCHEMATIC.pdf
> 
> There is no problem with these (except that the output transistor works agains only a simple resistor so likely it will not effectively use the full range of supply voltage), they can be a good start for the DIY amp hobby. Just be careful with the high voltages!


do you have the parts list and a pcb ?


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## chinsettawong

If you want to make a good amplifier for your headphones, I highly recommend building one of Dr. Gilmore’s amps - KGST, KGSSHV Carbon, KG Ground-grid, for example.  They aren’t that much more difficult to build.


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## ts8051

chinsettawong said:


> If you want to make a good amplifier for your headphones, I highly recommend building one of Dr. Gilmore’s amps - KGST, KGSSHV Carbon, KG Ground-grid, for example.  They aren’t that much more difficult to build.


ok, I checked ebay and the seller for 2 micron membrane does not sell any more. Do you know other seller?


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## lkos98

@tib8 
The )( shape is important for me for 2 reasons - 1st to make the stator sturdy, so it does not vibrate on electrostatic forces. (for my normal designs I use double sided 1mm FR4. 2-nd to "follow" the shape of the membranes (when +-360V is applied to them they bend against each other. With a flat stator the center of the membranes is closer to the stator. By the way, this also applies to the classic 2 stator design, because membrane is always attracted more to one of the stators. The option of ordering PCB is good, I have considered it many times, but this is going to be a pretty complicated board. And before I do that, I want to check if it's worth it   - for CNC this is pretty simple job. I made already 4 FR4 0.6 mm stators for about 1 hour including the about 2000 holes.
Soldering in the middle is a bit of a challenge, I need to solder inside a 1mm hole a thin layer (35um) of copper. 
Unfortunately I can't give you advise on improvement of the stretching, because I use the same wet "glass table" method. I stretch the membrane with a microfiber cloth to remove any wrinkles. Then as you do I just drop the frames and press for about half an hour with something flat and heavy. Your results are quite similar to what I measure with mine - about 140-160 Hz, +-360V and 0.6mm spacing. If I go higher they become unstable. Still I got pretty good bass measured down to 10-15 Hz. Once I got 5Hz, but with a DC amp (no decoupling capacitors) and membranes were unstable. By the way I measured many times the FR response and I think tension does not affect the bass so much as the sealing of the earpads.    
Since I do this stretching once in a year or when I make a new model, I don't have much data to share.  I believe tire jig is the answer, I just have to make one and do some experiments with different tensions and measurements. But the frames I have are only the ones I use in the phones and I'm too lazy to cut many of them to compare.  
The sound level is also good for my taste, but it's far from a dynamic headphones. So if I want to listen very loud, the amp starts clipping.


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## chinsettawong

To my ears, I like 3 microns Mylar the best.  It's also a lot easier to work with.  Try it, and you'll like it.


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## tib8

lkos98 said:


> @tib8
> The )( shape is important for me for 2 reasons - 1st to make the stator sturdy, so it does not vibrate on electrostatic forces. (for my normal designs I use double sided 1mm FR4. 2-nd to "follow" the shape of the membranes (when +-360V is applied to them they bend against each other. With a flat stator the center of the membranes is closer to the stator. By the way, this also applies to the classic 2 stator design, because membrane is always attracted more to one of the stators. The option of ordering PCB is good, I have considered it many times, but this is going to be a pretty complicated board. And before I do that, I want to check if it's worth it   - for CNC this is pretty simple job. I made already 4 FR4 0.6 mm stators for about 1 hour including the about 2000 holes.
> Soldering in the middle is a bit of a challenge, I need to solder inside a 1mm hole a thin layer (35um) of copper.
> Unfortunately I can't give you advise on improvement of the stretching, because I use the same wet "glass table" method. I stretch the membrane with a microfiber cloth to remove any wrinkles. Then as you do I just drop the frames and press for about half an hour with something flat and heavy. Your results are quite similar to what I measure with mine - about 140-160 Hz, +-360V and 0.6mm spacing. If I go higher they become unstable. Still I got pretty good bass measured down to 10-15 Hz. Once I got 5Hz, but with a DC amp (no decoupling capacitors) and membranes were unstable. By the way I measured many times the FR response and I think tension does not affect the bass so much as the sealing of the earpads.
> ...


Yes, soldering is can be difficult... I would apply some lead on the middle 10mm spot of the two not drilled panel and press them together with some (?) heated tool.
I would drill them together afterwards, and only after this would insert the (two half) spacer ring to get the )( shape.


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## lkos98

tib8 said:


> Yes, soldering is can be difficult... I would apply some lead on the middle 10mm spot of the two not drilled panel and press them together with some (?) heated tool.
> I would drill them together afterwards, and only after this would insert the (two half) spacer ring to get the )( shape.


Yes, thanks, I thought of that, but I already drilled them  . I noticed also that this 0.6mm FR4 I have, when overheated, the copper tends to peel off quite easy. My spacer ring is not two half, but a whole 1 piece, because I want to get the best possible seal between the )(. It could be done of course with some glue or silicon. Anyway I'll try few options to see how it goes.
@chinsettawong 
I saw that the ebay seller is not there anymore, so sadly no mylar at all. Now we have to find another provider.


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## chinsettawong

the seller on Ebay is still there.  https://www.ebay.com/itm/Electrosta...550352&hash=item1cfdb6be93:g:XBoAAOSwU9xUQPIj


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## tib8

ts8051 said:


> do you have the parts list and a pcb ?


well it is there, right beside the schematics:
https://nectarsound.net/diy-amplifier/

but I agree with @chinsettawong : with approximately the same effort and part cost you could build one of Kelvin Gilmore's solid state amplifier designs. 

I did that also with a heavily modified output stage, and nowadays available parts, reduced idle current (5mA is just enough), and of course I designed the PCB for myself because that is the funniest of the whole process. Needless to say: I'm happy with the result.

On the other hand, no matter what you build first, it is likely that you will build at least one more to be even better. 

My kids were asked me to build one for them also, so I already started to design my next one.


----------



## tib8

chinsettawong said:


> the seller on Ebay is still there.  https://www.ebay.com/itm/Electrosta...550352&hash=item1cfdb6be93:g:XBoAAOSwU9xUQPIj


Is he selling smooth, wrinkle free rolls?


----------



## lkos98

chinsettawong said:


> the seller on Ebay is still there.  https://www.ebay.com/itm/Electrosta...550352&hash=item1cfdb6be93:g:XBoAAOSwU9xUQPIj


Thanks!!! Strange I searched exactly as in the description.


----------



## tib8

lkos98 said:


> @tib8
> The )( shape is important for me for 2 reasons - 1st to make the stator sturdy, so it does not vibrate on electrostatic forces. (for my normal designs I use double sided 1mm FR4. 2-nd to "follow" the shape of the membranes (when +-360V is applied to them they bend against each other. With a flat stator the center of the membranes is closer to the stator. By the way, this also applies to the classic 2 stator design, because membrane is always attracted more to one of the stators. The option of ordering PCB is good, I have considered it many times, but this is going to be a pretty complicated board. And before I do that, I want to check if it's worth it   - for CNC this is pretty simple job. I made already 4 FR4 0.6 mm stators for about 1 hour including the about 2000 holes.
> Soldering in the middle is a bit of a challenge, I need to solder inside a 1mm hole a thin layer (35um) of copper.
> Unfortunately I can't give you advise on improvement of the stretching, because I use the same wet "glass table" method. I stretch the membrane with a microfiber cloth to remove any wrinkles. Then as you do I just drop the frames and press for about half an hour with something flat and heavy. Your results are quite similar to what I measure with mine - about 140-160 Hz, +-360V and 0.6mm spacing. If I go higher they become unstable. Still I got pretty good bass measured down to 10-15 Hz. Once I got 5Hz, but with a DC amp (no decoupling capacitors) and membranes were unstable. By the way I measured many times the FR response and I think tension does not affect the bass so much as the sealing of the earpads.
> ...


One more question: if you achieve this )( shape, then are you going to completely ommit the spacer beside the membrane and feed the bias by the outer edge of the stators? Or spacers are still needed?


----------



## lkos98

tib8 said:


> One more question: if you achieve this )( shape, then are you going to completely ommit the spacer beside the membrane and feed the bias by the outer edge of the stators? Or spacers are still needed?


I actually already did the dual stator assembly - soldering in the middle was not difficult at all. I hope the copper will not peel off, but I doubt it, because the spring force is really very small. 
I don't think I can omit the spacers, this means the membrane will be moving almost just in the middle. The spacer between stators is just 0.5mm and looking at them you can't even notice they are bended. On the other hand I have to have some contact for the bias for the membranes. Gluing them to an outer copper plate might not give a reliable electrical contact and most important - I always want the coating to face the stators to avoid humidity influence. Unfortunately I ran out of 0.5 mm FR4, so my spacers will be 0.65. This makes 0.65 +0.5 +0.25 = 1.4mm distance in the middle and 1.15 at the edges. I guess I will have to increase the bias to +-1kV so they sound loud.  Since my isolation is FR4, which has 4 times (if I remember correctly) higher dielectric constant than air, it may improve things a bit.


----------



## chinsettawong

Very nice looking driver.  What is the hole size?


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## lkos98 (Mar 6, 2021)

chinsettawong said:


> Very nice looking driver.  What is the hole size?


Thanks, holes are 1.2mm area is 88mm., 1.625 distance between and pattern is 60 deg.  I made a mistake in my previous post, the holes are 2677, 49.5% open area. I used as mentioned before 2 single sided 0.6 mm FR4, separated at edges with 0.6mm ring and soldered in the 6 middle holes. I was skeptical, but this shape gave surprisingly good sturdiness. I can't compare it with 1mm double sided stator, because the holes there were 1.8mm and open area was about 30%, but by finger it feels the same. Otherwise a single stator drilled like this is very soft and bends in all directions.


----------



## tib8

lkos98 said:


> I actually already did the dual stator assembly - soldering in the middle was not difficult at all. I hope the copper will not peel off, but I doubt it, because the spring force is really very small.
> I don't think I can omit the spacers, this means the membrane will be moving almost just in the middle. The spacer between stators is just 0.5mm and looking at them you can't even notice they are bended. On the other hand I have to have some contact for the bias for the membranes. Gluing them to an outer copper plate might not give a reliable electrical contact and most important - I always want the coating to face the stators to avoid humidity influence. Unfortunately I ran out of 0.5 mm FR4, so my spacers will be 0.65. This makes 0.65 +0.5 +0.25 = 1.4mm distance in the middle and 1.15 at the edges. I guess I will have to increase the bias to +-1kV so they sound loud.  Since my isolation is FR4, which has 4 times (if I remember correctly) higher dielectric constant than air, it may improve things a bit.


Looks incredibly good! 
Is this the complete driver with membranes or the stator only?
If the finished driver, does it fulfills your expectations?


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## lkos98

@tib8 
Thanks, you're being nice -   .The frames look terrible, because I made them from a plumber pipe cap, but for now it's just for testing. Later I will redo with either wood or some good looking plastic. Yes this is the final assembly without the membranes, earpads and connectors. And only one channel, can't find the time to do the second and glue the membranes. And testing with one channel makes sense for the FR only, maybe it's just me, but if I don't have both cups on my ears, I cannot evaluate the sound quality.


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## lkos98 (Mar 14, 2021)

Finally assembled the new design. )( shaped stator, single sided, copper inside, 88mm active area, 50%, 1.2 mm holes. 0.65mm spacers. First impressions compared to 100/70 ovals (60cm2 vs 55cm2):
1. A bit deeper bass - at first I was disappointed - I expected more, but then I realized that extending an FR lower with few Hz, which is already 15 Hz would not make much difference in hearing. Highs sound a bit better, middles are a bit lower. Overall sound is a bit softer - which I already noticed as a difference between circle and oval designs.
2. Surprisingly loud - (as mentioned in previous message the distance membrane - copper at edge is 1.15mm and in the middle is 1.4. (with the oval spacers are 0.6mm). I thought it would be much less loud with the same amp and bias, but it's actually almost the same. Two things only come to mind - the big dielectric constant of FR isolation and bit bigger area.
Overall I'm very happy so far - not much improvement over the same (almost) size ovals, which already sound great, so this was to be expected  I'm very keen to put some headband, and measure them, once I find some time for it.


----------



## tib8

lkos98 said:


> Finally assembled the new design. )( shaped stator, single sided, copper inside, 88mm active area, 50%, 1.2 mm holes. 0.65mm spacers. First impressions compared to 100/70 ovals (60cm2 vs 55cm2):
> 1. A bit deeper bass - at first I was disappointed - I expected more, but then I realized that extending an FR lower with few Hz, which is already 15 Hz would not make much difference in hearing. Highs sound a bit better, middles are a bit lower. Overall sound is a bit softer - which I already noticed as a difference between circle and oval designs.
> 2. Surprisingly loud - (as mentioned in previous message the distance membrane - copper at edge is 1.15mm and in the middle is 1.4. (with the oval spacers are 0.6mm). I thought it would be much less loud with the same amp and bias, but it's actually almost the same. Two things only come to mind - the big dielectric constant of FR isolation and bit bigger area.
> Overall I'm very happy so far - not much improvement over the same (almost) size ovals, which already sound great, so this was to be expected  I'm very keen to put some headband, and measure them, once I find some time for it.


