# DIY HE Adapter



## hasanyuceer

Hi all,
   
  I am thinking about building a HE Adapter for my HE500.
   
  HE Adapter makes HE6   8,8 ohm. If there isnt a series resistor, it would be 8,33 ohm. So it would be better at ohm without series resistor but it has.
   
  I wonder if I use only parallel resistor or do I need a series resistor?
  Does anyone have an idea about that?
   
  This is a photo of HE Adapter.


----------



## Spriggs

I see no one has reponded and this is kinda an old post but ill try and help you, the parallel reistor is not for the headphones it is merely to to provide the speaker amp with a resistive load and the series resistor is to atentuate the output power to something the headphones can use. so the parallel resistor can be anything as long as it is higher than the output impedance of your amp so standard would be 8ohms, so anything higher can work also but what should be noted is that the higher the resistance of the parallel resistor the harder you push your amp also the resistor should be of high wattage disapation so i tend to use 20w non inductive, small wattage resistors can blow under load. the series resitor doesnt really matter it is just so you dont blow up your ears from how powerfull your amp is so anything will work depending on how load you want it to get, the wattage dissapation doesnt matter much either.


----------



## DingoSmuggler

Quote: 





spriggs said:


> ...the higher the resistance of the parallel resistor the harder you push your amp...


 
  The opposite is true. A higher resistance puts less load on the amp, a lower resistance, more load.


----------



## Spriggs

Quote: 





dingosmuggler said:


> The opposite is true. A higher resistance puts less load on the amp, a lower resistance, more load.


 
  Yea sorry I guess i phrased that sentance wrong op dino is correct.


----------



## FraGGleR

Is this necessary to use?  I feel like there are an awful lot of people just hooking directly into speaker taps with HE-6s and other orthos.  Are there any kinds of amps that this would be more important to use?
   
  Also, can someone point me to some references that would help me calculate the types of resistors I would need to make my own?
   
  Thanks!


----------



## kozmo

Hope this helps.
   
http://sound.westhost.com/project100.htm
   
  or
   
  You could build as the HiFiMAN product shown in the photo of the first post, resistor values are found here: http://head-direct.com/Products/?act=detail&id=104


----------



## Spriggs

Quote: 





fraggler said:


> Is this necessary to use?  I feel like there are an awful lot of people just hooking directly into speaker taps with HE-6s and other orthos.  Are there any kinds of amps that this would be more important to use?
> 
> Also, can someone point me to some references that would help me calculate the types of resistors I would need to make my own?
> 
> Thanks!


 
  nah, you dont require one of these but it is technically safer to use one. Cause it provides a constant load to the amp so the output trannies dont short (if your using ss no need to worry)and also attenuates the output volume with drop resistors so the amp dosnt blow your ears out at like 1/8 of a turn on your volume knob.


----------



## FraGGleR

Thanks.  So better to have one in place for safety than not to.  
   
  If I were to try using a T-amp that puts out around 10W into 8ohms.  What would be good values of resistors to use for a 50ohm Hifiman?


----------



## Spriggs

Quote: 





fraggler said:


> Thanks.  So better to have one in place for safety than not to.
> 
> If I were to try using a T-amp that puts out around 10W into 8ohms.  What would be good values of resistors to use for a 50ohm Hifiman?


 
  The saftey aspect is really only usefull if you are running a tube amp cause the tube amp has output transformers that when running without a load can short across but if you are using a solid state amp you need not worry. Now to find what good resistor values, you need to know what kind of headphones you are using and its efficency basically how loud in db per watt or with headphones miliwatt voltage ect. cause diffrent headphones with diffrent efficentcy will operate at diffrent volumes with the same ammount of power. read the link that kozmo posted with http://sound.westhost.com/project100.htm that will show you a diffrent type of convertetr than the one used in the hifiman adapter but they both do the same thing, and also the article tells you which resistors to use with what amp and ect. All in all the hifiman adapter is extreamly overpriced as the parts in it are only around 10 bucks total at the most and that is if you are using much higher quality resistor that hifiman uses (the ones they use are like 5 bucks for all 4) and the metal box isnt all that nice either.


----------



## budx3385

Hey experts!
   
  That project100 link was indeed helpful. Thank you.
   
