# Millet Hybrid Construction Thread



## meat01

Since everyone is getting their boards and starting to build their amps, I figured I would start a thread for questions, comments and build photos.

 I have put in most of my components, but I forgot to order 2 diodes, so I have to wait for more parts. How is everyone elses coming along?


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## Emon

I've yet to order my parts, but I do have a question. On the Hybrid page with the parts list, the note for the C7 output coupling caps says:
  Quote:


 The output coupling caps determine the low frequency cutoff point. For 100uF is the lowest recommended value. For headphones with impedances <150 ohms, up to 470uF is appropriate. 35V, 7.5mm pin spacing, 16mm diameter. Alternate pin spacing is provided for 5mm pins. 
 

Looks like there's some typo action goin' on here...I'm going to drive HD600s with these, what should I choose? The part suggestion for Cerafines and Silmic IIs only has 100uF caps listed, so I figured those are the best value. What's with the 270uF vs 470uF Nichicons? Why not 100uF for those? (I was planning on Cerafines or Silmic IIs, but why not higher values for those or lower values for the Nichicons?)

 Also, would anyone happen to have a revised PCB from the group buy? I missed out on that deal and I'd rather not have to etch it myself or buy the original from DIYcable.


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## JWFokker

The size of the capacitor determines the the f3 of the amp, or the point at which bass response is down by 3 decibels. Bass response decreases very quickly after the f3. With low impedance phones like Grados, you need a larger capacitor, ideally 470uf or larger to keep the f3 as low as possible. With higher impedance phones, a smaller cap is required to prevent undue bass rolloff. Don't ask me why, because I possess no knowledge of the science behind it. This is just what I remember from the other thread. If I remember correctly, you can get away with 220uf caps with certain Sennheisers, and have an f3 of 10hz or so, lower than your headphones will ever go. But why skimp on caps? I'd pick up some 470uf or larger Cerafines just in case you end up with Grados or other low impedance phones in the future.


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## Emon

Hmm, so it seems like 220uF is a good compromise between low impedence and high impedence headphones? I may buy some 100uF and 470uF Cerafines and mount a DPDT switch on the chassis, as I do plan to buy some Grados later this year.


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## JWFokker

I wouldn't call the 220uf's a good compromise. There's no benefit to using smaller caps. According to amb:


 "For a 100uF output cap, -3dB point is 5.3Hz for 300 ohm load or 49.7Hz for 32 ohm load. For 470uF, it's 1.1Hz and 10.6Hz, respectively"


 I would say go with the 470uf's, but that's just me. They're only a couple bucks more than the smaller caps. And if the Cerafines are too pricey, Panasonic FM series (better than the FCs) at Digikey are a fraction the price, but still very good. You can get just about every part from Digikey except the diodes, enclosure and tube parts, so it'd be well worth it to pick up some FMs if you order from them. Mouser has Nichicon caps, though I don't remember what the high end series of Nichicon caps is. FX I think. But I'm not sure if Mouser caries 'em.

 And since no one else has posted it:


 Here is the parts list and build directions link:

http://www.diyforums.org/millett.html


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## Emon

The site said the maximum suggested value was 470uF I believe. What happens to the f3 with 300 ohm Senns plugged in? Or high impedence AKGs or Beyerdynamics that I may be interested in the future? Especially if the replacement diamond buffer Drew is working on turns out well, I may not bother with a different amp for quite some time.


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## amb

Quote:


  Originally Posted by *Emon* 
_The site said the maximum suggested value was 470uF I believe. What happens to the f3 with 300 ohm Senns plugged in? Or high impedence AKGs or Beyerdynamics that I may be interested in the future? Especially if the replacement diamond buffer Drew is working on turns out well, I may not bother with a different amp for quite some time._

 

470uF should be good for any loads from 32 ohms and up. See JWFokker's post above, where he quotes my prior post about where the f3 would be for different loads.


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## Emon

I did read it, but he just updated it. Thanks for the PM, by the way, JWFokker.

 So 470uF it is. I'm not worrying about spending a few more dollars for the Cerafines or Silmic IIs, I just wanted to have the right ones. By the way, is there any audible difference between the Cerafines and Silmic IIs? Any significant difference, that is? The Silmic IIs I think were actually a bit cheaper than the Silmic IIs when ordering from Handmade Electronics and Welbourne Labs, respectively. I know they're both high quality caps, just trying to make a little more informed decision.


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## JWFokker

Well, the Silmics did replace the Cerafines, so you'd assume they're better in some way. But the general opinion I've gathered of them is that there is little if any audible difference between the Cerafine and Silmic II's. I think the deciding factor will be that I don't know of any place that sells 35V 470uf Silmics, whereas Cerafines are still available in a much wider variety. The biggest Silmics rated for the voltage we need or higher, is 220uf that I've found. You can get 1000uf 35V Cerafines still. That made the decision easier for me at least.

 Update: So I finished my Millett Hybrid a little while ago after my power supply arrived. It's a Power One MAP130-1024. A bit much for the purpose (24VDC 6.25A), but it was $25 on ebay and it's considerably better than a wallwart. Interestingly, my Audigy 2 NX sounds like absolute crap compared to my beaten and battered portable Sony D-E301 from 1999. The thing has to be turned upside down to prevent skipping (if anyone's got any ideas why it does this, let me know), and supposedly it was made during Sony's Era of Suck, but it's line out sounds better than any output on my Audigy 2 NX. I guess I need a good DAC so I can use the optical or SPDIF out (it's got both).

 Preliminary results are quite excellent with the Discman. Everything is clearer, which I suppose is what gives the impression of improved attack and separation. The Audigy 2 NX does not gain any perceptible improvement. The device itself muddies the audio, regardless of if I use the headphone out or regular line out. Perhaps because it's a USB device? But I've not heard of this problem with other soundcards, internal or external, so it may be particular to this device. The Discman however, sounds great. It really brings out the best in my SR60's, to the point that I want better quality recordings. I had no idea Alice In Chain's "Dirt" was such a noisy album.

 Next upgrade will likely be a good bang for the buck DAC and eventually a new soundcard, maybe a new EMU when they debut late this year or early 2006.


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## Emon

Thanks for the Silmic II vs Cerafine comparison. Oh, and make sure CMSS and any EAX effects in software or on the device itself are shut off. CMSS, from what I remember of my roomate's Audigy 2 NX, bloated the bass and made the mids and highs rather tinny sounding. It was a while ago, but it sounded like crap. Make sure that's off. If not on the device itself, check the software. Creative software sometimes turns on CMSS or EAX effects by itself (even when they appear disabled)...so you may want to enable them, apply effects then disable them again.


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## flecom

well, i built a millet a while ago on the original pcb design... loved it a lot 
	

	
	
		
		

		
			





 so here is a pic...


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## Thaddy

I didn't make it, but here she is! This one is built on the old PCB as well, and it's holding me over until Nate finishes my uber-Millet


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## JWFokker

It turns out my PC volume control was not all the way up. Odd that it makes such a difference, yet it does. It still doesn't sound as good as the D-E301 line out, but better than before. Dynamics are a bit better with the software volume cranked.


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## .: ZMN :.

JWFokker: This site worked well for me to get Silmic II/Carafines in the 35V values I needed. Hope it helps.


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## multibit16

Well I have a couple of 680uf 35v BG NX spare, do you reckon I could use those?


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## tezzla

sorry this is a bit off topic but anyone in the uk, where are you getting your parts from?


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## multibit16

Quote:


  Originally Posted by *tezzla* 
_sorry this is a bit off topic but anyone in the uk, where are you getting your parts from?_

 

Most of the parts are available from Farnell,RS and Audiocominternational, theres also Silmic caps on E-bay.
 The thing thats hard to find in the UK is the actual tubes


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## multibit16

Quote:


  Originally Posted by *Thaddy* 
_I didn't make it, but here she is! This one is built on the old PCB as well, and it's holding me over until Nate finishes my uber-Millet 
	

	
	
		
		

		
			




http://www6.head-fi.org/forums/showp...6&postcount=12_

 

Very Very neat 
	

	
	
		
		

		
		
	


	




 I love the chassis


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## dviswa

Got mine working yesterday night. Sounds OK now, but badly needs burn-in. My pot is still to arrive so I have rigged an el-cheapo taiwan alpha for now. Obviously the case work will not be complete till the pot is taken care of.


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## rreynol

Finished up some more case work. 






 unibit 4 teh win (expensive but very much worth it).


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## USER NAME:

I was just fooling around in the shop trying to think of a good chassis solution for my Millet Hybrid. It's not done yet. It's just a fully dressed chassis with no board inside. I tried to add some carbon fiber to the mix, but it just looked awkward. I'm never satisfied. Maybe I should start looking in to aluminum? Anybody have any constructive criticism?


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## BlazerFRS

I'd just leave it be USER NAME: ; that case looks sweet.

 I like wood cases; I don't think carbon fiber would go with it tho IMHO.


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## meat01

That looks sweet the way it is now. Beautiful job!


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## Blooze

Very Nice! I've got some purpleheart coming to build my chassis out of. Thinking about putting maple or osage accents on the corners.

 Did you make the rod guards, also?

 Shane


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## USER NAME:

Thanks guys. It's starting to grow on me. I have to make one for my SEPP Millet now.

  Quote:


  Originally Posted by *Blooze* 
_Very Nice! I've got some purpleheart coming to build my chassis out of. Thinking about putting maple or osage accents on the corners.

 Did you make the rod guards, also?

 Shane_

 

The metal rods are drawer pulls from Home Depot. They have many different styles of these.


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## aeroes

Is it really important to have a matched tubes?


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## MisterX

Quote:


  Originally Posted by *aeroes* 
_Is it really important to have a matched tubes?_

 

Yes!


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## Emon

How do you go about matching tubes?


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## mrdon

I've completed everything via DREWD's instructions. However, when I plugged in the wallwart and connected to the female dc jack nothing powered up. 
	

	
	
		
		

		
		
	


	




 I checked to see if indeed there was power coming into the female jack by using a pair of electicians testers and there was a spark on the + terminal and then nothing. 
	

	
	
		
		

		
		
	


	




 I unplugged it and did it again but nothing. Any help and advice would be greatly appreciated. Thanks!


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## aeroes

Quote:


  Originally Posted by *mrdon* 
_I've completed everything via DREWD's instructions. However, when I plugged in the wallwart and connected to the female dc jack nothing powered up. 
	

	
	
		
		

		
		
	


	




 I checked to see if indeed there was power coming into the female jack by using a pair of electicians testers and there was a spark on the + terminal and then nothing. 
	

	
	
		
		

		
		
	


	




 I unplugged it and did it again but nothing. Any help and advice would be greatly appreciated. Thanks!_

 


 See the diodes if its in the right polarities!


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## mrdon

OK...I jiggled the DC male plug and the tubes lit up! It appears the problem is the female is not gripping the male plug. Well, that's easy to fix. 
	

	
	
		
		

		
			





 I am soooo close to completion but....upon initially testing the unit with a PCDP conected I am getting music from the left headphone speaker but not the right. 
	

	
	
		
		

		
		
	


	




 What I hear in the right side upon power up is a sound similar to a TV starting up, sort of a hum that builds, and then cuts out. 

 1. Is it a matter of adjusting the bias? 
 2. Is my 24VDC, 400mA wallwart powerful enough to power the 12fk6 tubes? 
 3. Something else?


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## rreynol

Quote:


  Originally Posted by *mrdon* 
_OK...I jiggled the DC male plug and the tubes lit up! It appears the problem is the female is not gripping the male plug. Well, that's easy to fix. 
	

	
	
		
		

		
		
	


	


_

 


 I too have an issue similar to this. Its something to do with what type of dc in connector you have on the amp vs the one on the adaptor. For instance, the mouser switchcraft 2.5/5.5mm plugs (Mouser 502-760) doesn't mate well with the kobicon 163-1100 jack (the plastic isolating one). However, the plug on the wire recommended for a STEPS build (72" 18 Gauge with 2.5mm/5.5mm connector at one end, Mouser P/N 172-4201) works well with the plastic jack. Also, the switchcraft plugs work great on the metal 2.5mm/5.5mm jack (Mouser P/N 163-1025). And by not working well, I mean that it doesnt always make a good connection. Something to keep in mind.


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## Thaddy

Quote:


  Originally Posted by *Emon* 
_How do you go about matching tubes?_

 

I just have the place I order from match them. It's only like $1 extra, and the tubes are cheap as hell, so your wallet doesn't take a huge hit.


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## rreynol

Quote:


  Originally Posted by *Thaddy* 
_I just have the place I order from match them. It's only like $1 extra, and the tubes are cheap as hell, so your wallet doesn't take a huge hit._

 

And what place is that?


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## Thaddy

Google 'Radio Electric Supply'. I always call them on the phone, they are very helpful and have always shipped my order the same day 
	

	
	
		
		

		
		
	


	




 Sorry, I should have mentioned them in my first post.


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## klappar

Hello

 I'm planning to build a "semi-maxed" version of Millet Hybrid but have some trouble getting the caps recommended here because I live in Europe.

 Currently my list is following:

 * electrolytes: Pana FC + Elna Starget on audio (could probably get os-cons but they are quite pricey)

 * polypropylene: no known good choices seem to be available... Lot of different Evox Rifa-s available, which would probably be good for non-audio path. Wima MKP10-s are available, but only starting with 630V which is 22.5mm for 0.1uF, 0.068uF is 15mm would it be too low? Also, some Vishay-Roederstein MKP1837 seem to be available in suitable format and price.