You are right about the dielectric constant. The epsilon relative of FR4 is about 4.3, which means that 4.3 times less voltage drops on it than on air (if we imagine two serially connected capacitors). So FR4 seems 4.3 times thinner than it is in reality. So your equivalent air-gap is 0.65+0.5/4.3=0.766mm. Which is only 1.27 times of your normal 0.6mm, that means only 20*log(1.27)=2dB loss in loudness. 
If that would be the price of the stable membranes the it definitely worths it. 👍


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## lkos98 (Mar 15, 2021)

tib8 said:


> You are right about the dielectric constant. The epsilon relative of FR4 is about 4.3, which means that 4.3 times less voltage drops on it than on air (if we imagine two serially connected capacitors). So FR4 seems 4.3 times thinner than it is in reality. So your equivalent air-gap is 0.65+0.5/4.3=0.766mm. Which is only 1.27 times of your normal 0.6mm, that means only 20*log(1.27)=2dB loss in loudness.
> If that would be the price of the stable membranes the it definitely worths it. 👍


Thanks for the calculations! I was thinking of it on another way - F=Q1.Q2.k/d^2. Which means with k = 4 times higher, F would be 4 times higher. and since the distance is about 2 times higher it becomes almost the same, but here the force is actually a sum (??) of 2 forces - within air and within FR4, and this I didn't know how to express. On the other hand the transparency is higher, meaning there is less copper area for the electrostatic field. It took me about 5 mins to give up on formulas, so I guess your method is better. Anyway, it's definitely far more stable (also because of the )( shape) and I think I can safely increase the bias twice, which will give me much more loudness, than I can get with the ovals.


----------



## tib8

lkos98 said:


> Thanks for the calculations! I was thinking of it on another way - F=Q1.Q2.k/d^2. Which means with k = 4 times higher, F would be 4 times higher. and since the distance is about 2 times higher it becomes almost the same, but here the force is actually a sum (??) of 2 forces - within air and within FR4, and this I didn't know how to express. On the other hand the transparency is higher, meaning there is less copper area for the electrostatic field. It took me about 5 mins to give up on formulas, so I guess your method is better. Anyway, it's definitely far more stable (also because of the )( shape) and I think I can safely increase the bias twice, which will give me much more loudness, than I can get with the ovals.


I imagine the voltage drop across your driver like this:





Since most of the voltage still drops in the air you should be careful with increasing the bias voltage. Do NOT go anywhere near to the 2kV/mm.
I would use only 1.25 .. 1.5 times higher bias voltage only to cover that extra voltage drop in the FR4, which would not happen if the Cu would be on the outer side of it. 

About the decreased (50%) useful area: 
F = Eair * Q
F = m * a
C = Q / U 
C = A * epsilon / d  
=>   a = E * Q / m = E * U * C / m 
Where the 'm' is the mass of the membrane (+ the air around it) and 'a' is the maximal acceleration of the membrane if a given Q is applied (due to a given U). 
If the useful area is smaller, that decreases the C (so decreases Q too), while the mass of the membrane is the same, but due to the larger hole area, the air could be moved a bit more easily, so there is a holpe that visible mass 'm' will be a bit smaller too. The amplifier has to pump less Q in each period - it sees smaller capacitive load, so will be able to extend its high freq range.
From the combination of these factors it is hard to predict which will be dominant, but they will likely affect the high frequency response of the driver...
It would be interesting to experiment with identical drivers, which differ onlyin useful area, and measure their freq response... and test the stage imaging, separation, etc, which can not be measured...


----------



## lkos98 (Mar 16, 2021)

Well I forgot to mention also that the area is higher than the ovals, so it becomes complicated. Otherwise I agree, it would be nice to experiment with identical drivers varying one by one different components. I guess this is done by the manufacturers, but who of us can afford it? Who has time to drill 10 different ratio stators? There are too many factors playing roles here. For example after listening for about 3 hours with the new drivers and swapping them from time to time with the ovals, I found some things that I didn't like so much. Bass is extremely powerful and on some songs masks the middles and highs. The cable is almost twice longer than with the ovals and because my amp is not very powerful it struggles with the increased capacitance, hence the highs are muffled. Once the phones get warmer from my head, the membrane tension decreases a bit and bass becomes even more. I love bass, but this is too much. I guess this can be fixed with increased tension and shorter cable. So my first impressions were wrong. Bass is too much, and highs sound weaker. I really need to do FR to see how it looks compare to the ovals.  
I wouldn't go nowhere near even 1kV per 1mm, my bias is now around +-350, and I intend to double it at most. So I will have max 700v/mm compare to the 580V /0.5mm in the classic design.


----------



## lkos98

I made some FR at last. Circle has about 10 dB (voltage on the mic) difference from 20-1000Hz, but it drops quickly down from 50-300 and then it's almost flat. Ellipse follows almost the same, but with just about 3dB drop. I guess this is the reason circle sounds so "bassy" and soft. From 1k-30kHz both are pretty similar and surprisingly both go up with 10dB at 30k. I don't know if this is real, because my mic is not good for a real FR measurements. The curves look very similar with all designs. For example I always see a bump between 20 and 100 hz, then almost flat, then some peak drops at 600 and 1000 and a slow but constant increase from 1k to 30k. I can only compare values at different frequencies with different phones.


----------



## lkos98

Made some measurements with REW software, which confirmed my suspicions that the microphone doesn't have flat response. Compared are my beloved open back Koss dynamic headphones (in red), and the last designed circle ES headphones (L&R ch.). Except for the nasty peak drop around 1000 hz, the FR is much flater and looks better. Again I'm not sure about the bump at 20-100 if it's caused by the microphone or the headphones.


----------



## tib8

lkos98 said:


> Made some measurements with REW software, which confirmed my suspicions that the microphone doesn't have flat response. Compared are my beloved open back Koss dynamic headphones (in red), and the last designed circle ES headphones (L&R ch.). Except for the nasty peak drop around 1000 hz, the FR is much flater and looks better. Again I'm not sure about the bump at 20-100 if it's caused by the microphone or the headphones.


Currently I have no tools for proper measurement, only a webcam, which unfortunately seems to cut above 8kHz and below 200Hz.

Ellipse (94x74mm active) with velour pads: orange, brown
Circle (87mm active) with leather pads: blue, green

Those high freq bumps likely due to the reflections from the leather pad.
Other smaller peaks also appeared/dissapeared during repeated measurements which are realted to the positioning of the headphone on the shoe box (which is also not reflexion free), which held the webcam/microphone.

There is an other pink noise measurement with ARTA: the ellipse is the orange, the circle is the green (-4dB).
And the last is a pink noise measurement with ARTA: my ellipse driver is the orange, my Sennhieser HD555 is the green (this time without my DAC + ESL amp, directly from my laptop soundcard, which increases the bass likely to get some out of its build in speakers, so again not good for real measurements).

I do not know if the above helps you. I just wanted to say that one measurement is not measurement. You need to do some averageing + take care of reflexions, positioning because your setup may be also very sensitive...


----------



## lkos98 (Mar 22, 2021)

One measurement is not enough - very true, but I made several. There was practically no difference, may be 1-2 dB in some places. I also don't think my microphone is good enough to call this a measurement. My setup is always noisy - wife's watching TV.  I put the microphone on a thick cloth directly on the table and the cup on top of it aiming the center. Then I took several measurements, but they all look the same. I also tried to increase the distance with some 20mm thick rubber/foam round ring (I used it before as earpad) and the 1000Hz drop moved to 600Hz, but the overall FR remained the same. So yes, cavity resonances can cause peaks and drops. Microphone position and distance, the material of the cups, etc. By the way the free air resonance is about 100 Hz, this is the lowest I have ever managed. With all other designs I couldn't go less than 140 - instability. Overall I'm happy with the sound, I just need to increase the tension a bit more - may be 110-120 Hz, just to remove some of this overwhelming bass. It's great on songs with low bass (ELO, Alan Parsons), but try to listen to ERA or some heavy metal....I could really feel the vibrations.  
Your 200-8k bandwidth looks good, but a shoe box can do a lot of damage - the volume is too big IMO and seal is almost not present. Just an idea - what about La Vache qui rit cheese box? Cut some holes bottom and top, fill with as much as possible cotton wool or something similar (without blocking the direct sound from the headphone to the mic) and seal with tape.  My previous set was with a round MDF board with a microphone size hole, the phone was from one side, mic from the other and sealed. This was giving pretty good results, unfortunately I lost the board somewhere .


----------



## tib8

audiophileeee said:


> I saw and listened to such drivers
> 
> 
> 
> ...


There is a plastic which can be put into oven to make it hard (children toy).
From that you could form something which matches your ear. 
Of course you should bake it without the driver (or at least without the membrane).


----------



## KristinNelson

It's incredible, I would also like such an amplifier. Recently, my husband got the idea to make a table that would be adjustable in height using linear actuators. He already ordered the drives and started carving the countertop 
Welcome to this wonderful forum


----------



## chinsettawong

It's been a very long time since I made a new design of the headphones.  With the COVID-19 lock down about to be imposed here in Bangkok, I think it's a good time to start something new.  Of all the headphones I made so far, I seem to really like the JF style headphones.  This time I will make the width of the diaphragm a bit narrower but keep the length to be the same.  










The active area will be 60 mm x 120 mm.  The tensioning of the diaphragm will be so much easier with this dimension.

The frame will be 3D printed. 






Let's see how they will sound.


----------



## ts8051

Hello, thanks for your information, but he sells only 3 micron and not 2 micron.


----------



## chinsettawong

There is nothing wrong with 3 microns Mylar.  I like it a lot.


----------



## ts8051

Why Stax uses < 2 micron mmbrane? The company knows something important about it. I think that 2 micron is better in high frequency reproduction.


----------



## Torac

3 micron is better at bass reproduction, 2 micron is better at detail reproduction but both marginally sacrifice the other. Personally I like the way 3 micron sounds as anything thinner sounds bass light to me.


----------



## chinsettawong

Well, if you really want to buy 2 micron Mylar, it's readily available on Ebay.  Search for "electrostatic Mylar".


----------



## Torac

If it helps anyone, where I am most sellers won't ship the thinner mylars on eBay but I was able to source different thicknesses from freeflightsupplies.co.uk


----------



## chinsettawong

I was having some problems with my CNC machine since I haven't been using it for over two years.  But, finally, everything is cut and ready.  Hopefully I can test them before the end of this week.


----------



## chinsettawong

They sing and sound very nice too!


----------



## Kerry

Very nice


----------



## chinsettawong

The picture below shows the size comparison between the old and new design.  As to my expectation, the bass on this new pair goes deeper since I was able to stretch the diaphragm a little less than the old pair.  The sound stage is nice and large similar to the old pair.  I like them a lot








I encourage you guys to try to build a pair of large headphones without the ear pads.  You might be surprised how good they sound.


----------



## Christer

chinsettawong said:


> The picture below shows the size comparison between the old and new design.  As to my expectation, the bass on this new pair goes deeper since I was able to stretch the diaphragm a little less than the old pair.  The sound stage is nice and large similar to the old pair.  I like them a lot
> 
> 
> 
> ...


These remind me of my Jecklin Floats Electrostats stripped of their plastic helmet.
The only real fault I remember with those was the lack of deep strong bass .
I´d love to hear what yours sound like with Bach´s Toccata and Fugue in D-minor. Or Strauss´s Also sprach Zarathustra.
Do they do 33HZ cleanly?
My Jecklin Float did not .
Cheers CC


----------



## ochildrift

Nice bass bro. I tried making one but, with ear pads and I must say, the quality is not good. It sounds distorted and fuzzy.


----------



## chinsettawong

Which one did you make?  I don’t see how any of the good built electrostatic can sound fuzzy and distorted.


----------



## chinsettawong (Aug 12, 2021)

I think the headphones are completed now.  







I would like to propose an open source project for this pair of headphones.  I will share all of the designs and hopefully they can be a good starting ground for future improvements and become one of the most popular DIY headphones.  Would this idea be of any interest to you guys?


----------



## BURNART

Sure! That will be great


----------



## chinsettawong

We need a good name for the headphones.  May I hear some ideas?


----------



## KDS315

How about Chinsettastats?

VERY impressive what you have done!!


----------



## chinsettawong

Thanks for your recommendation, KDS315.  I'm thinking of making the name Delta, as it'll be remembered that it's first designed and built during this COVID Delta variant time.    What do you think?  

I'll share all of my other designs too.  So, I'm thinking of the Orpheus clone - Alpha, and the Omega clone - Omega.


----------



## BURNART

Orpheus, Omega and Alpha is from Greek so maybe other mythology


----------



## chinsettawong (Aug 17, 2021)

Something Thai?  How about Bangkok, Pattaya, and Chiangmai?    Or Padthai, Tomyum, and Mudsamun?


----------



## BURNART

Digamma, Stigma, Heta, Jot, San, Koppa


----------



## KDS315

chinsettawong said:


> Something Thai?  How about Bangkok, Pattaya, and Chiangmai?    Or Padthai, Tomyum, and Mudsamun?


Kop khun kap!! 😉


----------



## chinsettawong

So, here are as I promised.  I present you with my newest headphones design.  Please respect my effort and do not make them for commercial purpose.  I welcome you to make any improvement changes and please share them back to us.

Here are the CAD files for my Float stator and spacer: https://www.dropbox.com/sh/f2v7gayclujcxvk/AAAdUYXyMobV4Vcdwu1fBDZTa?dl=0

And here are the 3D designs for the frame and front and back baffle:    https://www.tinkercad.com/things/7cnuEwkIMGL


----------



## Tachikoma

chinsettawong said:


> Thanks for your recommendation, KDS315.  I'm thinking of making the name Delta, as it'll be remembered that it's first designed and built during this COVID Delta variant time.    What do you think?
> 
> I'll share all of my other designs too.  So, I'm thinking of the Orpheus clone - Alpha, and the Omega clone - Omega.


The Covid-19 variants are already catching up to the Stax lineup - we're at Lambda now.

Maybe the Prayut since it vaguely resembles his head


----------



## quinnmcc (Aug 21, 2021)

I'm not sure if this is the correct thread for my question. I have long had the idea to paint my headphones  in a way like in this picture.  What paints can be used for that? I would like to use acrylic extra fine tip markers, but will they ok for plastic?


----------



## chinsettawong

quinnmcc said:


> I'm not sure if this is the correct thread for my question. I have long had the idea to paint my headphones  in a way like in this picture.  What paints can be used for that? I would like to use acrylic extra fine tip markers, but will they ok for plastic?


Sorry, can't help you with your question.


----------



## chinsettawong

I've been listening with my new headphones for a while now.  I can confirm that they sound really good.  I like them even better than my Orpheus and Omega clones.  They are very light and comfortable to wear.  I highly recommend you guys to build.  If there is any questions, I'm always here to help.