  So, if I have some Cardas non-Pb eutectic solder, and I want to use the HE-adapter only with the HE-6 on a tube amp with 4wpc on an 8ohm tap, which resistors should I use? Mills and Shinkoh? Dueland? Audio Note?
   
  it best to match 8 ohms for an 8 ohm speaker tap? So how about simply removing the series 25R 1/4w piece? then the total is 8.3R instead of 8.8, and there's nothing extra in the signal path.


----------



## Spriggs

Quote: 





budx3385 said:


> Hey experts!
> 
> That project100 link was indeed helpful. Thank you.
> 
> ...


 
  solder dosnt matter, if you have a tube amp your gonna want some nice allen bradley carbon resistors (the audio not tantalums are good also) no ww or metal film for the ones in series.
   
  for the 2 in parallel somthing above 8 ohms is better (matching dosnt matter this is all off of the 8ohm tap of your amp) i use 10 to 16 ohm resistors in parallel but they should be of high w disapation i use 20w resistors, the ones in series dont matter as much for w dissapation id say above 1/2 w is fine. 
   
  so in all together for you amp id use 10 or 16 ohm resistors 20w in parallel, then for the ones in parallel depending on the gain of your amp and how much surface noise there is maybe around 36ohms or 56ohms or 100ohms depending how much hum and other noise are in the amp by itself the higher value the quiter everthing any of these should be atleast 1/2w.(most speaker amps have a bit of hum just due to the fact they wernt designed for headphone use and you dont hear the hum on speakers)
   
  your idea of less things in the signal path wont help you much if you wanted the least stuff in your signal path just run your headphone straight into the taps of your amp, this adapter isnt required it just adjusts many of the things so its more suitable for headphone use.
   
  for example i made one of these for my 2a3/45 tube amp i used 16ohm 20w resistors in parallel and in series i used 100ohm resistors. sounds amazing from my hifimans and my lcd-3.
   
  if you have any more questions just pm me


----------



## Armaegis

A series resistor after the parallel ones would decrease the damping factor won't it? Going by the project100 schematic, the headphone sees an output impedance of R3 + R2.


----------



## DudeMyCans

I'd seen that project100 link before as I was thinking of building one for my 600 ohm Beyers but I wasn't sure if the 120ohm parallel resistor was the way to go. I know that nominally headphone outs are 120ohm, but I thought that typically modern amps were much lower and wasn't sure whether to go for a 10 to 20 ohm resistor instead.


----------



## mrphillgood

Hello.
  I'm a owner of he500 headphones and ussually I'm listening them directly from outputs of my audiolab 8200cdq (using headphone output or xlr outputs). Lately I borrowed HiFiMan's HE-Adapter to connect my headphones to my Rotel RB1080 200wpch/8Ohm solid state power amplifier. Sonud was generally better. I want to build cables with resistors and bananas but I'm wondering if I could try to connect my hps directly to my amplifier without damaging my equipment. My 8200cdq preamp has -80 to +12 volume control and with the HE-Adapter I was listening at -28 level without any distortion or hum. Has anyone tryed feeding he500 directly from 200W speaker amp?


----------



## Armaegis

Yes you can... just be very careful with the volume knob. That or attenuate the signal before feeding into the amp.


----------



## mrphillgood

Hi,
  Thanks for reply. I haven't try direct connection yet (becouse I'm still insecure).
  I can buy sth from this shop:
  http://www.loudspeakershop.eu/resistors-c-196.html
  I was thinking about Duelund 10R10W or Mills MRA-12 8R2 or 15R for parallel resistor. But as far as I'm concerned in my situation (powerfull solid state amplifier) resisitor in series would more important to protect my HP. What other values it might have than original 25 Ohm 1/4W to still protect my headphones?
  And how solid state amplifier would react to such high impedance (aprox. 50 Ohm) without big (for example 10W from additional parallel resistror) load (amplifier will be for example very warm?) If I connect he500 directly to taps?
  What would be sympthoms of "overpowering" my headhones if I use them without any resistors protection? Headphones  will play probably very loud on lower volume levels but when I will know if it's to much for them before they will be damaged (will any distortion in sound appear first)?
  Emil.