 What would you suggest from these options to get a best bang for buck type of amplifier with upgraded audio path parts?

 The international catalogues I have access are RS and Elfa.


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## aeroes

Anyone knows if tubestore match tubes? I emailed them and never got any answer.


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## steinchen

the Vishay-Roederstein MKP1837 should be a good pick, though they are metallized polypropylene (like Wima MKP-4 250V, they fit perfect on the board). Polypropylene film (e.g. Panasonic ECQ-P) are better for audio-path use, but more difficult to get (afaik only digikey).

 For power rail bypassing metallized polys like Wima or Vishay MKP are fine.


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## klappar

Has anyone heard of "Arcotronics Nissei" caps? They should be "film foil polypropylene" but never heard of this company before. Anyway I ordered these for audio path and evox rifas for power section. Maybe next week I can comment on their sound


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## roibm

Guys, any idea where I can get the tubes and the sockets here in europe(germany)?
 What tubes do you consider to be better for this project? What brand?


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## steinchen

sockets:
http://www.btb-elektronik.de/de/fassungen.html
http://www.oppermann-electronic.de/R...hrenfass_.html

 tubes:
 12AE6A / 12FM6 / 12FK6 tubes are very expensive in Germany, about 12 EUR = $15 each, U.S. prices are about $3


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## roibm

Quote:


  Originally Posted by *steinchen* 
_sockets:
http://www.btb-elektronik.de/de/fassungen.html
http://www.oppermann-electronic.de/R...hrenfass_.html_

 

Many thanks for the reply 
	

	
	
		
		

		
		
	


	



 What socket is the right one for this project? Miniatur 7?

  Quote:


  Originally Posted by *steinchen* 
_tubes:
 12AE6A / 12FM6 / 12FK6 tubes are very expensive in Germany, about 12 EUR = $15 each, U.S. prices are about $3_

 

Ouch 
	

	
	
		
		

		
		
	


	



 Have you got yours already? Maybe when enough interest a group by from US?


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## steinchen

yes, miniature 7 sockets are the right ones for this amp

 I ordered and received my tubes from the states already. Please note that group buys are on hold atm, talk to a mod (rickcr42, JMT, Voodoochile) before you start a thread.


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## mrdon

Well, I easily adjusted the bias to 12V on the Left Channel old school analog style. 
	

	
	
		
		

		
		
	


	




 However, the right Channel is still giving me problems. 
	

	
	
		
		

		
		
	


	




 After turning the screw clockwise and couterclockwise to the "click," the bias is stuck at 24V. Could it be a
 1. Faulty pot?
 2. Bad soldering point?
 3. Other?


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## n_maher

Fire up the digital camera and shoots some clear, detailed pics of the top and bottom of the board, that'll help us trouble shoot it with you. With the 24V bias are you still getting no sound out of the right channel?

 Nate


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## mrdon

Quote:


  Originally Posted by *n_maher* 
_Fire up the digital camera and shoots some clear, detailed pics of the top and bottom of the board, that'll help us trouble shoot it with you. With the 24V bias are you still getting no sound out of the right channel?

 Nate_

 

The only sound coming from the right channel is a "sucking" sound when I try to bias it. 

 I'm at work right now, so possibly this evening I can shoot some pictures up of the top and bottom.


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## Secret Squirrel

Preliminary Photo before my black knob gets here from Digikey. The sound is very clean and "Dead Quiet". Rathyeon 12FK6 tubes, Elna Cerafines and ALPS pot.


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## mrdon

Quote:


  Originally Posted by *mrdon* 
_Well, I easily adjusted the bias to 12V on the Left Channel old school analog style. 
	

	
	
		
		

		
		
	


	




 However, the right Channel is still giving me problems. 
	

	
	
		
		

		
		
	


	




 After turning the screw clockwise and couterclockwise to the "click," the bias is stuck at 24V. Could it be a
 1. Faulty pot?
 2. Bad soldering point?
 3. Other? 
 Don_

 

 Quote:


 Fire up the digital camera and shoots some clear, detailed pics of the top and bottom of the board, that'll help us trouble shoot it with you. With the 24V bias are you still getting no sound out of the right channel? Nate 
 

 Quote:


 The only sound coming from the right channel is a "sucking" sound when I try to bias it. 
 Don 
 

Here are the pictures Nate asked for. I tried to fire up the digital camera but a scanner works much better! BTW, I closely examined all the solder points and they all looked good except one on the Right bias pot which I resoldered. However, it did not seem to make a difference as the right channel is stuck at 24V bias. 

 I would really appreciate everyone's help in diagnosing the problem. I am really stumped and bummed 
	

	
	
		
		

		
		
	


	




 .


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## JWFokker

You've turned it counterclockwise all they way back and it still reads 24V?


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## JWFokker

Quote:


  Originally Posted by *Secret Squirrel* 
_Preliminary Photo before my black knob gets here from Digikey. The sound is very clean and "Dead Quiet". Rathyeon 12FK6 tubes, Elna Cerafines and ALPS pot. 
	

	
	
		
		

		
		
	


	







_

 


 Did you ground those tube protectors? You could have a Faraday cage of sorts.


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## Secret Squirrel

Interesting idea. The tube protector is tied to the rest of the enclosure, but all of the components are insulated.


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## multibit16

Have you checked these for solder shorts? (arrowed bellow)
 Try measuring the resistance of the trimmer pot with your meter


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## multibit16

How do you attach larger pics 
	

	
	
		
		

		
		
	


	



 Anyway check the solder joints of R6R the side that goes nearest the capacitor end of the track from pin 2 of VT1
 Check the solder joint of R2R trimmer, the solder looks very close to shorting out on your picture (the bottom side of pcb)


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## mrdon

Quote:


  Originally Posted by *multibit16* 
_How do you attach larger pics 
	

	
	
		
		

		
		
	


	



 Anyway check the solder joints of R6R the side that goes nearest the capacitor end of the track from pin 2 of VT1
 Check the solder joint of R2R trimmer, the solder looks very close to shorting out on your picture (the bottom side of pcb)_

 

I checked the arrowed joints and I think you are correct that they could be the problem areas. Those two joints (for whatever reason are not soaking up solder. The solder just collects on the pins and not on the pins and board. I tired cleaning with alcohol but to no avail. 

 How about this for a solution...Can I solder these "point to point" more precisely from pin to pin using jumper wires? I have this diagramed it on the attached photo.


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## steinchen

air-wiring won`t help since you need the connection to other components on the board.

 heat up pad and pin at the same time before applying fresh solder to make it work, maybe a smaller tip on the soldering iron helps

 btw, you should trim the pins on top of the solder points


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## saab

Maybe try addiing a bit of Flux? That always seems to get things flowing better.

 Not a soldering expert, so don't come after me if it gets ruined. 
	

	
	
		
		

		
		
	


	




 Good Luck
 -John


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## mrdon

Well my friends I finally have sound coming out of the right channel! This is how I did it. 
  Quote:


 Anyway check the solder joints of R6R the side that goes nearest the capacitor end of the track from pin 2 of VT1 
 

I did check and tried to resolder but the solder will not grab to the board. Anyway, in desperation I turned on the amp and started "test jumping" in that area using a lead from my multimeter and when I touched the bad point on R6R to the nearest point on C3R, sound came from the right channel! It appears I have found a backdoor solution? So, I soldered a jumper to those two pins. 





 Since I still had sound coming from the right channel, I then tried to adjust the bias and it has gone from being stuck at 24V to now being stuck at 5V. 
	

	
	
		
		

		
		
	


	



  Quote:


  Originally Posted by *JWFokker* 
_You've turned it counterclockwise all they way back and it still reads 24V?_

 

After turning counterclockwise and clockwise 3x's, it remains stuck at 5V. 
 Could the trimmer pot R2R be bad? Like R6R, solder will not grab the board but remain on the point. Therefore, it also may be that the resoldered point is still bad, but I can't seem to get it to work. 
  Quote:


 Try measuring the resistance of the trimmer pot with your meter 
 

I tried measuring the resistance and it does not appear to be very stable. On the multimeter is goes all the way up and then 1/4 of the way back down on the meter.

 Any other ideas?


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## mrdon

Quote:


  Originally Posted by *multibit16* 
_How do you attach larger pics 
	

	
	
		
		

		
		
	


	


_

 

Use photobucket!


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## multibit16

Quote:


  Originally Posted by *mrdon* 
_Well my friends I finally have sound coming out of the right channel! This is how I did it. 

 I did check and tried to resolder but the solder will not grab to the board. Anyway, in desperation I turned on the amp and started "test jumping" in that area using a lead from my multimeter and when I touched the bad point on R6R to the nearest point on C3R, sound came from the right channel! It appears I have found a backdoor solution? So, I soldered a jumper to those two pins. 





 Since I still had sound coming from the right channel, I then tried to adjust the bias and it has gone from being stuck at 24V to now being stuck at 5V. 
	

	
	
		
		

		
		
	


	




 After turning counterclockwise and clockwise 3x's, it remains stuck at 5V. 
 Could the trimmer pot R2R be bad? Like R6R, solder will not grab the board but remain on the point. Therefore, it also may be that the resoldered point is still bad, but I can't seem to get it to work. 

 I tried measuring the resistance and it does not appear to be very stable. On the multimeter is goes all the way up and then 1/4 of the way back down on the meter.

 Any other ideas?_

 


 I just got home from work and saw your posts
	

	
	
		
		

		
		
	


	



 Ok, remove that jumper thats on the left! if you linked those two joints (R6R and C3R) on the picture then you are shorting the +v 220uf bias cap to earth, could be the reason why the trimpot value is unstable.
 I actually meant in my original post to make sure they are not solder shorted there too
	

	
	
		
		

		
		
	


	




 Also don't heat up those trimpots too much, they damage easily, if you use good solder then a small amount of heat will also make the solder take to the trimmers leg and pcb pad better


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## shut85

Ok so i went back to my amp and realized my d1 was put in the wrong way. I replaced d1 and pf1 and put in d1 the correct way, however i am still having the same problem as before (the pf1 gettin really hot and the led not coming on). What damage could have been done by mounting d1 the wrong way. I am 99% sure i do not have any solder bridges unless i really did miss something checking over the board 20 times over. If it can be no other reason than a solder bridge i will try to take some pictures and post them here.


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## mrdon

Quote:


  Originally Posted by *multibit16* 
_How do you attach larger pics 
	

	
	
		
		

		
			




 Anyway check the solder joints of R6R the side that goes nearest the capacitor end of the track from pin 2 of VT1
 Check the solder joint of R2R trimmer, the solder looks very close to shorting out on your picture (the bottom side of pcb)_

 

I think I am going to give up. I realize now that will all the solder gun heat and playing around trying to fix this problem the solder pads are now history. 
	

	
	
		
		

		
		
	


	




 [Ah, the lessons we learn when we embrace new hobbies!]

 Therefore, should I

 1. Start over with a new PCB and affix some new parts as well as parts salvaged from the old pcb?

 OR

 2. Try and "repair" the pads by using this method recommended on AudioAsylum: "Another method of repair is to use the lead of the new replacement part to bridge over to the PCB trace. Make sure the trace is clean to bare copper and carefully tin it. Then just solder the lead to the trace. Careful with the heat."

 What do you think men?


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## Jaypetermen

The enclosure, I am thinking about using, has an internal height of 1.3". With a .25" standoff and the board thickness I have about .75" to 1" remaining. 

 What is a good boutique caps for C7 with a low profile (.75" to 1")?


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## ble0t

Quote:


  Originally Posted by *mrdon* 
_Try and "repair" the pads by using this method recommended on AudioAsylum: "Another method of repair is to use the lead of the new replacement part to bridge over to the PCB trace. Make sure the trace is clean to bare copper and carefully tin it. Then just solder the lead to the trace. Careful with the heat."

 What do you think men? 
	

	
	
		
		

		
		
	


	


_

 

I've done this before and it's worked with no problems. Just carefully scratch away the soldermask and it shouldn't be too hard.


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## n_maher

Quote:


  Originally Posted by *mrdon* 
_I think I am going to give up._

 

I think you should try soldering to the top side of the board first, before fully giving up. Also, these boards are through plated so if you get solder in and around the leads you should still get a working connection.

 And so you don't feel bad I've had amps that regardless of how hard I tried never worked. I sent them to other, more experienced builders, for review and even they couldn't find the solution. Some times there's a cranky part that you just can't fix. That's my experience anyway.

 Best of luck.

 Nate


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## mrdon

Thanks Nate and ble0t! You have given me hope! I'll let you know how it goes.


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## rreynol

Quote:


  Originally Posted by *mrdon* 
_Thanks Nate and ble0t! You have given me hope! I'll let you know how it goes._

 

To further emphasize what nate said, here is a page from my experiences. 

 During my graduate days, I taught an introduction to digital design lab. It was a real basic lab where they'd give you a kit of dip IC's (8255 Timers, 1 bit adders, etc), some resistors, and some wire and you had 10 labs over the course of the semester. It started out with simple things eventually working up to things such as 4 bit multipliers, etc. I took it as an undergrad and like I said, I taught the lab my entire time in grad school (so I knew the labs very well). On occasion, I would get a students circuit that just wouldn't work. Even after spending 2 hours trying to debug it myself, I would get nowhere.

 Cranky electronics do exist. Don't give up on it just yet.