----------



## Tjj226 Angel

When you say you like them more than your other headphones, is that strictly referring to sound quality, or is it the overall experience. If it is the latter, which ones are still your favorite for pure sound quality?


----------



## KDS315

Tjj226 Angel said:


> When you say you like them more than your other headphones, is that strictly referring to sound quality, or is it the overall experience. If it wb babyis the latter, which ones are still your favorite for pure sound quality?


Who hates his own baby??


----------



## Tjj226 Angel

KDS315 said:


> Who hates his own baby??



I think you found a glitch in the matrix there. That's not what my post says. 

Here is a copy and paste of my post. 

When you say you like them more than your other headphones, is that strictly referring to sound quality, or is it the overall experience. If it is the latter, which ones are still your favorite for pure sound quality?


----------



## chinsettawong

The best thing I like is the comfort.  The weight is very light and there is no clamping force.  I can wear them for hours without feeling tired.  The sound quality is very impressive.  I feel that there is enough deep bass.   By the way, if you want, you can make a pair of sealed ear pads for them.  And I’m sure that the bass will improve a little more.


----------



## chinsettawong

Seeing that Stax has come out with a pair new headphones with mesh stators, I really like to give it a try.  But how can I stretch the wire mesh so that it’s absolutely tight and flat?


----------



## Tachikoma

Maybe some combination of tension and heat annealing...


----------



## Ulfar4

I think you have to do some support for the mesh, maybe from fr4? But there will be definitely problem with flatness.

Can I ask what mesh is that?


----------



## chinsettawong

Ulfar4 said:


> I think you have to do some support for the mesh, maybe from fr4? But there will be definitely problem with flatness.
> 
> Can I ask what mesh is that?



According to the seller, it's 80 mesh.  About the back support, I will go with acrylic just like what Stax uses with its original Omega.  I have a laser cutter and so cutting acrylic isn't a problem at all.


----------



## Roukii

https://item.taobao.com/item.htm?sp...r9SPs&id=555248005538&ns=1&abbucket=17#detail
maybe this stuff can help you to tension the copper mesh and keep flat


----------



## GY3288

Torac said:


> 3 micron is better at bass reproduction, 2 micron is better at detail reproduction but both marginally sacrifice the other. Personally I like the way 3 micron sounds as anything thinner sounds bass light to me.


What if you use the <1.5 microns membrane?  What would be the adverse effect?


----------



## Torac (Oct 1, 2021)

GY3288 said:


> What if you use the <1.5 microns membrane?  What would be the adverse effect?


I have tried and I found anything thinner than 2 micron seems to just tear when you tension it, if you had the right jig it should be possible


----------



## lkos98

chinsettawong said:


> Seeing that Stax has come out with a pair new headphones with mesh stators, I really like to give it a try.  But how can I stretch the wire mesh so that it’s absolutely tight and flat?


I guess you can stretch it the same way as the membrane with bicycle tube and then solder to a FR4 ring. If you use a double sided 0.5-0.6 mm copper clad laminate, you can use it for spacer and stator at the same time. Still I'm afraid there are going to be vibrations of the mesh, which will lead to peaks and dips in the FR. The 31% open space also is a bit too small (but louder!!). Since Stax made it, they have definitely found a way to overcome all these.


----------



## MikaFoxx

Thought I should read all the posts before I asked any dumb questions. A few days and over 3800 messages later, here I am.

Congrats and thank you, Chinsettawong, on sticking around and continuing to innovate and educate about these homemade Endgames.

I'm just an audio and electronics hobbiest that's mostly worked on and made some vacuum tube equipment. The best I've got - and heard of headphones, is only the Hifiman 400i, so hopefully I'm in for a good surprise if things work out.
So far, I've been just doing small experiments using graphite rubbed cling wrap and 0.5mm card spacers with metal speaker grille mesh as the the stators. It sounds pretty decent (for what it is) running off a pair of 70v to 8ohm transformers in reverse, for a 90:1 step up ratio. Being lazy, I sacrificed a disused bug zapper for 500v bias, with an extra 22meg in series for some semblance of safety.

I attempted a design using metal mesh like was recently suggested after seeing the the Stax and Hifiman Shangri-la, by gluing the mesh to a sturdier backing to keep it mostly parallel, but it was fairly quiet due to slight warping away from the diaphragm, and the larger 80mm active size made the card spacers even more lacking in stiffness and insulation.

So far, it seems that I need to make a deal with someone local with CNC and 3D printing capability, and to suck it up and build a proper version of the KGSS amp. 
You most recent float design looks great, Chinsettawong, and if I can find some help, I'd love to provide a second opinion on how it sounds.


----------



## chinsettawong

MikaFoxx said:


> Thought I should read all the posts before I asked any dumb questions. A few days and over 3800 messages later, here I am.
> 
> Congrats and thank you, Chinsettawong, on sticking around and continuing to innovate and educate about these homemade Endgames.
> 
> ...



Nice!  I would love to hear what you think.  Please share your work here so that we all can enjoy together.


----------



## MikaFoxx

chinsettawong said:


> Nice!  I would love to hear what you think.  Please share your work here so that we all can enjoy together.


It's going to be a bit of a slow process to make a proper version of your floats, but once I get past the 5 messages or so I'd be happy to show off a few pics of the initial concept experiments, as bad as they are. I have a friend that has leftover 6 micron mylar from some quad ESL63's, how does it compare to your preferred 3 micron? I know the original Stax models of the 60's used it, so it can't be too bad. 
The KGSS is quite a radical design - no coupling capacitors anywhere - unlike any other audio gear I've made or worked on. Might try to make a dynalo amp first, the KGSS low impedance equivalent, to see how it Stax up.


----------



## chinsettawong

6 microns Mylar is nice too.  I’ve tried it before and really liked it.  

I would really love to see your work.

Yes, most of KG’s amp designs are direct coupling.  There is no need for the expensive coupling capacitors.  KGSSHV Carbon is very, very nice.  I highly recommend it.


----------



## MikaFoxx

Just a few more questions or ideas.
Have you thought about attempting a closed back electrostat like the Koss ESP 6-10?
I've got an old pair of crappy headphones with a similar build I could give a go with.
Speaking of Koss, I heard that the ESP 95x doesn't have dust covers? Not sure if that's true or not, but considering issues people have on this thread, it would seem like quite the oversight. Might be neat to investigate their driver make-up as nobody here seems to have talked about it yet.

As for the KGSSHV Carbon, I would be building it myself, and I can't find too much for schematics or details for the HV or Carbon, and the KGSS would still be miles and leagues above the repurposed transformers I'm using now. Plus I've most likely got silicon that's suitable for it but not the upgraded versions; I'm on a fair budget. My first few are probably going to look a lot more like the person's in the YouTube clips you've shared than your latest works. 
Someone previously mentioned microwave oven mesh as a material for stators and I may jump on that if I can source some before someone with a CNC. I'll be sure to share any progress, and I'll be making rectangular float sized drivers as that's a lot easier to cut.

One more thing. I've been using contact cement and it doesn't have a very good bond against the film if I coat only the spacer and press it against the film, even still wet. Once it dries, it doesn't have much holding power. Coating both holds far better, but then you most likely get some glue into the active membrane area. Any suggestions?


----------



## chinsettawong

The electrostatic headphones sound far better with open back.  You can try coving the back side with your hand and you'll know.  I really don't recommend a closed back design.

Any amp that can drive the headphones is fine.  Even simple step up transformers can sound very nice too.  I don't really care about the look of your headphones, I just like to see and appreciate your works.  

I'm not sure if we are using the same kind of glue.  The contact cement that works great for me is the yellow rubber type.  It smells rather bad and it's solvent base.  In my country, it's known as the glue for gluing shoe soles.


----------



## lkos98

I support everything Chensettawong said above. Any closed back even simple damping foam affects the sound badly. Once covered with hands it becomes like a mono phones. 
For the glue - yes contact cement glue is the best for me as well. In my latest design I made thin 0.8 mm channels (with CNC) in the frame (spacer) and press out the contact cement glue with a syringe in the channel, so it just covers it. It works great, the membrane sticks perfectly and there are no bumps, glue-less spots, etc.


----------



## ts8051

chinsettawong said:


> According to the seller, it's 80 mesh.  About the back support, I will go with acrylic just like what Stax uses with its original Omega.  I have a laser cutter and so cutting acrylic isn't a problem at all.


Hello, Please do you know a seller who sells the membrane 2micron or 3 micron for the electrostatic headphones ? The seller in Taiwan via ebay stoped selling this material. I live in Greece and here does not exist such material. I checked on the whole Europe and i found it in Germany before corona virus era, as i remember, with astronomical price per meter.


----------



## chinsettawong (Oct 16, 2021)

ts8051 said:


> Hello, Please do you know a seller who sells the membrane 2micron or 3 micron for the electrostatic headphones ? The seller in Taiwan via ebay stoped selling this material. I live in Greece and here does not exist such material. I checked on the whole Europe and i found it in Germany before corona virus era, as i remember, with astronomical price per meter.



I just checked Ebay and the Taiwanese seller is still selling it:  https://www.ebay.com/itm/Electrosta...2349624.m46890.l49286&mkrid=711-127632-2357-0


----------



## ts8051

Thanks!!!!


----------



## c12Windfury

Now that Koss no longer sales the extension cable what's a good one to use now that's affordable?


----------



## defaultchi

Thanks for sharing!


----------



## Roukii

I encountered a problem. After listening my SR-007mk1 for 10 minutes or so, the sound pressure level will gradually decrease. Put it aside and wait for a while, and it will recover again. Has someone met the similar situation?


----------



## KDS315

Sounds like a Biss voltage issue;


----------



## ts8051

chinsettawong said:


> Very nice work Congo5.  I really like the way you make your headband.
> 
> By the way, on my side, I've upgraded my headphones with professionally made stators and spacer rings.  The stators are made from double sided PCB with plate through holes.  Now it's very easy to solder the wires on either side and the copper trace doesn't get in the way of the spacer rings anymore.
> 
> For some unclear reasons, after the upgrades, my Orpheus clone and Omega clone are quite a bit more efficient.  They sound as loud as my Stax SR009 now.  I have to remake the diaphragms since using the old ones and they are not able to keep stable.  The dynamic and bass also get much better.  You guys should try.


Hello again,
In all cases when my diy electrostatic headphones, even with best frequency responce, sticks to one stator because of a accidental vibration (small). It sticks only with non conductive coating. How can i avoid this problem? After many years of development i cant find the solution.


----------



## chinsettawong

ts8051 said:


> Hello again,
> In all cases when my diy electrostatic headphones, even with best frequency responce, sticks to one stator because of a accidental vibration (small). It sticks only with non conductive coating. How can i avoid this problem? After many years of development i cant find the solution.


I did state again and again that the most difficult thing about making the headphones is to stretch the diaphragm to the right tension.  With the given voltage, you can either increase your diaphragm tension or increase the spacer thickness.  Lately, I have been making spacers using 20 to 40 microns plastic sheet to add additional thickness to the spacers.   I too run into the problem of having the diaphragm sticking to one of the stators, and by adding additional thickness, it helps a lot.


----------



## Ulfar4

I can only confirm what chinsettawong said above. I did the same, I increased spacer thickness little bit, I have amplifier with lot of power margin so it doesnt bother me that I lost some sensitivity.


----------



## ts8051

chinsettawong said:


> I did state again and again that the most difficult thing about making the headphones is to stretch the diaphragm to the right tension.  With the given voltage, you can either increase your diaphragm tension or increase the spacer thickness.  Lately, I have been making spacers using 20 to 40 microns plastic sheet to add additional thickness to the spacers.   I too run into the problem of having the diaphragm sticking to one of the stators, and by adding additional thickness, it helps a lot.


i recently discovered that when i make conductive the other side of membrane there is no problem about sticking to the stator surface. I thought this because always the membrane was sticking with its non conductive side.


----------



## ts8051

chinsettawong said:


> I did state again and again that the most difficult thing about making the headphones is to stretch the diaphragm to the right tension.  With the given voltage, you can either increase your diaphragm tension or increase the spacer thickness.  Lately, I have been making spacers using 20 to 40 microns plastic sheet to add additional thickness to the spacers.   I too run into the problem of having the diaphragm sticking to one of the stators, and by adding additional thickness, it helps a lot.


have problem with membrane tension because i use the same weights every time (the value of weights are from expemiments in order to have the resonance frequency  below 100Hz). Every membrame produced with this method is identical. It is possible to play for days without problem and some momement the membrane sticks to the stator (only with the non conductive side) because some vibration. But yesterday i made both membrane surfaces conductive and the result is that the it plays louder and without sticking to the stator.


----------



## chinsettawong

ts8051 said:


> But yesterday i made both membrane surfaces conductive and the result is that the it plays louder and without sticking to the stator.


Really?  I’ll try that!


----------



## chinsettawong

Can you share with us how you stretch your diaphragm?  How much weight do you use? @ts8051


----------



## ts8051

chinsettawong said:


> Really?  I’ll try that!


test it, but later i discovered some noises and cracks heared from headphones in high sound levels. Possibly the space between membrane and stator ionized and become conductive. Please test it and let me know. Now i cleaned the with accetone and it plays as before applying conductive layer. Possibly i put higher amount of licron.


----------



## ts8051

chinsettawong said:


> Can you share with us how you stretch your diaphragm?  How much weight do you use? @ts8051


I use weights as in the attched picture. Each weight is 600gr


----------



## chinsettawong

ts8051 said:


> I use weights as in the attched picture. Each weight is 600gr



Your method looks easy and interesting.  Thanks for sharing.


----------



## ts8051

chinsettawong said:


> Your method looks easy and interesting.  Thanks for sharing.


With this method the produced tensined membranes are identical.


----------



## ts8051

ts8051 said:


> With this method the produced tensined membranes are identical.


In stax headphones the gap is 0.5mm and the membrane stays safe when it plays loud or with mechanical vibrations. There is a secret which we must discover.