----------



## budx3385

Hi. I remember that feeling. But when I connected my HE-6 straight to the speaker outputs of my 100wpc Odyssey Cyclops Max ss integrated amp, with the volume control on zero, nothing happened. When I turned the volume control up, the sound qualilty was very good. I have used it like that for hours, with the volume control at about 25%,  
   
  There was quite a bit of sibilance, though, so I bought the HE-adapter, jiggered some cables, and the sound quality became outstanding.
   
  Then I hooked the HE-adapter up to my new Fi 421A SET with 4wpc, and ever since I have been enjoying the best music reproduction from CD that I have ever heard.
   
  I bought some new resistors, too, Mills MRA-5 10R0 and Shinkoh 18R0 1w, but I haven't installed them yet.
   
  Please let us know how your new resistors sound!


----------



## mrphillgood

Of course I'll post my impressions but I also have a question about resistors in series. Most of users recommend  using 10W-12W Mills or Duelund resistor for paralell connection. Are there any recommendation of resistors in series? Should it be also non-inductive resistor? Can anyone post some examples?
   
  http://www.soundlabsgroup.com.au/p/MU-MRESIST-10R-20W/10+Ohm+20W+MRESIST+Supreme+Resistor
  Would higher power resistors be better for powerfull solid state amplifeirs?
  E.


----------



## Spriggs

Quote: 





mrphillgood said:


> Of course I'll post my impressions but I also have a question about resistors in series. Most of users recommend  using 10W-12W Mills or Duelund resistor for paralell connection. Are there any recommendation of resistors in series? Should it be also non-inductive resistor? Can anyone post some examples?
> 
> http://www.soundlabsgroup.com.au/p/MU-MRESIST-10R-20W/10+Ohm+20W+MRESIST+Supreme+Resistor
> Would higher power resistors be better for powerfull solid state amplifeirs?
> E.


 
  the resistors in series doesnt have to nonind, id say some allen bradley carbon comp resistors or some audionote tantalums. the mundorf m resist should be fine as the resistors in parallel.
   
   to be clear i am talking about an adapter that consists of one parallel resistor and one series resistor like the first post, i am not talking about the project 100 schematic.


----------



## mrphillgood

Hi,
  Thanks fo reply.
  Yesterday I decided to connect my he-500 directly to my rotel rb1080 solid state amplifier (thanks for user Happy Camper). After first longer session I can say that I can hear slightly noise compared to the sound with HE-Adapter and the soud is louder. With adapter I was listening at -26 level and now -36 (range is from -80 to +12). And sound seems a bit brighter? Anyway I decided to start making my adapter with:
  http://www.loudspeakershop.eu/mills-12w-15r-p-1435.html?language=en&currency=USD  or:
  http://www.soundlabsgroup.com.au/p/MU-MRESIST-10R-20W/10+Ohm+20W+MRESIST+Supreme+Resistor
  for paralell resistor.
  Resistor in series I'll take sth like 1/4W 25Ohm and post my impressions later.
  Emil.


----------



## Armaegis

The adapters will attenuate, which does reduce noise. The standard adapters also reduce damping factor, which will give a slightly looser and darker sound. 
   
  I'm thinking if I make another adapter, instead of a single 10ohm resistor in parallel I'll use two 5 ohm in series, then split off between the resistors for the headphone output. This should present roughly the same load to the amp, give attenuation, and maintain damping factor for the headphones.


----------



## alan s

Quote: 





spriggs said:


> the resistors in series doesnt have to nonind, id say some allen bradley carbon comp resistors or some audionote tantalums. the mundorf m resist should be fine as the resistors in parallel.


 
   
  I think that the quality of a resistor in series may actually be more important than the resistors in parallel.
   
  The audio signal has to travel through the in-series resistor.
   
  Induction would probably change the sound quality. It my not introduce distortion (noise) but it could impact other characteristics.
   
  But in the end actual trial and error will decide the best results - given that different headphone and amp pairings will exist.


----------



## FraGGleR

How do I tell if a resistor is non-inductive?  Would a pair of these work: http://www.mouser.com/ProductDetail/Xicon/280-CR15-10-RC/?qs=sGAEpiMZZMtbXrIkmrvidNqDYkzv63xDQeKig%252b%252bO6x8%3d?
   