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## ble0t

BTW...I too am having problems 
	

	
	
		
		

		
		
	


	




http://www.diyforums.org/phpBB2/view...46246b5c302490

 If anyone has any ideas, let me know...it's true this can be a very frustrating hobby at times


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## mrdon

Quote:


  Originally Posted by *mrdon* 
_Thanks Nate and ble0t! You have given me hope! I'll let you know how it goes._

 

THANK YOU TO EVERYONE ON THIS BOARD THAT HELPED ME FIND A SOLUTION TO MY RIGHT CHANNEL PROBLEM AND CHALLENGED ME BEYOND ANYTHING I EXPECTED FOR THIS PROJECT. YOU GUYS ARE GOD'S GIFT TO ME AND I THANK YOU! 
	

	
	
		
		

		
		
	


	






















 BTW, I post pics later. 

 Don


----------



## n_maher

Folks, this may seem like an odd request but bear with me and please try and understand without asking questions, I won't discuss it anymore than what I have to say in the following paragraph, please don't PM me either.

 Let's keep Head-Fi discussions on Head-Fi. If you're using another site to discuss the Millett project please keep that discussion there. One, it'll keep things more simple for those of us trying to help you out, two there are other reasons that I'd prefer you do it that way.

 Thanks!

 Nate


----------



## n_maher

Quote:


  Originally Posted by *mrdon* 
_
 BTW, I post pics later. 

 Don_

 

Pics of your amp, done, and knowing that you're enjoying it are thanks enough for me 
	

	
	
		
		

		
		
	


	




 .

 N


----------



## drewd

For those who are having trouble setting the bias, do you have R6R/L populated? If you do, try removing that resistor. If it's not populated, then we'll have to look elsewhere. Also, make sure that D2L/R are installed the right direction and working properly. In a pinch, they can be replaced with a 50K resistor.

 Keep us up to date with the results.

 Oh, and ditto what Nate said a couple of posts before.

 -Drew


----------



## ble0t

My apologies for the link...I just wasn't sure how many people knew about the other forum and was looking for all the feedback I can get. I will just double post from now on


----------



## Voodoochile

Sidebar:
 No need to get all freaked out about posting a link to another forum, especially of it's specific to a project. Whether you wish to double-post or not is up to you. Seems a little excessive to me to double post a question only to have the same people double replying with an answer.

 In a nutshell, there is no shilling allowed here. But if a poster wants to reference something of relevance on another website in his post, that is not an issue. It's been going on for years between Head-Fi and Headwize, for example.

 So don't get too excited, there is nothing new about that. Just try to keep things in perspective and on track. That is also the only reason the group buy thread was closed: because a lot of build-related posts were landing in there, in spite of having a seperate build thread underway already. It makes it a real PITA to find this stuff later on, via the search function. Speaking of, don't forget we have that at your disposal, and many of these inquiries are old hat.


----------



## pabbi1

Along the lines of other observations, after setting my bias at 16v (both channels), after about 3 hours, one had moved to 14.9v and the other to 17v.

 This doesn't really bother me for the first few hours while things are "settling", but at what is causing the drift, and, at what point should it stop drifting?

 I'll measure again tonight, which will be at the 24 hour point.


----------



## drewd

Quote:


  Originally Posted by *pabbi1* 
_Along the lines of other observations, after setting my bias at 16v (both channels), after about 3 hours, one had moved to 14.9v and the other to 17v.

 This doesn't really bother me for the first few hours while things are "settling", but at what is causing the drift, and, at what point should it stop drifting?_

 

Heat, possibly. The tubes don't get hot enough to burn, but they do get pretty warm. Even with 2/3 of the tube sticking out of the case on my amp, the case gets warm.

 -Drew


----------



## shut85

So i found out what was causing my problem, turns out the power supply i was using had this replaceble plug mechanism and the plug was put in the wrong way. Now the amp turns on with the led and i can adjust the bias, however there is no sound coming out and on the left side the bias can be adjusted all the way down while the right side will only go down until around 18v. Also D1 is now really hot to the touch.

 Hah if worse comes to worse at least i have something that will light up now.


----------



## n_maher

Sounds to me like you've still got a wiring problem somewhere. It would probably be very helpful if you could post pictures of the top and bottom side of the board so we can see what've you've done. To try and guess all the things that might be wrong is impossible.

 Nate


----------



## mrdon

Thanks to Drew, Nate, and others here and at DIYforums.org, my millet is now complete with my custom built tiger maple and cherry case.


----------



## pabbi1

Well, once the temperature stabilized, the 'bias' has remained constant, so I guess it was a temperature issue. While my tubes barely poke out the top, I feel no heat on the Millett side. There is some warmth on the STEPS side, but since this is a Pars Metal 20, with side vents, temperature seems to be a total non-factor.

 Just letting this one burn, but the initial listen last night was VERY promising.

 I can get almost 600 hours of burn prior to the Ft Worth meet, so we'll have some head to head there. Honestly, already it is almost indistinguishable from the M³ in places, but can't quite resolve everything, so there is an odd sound here and there (say once every 5 minutes of questionable source (Old Stones) and every 15 minuted on SACD or digitally remastered material. Maybe some of this smooths out with burnin, but the guitar overtones are already, well, exciting. There is plenty of power for the HD600, but the bass is a bit mushy (hopefully the BG), and almost TOO pronounced. 


 A brighter can (SA5000) is certainly now a must try - 

 Ah, the curse of new toys.


----------



## USER NAME:

Great job mrdon!! Thats what I like to see. Remember wood sounds better too.


----------



## BlazerFRS

My god what a beautiful amp....


----------



## Emon

Quote:


  Originally Posted by *mrdon* 
_Thanks to Drew, Nate, and others here and at DIYforums.org, my millet is now complete with my custom built tiger maple and cherry case.[/IMG]_

 

Looks fantastic! Very simple and elegant.


----------



## skyskraper

aussie/nz guys, posted your boards today. apologies for aust posts incompetence in getting them to me


----------



## saab

I have tried to read as much as possible, but can't find what this is in the attached picture. I have seen some boards that don't have this. Do I need to do anything in these spots? There is no mention of them in the BOM or insructions.

 Thanks, and sorry if this is a dumb question.
 -John


----------



## n_maher

John, 

 That is the alternate diode postion. You either populate this position (on each channel) or the other one. Folks in Europe (I think) were having trouble sourcing the current regulating diode that the original amp used so we found a different one. It just has different pins so we had to creat a new location for it.

 Hope that clears it up for you.

 Nate


----------



## saab

So, since I populated the other diodes, I can just leave these alone?

 Thanks
 -John


----------



## n_maher

Yup. It's a "one or the other (but NOT BOTH)" scenario.

 N


----------



## BlueCan

I got the board yesterday. Haven't finished the casework yet--and I'm going to replace the black knob (and pins holding the faceplate) with something in brushed aluminum. 

 It did go together more easily than a CMoy. 

 I'm THOROUGHLY enjoying it--even though it's only been running for 15 hours.

 -Patrick


----------



## roibm

Can anyone comment on the tubes used and how they sound? A mini review with multiple tube types face off would be really great...


----------



## pabbi1

Start here:

Tubes in the design discussion 

 There is also so great stuff in the original article referenced here. 

 Then, for the harder core, there's this:

12AE6A 
12FK6 


 Anyone notice a fatiguing effect of this amp, especially compared to SS? Distortion or the (oft desired) 2nd ordered harmonics, or possibly occasional clipping? Or, possibly, the bass is just overbearing (which means C2 needs to come up from 100u to 220, 330, or even 470u)?

 I know, I know, it isn't burned in yet... 50 hours in, several hundred to go.


----------



## Thaddy

Pabbi, I believe only the 12AE6*A*'s work, right? Correct me if I'm wrong though.


----------



## pabbi1

My bad... I'll / I've edited. Actually, per the first link, they discuss using 12AE6, just having to bias it correctly for it so sound OK.


----------



## pabbi1

urp...


----------



## JWFokker

I just finished my second Millett Hybrid, this time with all Cerafines instead of Panasonic FMs and Silmic II's. It sounds a bit more balanced. This is entirely subjective as I don't have the means to measure frequency response, but highs are a bit smoother and less harsh (or maybe less revealing) than with the Silmic II's on the output. The bass seem fuller, but this could be an illusion resulting from the less harsh treble. I first noticed this when I swapped out the Silmic II's for Cerafines on my first amp, but with this amp the effect is even more noticable. Unfortunately, there are too many variables to draw a definite conclusion. I used Panasonic FM caps everywhere other than the output caps and used whatever resistors Digikey sells. I don't know what manufacturer they are. They're the blue ones. On this amp I used more of the same but the 221's were Allen Bradley 220 carbon films this time around because I ran out of the ones from Digikey. And to top it off, the output caps are now 1000uf Cerafines instead of 470uf Cerafines. At any rate, the effect is subtle, but noticable and definitely beneficial, at least in my opinion. All listening was done with SR60's. Next step is building a couple of wooden enclosures. Lacewood and ivorywood veneer is already on the way. I'm thinking of integrating a faraday cage for each amp because I want to mount the power supply in the enclosure immediately below the amp itself.


----------



## BlazerFRS

Sounds interesting JWF, I have really got to build one of these...

 BTW the blue 1/4 resistors from digikey are Yageo, 1% metal film, 100PPM/*C


----------



## AtomBoy

Quote:


  Originally Posted by *pabbi1* 
_Anyone notice a fatiguing effect of this amp, especially compared to SS? Distortion or the (oft desired) 2nd ordered harmonics, or possibly occasional clipping? Or, possibly, the bass is just overbearing (which means C2 needs to come up from 100u to 220, 330, or even 470u)?

 I know, I know, it isn't burned in yet... 50 hours in, several hundred to go._

 

I'm noticing the ocasional pop or barely there thump. If I had to guess, I'd say the tubes are waking up after 40 years and wondering why there's no three day work week, personal ufo's in every driveway and vacations on Mars. I'd be a little bitter about it too. They do sound better every day, though.


----------



## pabbi1

Started a "listening / review" thread in the Amp forum - but maybe it gets moved.

It's here...


----------



## Emon

Well I finished my Millet Hybrid tonight. I'm using a STEPS and it's currently inside a cardboard shipping box from Digi-Key since I haven't built the enclosure, which I'm building from scratch using aluminum angle for the frame and steel for the panels (painted, black). Making a u-shaped slide in cover (secured with screws) for the top and a slightly oversized (maybe 1/8" around the edges) front panel from 16 AWG steel. Oh, this is going to be slick!

 Anyways, about the amp...So far it sounds great. It sounded kind of harsh and almost tinny at first, but after about an hour of warmup it opened up quite a bit. I'm a bit skeptical of amp burn in, but since this thing has tubes and lots of caps (using Elna Cerafines, by the way) I do expect a difference. Gonna let it burn in all week. I'll probably be building the enclosure during that time and working on quieting my PC. Need to order a few parts for a thermal PWM fan control...

 Edit: By the way, I'm experiencing harsh highs on my HD600s in some recordings. It's almost like a fuzzy/harsh/buzzing sound to some of the highs, but somewhat smoothed over. I noticed this before when unamped, and my HD600 are second hand and already burned in so that's not it. My ER-6 produce nothing but clean, clear and crisp highs off my 1212m, so it's not that either. Can I expect these highs to clear up or do I just have a few bad recordings? Only reason I'm skeptical of it being the recordings is that the ER-6 had no such issue with them.

 Oh, and when I plug my ER-6 in I get a hiss/hum with no volume. Not the case with my HD600 or HD414 - what the crap?


----------



## nobuoa

Finished the amp and notice that I have to have the volume 3/4 of the way up to get to reasonable level with a Senn 497 for my testing. The power source is a wallwart putting out 26 volts through a TREAD putting out 23 volts. I used Cerafine Silmics 100 and Nichicon Muse 220 with an Alps pot. I tried adjusting the bias between 9-16 volts with the sound best around 11 -12 volts with 12fk6. The sound is clear but not a great volume. I'm using a discman and adjusting the headphone volume to 8-9. The only major problem with construction was that I did have to pull the buffers out because one of the legs bending. Is it the buffers or tube choice or none of the above? I've used the same source test set-up for C-moys and a meta 42.


----------



## n_maher

Quote:


  Originally Posted by *nobuoa* 
_Finished the amp and notice that I have to have the volume 3/4 of the way up to get to reasonable level with a Senn 497 for my testing._

 

That doesn't sound right, in fact it sounds like my first prototype in which I used the wrong resistor value (D'OH!) for R4L/R. Double check that value and if you have any suspicions that it may be wrong remove it and jumper it. It isn't 100% necessary.

 HTH,

 Nate


----------



## pabbi1

I also had harshness to the point of fatigue the first day, but this should smooth out with burn-in... at 100 hours, it is way smoother and not nearly as fatiguing.

 As for the gain, with my DH600, I can rarely exceed 12 o'colck, and never exceed 1 o'colck with the default resistor settings. That is with the STEPS at 28v, and 16v bias on 12AE6A tubes.


----------



## nobuoa

Thanks Nate, you were absolutely right the wrong resistor value for R4. I usually double check my parts list and when I put in the part but in my enthusiasm to get started must have missed it. Will try jumper and get the right part.


----------



## Emon

I find that 9 o'clock is about the perfect listening level for me out of my E-MU 1212m, with all volume levels at 0 (as in 0 above and 0 below the norm) in Patchmix DSP. The lack of sweeping range is probably due to the 100k Alps RK27 I'm using.