----------



## lkos98

ts8051 said:


> I use weights as in the attched picture. Each weight is 600gr


Hi, nice stretching jig. Why 4 diaphragms? And what is the deviation of those around 100 Hz? Asking, because with a similar method I got at least 5-10 Hz difference between the membranes - one is 90, other 95, some may go even up to 110. 
As for the membrane sticking to the stator - I think coating side has nothing to do with it, may be stator at the uncoated side is bend slightly in the middle or DC biased.


----------



## ts8051

lkos98 said:


> Hi, nice stretching jig. Why 4 diaphragms? And what is the deviation of those around 100 Hz? Asking, because with a similar method I got at least 5-10 Hz difference between the membranes - one is 90, other 95, some may go even up to 110.
> As for the membrane sticking to the stator - I think coating side has nothing to do with it, may be stator at the uncoated side is bend slightly in the middle or DC biased.


Hello, If before hanging the weights apply some presure on the membrane over glass in order to avoid bubbles then we can achive a uniform tension. I produce 4 membranes in order to have extra 2 as spares for the future and because the membrane has big surface. Realy the frequency responce is the same as you mentioned. I discovered that the weight of 600gr is enough. If i use for example 550gr the frequency responce is 85Hz but it is unstable and sticks easily to the stator. As you can see in the photo the membranes are in the center of tensioned membrane in order to have uniform tension. But in my later experiments i make 6 membranes having uniform tension. Also i observed that the mounting screws must be tight in order to maintain the membrane parallel to the stators and avoid sticking.  Always i put on ears the non conductive side of the membrane because in other case the humidity produced by ears is a cause of problems.


----------



## ts8051

ts8051 said:


> With this method the produced tensined membranes are identical.


Please do you know a simple  but effective amplifier for these headphones?


----------



## lkos98

ts8051 said:


> Please do you know a simple  but effective amplifier for these headphones?


My amp is DIY, but is different type (single ended), so I can't help you with that. It was discussed several times, if you are into tube amps, Chinsettawong has posted one (just browse first pages of the thread). Otherwise it can be made pretty simple with 3-4 HV transistors (per channel) as a differential couple and current source. 
What is your active area by the way, because 100Hrz free resonance is very low and I'm not surprised membrane sticks to the stator. Also try to avoid frequencies multiply to 50, because this is the line frequency (unless you live in USA), and 100 is the second harmonic - may create bump there. Just as a test, I would increase the weight so I get at least 105-110, thus you will get more stability and at the same time avoid the 50 Hz second harmonic.


----------



## wppk

Roukii said:


> I encountered a problem. After listening my SR-007mk1 for 10 minutes or so, the sound pressure level will gradually decrease. Put it aside and wait for a while, and it will recover again. Has someone met the similar situation?


Nope... and it seems very odd...


----------



## ts8051

lkos98 said:


> My amp is DIY, but is different type (single ended), so I can't help you with that. It was discussed several times, if you are into tube amps, Chinsettawong has posted one (just browse first pages of the thread). Otherwise it can be made pretty simple with 3-4 HV transistors (per channel) as a differential couple and current source.
> What is your active area by the way, because 100Hrz free resonance is very low and I'm not surprised membrane sticks to the stator. Also try to avoid frequencies multiply to 50, because this is the line frequency (unless you live in USA), and 100 is the second harmonic - may create bump there. Just as a test, I would increase the weight so I get at least 105-110, thus you will get more stability and at the same time avoid the 50 Hz second harmonic.


Hello, if you have resonance frequensy more than 100Hz did you tested what is the lowest frequency which can produce the headphones? In my headphones is 20Hz


----------



## lkos98

ts8051 said:


> Hello, if you have resonance frequensy more than 100Hz did you tested what is the lowest frequency which can produce the headphones? In my headphones is 20Hz


My design is a bit different - 2 membranes/1 stator, so I can't tell what is with normal 2 stators/1 membrane designs. My free resonance at the moment is 165 Hrz (90mm active area). I had an overwhelming bass (+15dB at 15Hrz) with 105 Hrz free AR, so I also thought that increasing it would decrease the bass. But it didn't change at all, almost same FR. IMO free air resonance doesn't affect much the lower produced bass, because these phones are not open at both sides like ESL. Volume is closed between your ear and membrane, so the pressure is equalized in low frequencies and free air resonance is damped (same when you put dynamic speaker in a sealed box). When this volume is not sealed properly, there is huge difference. It's easy to test - just pull out the phones slightly from your ears and deep bass is gone. Measuring the FR shows the same - sealed phones produce almost the same low frequencies independently of the free air resonance. I think active area has much more impact on the bass, than the free air resonance, because the area defines the moving volume. With my latest experience I think bias voltage also has big impact, still can't figure out why. Same phones with 600V bias produced much more bass than with 330V. (my wild guess is because of the increased SPL).


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## ts8051

Hello, It is very interesting concept. Where can i find more details about this concept? What amplifier is needed for this construction?


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## lkos98

ts8051 said:


> Hello, It is very interesting concept. Where can i find more details about this concept? What amplifier is needed for this construction?


In this thread . Amplifier is single ended driving one stator. Please note sensitivity is lower than with the standard design, so you have to drive it with high amplitude and high voltage biases.


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## ts8051

Hello, as i understood you apply signal to the stator from a single ended amplifier and apply high bias voltage on the two membranes. Is it correct?


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## lkos98

ts8051 said:


> Hello, as i understood you apply signal to the stator from a single ended amplifier and apply high bias voltage on the two membranes. Is it correct?


Yep, that's correct, but the biases are positive to one membrane and negative to the other. Could be made with 0 and +HV, but then the single ended amp should be DC biased to 1/2 of the +HV.


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## ts8051

As i understood the membranes are oscilating with180 degrees different in face. I think that it the same can be done if you use a stax amplifier signal on two membranes and positive bias on the single stator


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## lkos98

ts8051 said:


> As i understood the membranes are oscilating with180 degrees different in face. I think that it the same can be done if you use a stax amplifier signal on two membranes and positive bias on the single stator


No, membranes move in phase with trapped air between them, acting as one membrane (in dynamic speakers it's called isobaric configuration).  
Using differential amp driving the membranes cannot be done, because they are with very high resistance coating (in order to get constant charge), you need low resistance membranes (aluminum foil) to do that, but it adds distortion.


----------



## ts8051

lkos98 said:


> No, membranes move in phase with trapped air between them, acting as one membrane (in dynamic speakers it's called isobaric configuration).
> Using differential amp driving the membranes cannot be done, because they are with very high resistance coating (in order to get constant charge), you need low resistance membranes (aluminum foil) to do that, but it adds distortion.


Hello, first what better in frequency responce can we have with aluminum foil instead of membrane? The membrane can be tensioned but aluminum foil no. Did you tested this ? Did you measure the frequency responce? Also please explain why this system is better than the normal with one membrane and two stators?


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## ts8051 (Jan 4, 2022)

lkos98 said:


> No, membranes move in phase with trapped air between them, acting as one membrane (in dynamic speakers it's called isobaric configuration).
> Using differential amp driving the membranes cannot be done, because they are with very high resistance coating (in order to get constant charge), you need low resistance membranes (aluminum foil) to do that, but it adds distortion.


I found this diagram:






What can you say about the above diagram? I supose that the stator has the bias voltage and the membranes are connected with a stax amplifier. But if this can work, what is the benefit in contrast with a one membrane tranducer?


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## lkos98

ts8051 said:


> Hello, first what better in frequency responce can we have with aluminum foil instead of membrane? The membrane can be tensioned but aluminum foil no. Did you tested this ? Did you measure the frequency responce? Also please explain why this system is better than the normal with one membrane and two stators?


Hi. First, aluminium foil is not better because it's heavier and cannot distribute the charge evenly. It also produces a bit of metallic sound. 
On your second question - I can't say it's better, I think both designs are very good in sound. I just wanted to create something different, because the best fun is when you do something with your hands. As for the pros and cons (in my opinion), please browse back in this forum, I have posted pictures, explanations, FRs, etc.


----------



## MikaFoxx

Having heard of there being SR-X MKIII Pro clones, that got me thinking, before realizing it was a Gamma Pro driver swap. 
But why not clone the SR-X pro driver itself? Being so small, it should be relatively easy compared to the larger surface area diaphragms.

Does anyone here have some specifications of the driver dimensions, damping, etc, of these original series? From what I can tell the SR-5 and SR-X MKIII NB are identical drivers, whereas the SR-1–3, and SR-X MKI–II have smaller drivers, but that's about it.

Perhaps more models should have their driver specifications dumped in here, like the Lambda pro or Omega II. I'm sure someone, if not me, would like to give those rarer models a go.

I took a few month break from electrostat research but I did manage to throw together a ~5cm diameter driver in an afternoon from stuff laying around in the house. It's just thin card backed with aluminum foil on one side, with a graphite dusted kitchen wrap diaphragm. It sounded pretty good and surprisingly loud for something with a ~0.7mm gap. It ain't pretty, but it works.. somehow.


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## MikaFoxx (Feb 8, 2022)

Just some additional thoughts:

Since Stax connectors are so difficult to get, should a common DIY headphone and amp connector be chosen? Perhaps an XLR-6, if it's rated for the voltages involved. 

I'll probably try for another driver in the coming days, either using the screen from a microwave oven door, or painstakingly drilling holes manually in some FR4 that is probably thicker than it aught to be. I'll stick to ~5cm circular drivers considering the drilling involved. Plus it'll be close enough to an SR-X Pro if I get a pair of em going.

Update: Rectangular is a lot easier to do by hand. Going to try for 6cm square drivers, 1.6mm FR4 with 81x 2.5mm holes.
Gonna try a carpet cleaner instead of messy graphite.


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## chinsettawong

I used to use a 6 pins din connector for my headphones, and it worked fine.  It’s very cheap too.






As for the coating material for the diaphragms, have you ever tried the floor cleaning liquid?  I use this:


----------



## MikaFoxx

chinsettawong said:


> I used to use a 6 pins din connector for my headphones, and it worked fine.  It’s very cheap too.
> 
> 
> 
> ...


The DIN looks good, I probably have a few. What was your choice of pinout? (In case we do make this an alternative for homebrew)

I'll start out by testing various cleaners on cheap kitchen wrap diaphragms until I find one that works well.
In the meantime I've used a pair of 0.125-5W 70V-8ohm audio transformers at a ratio of ~45:1. Even my little 5 watt tube amp made it plenty loud. One could make it self-bias if they wanted.
Might be a good candidate for others looking to make cheap test energizers since they're audio rated cores. Capacitance and voltage rating notwithstanding..


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## lkos98

MikaFoxx said:


> The DIN looks good, I probably have a few. What was your choice of pinout? (In case we do make this an alternative for homebrew)
> 
> I'll start out by testing various cleaners on cheap kitchen wrap diaphragms until I find one that works well.
> In the meantime I've used a pair of 0.125-5W 70V-8ohm audio transformers at a ratio of ~45:1. Even my little 5 watt tube amp made it plenty loud. One could make it self-bias if they wanted.
> Might be a good candidate for others looking to make cheap test energizers since they're audio rated cores. Capacitance and voltage rating notwithstanding..


I'm using Aviation plug GX12 or GX16 5 pins, which is much more expensive, why I did it?? - my stupidity I guess - DIN looks perfect for this and is safe enough. 
For coating I also used floor cleaners, but lately a softeners (diluted about 50/50 with water), the floor cleaners which I buy here, seem to have too low conductivity. 
A quick question - so you use 5W tube amp which already has inside a transformer of lets say ~45:1 ratio, and you connect another transformer 1:45 to get high voltage on the output? Can't you just connect, if possible, the phones straight to the tube anodes? You will get a better response I think. 
I was also thinking of creating self biased energizer, but I gave up because I thought what can happen when you pause the music, ort it's extremely quiet? If you do this please let me know how it works for you, the charge should be stable for at least 2-3 mins, but in 10 mins, or just after you switch on the amp? Yes it's cheap, but there are also some cheap solutions with DC-DC converters on ebay.


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## tib8 (Feb 10, 2022)

I use 6 pin SP13 Aviation connector (IP68), which can be found cheap on AliExpress, it is plastic, but very good quality, does not melt like DIN connector during soldering.


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## MikaFoxx

lkos98 said:


> I'm using Aviation plug GX12 or GX16 5 pins, which is much more expensive, why I did it?? - my stupidity I guess - DIN looks perfect for this and is safe enough.
> For coating I also used floor cleaners, but lately a softeners (diluted about 50/50 with water), the floor cleaners which I buy here, seem to have too low conductivity.
> A quick question - so you use 5W tube amp which already has inside a transformer of lets say ~45:1 ratio, and you connect another transformer 1:45 to get high voltage on the output? Can't you just connect, if possible, the phones straight to the tube anodes? You will get a better response I think.
> I was also thinking of creating self biased energizer, but I gave up because I thought what can happen when you pause the music, ort it's extremely quiet? If you do this please let me know how it works for you, the charge should be stable for at least 2-3 mins, but in 10 mins, or just after you switch on the amp? Yes it's cheap, but there are also some cheap solutions with DC-DC converters on ebay.


Fabric softener? I'll give that a go first then.

I considered using the primary from the amp, but then it would be a single pole electrostat
 (not very good) as it's single ended class A.

Self biased energizers would be good for testing how leaky the membranes are, whereas a constant bias might hide that. It would also just be a neat experiment. I think I've got some tiny hammond tube output transformers that could be rigged up on the headphones like the Koss ESP6's, for a cute portable headphone. It probably wouldn't sound as good as a proper energizer or amp, but still far better than the (above) average dynamic.

I still haven't taken to the task of drilling the FR4 by hand, but my impatience is overcoming that daunting task. Perhaps this afternoon.


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## ts8051

chinsettawong said:


> Your driver looks really nice. How big is your active area?
> If I were to do a new set of stators, I would try double sided PCB with the thickness of around 0.6 mm. This is what Stax uses for making its stators too.


Hello, I use 1.6mm single sided pcb as stator material in order to have flat stators. If you use 0.6mm or 0.5mm  single or double sided pcb i suppose that the produced stators are not as flat as required. Of course the drilling is easier than in the case of 1.6mm pcb material.