  I am only using a 10W amp so I figure I don't need 20W resistors.  
   
  I'm going to take a TA2020 board and attach a 4-pin XLR to the outs, bypassing speaker taps all together, but wanted to basically build the simple HE adapter into it.  Probably going to get a bunch of different values for attenuation if needed.


----------



## Armaegis

I saw this schematic on another thread and thought I should link it here: http://www.head-fi.org/t/629352/he-500-lcd2-d5000-dt770-sr80-on-a-speaker-amp-emotiva-mini-x-a-100-project/1020#post_9364493


----------



## budx3385

Quote: 





spriggs said:


> solder dosnt matter, if you have a tube amp your gonna want some nice allen bradley carbon resistors (the audio not tantalums are good also) no ww or metal film for the ones in series.
> 
> for the 2 in parallel somthing above 8 ohms is better (matching dosnt matter this is all off of the 8ohm tap of your amp) i use 10 to 16 ohm resistors in parallel but they should be of high w disapation i use 20w resistors, the ones in series dont matter as much for w dissapation id say above 1/2 w is fine.
> 
> ...


 
   
  Hey Spriggs, as I read back through this thread, I note that I forgot to tell you THANK YOU. Sorry 'bout that. You've been real helpful to everyone here. Way to go!
   
  THANKS
   
  I hope I get a chance to try my new resistors soon.


----------



## FraGGleR

Yes, thanks to everyone who has helped.  I have parts on the way to integrate this into an amp.  Taking a TA2020 tripath board and hooking it up just as a headphone amp through a 4-pin XLR out, just for giggles.


----------



## Spriggs

Quote: 





budx3385 said:


> Hey Spriggs, as I read back through this thread, I note that I forgot to tell you THANK YOU. Sorry 'bout that. You've been real helpful to everyone here. Way to go!
> 
> THANKS
> 
> I hope I get a chance to try my new resistors soon.


 
  You are very welcome, Im glad you could use my help.


----------



## preproman

OK so I have the Emotiva a-100 miniX..  It works just fine right off the speaker taps with the HE-6, HE-5LE, and the HE-4.  Some have reported hiss with the HE-500.  Now I would like to know using this amp with headphones like Denons, Audio Technicas and Grados.  If I buy the HE-Adapter - can it be modded and have the resisters replaced with better ones that will work with the before said headphones - and what resisters would that be?


----------



## robrob

Here's a link to my Headphone Resistor Network Calculator webpage. It will help you optimize resistor values to match your headphones to your amp.
  
 I also have a much more detailed and complicated network calculator spreadsheet.
  
 Balanced Headphones Resistor Network:





  
 Single-Ended Headphones Network:




  
 After playing with resistor values an R2 value of 6 ohms 5 watts (wirewound) and R3 of 2 ohms 3 watts (wirewound) works well for almost any headphone & amp combo.


----------



## robrob

Here's the layout diagrams for a basic headphone interface:
  
  
_Basic Speaker Amp to Headphone Adapter - Single Ended TRS_




_This type of adapter is only for amplifiers that have their negative speaker terminals tied together (common ground)._
  
_Basic Speaker Amp to Headphone Adapter - Balanced Output XLR 4-Pin_




_This adapter will work with single-ended and balanced output speaker amplifiers._


----------



## Sonic Defender

I have no capacity/time to DIY; however I am considering the Can Opener which I am sure some of you are familiar with. I know I am asking a lot so please accept my sincere thanks for bothering if you do. I have a NAD M3 integrated amplifier and I want to use the speaker B channel (currently unused) to hook the Can Opener into for use with my HE 560. My concern is whether or not these various components match well or not. I have inbound a nice Yulong A18 headphone amplifier, but I always thought that the NAD M3 is a very good amplifier and if I could just get a headphone adapter with it my thinking was that it should be better than all but very expensive headphone amps. That said, I am not knowledgeable enough about dampening factor and how a device such as the Can Opener would work. If anybody has some thoughts to share about my scenario I would be very appreciative. Cheers.


----------



## camusmuse

Ahh...finally....diagrams....that I can understand...lol 
  
 THANK YOU robrob.
  
 I hope this thread isnt too dead to get some info, or at least be pointed in the right direction. 
  