----------



## klappar

I finished my board but I dont get any sound... even no noise/hiss. I can adjust the bias fine. Only wierd thing is that the tubes get quite hot in only few minutes. Tried both the 12FK6 and 12AE6. Bias was 12V for both. Checked my wiring and soldering and detected no shorts or bridges. My power supply is unregulated 24V/1A, with heaters on it gives 27.5V. Any suggestions how to debug this situation? Thanks!

 Photos:


----------



## n_maher

Quote:


  Originally Posted by *klappar* 
_Any suggestions how to debug this situation? Thanks!_

 

Sure, post up some pics of the board and how you have the input and output wired. You wouldn't be the first person to think that they had a jack wired correctly only to find out different, trust me 
	

	
	
		
		

		
		
	


	




.

 Nate


----------



## James281

could someone post some pictures of their compete project with all the wire in from top view?










 this is my first diy project and i don't want to make any mistake 
	

	
	
		
		

		
		
	


	




 here is what i got, this take me like 30 minutes and seem pretty darn easy so far.


----------



## klappar

Quote:


  Originally Posted by *klappar* 
_I finished my board but I dont get any sound... even no noise/hiss. I can adjust the bias fine. Only wierd thing is that the tubes get quite hot in only few minutes. Tried both the 12FK6 and 12AE6. Bias was 12V for both. Checked my wiring and soldering and detected no shorts or bridges. My power supply is unregulated 24V/1A, with heaters on it gives 27.5V. Any suggestions how to debug this situation? Thanks!_

 

Okay... found out that my output jack is of breaking type and my L + G are on breaking side ;P Will resolder it later today and see what happens.


----------



## klappar

Quote:


  Originally Posted by *klappar* 
_Okay... found out that my output jack is of breaking type and my L + G are on breaking side ;P Will resolder it later today and see what happens._

 

Okay, rewired the output jack but still no sound gets outputted... and the tubes get quite hot.


----------



## NOTHINGness

It looks like you need to jumper from L_POT_1 to L_POT_2 and from R_POT_1 to R_POT_2.


----------



## Jaypetermen

klappar,

 Is the output jack of the switching variety?

 If so, you may want to check to make sure that it's wire correctly.


----------



## drewd

Quote:


  Originally Posted by *klappar* 
_I finished my board but I dont get any sound... even no noise/hiss. I can adjust the bias fine. Only wierd thing is that the tubes get quite hot in only few minutes. Tried both the 12FK6 and 12AE6. Bias was 12V for both. Checked my wiring and soldering and detected no shorts or bridges. My power supply is unregulated 24V/1A, with heaters on it gives 27.5V. Any suggestions how to debug this situation? Thanks!_

 

If you are going to use the "outboard" pot connections, then you must install the jumpers on the other side of the board to connect the input signals to the pot. There are pads for two jumpers, one for each channel.

 The tubes should get very hot - not so hot that you can't touch them, but hot enough that you don't want to hold onto them for very long.

 -Drew


----------



## klappar

Jumpered r_pot and l_pot pads and now I have sound 
	

	
	
		
		

		
		
	


	




 Thanks for everyone for suggestions. Btw, wouldn't it be nice to put this information about outboard pots somewhere visible?


----------



## drewd

Quote:


  Originally Posted by *klappar* 
_Jumpered r_pot and l_pot pads and now I have sound 
	

	
	
		
		

		
		
	


	




 Thanks for everyone for suggestions. Btw, wouldn't it be nice to put this information about outboard pots somewhere visible?_

 

Yes, my bad - I will make that update today.

 -Drew


----------



## ntsour

Sorry for asking this again. I have searched on the forums but I am unable to source the exact models as were suggested in others posts.
 For the moment my candidates are:

 Mascot 2183000043 from rscomponents which is rather expensive €47: Mascot 2183 

 A cheap one suggested by lini that I don't know for sure that it will give enough juice for the hybrid:
http://www.pollin.de/shop/shop.php?c...=ODk1OTc5&ts=0

 Any suggestions?


----------



## MASantos

Quote:


  Originally Posted by *ntsour* 
_Sorry for asking this again. I have searched on the forums but I am unable to source the exact models as were suggested in others posts.
 For the moment my candidates are:

 Mascot 2183000043 from rscomponents which is rather expensive €47: Mascot 2183 

 A cheap one suggested by lini that I don't know for sure that it will give enough juice for the hybrid:
http://www.pollin.de/shop/shop.php?c...=ODk1OTc5&ts=0

 Any suggestions?_

 

Hello, what is your budget?
 With the exchange rate from €-$ you could build yourself a steps for around 60€ I think.

 There is also the veleman V-K1823 for 10£ from maplin.

http://www.maplin.co.uk/Module.aspx?...U=3488&T=17602.

 Manuel

 ps: greetings from Lisbon, Portugal


----------



## ntsour

Quote:


  Originally Posted by *MASantos* 
_Hello, what is your budget?
 With the exchange rate from €-$ you could build yourself a steps for around 60€ I think.

 There is also the veleman V-K1823 for 10£ from maplin.

http://www.maplin.co.uk/Module.aspx?...U=3488&T=17602.

 Manuel

 ps: greetings from Lisbon, Portugal_

 

Thanks for the suggestion. I would prefer not to use DIY kits for the PSU as I am not very experienced and have a tendency to make careless mistakes with my DIY projects. Playing with 230V on an uprotected circuit is not a good idea for tme.

 I am basically looking for a good enough comercial PSU. I was hoping to pay around 20€ for something reasonable but if there is no other choice I'll go for the more expensive mascot.


----------



## Secret Squirrel

Is there any issue using a 100 k alps pot with the millet hybrid?


----------



## drewd

Quote:


  Originally Posted by *ntsour* 
_I am basically looking for a good enough comercial PSU. I was hoping to pay around 20€ for something reasonable but if there is no other choice I'll go for the more expensive mascot._

 

The AC adapter from Pollin will probably do the job, but it's not the best choice. Ideally, you should use a linear, regulated power supply, but, since those are expensive, the next best thing would be to find a regulated switching power supply.

 I looked at the selection from RC and Pollin and there are a few that fit the criteria. I don't envy you having to pay those prices, though! Yikes! 
	

	
	
		
		

		
		
	


	




 Having said that, though, I've used a Millett Hybrid with a very cheap non-regulated, switching power supply and the amplifier did sound quite nice. You can hear the difference with a linear supply, but if that's out of your budget, get what you can afford and just save up for an upgrade later!

 -Drew


----------



## drewd

Quote:


  Originally Posted by *Secret Squirrel* 
_Is there any issue using a 100 k alps pot with the millet hybrid?_

 

No, I've used pots ranging from 10K to 100K with no problem.

 -Drew


----------



## ntsour

Since I have to order the Alps Pot from RS-Components (€22 mind you) I'd rather order a Mascot and avoid shipping costs from another source. 

 I finally found the 2083 model that people suggest on this board. It was there but not very intuitively placed.

 Anyway, final question. Two options:
 Mascot 2183: linear, regulated, 24V, 1A, 24W, 41€
 Mascot 2083: linear, regulated, 24V, 500mA, 14,4W, 29€

 Is 500mA safe enough in order to save me 11€. Absolute minimum is supposed to be 400mA but I don't now, is 100mA too smal a buffer? Or go for the 2183 that has more margin?

 Thanks all for your help.


----------



## rreynol

If you are working from Drew's partlist, you'll have a RXE050 PTC Fuse part on your board. This is a thermal fuse that will cut out if the current into the board exceeds 500 mA. With this in mind, I say you'll be fine with the 500mA supply.


----------



## shiggins

Quote:


  Originally Posted by *ntsour* 
_Playing with 230V on an uprotected circuit is not a good idea for tme._

 

Could always use any old cheap 'n' dirty PSU then regulate it with a Tread - Low voltage safety and high quality Tread regulation. Perfect.


----------



## AtomBoy

Well, it aint pretty yet, but since it's germane...







 It's a dead-bug version of the LM317 regulator grafted into the cord of the $3 CUI 24V 400mA wall wart. I can't tell the differance between this and my higher buck Condor 24V supply. Without the regulator, the Condor was much better than the wall-wart. The CUI had a hum.

 For referance, I used the data sheet here:

http://www.st.com/stonline/books/pdf/docs/2154.pdf

 And Tangent's TREAD info here:

http://www.tangentsoft.net/elec/tread/

 Just buying a TREAD would have been easier, but this was fun! 

 I left out a couple of caps that didn't seem essential. I almost left out the protection diodes- but thought better of it. It gets a little warm, but never too hot to hold on to. Its dropping 30V to 24V.

 I don't have all the reciepts handy, but I guess the whole set up including xformer cost me less than $10.

 I put it on the cord because I have a couple of Milletts I'm fooling with and I wanted to try it with each. It might make more sense to put it inside the case with the amp if you weren't going to experiment too much. I'm working on a PS for a Borebely Hybrid and this was kind of a dry run for that. If anybody wants the drawing I did to lay out the parts, I'd be happy to post it.

 BTW- I'm not really that much of a cheap person. I just think its fun to see how low you can go!


----------



## Botch

Quote:


  Originally Posted by *AtomBoy* 
_Well, it aint pretty yet, but since it's germane...






 snip._

 

AtomBoy, just a quick question as it's hard to see from you pic but do you have some insulation between the heat sink of the LM317 and the chassis that it is screwed to? The heat sink / mounting hole on the reg is not at Gnd but at Vout.

 Botch...


----------



## slindeman

Quote:


  Originally Posted by *ntsour* 
_Is 500mA safe enough in order to save me 11€. Absolute minimum is supposed to be 400mA but I don't now, is 100mA too smal a buffer? Or go for the 2183 that has more margin?_

 

I use a 24V 330mA linear regulated PSU without any problems. The current draw of the amp is under 200mA.


----------



## Erik S.

Quote:


  Originally Posted by *ntsour* 
_Since I have to order the Alps Pot from RS-Components (€22 mind you) I'd rather order a Mascot and avoid shipping costs from another source. 

 I finally found the 2083 model that people suggest on this board. It was there but not very intuitively placed.

 Anyway, final question. Two options:
 Mascot 2183: linear, regulated, 24V, 1A, 24W, 41€
 Mascot 2083: linear, regulated, 24V, 500mA, 14,4W, 29€

 Is 500mA safe enough in order to save me 11€. Absolute minimum is supposed to be 400mA but I don't now, is 100mA too smal a buffer? Or go for the 2183 that has more margin?

 Thanks all for your help._

 

The 2083 works fine, I use it myself.

 But remember
  Quote:


  Originally Posted by *BrokenEnglish* 
_your mascots lack some reversed biased protection diodes, that could help them coming up when there's a lot of capacitance in the amp. to work around this issue, try this: first connect the mascot to your millet, then switch the millet on and connect the mascot to mains as last step. it should work then..._

 

...and it does 
	

	
	
		
		

		
		
	


	




 Thanks goes out to BrokenEnglish for his help


----------



## AtomBoy

Quote:


  Originally Posted by *Botch* 
_AtomBoy, just a quick question as it's hard to see from you pic but do you have some insulation between the heat sink of the LM317 and the chassis that it is screwed to? The heat sink / mounting hole on the reg is not at Gnd but at Vout.

 Botch..._

 

Yes, there's a mica insulator beneth the chip and a plastic insulator arround the screw. The TO-220 mounting kit cost more than the chip!


----------



## ntsour

Quote:


  Originally Posted by *Erik S.* 
_The 2083 works fine, I use it myself.

 But remember

 ...and it does 
	

	
	
		
		

		
		
	


	




 Thanks goes out to BrokenEnglish for his help 
	

	
	
		
		

		
		
	


	


_

 

I'll go for the 2083 then.

 Thanks a lot to all that replied to my question.


----------



## roibm

I see lots of you are going the wall wart way... was just wondering, wouldn't be better to use a decent toroidal transformer with a decent regulated PSU?
 I seem to remember some simulations run on my DAC(1541...) and there were situations when the A demand was as high as 2A... Now I don't know about these tubes, never tried them before, so you tell me, wouldn't it be better with a "real" transformer?


----------



## BlueCan

Quote:


  Originally Posted by *roibm* 
_I see lots of you are going the wall wart way... was just wondering, wouldn't be better to use a decent toroidal transformer with a decent regulated PSU?_

 

Give it time. I'm going to be building a matching STEPS for mine eventually. In my haste to "give 'er a listen", I am using a regulated 24V "wire wart".

 It sounds pretty good even WITH the wart...

 -Patrick


----------



## Thaddy

n_maher is building a Millet right now with a STEPS, and it will also be rearing it's head at the Boston meet tomorrow. Keep your eyes open for the impressions 
	

	
	
		
		

		
		
	


	




 That said, I have a 24v Elpac with my current Millet, so I'm not sure how much of a difference the STEPS will make.

 edit: You all need to check out this thread here. He's got 8 left!


----------



## n_maher

What, you mean this little thing???






 And in my humble opinion the difference between the Elpac and STEPS is easily audible. To quote my friend Ian, "Holy $#%@, it's like a whole different animal!"

 And Zack is correct, the Millett lands in Boston tomorrow, around 2.