Theologos


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## chinsettawong (Mar 2, 2022)

@Trance_Gott  confirmed that the dimension of the new Audeze CRBN is almost the same as my DIY phones.


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## Ulfar4

chinsettawong: Very nice to see them side by side. I am tempted to do another pair with those oval shape to compare the sound to 80mm circular shape which I used before.

Btw, do you stick with the stators from pcb manufacturers or did you go back to self CNC drilled one?


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## chinsettawong

I haven’t used my CNC for a long while now.  I guess my fire has run out.


----------



## miketlse

chinsettawong said:


> I haven’t used my CNC for a long while now.  I guess my fire has run out.


Remember life is a journey, not a destination.
If you have paused for a while, that is not a disaster.
Maybe one of the followers of your thread needs to pick up the baton for a while, until you can return.


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## chinsettawong (Apr 12, 2022)

I want to share a new coating material that I’m trying right now.  Since the Audeze comes out with CRBN and it’s membranes contain carbon nanotubes, I’ve been reading about the material and somehow come to know that a similar material called graphene.  It has a good electrical conductive property as well.  Well, guess what, quite a few car care products nowadays have graphene as one of the main ingredients.  So, I’ve bought a bottle to try, and I’m happy to report that it works.  Try google “graphene car care”!  You’ll find many products.

Now I can proudly say that my headphones’ diaphragms contain nano carbon particles too.


----------



## tumpux

How do you exactly make the grapheme stick to the membrane?
Is spraying it enough to make it stick?


----------



## chinsettawong

tumpux said:


> How do you exactly make the grapheme stick to the membrane?
> Is spraying it enough to make it stick?


I spray the coating on a piece of lint free cloth and simply wipe it on the diaphragms.  When it’s dried, I buff it off with a dry cloth.


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## lkos98

chinsettawong said:


> I spray the coating on a piece of lint free cloth and simply wipe it on the diaphragms.  When it’s dried, I buff it off with a dry cloth.


Very nice! Thanks for the info. This could be a very good coating, because graphene is of relatively low weight. I would like to ask you if you can measure the resistance (coin method), because I'm afraid it could be quite low. Also if you can share the long term experience (did it stick to the membrane for a long time)? Thanks Wachara.


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## chinsettawong

When I have the test results, I’ll let you know.  About a long term experience, you’ll have to wait a few more years.


----------



## mattmatt

Hey guys, anyone have tried having your parts milled by 3rd party manufacturers like jlcpcb? is there a way to create a gerber file from dxf file?


----------



## Torac

mattmatt said:


> Hey guys, anyone have tried having your parts milled by 3rd party manufacturers like jlcpcb? is there a way to create a gerber file from dxf file?


I have had many parts made with jlc. I use Eagle and import my dxf onto the different layers necessary and then export the Gerber and drill files necessary. The only thing to be wary of is tolerances as they won't want to drill holes too close too each other.


----------



## mattmatt

Torac said:


> I have had many parts made with jlc. I use Eagle and import my dxf onto the different layers necessary and then export the Gerber and drill files necessary. The only thing to be wary of is tolerances as they won't want to drill holes too close too each other.


Hello Torac, is it okay to shoot you a pm and ask some questions?


----------



## Torac

mattmatt said:


> Hello Torac, is it okay to shoot you a pm and ask some questions?


Sure


----------



## CarlosBryant

Hi all
what is the cheapest and best sound option for using transformers?

who uses any transformers, I have so far found with the best transformation ratio 220v-> 3v
but I think there is more with a larger coefficient
e.g. 380 -> 1v or something like that
but they are hard to find


----------



## miketlse

CarlosBryant said:


> Hi all
> what is the cheapest and best sound option for using transformers?
> 
> who uses any transformers, I have so far found with the best transformation ratio 220v-> 3v
> ...


This thread sometimes discusses suppliers of bespoke transformers, but the number of suppliers is decreasing.


----------



## lkos98

chinsettawong said:


> When I have the test results, I’ll let you know.  About a long term experience, you’ll have to wait a few more years.


Sure, if the coating goes off for 3 days, it can't be any good.


----------



## lkos98

CarlosBryant said:


> Hi all
> what is the cheapest and best sound option for using transformers?
> 
> who uses any transformers, I have so far found with the best transformation ratio 220v-> 3v
> ...


Hi, I used transformers at one point - 220 - 12V. It was ok, but the bass struggles a lot and there is huge distortion at very low frequencies (bellow 50 Hrz). You can find audio transformers for ESLs (or reverse an audio transformer of tube amp), but they are so expensive, that I think it's worth using an amp.


----------



## chinsettawong

lkos98 said:


> Sure, if the coating goes off for 3 days, it can't be any good.


The coating has been good and I’ve converted all of my phone’s coating into this one.  So far, I think it’s better than the floor cleaner I had been using.  Some diaphragm unstable issues on my phones are gone after using this coating.  The sound also seems to be more balanced.  Anyway, I’ll report back my experience from time to time.


----------



## lkos98

chinsettawong said:


> The coating has been good and I’ve converted all of my phone’s coating into this one.  So far, I think it’s better than the floor cleaner I had been using.  Some diaphragm unstable issues on my phones are gone after using this coating.  The sound also seems to be more balanced.  Anyway, I’ll report back my experience from time to time.


Great news, any idea of the resistance? I mean do they sound louder (or quieter) with this coating, than with the floor cleaner? I'll start looking for this, because I think it's lighter than the soap derivatives and probably could be distributed evenly on the membrane. For example I'm using now fabric softener which sounds louder than floor cleaner, meaning lower resistance, but high enough to be measured directly with ohmmeter.


----------



## chinsettawong

lkos98 said:


> Great news, any idea of the resistance? I mean do they sound louder (or quieter) with this coating, than with the floor cleaner? I'll start looking for this, because I think it's lighter than the soap derivatives and probably could be distributed evenly on the membrane. For example I'm using now fabric softener which sounds louder than floor cleaner, meaning lower resistance, but high enough to be measured directly with ohmmeter.


No, the sound is not louder, but I feel that the sound is a little more balanced between the left and right channels.  The diaphragms are also more stable.  Previously on my Orpheus clone, sometimes when I move the cups, the diaphragm might collapse to one of the stators.  After using this new coating, this problem improves a lot.  Now I can even press on the cup against my face and the diaphragm remains stable.  I think the floor cleaner I previously used might have much lower resistivity than this graphene coating.  I’ll try to make some measurements this weekend and will report back.


----------



## chinsettawong (Apr 24, 2022)

I’m not sure if the method I measure is correct, but the result of the resistance per square using 1,000V shows that the resistance is more than 4,000 MOhm.


----------



## KDS315 (Apr 24, 2022)

You're using a MegaOhm Meter, so it should be correct (If not out of range)


----------



## chinsettawong

It’s actually out of range.  Using 1000V and it’s measured over 4 Giga Ohm.  My meter is unable to measure it.  I think the resistivity is very high and it should be good for our application.  By the way, until today the coating is still performing well and my phones sound very nice.


----------



## lkos98

chinsettawong said:


> I’m not sure if the method I measure is correct, but the result of the resistance per square using 1,000V shows that the resistance is more than 4,000 MOhm.


Thanks! If you can't measure with Mohm meter, the resistance is high enough. I even think 4Gohm is too high, because it's comparable with parasitic resistances (especially with wooden frames), but nevertheless if it sounds good, all is ok. I'll start looking for this coating. Thanks Wachara.


----------



## tib8

chinsettawong said:


> No, the sound is not louder, but I feel that the sound is a little more balanced between the left and right channels.  The diaphragms are also more stable.  Previously on my Orpheus clone, sometimes when I move the cups, the diaphragm might collapse to one of the stators.  After using this new coating, this problem improves a lot.  Now I can even press on the cup against my face and the diaphragm remains stable.  I think the floor cleaner I previously used might have much lower resistivity than this graphene coating.  I’ll try to make some measurements this weekend and will report back.


Thank you for this post and the measurement! I also had problem with the membranes collapsing to the stators (I am using 'Antistatik 100' spray for coating).
Now inspired by this post, I recoated my membranes, but this time immediately after spraying I wiped most of the fluid off from the membrane to achieve higher resistance.
The drivers still work - and they seem to be more stable. Of course only a few days passed since then and only the time will tell if they become really stable or not, but I'm optimistic.


----------



## chinsettawong

tib8 said:


> Thank you for this post and the measurement! I also had problem with the membranes collapsing to the stators (I am using 'Antistatik 100' spray for coating).
> Now inspired by this post, I recoated my membranes, but this time immediately after spraying I wiped most of the fluid off from the membrane to achieve higher resistance.
> The drivers still work - and they seem to be more stable. Of course only a few days passed since then and only the time will tell if they become really stable or not, but I'm optimistic.


Very nice!  Are you using the same brand that I use?  Do you spray it on the membrane and wipe it off with a dry cloth?  Or do you spray it on the cloth and wipe over the membrane?

Do you clean the membrane before applying the new coating?


----------



## chinsettawong

tib8 said:


> Thank you for this post and the measurement! I also had problem with the membranes collapsing to the stators (I am using 'Antistatik 100' spray for coating).
> Now inspired by this post, I recoated my membranes, but this time immediately after spraying I wiped most of the fluid off from the membrane to achieve higher resistance.
> The drivers still work - and they seem to be more stable. Of course only a few days passed since then and only the time will tell if they become really stable or not, but I'm optimistic.


I reread your post and understand now that you’re still using Antistatik 100.  Actually if you can find a good antistatic cleaner in your area, it should work well too.  I think the problem with the floor cleaner I used is that it somewhat absorbs the moisture in the air, and the resistance can change with the change of humidity.

By the way, the graphene coating is still performing very well on all my phones.


----------



## Ulfar4 (May 3, 2022)

For me Antistatik 100 never worked in long term. Probably as Wachara said above, it is because of humidity or it will just break a bond over time. Now I am using graphite coating which I rubbed on the membrane and it is working without any problem for long time. But I will give a try to graphene coating, because graphite rubbing is really time consuming when creating.


----------



## lkos98

Since I am now a proud 3D printer owner I decided to play with the "inear" ES phones I made some time ago. I did not like the bass they were producing, may be this was because of the wooden (MDF) enclosure. Today I printed new enclosures and mount all inside. I cannot express how pleasantly surprised I was with the sound! Unbelievable! They even sound louder than my over-the-ear ES phones (the spacers are only 0.5mm versus 1mm). Bass is also very good (I cannot hear any difference). I'm really very happy with these, I just need to find a way to keep them from falling from my ears all the time (may be some hook over the ear).


----------



## chinsettawong

Wow!  That’s a great news.  I’ll try to make a pair some days.  

Please share with us more photos.


----------



## lkos98

I made some back caps today with mounts for hook (copper wire). It's much better now, no need to hold the phones all the time. After some listening, I found the bass is just bit worse than with my 90 mm over the ear ES phones, which is normal (cannot compare 22 to 90 mm active area). Still I'm extremely pleased with the sound. 
Some more pictures, I don't know what else to show, so I put also the cad model.


----------



## lkos98

chinsettawong said:


> Wow!  That’s a great news.  I’ll try to make a pair some days.
> 
> Please share with us more photos.


Do it, it's fun   . Just a small advice - make the nozzle as long as possible. I made the same model with 2mm shorter nozzle. All the rest is the same. Here's the results:



I also made a wider-mesh back cover for better transparency and I'm not sure but I think the FR was more flat before. (the peak at 1khz)


----------



## chinsettawong

As long as they sound good, the FR graphs mean nothing.


----------



## lkos98

chinsettawong said:


> As long as they sound good, the FR graphs mean nothing.


True, especially in high frequencies. Please ignore my previous advice. Seems the lows depend much more on the placement of the membrane in the enclosure than the length of the nozzle. I made some more measurements and it's now opposite . It also depends a lot of the distance and angle of the earphone to the microphone axis.


----------



## tib8

lkos98 said:


> I made some back caps today with mounts for hook (copper wire). It's much better now, no need to hold the phones all the time. After some listening, I found the bass is just bit worse than with my 90 mm over the ear ES phones, which is normal (cannot compare 22 to 90 mm active area). Still I'm extremely pleased with the sound.
> Some more pictures, I don't know what else to show, so I put also the cad model.


Congratulations! You - as always - are a few steps ahead of me.
Do I see it well from the CAD model that this is again a 2 membranes/1 stator configuration?
What rate the pipe expands to the stator? Is it a simple cone with a filet or is it an exponential "horn"?
I'm not an expert in this but I heard somewhere that for acoustic impedance matching the exponential shape is the best...


----------



## tib8 (May 17, 2022)

lkos98 said:


> True, especially in high frequencies. Please ignore my previous advice. Seems the lows depend much more on the placement of the membrane in the enclosure than the length of the nozzle. I made some more measurements and it's now opposite . It also depends a lot of the distance and angle of the earphone to the microphone axis.


lkos98,
I wanted to ask your advice in the following:
I have just finished on the weekend my first 2 membrane / 1 stator headphone + the corresponding single ended amplifier.

It is has 86mm active diameter, 2um mylar membranes with 108Hz free air resonance.
The stator is made of two 0.8mm single sided PCBs, which I plan to replace with a thinner two-sided later If I can solve the below mentioned issues.
The amp has almost 800Vpp output, also the membranes are powered from the amp's power supply for simplicity (and this removed humming too).

I can use 0.6mm or 1.2mm spacers - and I use currently 1.2mm because I haven't heard difference in loudness between the two versions.
I also tried to experiment with higher or lower membrane voltages, but that did not effect the loudness either.
First question: Why? In my expectations both the distance and the voltage should be linear factors... Or should I simply use measurements instead of my ears for testing?
Also, do you have the same experience or not with yours?

I compared it with my previous "classic" 1 membrane headphone + amp.
I have only one DAC so I was not able to compare their loudness exactly, because it takes long time to switch the gears, my feeling is to get the same sound level, the DAC needs to be set 20dB lower for the old classic version. This new one has just barely enough level for normal listening at full distortion free volume (800Vpp).
Second question: I expected only -6dB difference, can't really explain this -20dB. What is your experience with yours?