 I was primarily interested in why you put the series resistor "in-front" of the parallel resistor?  I really only ask because I plan to use a tube amp and run the headphones "balanced" with custom cables as I have some "amp" rolling to do....some quite literally...oh wheels...lol. 
  
 I have posted in another related speaker amp/headphone thread, so dunno if I will get in trouble, but I didnt find any "current" info....really.  If there ever was a final word about the best route to use to run headphones off of just about any kind of amp.


----------



## robrob

> I was primarily interested in why you put the series resistor "in-front" of the parallel resistor?


 
  
 If you put the series resistor 'behind' the parallel resistor the parallel resistor becomes a load resistor and causes no attenuation. With it 'in front' the two resistors form an L-pad attenuator and do both--bring the speaker load down to desired levels and add attenuation.


----------



## camusmuse

YES!  For once I "guessed" something right!  I have some experience in passive crossover design and build for custom speakers of all types.  I recognized the "L-pad" early in my research, but only seen it called out by that name a handful of times in the few threads I am still reading.  I hate to crosspost, but you seem like you might be able to help me some. And I am itching to buy a bunch of resistors and parts to add to my “pile”. How important is matching the resistors? I will be ordering in bulk anyway, doesnt everyone LOVE sitting around with a DMM and a pile of resistors trying to pair or quad a set of *exactly* matching resistors??? I will probably do it regardless... 'cause of my pseudo-OCD self. Lol....

  
 I have noticed some people are inserting a third resistor, essentially creating a "center tap" from two resistors in series(instead of the one in parallel across pos and neg), and then running the "series" resistor from that "center tap" where the first two resistors connect to each other.  Does this have any benefit you could think of?  I'm a bit confused about this, it seems as if they might be able to better control impedance matching.  They usually halve the impedance of the parallel for the two, but I thought that staggering it might have some effect, desired or not as long as they added up to the original value of the single parallel resistor.  I realize that this puts the series resistor "behind" the parallel though.  Any thoughts? I just found it curious.

  
 I was also wondering about using a stereo stepped attenuator for different headphones.  I have 80 Ohm for now, but plan on 600Ohm in the future, plus the flexibility to play ANY headphone is nice.  I am going to build a Headphone switcher out of a Parasound 1U/"half rack width" speaker selector(once I make sure it is balanced and not common ground, or MAKE it balanced as it is just a passive switch), and an "empty" Parasound Zamp case(same dimensions as speaker selector, and I can “link” them into a “full rack width” 1U unit) to hold both front and back panel inputs and outputs.  Obviously everything will be "balanced", and I hope to have a digital display(for each resistor) indicating what impedance is being introduced into the audio circuit, both to attenuate and to match impedance.  Do you think that is possible, any suggestions?  I am not completely helpless with a soldering iron, but far from a circuit design guru, but I think I already know of a circuit I can use to display the values....ironically it uses different value resistors to change numbers(old school "alarm clock" like LED), just for basic functionality.  I am worried that the readings would be skewed by being “in circuit”. So I even thought of using a “bank” of reference resistors to display the value that is being used in the circuit.

  
 I figured if anything I could build a box like that and use it to easily and quickly get the right value components and then switch it out with "hard wired" replacements; much like I use active crossovers to determine the best roll off frequencies, and then go back and fine tune with passive components. 

  
 So Mr. robrob, if you are still reading....What are you resistor value suggestions for the following amps?  I plan to use an LPad regardless, and was going to use my Beyer 80ohm cans for now and will modify the cord to run true balanced with 4pin mini xlr, but like I said...will jump on the next set of high impedance cans I can find.  Even just the drivers would work...I have a few pair of junk headphones that I would love to mod.  People are less likely to steal what looks like a cheap pair of "no name" headphones. 

  
 Anyway, here is my “other post”....really dont know if I should post a link or the whole thing, but to make things easier on the “reader” I will just post the whole thing....