----------



## drewd

Quote:


  Originally Posted by *roibm* 
_I see lots of you are going the wall wart way... was just wondering, wouldn't be better to use a decent toroidal transformer with a decent regulated PSU?_

 

The quick answer is "yes". A linear, regulated power supply is really the best way to go with the Millett amp. I think that I've mentioned before that, because it uses a single voltage power supply, it is much more sensitive to a noisy power supply. I can clearly hear a difference between the Elpac power supply and a STEPS supply and if I can hear the difference, then there's no question that it's real! 
	

	
	
		
		

		
		
	


	




 My humble office rig:






 -Drew


----------



## multibit16

I'm going to try an ALW super regulator to power mine seeing as though I have one spare.
 Is there any difference in sound if these amps are run at slightly higher voltage rather than 24v? I just wondered because my spare reg is set to 24v but can be altered if needed

 All I need is the ccs diodes and tube bases to be able to get started
	

	
	
		
		

		
		
	


	




 Oh I almost forgot
 Nice work Guys!


----------



## mrdon

Quote:


  Originally Posted by *n_maher* 
_What, you mean this little thing???

 And in my humble opinion the difference between the Elpac and STEPS is easily audible. To quote my friend Ian, "Holy $#%@, it's like a whole different animal!"

 And Zack is correct, the Millett lands in Boston tomorrow, around 2._

 

OK, now you really found me a way to squeeze more audio juice out of my Millet! 
	

	
	
		
		

		
		
	


	




 But the budget is the bottom line so... how much does it cost to build the STEPS PSU? I know the PCB from Tangent is $8 for version 1.0 and $12 for version 1.2. How much are parts?


----------



## Voodoochile

You can spend between $60 and $90 on a STEPS, for an assembled uncased PSU, in my experience.

 This is why it is nice to have the WW option. Spending a little on the wart now if your funding is tight, then building the nicer PSU later on. It was always nice how Headroom allowed you to do this with their smaller amps. Start basic, and upgrade later if you like.


----------



## MASantos

How, that's a large enclosure...

 what do you plan to place between the PSU and amp?

 another amp board and run it balanced?? 
	

	
	
		
		

		
			





 Or is it just for the outer looks?


  Quote:


  Originally Posted by *n_maher* 
_What, you mean this little thing???






 And in my humble opinion the difference between the Elpac and STEPS is easily audible. To quote my friend Ian, "Holy $#%@, it's like a whole different animal!"

 And Zack is correct, the Millett lands in Boston tomorrow, around 2._


----------



## Jazper

Quote:


  Originally Posted by *mrdon* 
_OK, now you really found me a way to squeeze more audio juice out of my Millet! 
	

	
	
		
		

		
		
	


	




 But the budget is the bottom line so... how much does it cost to build the STEPS PSU? I know the PCB from Tangent is $8 for version 1.0 and $12 for version 1.2. How much are parts?_

 

 Quote:


 You can spend between $60 and $90 on a STEPS, for an assembled uncased PSU, in my experience. 
 

or you can build one on protoboard for a bit less and use the extra money for extra parts /upgrades to it

 (my psu for the m3 uses a simple design very similar to the steps, with a few additions and subtractions, the only thing that was costly was the expensive/high quality rectifier diodes and the transformer)

 a breakdown of parts I used:

 7x 1000uF/50v panasonic FM caps (could have used 4, would have been plenty)
 4x RHRP860 rectifier diodes ($5 AU each! ) 
 4x 0.1uF polypropylene caps (for bypassing the rectifier diodes)
 1x 100ohm resistor (1/8 w) 
 2x .1uF polyester film (snubber) caps
 1x 1uF polyester film cap (bypass)
 1x 470nF polyester film cap (bypass cap)
 2x 47uF electrolytic caps (panasonic FM - used 1x 100uF in one of the spots, but it was overkill, 47 would have been better)
 1x 47ohm resistor
 1x 1k resistor (2w!) 
 1x LM317T (will probably be replaced by a 338 later on, but it works fine .. ) 
 1x heatsink for lm317
 2x 1n4004 diodes (for the regulator circuit)
 1x 47nF output bypass cap (polyester) 
 1x 27ohm resistor
 1x 10k resistor 
 1x red LED
 2x terminal blocks

 1x 24v AC 160va transformer (pricy but the model below was only a few dollars less) 
 1x EMI/RF filtered IEC socket.


----------



## aeroes

If STEPS is better than ELPAC, should I expect a difference between ELPAC and TREAD? I've heard TREAD is identical to STEPS in Ripple Rejection Test.

 TREAD could be a good solution to those who are prudent.


----------



## en480c4

Quote:


  Originally Posted by *MASantos* 
_How, that's a large enclosure...

 what do you plan to place between the PSU and amp?

 another amp board and run it balanced?? 
	

	
	
		
		

		
		
	


	




 Or is it just for the outer looks?_

 


 Actually, that's just a temporary aluminum enclosure for the Boston meet. Nate placed an order somewhere (I don't remember where) and didn't have the minimum order together yet, so added stuff 'til he had enough. That case, which came with no top, was one of the things he added to meet a minimum order. Yup, he's crazy!
 A Par-Metals case has been ordered, but hasn't arrived yet.


  Quote:


  Originally Posted by *aeroes* 
_TREAD could be a good solution to those who are prudent._

 


 I'm sure it would be, but when have people on Head-Fi been prudent?


----------



## jamont

Quote:


  Originally Posted by *multibit16* 
_I'm going to try an ALW super regulator to power mine seeing as though I have one spare._

 

I've always thought this would make a lot of sense with the Millet amp. Let us know how it works.


----------



## guzzler

Quote:


  Originally Posted by *jamont* 
_I've always thought this would make a lot of sense with the Millet amp. Let us know how it works._

 

24V is quite high for a Jung type super regulator, and any failure will lead to the full voltage going across it. You'll need 29V minimum for the regulator to function properly, 30V to be safe. Personally, I'd make two regulators, one positive one negative, and leave out the ground lead. You'll have a much better safety margin then, and can use lower voltage opamps... Still, nice to know how you get on...

 g


----------



## multibit16

Quote:


  Originally Posted by *jamont* 
_I've always thought this would make a lot of sense with the Millet amp. Let us know how it works._

 

No problem
	

	
	
		
		

		
		
	


	




 BTW I've run these regs output at 30v with no problem to power a Naim Pre-amp, 27v for the main psu in a cdp etc, I've never had one fail yet.
 Theres a lot of guys who use the SR's set to 24v to run the old Nac42.5 pre's on Pinkfish media


----------



## jamont

Quote:


  Originally Posted by *multibit16* 
_No problem
	

	
	
		
		

		
		
	


	




 BTW I've run these regs output at 30v with no problem to power a Naim Pre-amp, 27v for the main psu in a cdp etc, I've never had one fail yet.
 Theres a lot of guys who use the SR's set to 24v to run the old Nac42.5 pre's on Pinkfish media_

 

Which opamp do you use?


----------



## multibit16

Quote:


  Originally Posted by *jamont* 
_Which opamp do you use?_

 

AD825 http://www.alw.audio.dsl.pipex.com/products.htm


----------



## Jazper

the ad797 can handle 36v max (rail to rail)


----------



## multibit16

Quote:


  Originally Posted by *Jazper* 
_the ad797 can handle 36v max (rail to rail)_

 

Yes but its not as stable as the AD825 in this circuit, ALW uses the AD825's in his kits because they are supposed to work better


----------



## klappar

Has anyone tried stacking buffers a la pimeta on their millet? Would it be feasible at all in this configuration?


----------



## rreynol

Quote:


  Originally Posted by *klappar* 
_Has anyone tried stacking buffers a la pimeta on their millet? Would it be feasible at all in this configuration?_

 

It was mentioned in one of the millet threads by drew (or nate, can't recall) that stacking buffers was done for grado usage.


----------



## drewd

Quote:


  Originally Posted by *klappar* 
_Has anyone tried stacking buffers a la pimeta on their millet? Would it be feasible at all in this configuration?_

 

Yes, it was helpful for my Grados and DT-880s.

 -Drew


----------



## Finch&Music

I take the risk of asking a rather stupid question, but ................

 At a german site I see divices that can let you see the amount of bias voltage. See for yourself at Thel.de 

 Go to their Tube sections, more specific the lcd instrument to give information on tube performance for biasing voltage. 

 Those divices are in my opinion rather pricey, but could give you on the outside of your case severly wanted information about some aspects of the performance of the tubes in your Millet Amp. 

 That company use a lcd to let you see on the front of the amp-case what bias is actually performing. 

 May be such a divice can be combined with an off board potmeter mounted on front of the case (instead of the on board pot on the Millet Amp). 

 In that way we can always from the outside finetune the bias setting. In that way the biassetting can be done instanteniously and after the temperature inside the case has stabalised. 

 I hope this make any sense. 

 May be there are more cost effective solutions to make those bias figures actually visiable and adjustable from the outside. 

 I am interested in your reactions on this topic.

 Pieter Vink.


----------



## JWFokker

Quote:


  Originally Posted by *drewd* 
_Yes, it was helpful for my Grados and DT-880s.

 -Drew_

 

What benefit did this have? Being a fan of Grados, this interests me.


----------



## n_maher

I'm sure my statement will require a bit of correction but my understanding is that stacking the buffers (running them in parallel) increases the current output capability of the amp, which is exactly what the higher end Grados need to shine.

 HTH,

 Nate


----------



## drewd

Quote:


  Originally Posted by *JWFokker* 
_What benefit did this have? Being a fan of Grados, this interests me._

 

It cleared up a bit of distortion that I was hearing at higher volumes with dynamically active music, especially in the low end.

 Adding a STEPS with a 1.5A regulator helped a lot, too.

 -Drew


----------



## JWFokker

I've seen them stacked as much as four high on Pimetas. Any recommendation for the Millett Hybrid?


----------



## drewd

Quote:


  Originally Posted by *JWFokker* 
_I've seen them stacked as much as four high on Pimetas. Any recommendation for the Millett Hybrid?_

 

Two works just fine for me. As with all things audio, let your ear be your guide.

 -Drew


----------



## amb

Speaking of the BUF634Ps, I have an idea that I might try when I build my Millett Hybrid.

 Since the buffer here runs open loop, and the BUF634 is itself an open loop buffer, I wonder if there might be a benefit to using something that's closed loop instead. Also, unlike in the Pimeta or MINT, the buffer here is not wrapped inside a global negative feedback loop.

 The BUF634P happens to have the same pin-out arrangement as a DIP-8 single-channel opamp, except that the BUF634P has no connection to pin 2 (opamp inverting input), and pin 1 is used for bandwidth/quiescent control (not used on most single opamps). I think it might be interesting to substitute a TI/Burr-Brown OPA551PA high-current opamp in place of the BUF634, and install a small wire jumper between pins 6 and 2 at the DIP-8 socket. This makes the OPA551 operate as a closed-loop voltage follower. The OPA551 is rated for 200mA continuous output current, which should be high enough for most headphones.

 Granted the OPA551 doesn't have quite as high a slew rate as the BUF634, but it's not really that slow and it's being driven by a tube which is not known for ultra high-speeds anyway, so that is not an issue. I wonder if there might be an appreciable difference in sound, possibly an improvement.

 Btw, the OPA551 is cheaper than the BUF634 (Digikey prices).

 Another chip that is a possible candidate for this trial is the Analog Devices AD811AN. It has very high slew rate but lower output current (100mA max), and more expensive.

 Just food for thought for now...


----------



## Emon

I'm still waiting on those discrete buffers. Methinks it'll be a huge jump in sound quality...man I love this amp as it is, I can't imagine it with a discrete output stage!


----------



## rreynol

C'mon people, let's see some more builds. There were what, 200 board ordered?

 Let's see em.


----------



## pabbi1

Or some (additional) listening impressions?


----------



## rreynol

I like it. In addition, I do agree with the other observations concerning 12AE6A vs 12FK6 tubes (the latter providing more detail and sounding better). Once my parts arrive for amp #2, I'll have some more pictures to share.


----------



## pabbi1

OK, I'm convinced - I like the 12AE6A pretty well, but wanted to burn in the amp first before switching over to the 12FK6. Any observations about the tubes having a "wake up / warm up" period (after the initial 30 minute warming)?

 And, is there a significant difference in the 'bias'?

 Edit:

 My 16v bias for the 12AE6A was an initial 9.9v bias with the 12FK6, given about -1v for them being not warmed up.

 And, I must agree: the 12FK6 are the better tubes. In my case the 12AE6A are RCA and the 12FK6 are Tung Sol.


----------



## Secret Squirrel

Ok, I tried stacking the buffers a few minutes ago. My lower impedance Ath-A900’s (vs. HD-580’s) seem to react to this change positively. I need more time comparing this change to my single buffer unit.


----------



## SHLim

A question about the tube socket. I know I need to solder all the socket feet, but do I need to solder the center metal piece on the socket to the pcb? 

 TIA,
 Sam


----------



## n_maher

Quote:


  Originally Posted by *SHLim* 
_A question about the tube socket. I know I need to solder all the socket feet, but do I need to solder the center metal piece on the socket to the pcb? 

 TIA,
 Sam_

 

Nope, you may notice that the sockets that some of us use don't have a center piece at all. 
	

	
	
		
		

		
		
	


	




 Nate


----------



## JWFokker

I have to say, I quite like the stacked buffers too. It's a subtle thing, but certainly for the better. It seems to me that it improves resolution or clarity of individual notes. Soundstage doesn't seem to be affected, but each instrument is clearer. This is especially noticable with sharp sounds with rapid decay, like drums or hard guitar distortion (ie, Tool). Well worth the extra $12 in my opinion.