This new one is a bit bass heavy for me and the highs are way too weak! They seemingly somehow "leaking" out: If I cover the headphone from outside with my hands, the highs reflect back they improve a lot! So it seems this is not the fault of my amp, but I guess it is easier for the outer membrane to vibrate highs on the outside since there is not my ear and head on that side. As a solution for this problem my only idea is to create a closed housing.... - but I'm not fond of those.
Last and most important question: Do you have the same experience? Or any idea how to solve this?

Thank you in advance!


----------



## lkos98

chinsettawong said:


> I want to share a new coating material that I’m trying right now.  Since the Audeze comes out with CRBN and it’s membranes contain carbon nanotubes, I’ve been reading about the material and somehow come to know that a similar material called graphene.  It has a good electrical conductive property as well.  Well, guess what, quite a few car care products nowadays have graphene as one of the main ingredients.  So, I’ve bought a bottle to try, and I’m happy to report that it works.  Try google “graphene car care”!  You’ll find many products.
> 
> Now I can proudly say that my headphones’ diaphragms contain nano carbon particles too.


Thanks Wachara for the tip! I ordered from aliexpress (I was not able to find anything here which is reasonable priced) 50ml EELHOE Graphene Car Coating 12H, and it works great! It sounds louder than laundry softener and seems sticks well to the mylar.  I checked first with applying it just to one of the phones and it definitely sounds louder.


----------



## lkos98

tib8 said:


> Congratulations! You - as always - are a few steps ahead of me.
> Do I see it well from the CAD model that this is again a 2 membranes/1 stator configuration?
> What rate the pipe expands to the stator? Is it a simple cone with a filet or is it an exponential "horn"?
> I'm not an expert in this but I heard somewhere that for acoustic impedance matching the exponential shape is the best...



Hi, yes that's correct, I always use my design with 2 membranes - first of all because I don't want to put dust covers and secondly I don't have at the moment differential amp. 
The pipe as far as I remember I just made it with a slanted cone to the cylinder and then made a filet, because it was easier. Exponential horn is better of course, but I don't think it make any difference with such small size and I'm sure no one (even a dedicated equipment) can sense the difference.


----------



## lkos98 (May 18, 2022)

tib8 said:


> lkos98,
> I wanted to ask your advice in the following:
> I have just finished on the weekend my first 2 membrane / 1 stator headphone + the corresponding single ended amplifier.
> 
> ...


Congratulations! Please share how they sound to you.
1. 800Vpp so did you apply +-400V to the membranes? 1.2mm with such voltage will sound quiet. But if you double these 400 to +-800, you will see a huge difference. Going to 0.6mm though even with +- 400v  will stick membrane to the stator especially with such low stretching (108Hrz). Remember it's not like normal design with one membrane which experience equal force from both stators in idle. These 2 membranes are attracted to each other with 800V electrical force, so they are always bended in the middle and closer to the stator, hence I used in my latest design dual middle stator bended like this )( . With a straight stator my experience with 0.6 mm spacers, 140 Hrz and +- 630V is that one of the membranes sticks after 5 mins to the stator. So 1.2mm is good if you want stability with +-800. And by the way distance is definitely not a linear factor - in fact it is quadratic to the e-force - (k x Q1 x Q2) / d^2. The reason you did not hear a difference is in my opinion, that membranes are stuck to the stator, discharged and of course very quiet. With 1.2mm distance and 400V it cannot be loud. Even normal design with 1.2mm spacers will be quiet (see p.3)
2. 2u mylar is in my opinion too thick for this configuration - that's one of the reason for the big bass - heavier membranes. You can try to stretch the membrane a bit more, to remove the bass, but with me this did not work - my current stretching is 170 Hrz and bass is almost the same as with 120Hrz. My opinion is that ear sealing plays much more role for the bass than stretching. I guess the only solution is to make the area smaller (which is good from esthetic point of view) and to order 1um Mylar. I love bass, so it's not that bad for me, I made some equalization to make it flat and it became a bit poor.
3. As for the loudness, ignoring the smaller space (because of the constant attraction in my design), +-400V (800V) and 800Vpp (single) should be equal to single 400V and 400Vpp (800 differential) in normal design. Assume stator is at +400V then one membrane sees 0V the other 800V. Now with normal design one stator is at -400 the other is +400, membrane is at +400. Again - one side is 0V, the other is 800, so it's the same es-force. And this is the main flow of single stator design - you have to double either the output of the amp or both biases to get the same level. I can't explain how you got such huge 20dB difference (my guess is the spacers are not the same thickness), I don't have much experience with a single membrane, but as I mentioned, I'm with +-630V now and about 580Vpp (single ended) and it's quite loud, my normal listening is at half volume. It's still quieter than a dynamic phones at the same source level, but still loud enough. If I go to high volumes my wife starts complaining - she can hear the phones pretty loud standing 2m away  .  I see now how you are going in my steps - I used to have +-300V biases and yes it was quiet, but +-630 made a huge difference. Stretching is also a nightmare - you have to stretch 4 membranes in about the same frequency (better - slightly different) and glue them and check after that again and match them by pairs. The smaller space between center of membrane and stator also plays some role in the loudness.  And if this is not enough you can always go for a higher biases (increasing amp output is not easy), by doubling the power rails voltage of your amp. 
4. Highs - something is wrong with your setup - I have measured 30kHz there without any problem. This design also has theoretically almost 0 capacitance (only cable capacitance), so it shouldn't have any problems with high frequencies. May be you have somewhere high load capacitance to the output of the amp? By the way hum and crosstalk of channels is removed with small capacitors (NO MORE than 10nF, considering about 3MOhm biasing resistors)  AFTER the biasing resistors on both +- biases to gnd. PLEASE be careful - biases become now very unpleasant - 10nF although not lethal is not pleasant to discharge through you. If you can - put 20Mohm and 1nF. And before anyone starts to blame me - I saw original STAX amp schematic with 10nF capacitors after the resistors. Just make sure you never touch naked wires, membranes is ok to touch you won't even feel the voltage. The best is to put the caps inside the phone frames, but that would require a gnd wire to run to the phone, which is inconvenient and adds additional capacitance.  
5. The highs will surely go much higher when you close the back of the phones, this should also happen with normal design or any open baffle design, but that's not a solution at all. Electrostats don't tolerate closed volume (except at your ear), they must be opened at the back. You can put a very transparent grill at the back, that would not disturb the sound waves in any way.

PS. Just remembered something. I have an ellipse design - 100x70mm AA. Used the same amp and biases. The spacers are 0.6 and membranes stuck to the stator all the time. I made some additional spacers on a 3D printer - 0.2mm (single layer) and now membranes are stable with about 0.8-0.85 mm. I think, that the shape affects also stability, because the shorter 70mm distance of the ellipse equals to a circle with 70mm diameter, but the area is much bigger. I can tell these ellipses sound the same as my 90mm circles - may be a bit louder in the mids-highs. This could be also because my circles have these thin foam inside the earpads.


----------



## chinsettawong

It’s been more than a month now, and I’m happy to report that the graphene coating has been performing very well.  I’m really happy with it.  

As always, I’m taking a set of headphones with me when traveling.  So far this is my favorite set.  What is yours?


----------



## Ulfar4

lkos98 said:


> Thanks Wachara for the tip! I ordered from aliexpress (I was not able to find anything here which is reasonable priced) 50ml EELHOE Graphene Car Coating 12H, and it works great! It sounds louder than laundry softener and seems sticks well to the mylar.  I checked first with applying it just to one of the phones and it definitely sounds louder.


That is very good price, and it is good that it is working too, I will order one too to try it.



chinsettawong said:


> It’s been more than a month now, and I’m happy to report that the graphene coating has been performing very well.  I’m really happy with it.
> 
> As always, I’m taking a set of headphones with me when traveling.  So far this is my favorite set.  What is yours?


I am still using this pair for long time, I've tried tried many different headphones over time but in the end I always ended with them.


----------



## Christer

chinsettawong said:


> It’s been more than a month now, and I’m happy to report that the graphene coating has been performing very well.  I’m really happy with it.
> 
> As always, I’m taking a set of headphones with me when traveling.  So far this is my favorite set.  What is yours?


Hmm these look very similar to my old Jecklin Float electrostats.
The  Jecklin Floats still remain one of the three most open  sounding and transparent headphones I have ever used.
I still have them ,but they are not working any longer and compared to planars with an open cup they were very transparent but weak in the bass. How deep do these go? 
And how do they compare to the  latest Stax models?
Cheers CC


----------



## chinsettawong

Christer said:


> Hmm these look very similar to my old Jecklin Float electrostats.
> The  Jecklin Floats still remain one of the three most open  sounding and transparent headphones I have ever used.
> I still have them ,but they are not working any longer and compared to planars with an open cup they were very transparent but weak in the bass. How deep do these go?
> And how do they compare to the  latest Stax models?
> Cheers CC


That’s exactly where I got the inspiration from.  I also have a pair of JF.  They sound very nice and relaxed except that they can’t be played off a Stax amp.  My version has 0.5 mm spacer and uses Stax bias voltage and thus can be played with any Stax amp.  In the picture, the phones are played off Stax D10 and they sound very nice together.

The phones have plenty of bass on my standard.  Of course, it’s not as deep and heavy as the ones with proper sealed ear pads.  But, for some unknown reasons, I always prefer them to any other headphones.


----------



## Christer (May 21, 2022)

chinsettawong said:


> That’s exactly where I got the inspiration from.  I also have a pair of JF.  They sound very nice and relaxed except that they can’t be played off a Stax amp.  My version has 0.5 mm spacer and uses Stax bias voltage and thus can be played with any Stax amp.  In the picture, the phones are played off Stax D10 and they sound very nice together.
> 
> The phones have plenty of bass on my standard.  Of course, it’s not as deep and heavy as the ones with proper sealed ear pads.  But, for some unknown reasons, I always prefer them to any other headphones.


Hello and thanks for your rapid response. So how does  your build  compare with the old original JFs´or modern Staxes?
There is also a German made, "newer" better? Jecklin Float model which I have not heard that looks almost identical to your build.
Is that the one you have?
Or  do you also still have an old orginal Jürg Jecklin model?
I stopped using mine when I bought my HD800 which had better bass but are not quite as transparent, which I have used on all my travels to SE Asia including Thailand very frequently until Covid hit.

15 winters usually  Nov to May, and  really hoping to be able  to come  again in November 2022.

If so I would really like to hear your model and compare it to my two travel headphones HD800 and HIFIMAN HEKV2 if possible.
Do you build on demand?

Personally I never listen to music  while "on the run"  only in a  quiet hotel room or the condo I used to rent in Phuket for 2-3 months every winter.
And even with my two current headphones I sometimes turned off A/C  to avoid disturbing noise.
At home I use  my quite transparent  ML  electrostatic speakers on a daily basis. But I have not used electrostatic headphones for quite a few years  now.
I sometimes still miss the amazing openess of my old JF "earspeakers".
Cheers CC


----------



## chinsettawong

I don’t want to say which headphones are better, because everybody has his own preferences.  I welcome you to try all my DIY phones when you come to Thailand again next time.  Let’s meet up and see for yourself.

If you are handy enough, you should try to make the headphones yourself.  Please read through the old posts and you’ll see that the phones aren’t that difficult to make at all.  Unfortunately, I can only teach and guide you.  I don’t sell my works.


----------



## tib8

lkos98 said:


> Congratulations! Please share how they sound to you.
> 1. 800Vpp so did you apply +-400V to the membranes? 1.2mm with such voltage will sound quiet. But if you double these 400 to +-800, you will see a huge difference. Going to 0.6mm though even with +- 400v  will stick membrane to the stator especially with such low stretching (108Hrz). Remember it's not like normal design with one membrane which experience equal force from both stators in idle. These 2 membranes are attracted to each other with 800V electrical force, so they are always bended in the middle and closer to the stator, hence I used in my latest design dual middle stator bended like this )( . With a straight stator my experience with 0.6 mm spacers, 140 Hrz and +- 630V is that one of the membranes sticks after 5 mins to the stator. So 1.2mm is good if you want stability with +-800. And by the way distance is definitely not a linear factor - in fact it is quadratic to the e-force - (k x Q1 x Q2) / d^2. The reason you did not hear a difference is in my opinion, that membranes are stuck to the stator, discharged and of course very quiet. With 1.2mm distance and 400V it cannot be loud. Even normal design with 1.2mm spacers will be quiet (see p.3)
> 2. 2u mylar is in my opinion too thick for this configuration - that's one of the reason for the big bass - heavier membranes. You can try to stretch the membrane a bit more, to remove the bass, but with me this did not work - my current stretching is 170 Hrz and bass is almost the same as with 120Hrz. My opinion is that ear sealing plays much more role for the bass than stretching. I guess the only solution is to make the area smaller (which is good from esthetic point of view) and to order 1um Mylar. I love bass, so it's not that bad for me, I made some equalization to make it flat and it became a bit poor.
> 3. As for the loudness, ignoring the smaller space (because of the constant attraction in my design), +-400V (800V) and 800Vpp (single) should be equal to single 400V and 400Vpp (800 differential) in normal design. Assume stator is at +400V then one membrane sees 0V the other 800V. Now with normal design one stator is at -400 the other is +400, membrane is at +400. Again - one side is 0V, the other is 800, so it's the same es-force. And this is the main flow of single stator design - you have to double either the output of the amp or both biases to get the same level. I can't explain how you got such huge 20dB difference (my guess is the spacers are not the same thickness), I don't have much experience with a single membrane, but as I mentioned, I'm with +-630V now and about 580Vpp (single ended) and it's quite loud, my normal listening is at half volume. It's still quieter than a dynamic phones at the same source level, but still loud enough. If I go to high volumes my wife starts complaining - she can hear the phones pretty loud standing 2m away  .  I see now how you are going in my steps - I used to have +-300V biases and yes it was quiet, but +-630 made a huge difference. Stretching is also a nightmare - you have to stretch 4 membranes in about the same frequency (better - slightly different) and glue them and check after that again and match them by pairs. The smaller space between center of membrane and stator also plays some role in the loudness.  And if this is not enough you can always go for a higher biases (increasing amp output is not easy), by doubling the power rails voltage of your amp.
> ...