  
 Basically, I have GAS(Gear Acquisition Syndrome)....sadly no dedicated headphone amps.  Just a few pre and int. amps with "ok" sounding HP outs.  Right now I have some stock Beyerdynamic Dt770/80, though I plan to get the 250 ohm version as well for doing mods.  I do have several home amplifiers that I wouldnt mind trying.  I have read about the parallel and series resistors and suggested values.  Strange I always called that resistor configuration an L-pad and used it as a standard part of passive crossover design for speakers.  Usually one was a variable resistor to adjust the attenuation.  Now I realize that the resistors are more about impedance matching, but couldnt we use vari resistors to fine tune an amp to a pair of head pho9to figure out the right valuesnes?  I am picturing a neat little case with a couple of knobs and some sort of digital readout of what values are currently being used.  At the very least use the device to setup level for hard wiring; much like using active crossovers to determined the best crossover point to build in passive in speaker building. 
  
 Am I asking too much, is there already a product like this out there?  If so, I cant afford it and still want to build one myself.
  
 Some amps I am considering. The specs I think I need for the 80 Ohm cans (16 Ohm/20W “parallel”, and a 550 Ohm/ 0.25W “series”) What do you think of the higher impedance for the parallel(most have called for 8 ohms/10W, I have always thought that higher impedance speakers sounded better, and this would get the amp a bit further into its “sweet spot” if I understand this all correctly. Finally on resistors...do you really think there is much sonic difference between the “cheap” and the “megabuck”? Including my “matching” of resistors, I figured that the mid priced parts should do alright.
  
 Amp 1 Conrad-Johnson MV-50 tube
  
 Amp 2 Crown PSA2  SS (actually have two...talk about silliness, but would just use one...for a while...lol then I would HAVE to try both) If I pop my cans its a good excuse to get the 600ohms....(actually I would cry...I have big plans for the modest BD-DT770.
  
 Amp 3 Parasound 855a SS five channel but I will only use two.
  
 Amp 4 Crown D-150(I can hear the cringing from here...lol) VERY “SS” ssssssounding...lol, but certainly a powerhouse...
  
 Amp 5.  Some sort of Chip amp like the lm3887(or whatever it is, cant remember off hand)....SS, and I would still need to build it...lol
  
 AMP 6  Even more out there...I have some VERY NICE car audio amplifiers, as well as a very powerful 12v supply (70A) that I use on my test bench for repairs and what not.  In the past I used it to drive a pair of Soundstream 10.0 "Class A" amps to a pair of Magnepan MgIIbs.  Sounded pretty good, also used some Denon car amps...and a slew of others(classics from the 1990's)...  Some of the high current amps have me curious.  The "cheater" amps rated at 50watts at 4 ohms, but would do 800watts if the impedance was driven low enough..usually 1ohm stable, 1/4ohm if actively cooled.  More silliness I know, just would like to get some ideas before I start liquidating the majority of my collection.....car, home, HT, and pro sound(mostly amps and speakers).....baaaad gas.  I know that a car amp seems silly but it could be battery powered, and some really do sound good, especially in the first watt, where I expect my headphones to stay.  I have other "outlets" for LOUD......  
  
 FWIW I also have Parasound Speaker Switch that I plan to incorporate, eventually.  My custom speaker build has been put on hold. 
  
 Thanks for any productive replies, your time is very much appreciated.  Obviously most concerned about the MV-50 tube amp, and was hoping someone had already successfully done one.  I am under the impression that the both the parallel and the series need to be used for tube amps.  It is el34 based, pretty sure common ground but will check when I unbox it...guess I could look at the schematics...heh.  But pretty sure it will be fine, I was thinking of going a little higher that 10 ohms, maybe 16 or so, depending on what is available.  Not really sure what to use for the "series" leg resistor though.  Help!?!

  

  
 Thanks again robrob, and anyone else who can help me out here. Nathan


----------



## robrob

Nathan,
  
 Recommendation: Try the amp connected directly to your balanced headphones first. Most amps, even tube amps will work fine with headphones. Do you have enough control with the volume control for comfortable listening? If the knob is too sensitive to movement then adding attenuation should help. Do you hear hiss? If yes then attenuation may help lower the noise floor and reduce the audible hiss. If you don't need attenuation you can run a 10 ohm 5 watt 1% resistor across the + and - terminals (one resistor for each channel) to give the amp close to 8 ohms of load with headphones from 30 to 600 ohms.
  