----------



## pabbi1

Is this true for all cans, or just the lower impedence ones?


----------



## Secret Squirrel

The effect of the stacked buffers seems to be audible with lower impedance headphones around 32-100 Ohms. My HD-580’s (300 ohms) seem unchanged. I will try to borrow a co-worker’s HD-555 (50 Ohms).


----------



## pabbi1

Well, I've got some extras, and some SR-225s on the way, so what the heck?

 Any further developments on the discrete buffers?


----------



## n_maher

Quote:


  Originally Posted by *pabbi1* 
_W
 Any further developments on the discrete buffers?_

 

No, not as far as I know. A couple of other members were going to take a stab at it, but Drew's busy with life and I'm getting married in two days so neither of us has any time for it right now. Not that Drew or I has to be at all involved in the diamond buffers, but that design is currently on hold.

 The amp sounds pretty dang good to me right now so I'm inclined to leave well enough alone till I've got the time to give the buffers the proper attention or until someone else picks it up.

 Nate


----------



## pabbi1

Quote:


 I'm getting married in two days 
 

Congratulations are in order! Best wishes, and good luck.

 I do concur on the sounds pretty good, as I'm getting excellent mids, and second order harmonics (especially on horns), and the bass is very tight with the Tung Sol 12FK6.
 There was a batch of 5 Raytheon 12FK6 I snagged on eBay yesterday for $14.35 shipped, so tube rolling is affordable.

 And, we'll see about that Millett/Grado synergy thing, though the HD600 are sounding very good.

 The Ft Worth meet next week should generate some independent feedback for others, since there is a distressing lack of feedback to date, especially given the number of boards sold in the group buy.


----------



## steinchen

Quote:


  Originally Posted by *pabbi1* 
_Any further developments on the discrete buffers?_

 

Unfortunately the feedback on Nate's and Drew's forum was zero, so I designed a pcb on my own. The design is not restricted to the Millet hybrid, it' a universal replacement for buf634 measuring 19x19mm in size (incorporating smd 1206 package parts). I'm going to order a prototype run this weekend. In about 2 to 3 weeks I should be able to run listening tests, I'm going to roll in several transistor combinations, try some resistor values and bias settings.


----------



## n_maher

Quote:


  Originally Posted by *pabbi1* 
_Congratulations are in order! Best wishes, and good luck._

 

THANKS!

  Quote:


  Originally Posted by *pabbi1* 
_And, we'll see about that Millett/Grado synergy thing, though the HD600 are sounding very good._

 

 Frankly I think it sounds good with both.

 And steinchen, I'll drop you a PM when I get back from my honeymoon to see if I can be of help with the prototyping of the buffers. I should have time to breath then 
	

	
	
		
		

		
			





.

 Nate


----------



## JWFokker

Quote:


  Originally Posted by *pabbi1* 
_Congratulations are in order! Best wishes, and good luck.

 I do concur on the sounds pretty good, as I'm getting excellent mids, and second order harmonics (especially on horns), and the bass is very tight with the Tung Sol 12FK6.
 There was a batch of 5 Raytheon 12FK6 I snagged on eBay yesterday for $14.35 shipped, so tube rolling is affordable.

 And, we'll see about that Millett/Grado synergy thing, though the HD600 are sounding very good.

 The Ft Worth meet next week should generate some independent feedback for others, since there is a distressing lack of feedback to date, especially given the number of boards sold in the group buy._

 


 So you're the one who stole the auction from me. Auction snipers are scum. And yes, that means you.


----------



## Finch&Music

Quote:


  Originally Posted by *steinchen* 
_Unfortunately the feedback on Nate's and Drew's forum was zero, so I designed a pcb on my own. The design is not restricted to the Millet hybrid, it' a universal replacement for buf634 measuring 19x19mm in size (incorporating smd 1206 package parts). I'm going to order a prototype run this weekend. In about 2 to 3 weeks I should be able to run listening tests, I'm going to roll in several transistor combinations, try some resistor values and bias settings._

 

I think you are taking a little too soon definitive conclusions on interest for the possibility of plugg-in discrete buffers for the Revised Millet Hybrid Board!

 In the last two months I have seen several posts on this topic spread over different threads or sites on Headfi and also on separate sites. 

 The message was mostly that it will take some time to devellop a fully tested discrete buffer for the Millet Hybrid (a plugg-in I hope). 

 Given the fact that there were at some moment different threads, posts, sites to mail any thought on this topic to has given - me at least - some confusion on what was going on and what was possible in the short run on this topic. 

 All those different signs gave me a feeling of enduring some patience with the topic. I for myself expected that after the summer season in Europe and the USA this item would devellop itself soon.

 May be you could start a separate thread on this item, so that there will be a real insight in the interst for a plugg-in discrete buffer for the Revised Millet Hybrid Board. 

 May be you can combine your own efforts as mentioned above with the interest that may be shown through that new thread.

 I for myself would be very interested in a plug-in solution that is tested and really works sonically!

 Greetings


----------



## n_maher

Quote:


  Originally Posted by *JWFokker* 
_So you're the one who stole the auction from me. Auction snipers are scum. And yes, that means you._

 

Please stay on topic, stuff like this is PM material at best.


----------



## pabbi1

Quote:


 So you're the one who stole the auction from me. Auction snipers are scum. And yes, that means you. 
 

Why, thank you... eBay is a full contact sport. 

 As for the discrete direct plug-in buffers for the Millett, I am sure there is _some_ just given the sheer numbers of boards out there. I, for one, am definitely interested in enough for my two boards, and a spare or two.


----------



## SHLim

Considering the sound improvement on PPA with discrete buffers, I'm keen to have it on Millett. Prefere direct replacement but if can't be done, a bit of tinkering is 'OK' with me -as long as it sound good. 
	

	
	
		
		

		
		
	


	





 Sam


----------



## SHLim

Can I connect Millett to this 24VDC 1A Regulated Power Supply? Will build a STEPS later as I needs to order parts from US for it.
http://www.jaycar.co.nz/productView....Max=&SUBCATID=

 TIA,
 Sam


----------



## JWFokker

Looks fine, but you can get something better than that for less than that on Ebay. I paid $25 for a 24V/28V 6.2A/5.4A DC regulated power supply. Came in a nice metal chassis too. Of course, it didn't come with cords so I had to make them myself. If you have the skill to building an amp, you can make a couple cables easily enough.


----------



## aeroes

Im almost done with the millet construction when I find out that I have a different Panasonic pot!

 Is it ok if I use EVJC20F02D54 instead of EVJC20F02A54?

 What are the differences between this two pots?

 Thanks!


----------



## MisterX

One has a "D" taper the other has an "A" taper. 
	

	
	
		
		

		
			





 Check the PDF for more details------------> http://www.panasonic.com/industrial/...AOK0000PE1.pdf


----------



## aeroes

Quote:


  Originally Posted by *MisterX* 
_One has a "D" taper the other has an "A" taper. 
	

	
	
		
		

		
		
	


	




 Check the PDF for more details------------> http://www.panasonic.com/industrial/...AOK0000PE1.pdf_

 


 Yes but is it ok to use the D taper instead of A taper in millet?


----------



## MisterX

Yea, look at the graphs on the lower part of page 7 of the pdf to see the difference. 
 The D taper "ramps up slower across the lower half of it's range" and it will may work better with the millet cause the gain is a little to high with some phones.


----------



## SHLim

Quote:


  Originally Posted by *JWFokker* 
_Looks fine, but you can get something better than that for less than that on Ebay. I paid $25 for a 24V/28V 6.2A/5.4A DC regulated power supply. Came in a nice metal chassis too. Of course, it didn't come with cords so I had to make them myself. If you have the skill to building an amp, you can make a couple cables easily enough._

 

We are on 230V main in NZ and it will be to expensive to send it to downunder. 

 Thanks,
 Sam


----------



## JWFokker

Have you considered a TREAD? They're supposed to be cheap and easy to build. If you need one ASAP, the one you previously liked is fine, just a bit pricey if that's in US dollars.


----------



## aeroes

Do we have to change some resistor value when we stack buffers? and what resistor was that?


----------



## drewd

Quote:


  Originally Posted by *aeroes* 
_Do we have to change some resistor value when we stack buffers? and what resistor was that?_

 

If you are using the bandwidth control resistors (R6R/L), then change them to 470 ohms. I don't use them because, at least with this amp, I can't hear a difference.

 -Drew


----------



## James281

how did you guys wire the 2 led under the tubes?

 i plan to wire them like this, will this work??





 on the pcb i don't know which side is positive for the led i guess i will have to try to figure this out.


----------



## MaxW

Quote:


  Originally Posted by *James281* 
_how did you guys wire the 2 led under the tubes?

 i plan to wire them like this, will this work??





 on the pcb i don't know which side is positive for the led i guess i will have to try to figure this out._

 

I'm not sure what voltage this amp uses but I think it will be too high to connect them in a series with no resistor. See this for calculating the resistor you need:
http://linear1.org/ckts/led.php
 and this is the way to connect it:
http://www.kickassmods.com/Guides/P&HDled/4.jpg
http://www.tonystrains.com/technews/...all-led-01.gif


----------



## rreynol

Quote:


  Originally Posted by *drewd* 
_If you are using the bandwidth control resistors (R6R/L), then change them to 470 ohms. I don't use them because, at least with this amp, I can't hear a difference.

 -Drew_

 


 I believe that when you double the number of buffers, you halve the bandwidth setting resistor to keep the same setting. According to tangent's site, at least.

 So 110 ohms.

 Edit: The reason being that it is two buffers in parallel with a 220 Ohm BW resistor on each one so two 220's in parallel is equivalent to a single 110 Ohm.


----------



## rreynol

Minus a few finishing odds & ends (getting a knob for it, stacking the buffers, screws for the panels, etc), Amp #2 is done.

 All caps are either Cerafines or Wimas (electrolytic caps on the bottom of the board), Alps pot, Hammond 1455T1601BK case, TREAD powered.











 More pics when its completely done.


 edit: not 1455R, 1455T.


----------



## drewd

Quote:


  Originally Posted by *rreynol* 
_I believe that when you double the number of buffers, you halve the bandwidth setting resistor to keep the same setting. According to tangent's site, at least.

 So 110 ohms.

 Edit: The reason being that it is two buffers in parallel with a 220 Ohm BW resistor on each one so two 220's in parallel is equivalent to a single 110 Ohm._

 

So true...halving, doubling...ack!

 -Drew


----------



## NOTHINGness

Is it normal for noise to be generated when touching the tubes?


----------



## grandenigma1

Quote:


  Originally Posted by *NOTHINGness* 
_Is it normal for noise to be generated when touching the tubes?_

 

yes it is called microphonics...just dont touch them


----------



## rreynol

Quote:


  Originally Posted by *NOTHINGness* 
_Is it normal for noise to be generated when touching the tubes?_

 

http://herbiesaudiolab.home.att.net/


----------



## AtomBoy

Quote:


  Originally Posted by *NOTHINGness* 
_Is it normal for noise to be generated when touching the tubes?_

 

I have had a couple of different Milletts where tapping near the tubes would produce distinct ringing noise in the headphones. The effect faded after a couple of days running. Has anyone else noticed this? Any explanations? I'm not a huge believer in burn-in, but I reckon 40 years on the shelf might do something to a tube?


----------



## adhoc

Quote:


  Originally Posted by *AtomBoy* 
_I have had a couple of different Milletts where tapping near the tubes would produce distinct ringing noise in the headphones. The effect faded after a couple of days running. Has anyone else noticed this? Any explanations? I'm not a huge believer in burn-in, but I reckon 40 years on the shelf might do something to a tube?_

 

this is *perfectly * normal.

*most * tubes (except certain built-for-military ones) exhibit such characteristics, known as microphonics, which is caused by external physical stimuli - ie vibration. this vibration can be brought about by tapping on the amp, tapping on the tube or (in real bad cases) even 'speaking' to the tube. 

*once again, i repeat - this is perfectly normal.* 

if the design and construction were the same, a NOS tube would show little variance in it's tendency for microphonics when compared to a spanking new tube straight off the production line. in other words, unlike many women, noise does not increase with age. 
	

	
	
		
		

		
			





 (fwiw though, most newer tubes tended to have designs which attempted to minimise microphonics - so newer versions of a particular tube would tend to show lesser microphonics while varying _*vintages* of the same tube_ would show little variance in their tendencies to be microphonic.)


*but why microphonics?* 

 we all know that a triode (the most common type of vacuum tube) consists of *1.* a (heated) cathode which emits electrons, *2.* next to which is a grid (which has a varying voltage applied to it) which modulates this flow of electrons and finally *3.* an anode 'plate' which absorbs these electrons. three parts: hence tri-ode.

 all vibration does is _vary _ the distance between the grid and the cathode in a regular to-and-fro pattern, resulting in a patterned distortion (corresponding with the vibration's amplitude and frequency) as the influence of the grid on the electron flow from the cathode changes. *as this electron flow IS  our amplified signal, you hear microphonics.* while this may seem trivial, do note that the typical cathode-grid distance for small signal tubes is typically _a few thousandths of an inch. _






 [size=xx-small]_forgive me, i am such a pedant sometimes.._[/size]


----------



## AtomBoy

Quote:


  Originally Posted by *adhoc* 
_this is *perfectly * normal._

 

Thanks for your excellent explanation. I should have been clearer- what I don't understand is how microphonics could change over the first couple of days of running. It's like the tubes take a couple of days to shake the dust off.