Ikos 98, 
Thank you for your advises, and sorry for the late feedback - I had no time to work on this project util last night.
With some heating I increased stretching to about 160Hz, then I tried to remove one of the spacers -> you were right: 0.6mm is not enough: at 'large' volume the membranes touched the stator, so I went back to 1.2mm.
Then I changed back to use again the bias power supply instead of the amplifier's power rails.
When I increased the voltage, it started 'popping' noises = arcing, so I replaced the metal screws with plastic ones (in the single membrane version metal screws were working fine, but here both membranes touching a bit the screws - this is not good!).
Probably this was the point when *they started to sound well*! (not like if the sound would come out of a bucket)

Also I tested again, and the loudness now do increase as I turn the bias setter pot (I can set between +-240V .. +-750V).
So with everything on the max the volume is just fine for normal listening, but I still miss that I can not increase the volume a bit sometimes.
Not much time left for testing, but my first impression compared to the classic version is that is has a bit warmer sound and a bit even more impactfull bass.
Then I accidentally made a few holes in one of the membranes, so I went to sleep.

This accident on the other hand gave me good reason to try the 1um mylar you recommended for membranes (which I did not use at the first place because it is so easy to break them).

My long term goal with these is to integrate the amp onto the headphone (except of course the power supply).
(if we get rid of the cable capacitance, smaller currents can be used and the heating of the amp hopefully decreased enough to be dissipated on the headphone frame...)
To do this I'll try to increase stretching even more - it would be really nice to use only 0.6mm gap and less voltages (or higher volume).

I'll report my findings.


----------



## lkos98

tib8 said:


> Ikos 98,
> Thank you for your advises, and sorry for the late feedback - I had no time to work on this project util last night.
> With some heating I increased stretching to about 160Hz, then I tried to remove one of the spacers -> you were right: 0.6mm is not enough: at 'large' volume the membranes touched the stator, so I went back to 1.2mm.
> Then I changed back to use again the bias power supply instead of the amplifier's power rails.
> ...


Great, please share if there's difference in the bass after changing to 1um. I'm unable to find anywhere 1um mylar - the seller no longer sends to my country. 
0.6mm won't work with big areas. On my ovals 100x70 with about 180Hrz FAR, I'm using a flat stator and ~0.85 mm spacers and still if I listen for very long time and high volume some membrane may stick to the stator, but it's really rare. 
Using plastic bolts is good, but to find small size is not easy, so I use metal bolts M3 with heat-shrink tubes on them, (the holes are actually 4mm, so neither of the membrane, stator or frame is touching the metal and I don't have this sparking noises anymore.


----------



## chinsettawong

M3 nylon screws are easy to find.  Try ebay!


----------



## tib8

lkos98 said:


> Great, please share if there's difference in the bass after changing to 1um. I'm unable to find anywhere 1um mylar - the seller no longer sends to my country.
> 0.6mm won't work with big areas. On my ovals 100x70 with about 180Hrz FAR, I'm using a flat stator and ~0.85 mm spacers and still if I listen for very long time and high volume some membrane may stick to the stator, but it's really rare.
> Using plastic bolts is good, but to find small size is not easy, so I use metal bolts M3 with heat-shrink tubes on them, (the holes are actually 4mm, so neither of the membrane, stator or frame is touching the metal and I don't have this sparking noises anymore.


I have replaced the membranes on the broken side with 1um mylar.
I had to decrease somewhat the bias voltage because at +-750V no mater how I stretched this 1um, it sticks to the stator.
Otherwise I hear no difference compared to the 2um (but I did not heard any difference with my older headphones either) - so next time I likely switch back to 2um.

Now I plan to measure and compare this and the old one, because it seems to me that the lower half of the spectrum is too loud (or the upper half is weak?)
I need to know what is happening exactly: is it the resonance of the "box" created by the two membranes, or my amp has problem with highs?
Other than this issue I really like the stability of this construction!


----------



## chinsettawong

tib8 said:


> I have replaced the membranes on the broken side with 1um mylar.
> I had to decrease somewhat the bias voltage because at +-750V no mater how I stretched this 1um, it sticks to the stator.
> Otherwise I hear no difference compared to the 2um (but I did not heard any difference with my older headphones either) - so next time I likely switch back to 2um.
> 
> ...


How do you stretch the diaphragm?  Are you using a stretcher?


----------



## Ulfar4

Does anyone have tip where to buy good earpads? I am looking for oval angled sheepskin earpads but I had no luck with finding any. Round types are easy obtainable, but the situation is much worse with oval ones with bigger dimensions.


----------



## lkos98 (Jun 1, 2022)

Ulfar4 said:


> Does anyone have tip where to buy good earpads? I am looking for oval angled sheepskin earpads but I had no luck with finding any. Round types are easy obtainable, but the situation is much worse with oval ones with bigger dimensions.


I have bought from ebay or aliexpress few years ago, but not angled and cheap artificial leather.  They were not very big either, but covered my whole ear. I guess you won't like them. Otherwise give me a hint, I'll look through my orders.

Edit: 
Just out of curiosity I browsed and found these:
https://www.aliexpress.com/item/400...616541212174365180e8329!10000014548379220!sea 
With this price they don't look to me a genuine leather, but still.... Otherwise found a lot other sheepskin leather, but not angled.


----------



## lkos98

tib8 said:


> I have replaced the membranes on the broken side with 1um mylar.
> I had to decrease somewhat the bias voltage because at +-750V no mater how I stretched this 1um, it sticks to the stator.
> Otherwise I hear no difference compared to the 2um (but I did not heard any difference with my older headphones either) - so next time I likely switch back to 2um.
> 
> ...


Yeah they tend to boost the low bass, but from 200-300 hrz up they are pretty flat. Since with my inear 22mm active area the bass roll off starting from around 150Hrz, I guess active area has the most impact on those. I remember I made some 76-80mm some time ago and the bass there was not enough for my taste. Also if you can avoid stretching with heat - my experience is that it decreases the elasticity of the mylar and after some time membranes are loose again. 
Where did you find 1um mylar delivered to Europe? Please share if you can. Thanks.


----------



## tib8

lkos98 said:


> Yeah they tend to boost the low bass, but from 200-300 hrz up they are pretty flat. Since with my inear 22mm active area the bass roll off starting from around 150Hrz, I guess active area has the most impact on those. I remember I made some 76-80mm some time ago and the bass there was not enough for my taste. Also if you can avoid stretching with heat - my experience is that it decreases the elasticity of the mylar and after some time membranes are loose again.
> Where did you find 1um mylar delivered to Europe? Please share if you can. Thanks.


This is my only source, I ordered 1, 2, 5um from here:
https://www.freeflightsupplies.co.uk/index.php/products/lightweight-covering-materials
Unfortunately it is far from wrinkle free condition, but with stretching, relatively fine...

I also finished the measurement. Both of my amps (the old symmetric and the new single ended) are perfectly flat in the first 20kHz, I checked this on my scope, so they make no difference.

I attached some freq. response from my 'classic' single membrane, the new '2 membrane' and my HD58x.
The high frequency part should be ignored, but it is clearly visible that the HD58x (also my HD555) and the Classic are all 'flat' (except that bump around 6kHz, which is likely due to the poor measurement setup). On the other hand the 2Membrance has way too many mid and bass compared to the highs (my ears tell the same).

I also compared the 1 and 2um mylar (not very reliable measurement) but seems that 1um has even more bass!

So I hope, I can solve the stability issues of my classic, when the graphene arrives from china, because it is still by far the best sounding headphone from these (and from anything I have heard - only my brothers HD800 is comparable: its bass is not that good, but the spatial resolution is better - I'll likely build a new amp to improve on that...).


----------



## lkos98

tib8 said:


> This is my only source, I ordered 1, 2, 5um from here:
> https://www.freeflightsupplies.co.uk/index.php/products/lightweight-covering-materials
> Unfortunately it is far from wrinkle free condition, but with stretching, relatively fine...
> 
> ...


Thanks. I will try to make some new measurements to see how close are yours to mine. Unfortunately my mic setup is not very good, so I don't know how reliable it is.


----------



## Ulfar4

lkos98 said:


> I have bought from ebay or aliexpress few years ago, but not angled and cheap artificial leather.  They were not very big either, but covered my whole ear. I guess you won't like them. Otherwise give me a hint, I'll look through my orders.
> 
> Edit:
> Just out of curiosity I browsed and found these:
> ...



Thanks, i quess i will have to try nonagled version then, I found with 110x90mm dimmensions.
https://www.aliexpress.com/item/1005003380649489.html?spm=a2g0o.cart.0.0.aad43c00QXLE5W&mp=1


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## lkos98 (Jun 3, 2022)

Made some measurements. In the bass region it look like yours Tib8, but in middles and highs nowhere near. Bass is boosted starting from about 200-250, but from there all the rest is pretty flat up to 20kHrz (laptop output, otherwise it goes much higher). 
Again   many thanks Wachara - look what graphene did at the range 2k-6k (about 10db better) - the orange graph is with softener, the rest are with graphene . I also played with some HPF at about 120 Hrz, 20dB/ decade - made it completely flat bellow 300. Then I tried also the windows EQ (blue line) which made it better looking. Yes - better looking - but not better sounding. May be I got used to the boosted bass, but after that EQ , I did not enjoy it anymore.
Anyway, I think the reason for the boosted bass with the 2 membrane design is the twice lower equivalent volume (Thielle-Small). May be it's time for another build with much smaller active area, to see how it will perform.


----------



## HifiXMen

Hi everyone, this is my first post on head-fi, I'm very happy to share my experience of making electrostatic headphone with you, many thanks to chinsettawong for the invitation. I've already posted about making Shangri-la clone headphone on both head-case and the China Headphone Club. 
https://www.head-case.org/forums/topic/21643-a-diy-shangri-la-headphone-for-hifi-xmen/
http://www.headphoneclub.com/thread-753621-1-1.html
The Chinese version is more detailed, I wanted to repost it to head-fi, but it seems that new accounts cannot upload pictures though.  Anyway, If you have any questions, feel free to ask me.


----------



## Ulfar4

Wow, that is impressive work.


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## tib8 (Jun 10, 2022)

lkos98 said:


> Made some measurements. In the bass region it look like yours Tib8, but in middles and highs nowhere near. Bass is boosted starting from about 200-250, but from there all the rest is pretty flat up to 20kHrz (laptop output, otherwise it goes much higher).
> Again   many thanks Wachara - look what graphene did at the range 2k-6k (about 10db better) - the orange graph is with softener, the rest are with graphene . I also played with some HPF at about 120 Hrz, 20dB/ decade - made it completely flat bellow 300. Then I tried also the windows EQ (blue line) which made it better looking. Yes - better looking - but not better sounding. May be I got used to the boosted bass, but after that EQ , I did not enjoy it anymore.
> Anyway, I think the reason for the boosted bass with the 2 membrane design is the twice lower equivalent volume (Thielle-Small). May be it's time for another build with much smaller active area, to see how it will perform.


Ikos98,
The whole idea of this two membrane construction is that they* help each other* in movement and this way they cancel out the distortion which would be there due to single ended drive if we would omit the membrane from the outer side, right?
But the membranes are "far" from each other, which means that this "help" arrives with some *delay* from the other side.
The question: how big is this delay and how big its effect can be?

If we assume that the pressure wave moves with the speed of sound, then in my case the 4mm distance needs about t= s/v = 0.004m / 300m/s = 13us; f = 1/t => 75khz - so that is likely not an issue...
On the other hand if we calculate with the speed of the gas molecules (which were hit by one of the membranes, so their speed has changed) and travel to the other side then the picture is pretty different: vrms = sqrt(3*R*T/M) = sqrt(3*8.314*293/30) = 15.6m/s   => f = 3900Hz sqrt(3*8.314*293/0.03) = 493m/s => f = 123kHz
(also they are likely not travelling along a straight line, which further lowers this frequency)
So my idea is that this bass boost is due to this second effect: on low frequencies the membranes are really able to help each other!
This theory could be checked by reducing the distance of membranes - if the boosted region extends to higher frequencies, then I was right. 
(Also, more "open" and thinner middle stator (like a mesh) can help this boosting effect extend further to highs.)
Unfortunately to reach my limits (about 14kHz,) the distance should be reduced to about 1mm, which is not really possible with FRV stators, and surely much smaller driver diameter will be needed for the smaller airgaps too.

Of course this speculation can be totally false, so I need to repeat measurements when I find time, to decide.

In any case if the "help" arrives with a delay which opposing the phase, then that is not help, but the opposite, so even with the first assumption may have some effect...

*EDIT:* I realized that I used wrong mass unit to calculate the speed in second case, so this post is mostly not relevant anymore.


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## lkos98

Yes, one of the things is the "mutual help" of the 2 membranes, the other is to reduce the capacitance - with my setup I have about 50pF (40 cable and 10 from the phones) as a load to the amp. On 22 kHrz this gives me around 150kOhm impedance, so the max current is 220RMS/150k ~= 1.5mA, while most of the amps I heard of are running at 8-10mA. In fact this increases the efficiency - 0.35W against 2W (not even mentioning the efficiency of the amp itself).    
About the delay - I would use some simpler math. The wave length of 30kHrz is 11mm much longer than 0.8+0.8+1.6 = 3.2mm distance between the membranes. In other words, these 2 membranes act as single one up to some 50's kHrz before half wave length kicks in. This cannot be an issue for the bass boost, since the wavelength there is few meters. 
I still can't explain where this bass boost comes from - I hear it in all my models, especially after I doubled my biases. I have some idea, but need to experiment more, to figure it out. In any case I like it, it' not irritating, it's deep, but tight and once you get used to it, it's very enjoyable. I have one pair dynamic Klipsh, which are also very bassy and I have heard also those (some DJ produced - can't remember the name, they were quite famous 5-10 years back) - bass is way too much and boomy.