 Matching the resistors isn't needed because small differences between them will have miniscule effects. You could design a stepped attenuation circuit but it really isn't needed. An L-pad will match headphones from 30 to 600 ohms with no problems. Play around with my headphone resistor network calculator and you'll see what I mean. If you do need attenuation I recommend you start with an L-pad that gives you around 18dB of attenuation.
  
 I'm not familiar with the amps you mention so I can't help you there.


----------



## camusmuse

No problem on the amp suggestions.  Some of my amps have "volume" knobs but I will be using either a Parasound Zpre(SS) or a Conrad Johnson PV-1 (tube) for a preamp.  Most likely will use the CJ-MV50 in the end, but want to try some of the other "monsterMay use both as the PV-1 has a phono section, right now the Zpre is setup as a "zone" from my HT preamp (Parasound AVC-2500).  I more or less know what I need to do to protect the amps.  Stay balanced, tube amps need that extra dummy load regardless IMO(not willing to take that chance); I have seen a "runaway" tube in an amp where the speaker wire came off, pretty light show....but releases the "magic" smoke stored inside of amps.  Many dollars to put that "smoke" back in the amp too.  I think the MV-50 has a 16ohm speaker tap, I know my old Dynaco St-70s did, would it be best match the tap with a 16 ohm parallel resistor?  I used to run the 4 ohm taps because my Infinity Q5 would drop impedance dangerously low at certain frequencies(mainly due to the odd Watkins dual VC 12" woofer: different Nominal Impedances on each coil, along with different crossover points[bandpass; I think], made for an "interesting" curve.  I used the 16 ohm taps when I switched to some very efficient Altec VOTT A7 "pseudo-clones"(511 horns and 15" Altec woofers in vented boxes).  I tried the 4 ohm tap first, but the 16 sounded better....I know much less about headphones than speakers, but know the "basics" are the same.  Just with some radically different impedances. 
  
  
 Admittedly rusty on my Lpad design(beyond a simple parallel and series setup), could you suggest R values for your 18db of attenuation?  You have already helped me enough that I could happily go look it up myself, but I am always looking for someone that knows more than me, and that is quite obvious here.  What do you think would be optimal for the tube amp?  I still am interested in that 16 ohm dummy load and your thoughts.  I will read your calc page, probably more than a few times. 
  
 Thanks again...Need to make that Calculator a sticky...though I hear that is quite difficult.  I doubt I would of asked a single question if I had found that earlier.  But again....always looking for new/fresh info/opinions/options..... You da man robrob!!!  Anything I can do for you?  Within reason of course....lol....I do know a few things about *gasp* speakers....among otherthings...always happy to return a favor!


----------



## robrob

R2 of 14 ohms 5 watts 1%
  
 R3 of 2 ohms 5 watts 1%
  
 With headphones from 30 to 600 ohms of impedance will show your amp a speaker load of 16 ohms with 18dB of attenuation at the headphones.
  

  
 If you don't need attenuation then an 18 ohm 10 watt 1% resistor across the + and - terminals will give your amp approximately 16 ohms of speaker load.


----------



## camusmuse

Very Nice! Thank You very much!  But.... D'OH!!  I gotta admit I was a bit impatient and went ahead and ordered some resistors earlier today.  16ohm 10w x (6) and 523ohm 1/2watt  x (10).  I was thinking(could be a problem, I know) if I needed to get to 8ohms for the parallel resistor, I could just parallel two of the 16ohm to bring it to 8ohm and use that.  Not sure if the dual resistors would have any ill effects or if I just "flunked" impedance calc 101....lol, but I got a few extra just in case they become permanent fixtures on certain amps.  For the series resistor, I was under the impression that it did not have to have that high of a wattage rating, though it does make sense that it should be the same.  I think I picked up that idea from somewhere else?  Not a big deal at ten cents each....   
  
 I will be placing a second order with suggested parts, and a few other odds and ends after I get a bit further on some other projects I am working on and also get a chance to play with your resistor calc some.  Could post results for this if anyone is interested.  I have modest test equipment; a "vintage" hand held battery powered RTA with built in microphone.  Still very useful despite its age(it even comes with its own battery powered pink noise generator...lol)...just a little time consuming...lol...good for "tuning" a listening room.  I havent had much success, or tried very hard either, to use it to measure either of my own headphones.  I think I need to "seal" the mic to the ear pad(some sort of adapter), much the way the ear pad seals the can to your head; to create the same airspace and sound pressures that are actually present when using a headphone, "on your head".  All this in mono with just one speaker of course....cross talk and other stereo stuff is a bit more complicated....I do have an oscope and a "few" other pieces of test gear too.....
	