 In two Milletts, I've had them go from where putting a screwdriver down on the bench was clearly audible in the phones (like dropping a big bag of loose lightbulbs) to where I can tap on the tubes with a fingernail and just hear it as a light "ting".

 I saw a mention somewhere of ultrasonic frequncies playing a role in microphonics? If your circuit doesn't filter ultrasonics, the tube is more likely to ring? Could it be the new caps forming up, or moving from the garage to the living room? I've got some tubes I haven't plugged in yet, so some experiments might be interesting...


----------



## adhoc

Quote:


  Originally Posted by *AtomBoy* 
_Thanks for your excellent explanation._

 

you're most welcome! 
	

	
	
		
		

		
		
	


	




  Quote:


  Originally Posted by *AtomBoy* 
_I should have been clearer- what I don't understand is how microphonics could change over the first couple of days of running. It's like the tubes take a couple of days to shake the dust off._

 

*yes* - you are right! tubes do take some time to 'settle in'. 

 in the days following the deflowering of a 'virgin' tube (
	

	
	
		
		

		
		
	


	




), the following usually happen:

 - a*d*sorbed (yes - 'd' not 'b') gas on metal/glass surfaces are slowly released and consequently react with the getter flashing
 - the tiny amounts of gas which leaked in through the imperfect metal-glass seals at the pins react with the getter
 - impurities in the filament/cathode (depending on whether your tube is directly or indirectly heated) burn off
 - stresses in the grid/cathode may 'ease' themselves out with the heat

 all these would certainly contribute to a (imo very minor) change in the sound.

 do note however that in the _golden age of tubes_ (1930s - early 60s), factories almost always _already_ conducted some form of 'tube burn-in' in order to weed out tubes that were either unstable, exhibited unacceptable microphony or were not performing up to spec. i'm not sure if new(er) stock tubes were subjected to such stringent tests though. 

  Quote:


  Originally Posted by *AtomBoy* 
_I saw a mention somewhere of ultrasonic frequncies playing a role in microphonics? If your circuit doesn't filter ultrasonics, the tube is more likely to ring? Could it be the new caps forming up, or moving from the garage to the living room? I've got some tubes I haven't plugged in yet, so some experiments might be interesting..._

 

fwiw, i have never heard of this - it would be much appreciated if you could perhaps PM me some links.


----------



## James281

this is my first amp, i wonder if this is normal, when i first boot up the millett, the sound kinda low and seem like as the tubes heat up the volume get a little louder.


----------



## Teerawit

Nice work, James! I like the see-through motif.

 PS. Welcome to Head-Fi, and sorry about your wallet!


----------



## USER NAME:

Quote:


  Originally Posted by *James281* 
_this is my first amp, i wonder if this is normal, when i first boot up the millett, the sound kinda low and seem like as the tubes heat up the volume get a little louder._

 

What tubes are you using? What is your Bias set at?


----------



## James281

Quote:


  Originally Posted by *Teerawit* 
_Nice work, James! I like the see-through motif.

 PS. Welcome to Head-Fi, and sorry about your wallet!_

 






 thanks, i already think about the M3 but i'll wait for a month or two 
	

	
	
		
		

		
		
	


	






  Quote:


  Originally Posted by *USER NAME:* 
_What tubes are you using? What is your Bias set at?_

 

right now i have the 12FM6 tubes, and bias set to 16v both left and right.


----------



## USER NAME:

You should be fine.


----------



## adhoc

Quote:


  Originally Posted by *James281* 
_this is my first amp, i wonder if this is normal, when i first boot up the millett, the sound kinda low and seem like as the tubes heat up the volume get a little louder._

 

i've tested tubes that didnt measure too well at first, but then as time went along (~10mins) their transconductance *actually rose*. 

 iirc sacd lover was the first to mention this phenomenon to me. i'm not too sure why this happens, but if you put a gun to my head and asked me to make a guess i'd say it probably has something to do with thermal expansion.


----------



## klappar

Quote:


  Originally Posted by *James281* 
_this is my first amp, i wonder if this is normal, when i first boot up the millett, the sound kinda low and seem like as the tubes heat up the volume get a little louder._

 

Have you measured DC offset on output immediately after poweron? My Millet has a few volts offset after poweron but it fades to few mV in ~20 seconds.


----------



## pabbi1

After several weeks of listening, I find the with the 12FK6 I'm spending more time with the volume knob at between 1-3 o'clock, without really pushing my notorious threshold of hearing damage, and yet desire more gain.

 I am using the HD600 almost exclusively (the Grados clip too much, and I've yet to stack the buffers). 

 What resistors should I tweak to increase gain, and tweak for the 600/650? R6 is 220ohm, and all others are populated with the 'default' suggested values per the DIYAudio link page.

 P/s is 27.5 v, and bias is 18v.


----------



## rreynol

Quote:


  Originally Posted by *pabbi1* 
_After several weeks of listening, I find the with the 12FK6 I'm spending more time with the volume knob at between 1-3 o'clock, without really pushing my notorious threshold of hearing damage, and yet desire more gain.

 I am using the HD600 almost exclusively (the Grados clip too much, and I've yet to stack the buffers). 

 What resistors should I tweak to increase gain, and tweak for the 600/650? R6 is 220ohm, and all others are populated with the 'default' suggested values per the DIYAudio link page.

 P/s is 27.5 v, and bias is 18v._

 

R6 is the bandwidth resistor for the Buf634. You would have to change this if you stack the buffers and would like to keep the same bandwidth setting. (halve the resistor value each time you double the number of buffers, so 110 Ohms for a stack 2 high). 

 As for adjusting the gain, I don't know.


 Edit: from my understanding of the Pete Millet article, it looks like D2 (0.56mA current regulating diode) has a hand in the gain.


----------



## pabbi1

From my discussions with Pete at the Ft Worth meet, stacking the buffers and jumpering R6 would help with the Grados, but didn't think I could do much for the Senns.

 Will the discrete buffers (yeah, I know, don't mention unless I want to do it) do anything towards boosting gain?


----------



## rreynol

Quote:


  Originally Posted by *pabbi1* 
_From my discussions with Pete at the Ft Worth meet, stacking the buffers and jumpering R6 would help with the Grados, but didn't think I could do much for the Senns.

 Will the discrete buffers (yeah, I know, don't mention unless I want to do it) do anything towards boosting gain?_

 

From my limited understanding of the design, I'd say no. The buffer component is set up as a voltage follower with unity gain. This the case for the BUF634 and I'd assume its the same for a discrete buffer since I would think that the discrete buffer replacement would perform the same task but sounding better doing it.


----------



## slindeman

12AE6A has more gain in the circuit than 12FK6. My 12Fk6's range from 5-7 in gain, whereas my 12AE6A's range from 11-15. Anyway, if you really want to put some voltage into your Senn's, look for an Eddie Current HD300. Now that is an amp designed for low sensitivity, high impedance headphones.


----------



## pabbi1

The Raptor is the answer... no offense to Craig / EC.

 Yep, sell the Millett, and drop back to (one of) the m³(s)... or sell all and get the Raptor.

 Yes, I was afraid those were the answers to the buffer / gain, and could tell immediately the FK6 had less output than the EA6A. 

 What is there sounds really (REALLY) sweet, but sometimes sweet just ain't enough.


----------



## JWFokker

Or sell the Senns, because who needs high impedance headphones when you've got Grados?


----------



## skyskraper

or who needs grados when you can enjoy the same level of performance and sound from a hat radio with built in fan (for the uber specced op amps that have been painted over)


----------



## dsavitsk

Here's a friendly warning, perhaps, to Millett builders.

 I have an old Millett built on the DIYCable board that I have been using on and off for a couple of years. While the board looks different, the circuit is the same. I had not used it as a preamp for a long time, but decided to try it out tonight as I made some tweeks to it since the last go round.

 Anyway, after listening to it for a while (not bad, but not great either, and too much gain) I powered it down (only the DC) before turning off my power amp -- I regularly turn it off with phones plugged in with no problem -- and it sent a truly horrible noise through my speakers (enough to bring my wife up from the downstairs to ask if I was alright). Long story short, I now have one less power amp. It does not seem to have damaged my speakers which are running with a different pre/power pair right now.

 I have no idea whether this was a fluke, or if it is expected behavior. I won't have time to take apart either the Millett or the power amp for a month or two to investigate, but thought I'd pass on the warning to turn off the power amp before the Millett pre.

 -d


----------



## skyskraper

youch, i thought it was hifi law to power down the signal chain from the last step to the first?


----------



## dsavitsk

Quote:


  Originally Posted by *skyskraper* 
_youch, i thought it was hifi law to power down the signal chain from the last step to the first?_

 

Probably is, but I have been doing it wrong with this amp and various other preamps for 14 years without a problem, so I stopped thinking about it. Also, the fact that it never damaged any phones led me to believe that it would't do this sort of thing.

 The upside is I can probably use the transformer, the pair of 10000uF blackgates in the PS, the case, and all the hardware for a digital amp or a GC or something. This amp has been out of use for a few months, so at least I'm not hurting for music.


----------



## skyskraper

ah i was brought up working on pa/studio gear and in clubs. if you turn off a pre or mixer in a club without powering down the amps you are putting a lot of money at risk. hehe


----------



## amb

Yes, due to the single supply and the big output coupling cap, the Millett hybrid produces a big transient and DC offset shift at turn on/off. Definitely unplug headphones (or turn off power amp if Millett is used as preamp) before turn off and wait at least 15 seconds before connecting headphones after turn on.


----------



## dsavitsk

Perhaps some good news ... the power amp in question has 4 fuses on the PCB (as well as one on the back panel for AC.) 2 of 4 are blown, one on each side, so maybe some kindly commercial manufacturer decided to protect me against my own stupidity.

 Anyway, to keep this on topic, the warning still stands.


----------



## Blooze

I'm sure this has been touched on and I've just missed it scanning through the threads.

 I'm looking to finally order the parts to populate my board and was wondering what the first worthwhile upgrade to the standard parts list would be worth doing. I'm not looking to max out the unit, just thinking that upgrading to cerafines and a few other things would be a good place to start.

 Has anyone made an upgraded, tweaked parts list?


----------



## dsavitsk

Quote:


  Originally Posted by *Blooze* 
_I'm sure this has been touched on and I've just missed it scanning through the threads._

 

Indeed it has. You should reread a bit until you stumble upon it.

  Quote:


  Originally Posted by *Blooze* 
_I'm looking to finally order the parts to populate my board and was wondering what the first worthwhile upgrade to the standard parts list would be worth doing. I'm not looking to max out the unit, just thinking that upgrading to cerafines and a few other things would be a good place to start._

 

The biggest upgrade is the output caps. Even blackgates in this spot will only set you back about $12 for the pair, so they are not a bad choice. For cheaper, but still good, lines, Nichicon Muse is a good option, as are cerafines, etc. Upgrading the Wima on the output to something like a auricap might also be a good, though probably more expensive, option.


----------



## Blooze

Quote:


  Originally Posted by *dsavitsk* 
_Indeed it has. You should reread a bit until you stumble upon it.



 The biggest upgrade is the output caps. Even blackgates in this spot will only set you back about $12 for the pair, so they are not a bad choice. For cheaper, but still good, lines, Nichicon Muse is a good option, as are cerafines, etc. Upgrading the Wima on the output to something like a auricap might also be a good, though probably more expensive, option._

 

Thanks. I've kinda been out of the loop for a spell.


----------



## pabbi1

I'll absolutely 2nd using Cerafine everywhere except on C7 - and using BlackGates there. This is an absolutely outstanding combination.

 That said, to replace the Wima with Auricap (.1uf), would a selective use help, or would it need to be for all 8?

 If all 8, that's a $75 upgrade.


----------



## dsavitsk

Quote:


  Originally Posted by *pabbi1* 
_That said, to replace the Wima with Auricap (.1uf), would a selective use help, or would it need to be for all 8?

 If all 8, that's a $75 upgrade._

 

Just on the output would be enough. Though, there are some who believe that because of the phase distortions introduced by bypassing output caps that taking the Wimas out in that position might be the better option -- just using the electrolytics (I think rick would fall into this camp). It is probably worth experimenting as there are smart people on both sides of the issue.

  Quote:


  Originally Posted by *Blooze* 
_I've kinda been out of the loop for a spell._

 

My response sounds kind of nasty -- didn't mean it to. What I was trying to say is that there has been a ton of discussion in this regard, and a read through the thread will be most helpful (for instance, you will stumble upon my suggestion to use good quality carbon resistors (Riken, Kiwame, etc.) as the output resistors as this adds a bit of a euphonic color that matches the SET design pretty well.)


----------



## adhoc

Quote:


  Originally Posted by *pabbi1* 
_I'll absolutely 2nd using Cerafine everywhere except on C7 - and using BlackGates there. This is an absolutely outstanding combination.

 That said, to replace the Wima with Auricap (.1uf), would a selective use help, or would it need to be for all 8?

 If all 8, that's a $75 upgrade._

 

i'm not sure i understand this post completely - are you saying that one should *vary amongst different cap brands based on their position in the circuit*? 

 if so, why?


----------



## pabbi1

Yes - the C7 caps are the "output" filter caps, and in the signal path. The other positions not so (like I can explain this - not).