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## Ulfar4

Finaly I bought MiniDSP Ears so I was able to do some better measurement of my estats.


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## Tjj226 Angel

Infactum said:


> hi all
> what bias boards you use?
> I tried different ones like *QS30-1.IN-14*
> but I think there is something better
> ...



What sort of bias voltage do you wish to achieve?


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## Tjj226 Angel

Infactum said:


> with bias everything is simple
> 
> I'm more interested in audio transformers
> 
> ...



Since you are in the UK, you should probably reach out to sowter and get some quotes on custom transformers.


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## Tjj226 Angel

Out of curiosity, has anyone tried to go for a relatively loose tension on the mylar? Im thinking about using water tension to stretch the mylar flat and use fairly thick spacers (1-2mm) to avoid stator slap. 

Obviously this would require very high bias voltage, but so long as I manage to keep things 3KV and below, it should be pretty easy. 

I just want to get all of your thoughts before I waste time and material going down this rabbit hole


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## chinsettawong

I've never tried the loose tension to that extent.  It would be very challenging and frustrating.


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## chinsettawong

Today I had a good friend, @purk, to come to visit me, and I showed him all of my DIY headphones including the newest pair of Float Clone.  

He seemed to like my Omega Clone the most.


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## HifiXMen

Tjj226 Angel said:


> Out of curiosity, has anyone tried to go for a relatively loose tension on the mylar? Im thinking about using water tension to stretch the mylar flat and use fairly thick spacers (1-2mm) to avoid stator slap.
> 
> Obviously this would require very high bias voltage, but so long as I manage to keep things 3KV and below, it should be pretty easy.
> 
> I just want to get all of your thoughts before I waste time and material going down this rabbit hole


A friend of mine tried a similar idea, directly using low tension copper foil as estats diaphragm, using 2mm spacer、2000V+ bias and a step up transformer to drive it like an electrostatic speaker,  it just works, but soon, he switched to stax pro bias driver.  

Similar design electrostatic headphone is already commercially available. For e.g., Sonoma M1 and its subsequent models Aperio and Bravora，these estats use low tension metal-coated interlayer film as the diaphragm + flexible mesh stators, and their bias voltages are set at 1350VDC (M1 and Bravora) and 1800VDC (Aperio) respectively.


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## purk (Jun 30, 2022)

All of them are great sounding!

Correction!  Incredible sounding!!

Such a pleasure to listen to these fine creations.  Thank to P Wachara for taking the time out of his busy schedule to chat with us.  Note that the meeting took place in his very own conference room.


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## chinsettawong (Jun 30, 2022)

Here is another shot for our good memory.


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## Tjj226 Angel

HifiXMen said:


> A friend of mine tried a similar idea, directly using low tension copper foil as estats diaphragm, using 2mm spacer、2000V+ bias and a step up transformer to drive it like an electrostatic speaker,  it just works, but soon, he switched to stax pro bias driver.
> 
> Similar design electrostatic headphone is already commercially available. For e.g., Sonoma M1 and its subsequent models Aperio and Bravora，these estats use low tension metal-coated interlayer film as the diaphragm + flexible mesh stators, and their bias voltages are set at 1350VDC (M1 and Bravora) and 1800VDC (Aperio) respectively.



Just to clarify, did he switch back to probias because he liked the sound better or because it was easier to live with the pro bias?


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## c12Windfury

Hey guys when designing your stator what program do you use to draw it out before turning it into a cnc file?


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## chinsettawong

A very old and obsolete program called ArtCam is very good.


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## lkos98

c12Windfury said:


> Hey guys when designing your stator what program do you use to draw it out before turning it into a cnc file?


I'm using Fusion 360 for all parts (free personal license). Unfortunately Fusion becomes extremely slow with too many surfaces, so I'm using this: https://github.com/LinuxCNC/simple-gcode-generators/tree/master/grill 
for the holes in the stator.


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## c12Windfury

Hey guys when cnc a part does the gcode determine the size of the part or does the machine software itself?


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## lkos98

c12Windfury said:


> Hey guys when cnc a part does the gcode determine the size of the part or does the machine software itself?


CNC machine you mean? Partly, because it's firmware configuration determines how many mm (or inch) will it move by a gcode command. Otherwise the CAD program determines the size, gcode just translates this size to a CNC movement. What I'm trying to say is, that if your CNC is configured wrong, a command for example G0 X200 (move fast X axis 200mm) might move on X lets say 300mm.


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## lokhanglee

chinsettawong said:


> Hi,
> 
> I've just joined this site today.  I just want to say hi to everybody and show you my version of electrostatic headphones and amplifier.  I've successfully made the phones and the amp for about a year now.  I just love them.
> 
> ...


It is absolutely brilliant… I am jealous of your skills


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## lkos98

Finally found some time and willingness to redesign my 90mm circles. I have bass boost (about 15-20 dB) at 30Hrz, which is overwhelming. I made some 74mm active area phones and the bass was much better, but still a bit boosted. Obviously this boost depends more on the active area, than the stretching. So I decided to modify the 90mm circles by dividing the area by segments. I made one with 3 segments and one with 2. The dynamics of the 3 segmented sounds worse than the 2 segmented. The attached measurements could not explain why.  
Here are the FRs of both. I excluded the frequencies above 1.3kHz, because the graphs look the same, but depend a lot on the cavity where the microphone is placed.        



Some bass boost on 2 segmented is still there - about 3dB, but first - I cannot count on my microphone setup and second - I like it more than the "flat" 3 segmented. 
I would like very much to hear your thoughts on why dynamics of the 2 segments sounds better? By the way if I remove the 1/6 smoothing, 3 segmented has many resonances of about +-3dBs bellow 80-100Hz.


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## chinsettawong

I don’t quite understand your mention about 2 segments and 3 segments.  Are you segmenting the stators?  How?


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## lkos98

chinsettawong said:


> I don’t quite understand your mention about 2 segments and 3 segments.  Are you segmenting the stators?  How?


Yeah, sorry, I was not clear. Segments are on the frame that's holding the membrane. The pictures I showed is of the frame where membrane is glued to - on the blue 2 big circles (3 segments) and on the red - one line  in the middle (half circle - 2 segments). The rest of the lines are not touching the membrane - they are just for support and as a safety grill. Martin -Logan ESL for example have such segments on the whole panel.   
So, instead of moving the whole membrane at once, it's divided, separate areas are moving together. This is done to avoid high amplitude movement of the central area of the membrane, hence touching the stator. Pros are lower stretching, higher stability and somewhat flattening of the FR, but you lose bass (which I wanted anyway). A comparison is with lets say one 12" dynamic speaker (subwoofer) and few 6" speakers. The area is the same, but moved air volume is different. Bass is less, middles and highs are more. Bellow is the comparison FRs. By just halving the membrane (everything else is the same) there is 18dB lost in 30Hz.


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## chinsettawong

From the picture, it’s impossible to see how you segment the diaphragms.  Are you using a silicone dot to segment the diaphragm?  I actually though about that a long time ago but I’ve never tried it.  Losing bass is what I’m afraid of.


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## lkos98

chinsettawong said:


> From the picture, it’s impossible to see how you segment the diaphragms.  Are you using a silicone dot to segment the diaphragm?  I actually though about that a long time ago but I’ve never tried it.  Losing bass is what I’m afraid of.


Yes, I remember that you proposed that. I also never tried it and sure some bass will be lost. But placing a small 0.5-0.6 mm drop of silicone would be quite difficult and inconsistent. The idea of segmenting is the same - placing some braces between the membrane and stator. Elastic force of the membrane is stronger at the edges and weaker at the middle and by segmentation this force is better distributed.    
My design with no segments tends to boost the bass a lot. I tried to equalize it with simple high pass RC filter inside the amp, and it works, but this means this amp will be married to these phones only. 
Bellow is a simple picture of two segmented frame (spacer) to which the membrane is glued. Stator is the same, all the rest is the same - it's just now instead of one I have two moving parts of the same membrane. I hope it's clear now. 
So far I made just one channel of the phone, so left is with 3 segments, right with 2 and they don't sound the same. I am now making the second channel with 2 segments, once done I will have a better view of how it sounds compared to the full (not segmented) phones.


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## chinsettawong

Thanks for showing the picture.  It's clear now.  With this design, I think you lose quite a bit of bass.  Is it worth it?


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## tib8

chinsettawong said:


> Thanks for showing the picture.  It's clear now.  With this design, I think you lose quite a bit of bass.  Is it worth it?


Please do not forget that lkos98 is using "inside out" drivers: there is one stator in the middle between two membranes, and it is driven by a single ended amp.
I have built this configuration myself. It works well except one thing: it has way to much bass compared to the highs.
If this segmentation solves this, I can just congratulate to Ikor98 for the idea. 
I have seen this kind of segmentation only on electrostatic speakers (like:  ).


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## chinsettawong

Unlike our headphones, Charlie, in the VDO, isn't making his Electrostatic loudspeakers full range.  He has a woofer to help boost the low frequencies.  So, his ESL's sound doesn't have to go down very low, and therefore his spacer is thin and the diaphragm width is narrow.


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## lkos98

tib8 said:


> Please do not forget that lkos98 is using "inside out" drivers: there is one stator in the middle between two membranes, and it is driven by a single ended amp.
> I have built this configuration myself. It works well except one thing: it has way to much bass compared to the highs.
> If this segmentation solves this, I can just congratulate to Ikor98 for the idea.
> I have seen this kind of segmentation only on electrostatic speakers (like:  ).



Thanks for clearing that out. This design is so called fully inverted and it's definitely boosting the bass. Middles and highs are quite normal.
I think I found the reason for it - bass boost is caused by the fact that membranes are charged opposite and attract each other all the time. This makes them closer in the middle (and to the stator), therefor ES force is higher, but opposing elasticity force is lower. This creates bigger air volume in low frequencies. Middles and highs are not affected that much, because even light, membranes are much heavier than air and can't vibrate with high volume too fast. Another prove of this is that when I increase the bias voltages (membrane centers get closer), the bass boost is increased even further. 
Splitting the membrane in half is reducing the bass, in my opinion exactly what I needed. As seen from the FR, segmented phone is almost flat unlike before. I made the second channel and I'm very, very happy how they sound now.


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## chinsettawong

That’s an amazing news.  I’ll have to give it a try.  By the way, what bias voltage and spacer thickness do you use?


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## lkos98 (Sep 16, 2022)

chinsettawong said:


> That’s an amazing news.  I’ll have to give it a try.  By the way, what bias voltage and spacer thickness do you use?


I started with +- 330V, but it was too quiet, so I made a voltage doubler - about +-630. It made it much louder, but I noticed the huge bass boost. Since this was a new model, I was still not aware that bias voltage affects the bass boost, so I made voltage trippler and increased the serial resistance up to 6.6MOhm. It's now around +-750-800 (it's not a reliable measurements because of the multimeter resistance, so it could be +-900V). Fairly said I did not notice big difference in loudness between 600 and 800.
The spacers are 0.7mm (I ran out of 0.55mm FR4), but there is another space there - my stator is made of 2 x 0.55mm soldered copper to copper, so the membranes are facing the non-laminated side of it (I was tired of the sparks and varnishing, etc.) This makes the spacing 1.2-1.3 mm, but since FR4 has about 4 times higher dielectric constant than air, the distance can be expressed around 1mm in total. I guess this is quite a lot, that's why I increased the bias so much.
If you like - try it, but bear in mind - you have to start from scratch and it might be difficult to modify your amp (need to use just one of the differential outputs), one stator - double sided (or like me- 2 single sided) and so on, so on.
What I like about it:
First - no moisture caps (coating is inside the cavity created by the membranes and is not affected much by humidity)
Second - extremely low phone capacitance - I was really surprised when I measured it directly at the phone and it showed 0! (it's probably 2-3pF, which my multimeter could not measure).
Third - the membrane frame can be made as thick as you like, because membrane is not facing the stator from the side it's glued.
Four - four cables to the phone ( I use 6 just for convenience).
Disadvantages in my opinion - need for high and dual biases and high voltage amplitude at the output. Need to take care of the hum, noises and crosstalk, because they don't cancel each other like in the normal 2 stator design. Need for protective grills on each side ( I guess this is also advisable for normal design)
There are some more I guess, just cannot recall any at the moment.


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## chinsettawong

Ok, now I understand how you can get so much bass to begin with.  With the spacer being more than 1 mm thick, the tension on the diaphragm can be set at a lot lower than my 0.5 spacer thickness.  To be efficient, the bias voltage has to be at least 1KV.  In your case, are you feeding one diaphragm with +700-800V and the other diaphragm with -700-800V?  How much is voltage swing on your amp?


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## lkos98

chinsettawong said:


> Ok, now I understand how you can get so much bass to begin with.  With the spacer being more than 1 mm thick, the tension on the diaphragm can be set at a lot lower than my 0.5 spacer thickness.  To be efficient, the bias voltage has to be at least 1KV.  In your case, are you feeding one diaphragm with +700-800V and the other diaphragm with -700-800V?  How much is voltage swing on your amp?


Unfortunately low - it's +-300 (600 p-p) at max. It's not easy to build single ended amp with much more. Most of differential output amps also have around 600V p-p on one arm, so the combined is 1200V p-p. To achieve such swing with a single ended amp is almost impossible. My amp is made mostly with n-channel mosfets, but to shift the levels I need to use at least one pnp and all I can find is with 400-500V C-E. I ordered a 900V pnp from Aliexpress and I got a npn, not even knowing it's parameters. On top of it, my power rails are +-320V. Still I can't complain about the phones loudness - it's not extreme, but quite enough at normal listening levels.  
Tension did not change the bass much, I have made a lot of experiments trying to reduce it and even with a very high tension it's still there. In my experience the ear pad sealing and active area play major role for the bass. May be with standard design it's different, the logic tells me not, but I haven't tried it and can't confirm.  
The other option is to reduce the space, but I ran out of 0.5mm FR4. 
Anyone know where I can find thinner FR4 like 0.2-0.3mm? I can still solder 2 of those face to face adding some sturdy structure in between.


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