	
	
		
		

		
			





  Have to see what I can cobble together.
  
 Results could be interesting, but I'm not sure how useful they would be for others unless they have the same rig as I do....  never know though.... 
  
 Thanks again and again robrob...."If ya ever need a favor..."...just ask.


----------



## robrob

The 16 ohm resistors would work just fine as load resistors (no series resistor). Your amp would see around 14 to 15 ohms of speaker load and that wouldn't be a problem at all.


----------



## DJ The Rocket (Jun 9, 2017)

I'm confused. I had figured I could simply splice a resistor into each line in a headphone cable, and I came online to find out if I needed a resistor in all three lines, or just the two hot ones. But I'm seeing all sorts of complicated stuff like this:






I can't come up with any idea why you would want to connect the L and R channels to the ground INSIDE THE ADAPTER!  Does that make sense? That's not how normal operation works. So why would this make sense? 

Can I still just splice a resistor in each channel? I'm using 100 ohm resistors because that's what I have available. What about on a TRRS setup? 

My end goal is to listen to my (TRRS) 16 ohm Audeze iSine 10s (or even 120 ohm Hifiman RE-262) on my Pioneer 50 watt amp off the speaker posts. It's possible to do it directly, but there is just so much noise, and it's just barely into the volume pot's usable range


----------



## snellemin

DJ The Rocket said:


> I'm confused. I had figured I could simply splice a resistor into each line in a headphone cable, and I came online to find out if I needed a resistor in all three lines, or just the two hot ones. But I'm seeing all sorts of complicated stuff like this:
> 
> 
> 
> ...



I have been using the Rolls PM52 speaker tabs.  I mod them a bit to run of my amps.  I beef up all the traces and swap over the resistors to something like 60-80 ohms.  100 ohms for the TRRS is sufficient.


----------



## DJ The Rocket

@snellemin 

So just using 4 resistors, spliced into each channel (one each for L+, L-, R+, R-) will do what I want?


----------



## snellemin

DJ The Rocket said:


> @snellemin
> 
> So just using 4 resistors, spliced into each channel (one each for L+, L-, R+, R-) will do what I want?



I just wired 1 each to the left and right positive.  

If you are unsure what value you want to use, you can always get a speaker walmount volume control that is resistor based.  I am still using one with my headphones.


----------



## DJ The Rocket

snellemin said:


> I just wired 1 each to the left and right positive.



This was for a single-ended TRS cable, correct? Or did you truly mean it the other way? 

It worked out like you expected? Volume attenuation + lowering hiss on low impedance IEMs (if you have tested that)?

In my TRRS setup, all 4 channels are hot, so every way I try to imagine what's happening in the circuit, using a resistor each makes the most sense. In a TRS system though I can see how just doing the hot chanels could possibly be correct. I just don't any confidence that my imagination is accurately modeling reality.


----------



## Mightygrey

robrob said:


> R2 of 14 ohms 5 watts 1%
> 
> R3 of 2 ohms 5 watts 1%
> 
> ...


Hey mate, replying to this ancient thread as you will probably be able to help point me in the right direction - I've made a TRS --> Banana adapter for my Hifiman HE-5's to specifically play with my NAD D 3020 30WPC (@ 8 ohms) speaker amp. I've connected the L/R to their respective poles on the female TRS lugs, and both grounds from the respective amp speaker outs are connected to a common-ground on the female TRS jack. Does this sound safe/correct to you?


----------



## robrob

Mightygrey, that sounds correct.


----------



## Garuspik

Best HE adapter is a good cable from amp output to headphones. Don't worry it won't be too loud. You'll be listening your headphones almost on the same volume knob position as your speakers.


----------



## patatchod

Garuspik said:


> Best HE adapter is a good cable from amp output to headphones. Don't worry it won't be too loud. You'll be listening your headphones almost on the same volume knob position as your speakers.


Totally agree with you, especially if you use the HE6SE with an SS amplifier!


----------