 The Black gates are ~$7, and the Cerafines ~$1.50. In keeping the spirit of THIS Millett, basically its $22 vs $63 for electrolytics alone,

 Were I to build another (rather than buying a Millett designed Wheatfield HA-1 - heading to PayPal now), I'd personally go all BlackGates and try all Auricaps, just to know what the absolute upper boundaries of this amp is (since I know what the Cerafine / BlackGate/Wima sound is - and wondering if it gets just a BIT better).

 Not sure I could just jumper out the polypro caps - Pete put them there for a reason, and I trust his opinion - especially since I have tangible results about how it sounds WITH them.


----------



## jerb

I originally priced out this amp with just the stock, recommended parts but the more i read people are putting all the emphasis on upgraded Cap's. now when i price the caps out for just C1, C9L/R, C10L/R the difference appears boldly, the price for the stock caps is a meer $6.80 but if i substitute those for cerifines the price quickly jumps to $16.00! 

 There are 5 seperate fields on the Hybrid Headamp partslist for caps, if I replace all these with the nicer caps this will quickly add up to more than i need to spend right now.

 Ive read through the threads, but i still dont know what where to spend my money. Should I populate C1-10 with the Boutique Caps? After scanning the pcb really quickly and it looks like the only ones in the signal path are C7 and C4, should i just buy cerifines for those two locations? Did I miss any Caps in the signal path?

 Right now I'm looking to buy the cerifines from This dealer, they seem reputable but if any one could inform me on a cheaper dealer my wallet would appriciate it.


----------



## pabbi1

Yes, just C4/C7... that's where I put BG, but Cerafines are an excelltnt chioce as well.


----------



## dsavitsk

Quote:


  Originally Posted by *pabbi1* 
_Not sure I could just jumper out the polypro caps_

 

Don't do that as the DC that the caps are blocking will just go right to your phones. Instead, just leave them out.


  Quote:


  Originally Posted by *pabbi1* 
_Pete put them there for a reason, and I trust his opinion - especially since I have tangible results about how it sounds WITH them._

 

You might be surprised ... then again, you might not. With a bypass cap, you are getting a tradeoff. On the upside, you get a bit of the sound of the film cap rather than the electrolytic which is good. On the downside, you are getting phase distortions as the film cap discharges faster than the electrolytic which can lead to a distorted signal. So, whether the good outweighs the bad is debatable, but certainly something that can be experimented with. I would guess (and it is only a guess) that with blackgate output caps, that you might be better without the wimas, but with lesser caps, the Wimas might help. 

 Keep in mind that the circuit here is already crippled (in a sense) by the tube choice and the buffer choice. It strikes a nice balance at the price point, but
 it may be that the upper eschelon of caps is not warrented as, once one is into blackgate country, the caps are not the limiting factor. So, an all blackgate/auricap version might not sound any better than one with caps in choice positions. Instead, the money might be better spent on some other buffer, or some other tube ... but at that point, you have some other amp.

 -d


----------



## pabbi1

I agree wholeheartedly about this design being crippled by the tube, but in 
 talking with Pete, there are no other options anywhere south of US wall current (110v), and most (like the Raptor, etc) are more like 240v. So, at low voltage, this is not only as good as it gets, it is the only game in town.

 The flip side is that this is the ONLY (relatively) safe game where DIY, almost regardless of the level of expertise, can play with tube, with some rolling possibilities, and playing with options.

 Since Auricap is the only other thing sonically (better?) than what I've already done, I'd be tempted. And yet, the call of the Wheatfields (Pete's commercial designs) is too strong to ignore, where the design isn't crippled (well, not in this way - every design has tradeoffs).

 Were that there was half as much interest in those (HA-1. HA-2, and for SS, HA-4) designs.


----------



## dsavitsk

Quote:


  Originally Posted by *pabbi1* 
_I agree wholeheartedly about this design being crippled by the tube, but in 
 talking with Pete, there are no other options anywhere south of US wall current (110v), and most (like the Raptor, etc) are more like 240v. So, at low voltage, this is not only as good as it gets, it is the only game in town._

 

Not quite. If you are curious about other low voltage tubes, look into the 6GM8 (not for this amp, obviously). The datasheet is not very promising, but Welborne has had good luck with it running at low voltage with a battery supply, and it does have a bit of an audiophile following. Also, beyond the tubes, it is the buffers that are limiting in this design more severely. In fact, I believe that the Headroom version has moved to a different buffer.


  Quote:


 Since Auricap is the only other thing sonically (better?) than what I've already done, I'd be tempted. 
 

Cap rolling provides many more possibilities than does tube rolling, but they will get very very expensive very quickly, and likely not provide any benefit. Look at the Percy catalog, or at PartsConexion website for gobs of overpriced caps you can use.


  Quote:


 And yet, the call of the Wheatfields (Pete's commercial designs) is too strong to ignore, where the design isn't crippled (well, not in this way - every design has tradeoffs).

 Were that there was half as much interest in those (HA-1. HA-2, and for SS, HA-4) designs. 
 

If you want another low voltage design, look at the earlier mentioned Welborne Ultrapath bp preamp. Depending upon your phones, it might be a good high quality low voltage option. Otherwise, I don't think I've seen a point to point Wheatfield, so someone should try it.

 -d


----------



## multibit16

Finally had time to fire up the Millet amp today, before having a proper listen I'm going to leave it on for a while to bed in, everything measures perfect so far.
 I'll post some pictures once I can get a case sorted out 
	

	
	
		
		

		
		
	


	




 All electrolytics are Rubycon ZA appart from the coupling caps which are BlackGate FK.
 PSU is a small toroidal,MBR10100 schottky diodes, 10k BHC cap and ALW Super regulator

 Big thanks to Evo for kindly ordering me the pcb and GEC 12FK6 tubes

 Leo


----------



## rickcr42

Quote:


 Not quite. If you are curious about other low voltage tubes, look into the 6GM8 (not for this amp, obviously). The datasheet is not very promising, but Welborne has had good luck with it running at low voltage with a battery supply, and it does have a bit of an audiophile following. Also, beyond the tubes, it is the buffers that are limiting in this design more severely. In fact, I believe that the Headroom version has moved to a different buffer. 
 

the 6GM8 is not suitable for driving headphones directly and must either use a matching transformer (see Sowter),be used as a cathode follower or other follower stage (example though not an optimised deign http://64.233.161.104/search?q=cache...gm8+tube&hl=en ),as an SRPP/MU/Hybrid MU Stage or have a solid state impedance matching/current pump output stage added.
 By itself the output impedance is just not good as in most if not all SE triode stages.No free rides to low impedance and current drive.

 some other low V triode information here :

http://digilander.libero.it/paeng/projects_frame.htm


----------



## mrdon

Quote:


  Originally Posted by *pabbi1* 
_Yes, just C4/C7... that's where I put BG, but Cerafines are an excelltnt chioce as well._

 

For C7L/R would Tangent's ELNA Cerafine 470µF/25V caps work?


----------



## shiggins

Just a heads-up for anyone planning on making a lot of hybrids - 48 * 12FM6 tubes on ebay


----------



## shut85

I've finished my Millett and i get fine sound from both channels....however i can only turn the bias down on the left channel to around 17.5 until the the trimpot starts clicking and won't go anymore....the right channel can be adjusted from around 6 on up. Again it sounds fine but is there some problem that has to be addressed that's causing the bias to not be able to go down further?


----------



## Edwood

Quote:


  Originally Posted by *shut85* 
_I've finished my Millett and i get fine sound from both channels....however i can only turn the bias down on the left channel to around 17.5 until the the trimpot starts clicking and won't go anymore....the right channel can be adjusted from around 6 on up. Again it sounds fine but is there some problem that has to be addressed that's causing the bias to not be able to go down further?_

 


 Probably not matched tubes. 

 I am auditioning MisterX's Mullet Hybrid. The pair od 12 AE6A's ? That were used were not matched well. The gain was too high, and clipped alot. Not to mention they were fairly noisey.

 He sent me a matched pair of RCA 12FK6's, and their initial bias was within 1.0 of each other. Adjusted the bias, and oh, what a difference these tubes made.

 The gain was at a more reasonable level, and no more horrendeous clipping. 
 The sound is a little on the "shrilly" side, though.

 FWIW, with the RCA 12FK6's (bias at 12) the Millet can drive K1000's effectively, with plenty of volume. I turned them up for as loud as I could stand for a few seconds, and could not hear significant clipping or other distortions.

 However the treble frequencies are pretty harsh, though.

 -Ed


----------



## MisterX

Ed has a good point.... try swapping the tubes between the channels and see if anything changes.


----------



## pabbi1

I totally agree about the 12AE6A - I'd only use them to initially set the bias and burn in the caps (especially BG) - but, the 12FK6 I used (TungSol) had about 70% (guessing) as much gain as did the (RCA) 12AE6A. There is no comparision, IMHO, between the sound between these tubes.


 The TungSol really sound sweet - I also have some Raytheons to try, but it's hard to roll something that is already really sweet.


----------



## ahmose

Anyone know where i can buy a Millett board from ?
 I'm a little concerned about ordering from Drew especially after some of the threads that i read recently.
 Is there any alternate source ? Has anybody ordered boards recently from
http://www.diyforums.org/order.html?


----------



## guzzler

In all my dealings with Drew, he's been friendly and professional. I can't speak for things at Shellbrook, but he certainly gets a thumbs up from me.


----------



## Thaddy

Quote:


  Originally Posted by *pabbi1* 
_I totally agree about the 12AE6A - I'd only use them to initially set the bias and burn in the caps (especially BG) - but, the 12FK6 I used (TungSol) had about 70% (guessing) as much gain as did the (RCA) 12AE6A. There is no comparision, IMHO, between the sound between these tubes.


 The TungSol really sound sweet - I also have some Raytheons to try, but it's hard to roll something that is already really sweet._

 

I'm also stuck in a monogomous relationship with my Tung-Sol 12FK6's, they sound wonderful. I'm hoping to pick up some nicer 12AE6A's soon, since my Uber-Millet is just about completed.


----------



## rreynol

My home amp has a pair of raytheon 12FK6's and my work amp has RCA 12FK6's. I also have a pair of GE 12FK6's sitting in the box. I prefer them to the 12AE6 as well.

 Where are you guys getting your Tung Sol tubes at?


----------



## steinchen

Does the manufacturer make such a difference ? I have 12FK6 from GE, Raytheon and Westinghouse but haven't compared them yet on the same amp against each other.

 Personally I like the 12FK6 best, followed by the 12FM6 which is a tad brighter and a little harsh in treble.

 imo the 12AE6A lacks detail and sounds some kind of muddy. The 12AJ6 is way too bright and lacks bass.


----------



## mrdon

FYI, they do work. 
  Quote:


  Originally Posted by *mrdon* 
_For C7L/R would Tangent's ELNA Cerafine 470µF/25V caps work?_


----------



## mrdon

Quote:


  Originally Posted by *steinchen* 
_Personally I like the 12FK6 best, followed by the 12FM6 which is a tad brighter and a little harsh in treble._

 

I too prefer the 12FK6. However, I found the 12FM6 to be tubby with more emphasis on lower mids. Hmm...very interesting.


----------



## pabbi1

I got mine from 

TubeDepot but didn't specify the manufacturer. I guess I just got lucky... or have learned to like these tubes (or too lazy to burn in some different ones without a good reason). I don't know if you can specify the maker, but it wouldn't hurt to ask.

 Pete told me that when he was writing the original article he called a couple of the larger tube dealers, who indicated they had PALLETS (10,000 to a pallet) of tubes that worked in this amp... and at the time, the price of the tubes was about $2 each. Thinking about this, and how many car radios would eventually need tubes (well, unless replaced by transistor radios, which happened faster than anticipated), these tubes have almost no other use.

 On a sad note, I receive my Wheatfield HA-1 tomorrow (OK, maybe not so sad), so my hours of listening to the Millett Hybrid are most likely winding down...


----------



## rreynol

Quote:


  Originally Posted by *steinchen* 
_Does the manufacturer make such a difference ? I have 12FK6 from GE, Raytheon and Westinghouse but haven't compared them yet on the same amp against each other.

 Personally I like the 12FK6 best, followed by the 12FM6 which is a tad brighter and a little harsh in treble.

 imo the 12AE6A lacks detail and sounds some kind of muddy. The 12AJ6 is way too bright and lacks bass._

 

I don't think it does. I can't hear a difference between the 3 brands of 12FK6 I have. I was just curious.


----------



## ahmose

Can anyone please recommend a super bright LED (mouser part #) that I can use under the tubes. 
 What are the guidelines for choosing LEDs ? (voltage, diameter etc...)
 thanks very much for the help


----------



## MisterX

What color?

 Diffused Blew 5mm superbright------------> http://www.mouser.com/access/?pn=696-SSL-LX5093USBC

 A good LED resistor calculator can be found here----> http://www.muzique.com/schem/led.htm


----------



## rreynol

Quote:


  Originally Posted by *ahmose* 
_Can anyone please recommend a super bright LED (mouser part #) that I can use under the tubes. 
 What are the guidelines for choosing LEDs ? (voltage, diameter etc...)
 thanks very much for the help_

 

If you want *uber*bright, try www.lsdiodes.com.


----------



## ahmose

Quote:


 What color?
 Diffused Blew 5mm superbright------------> http://www.mouser.com/access/?pn=696-SSL-LX5093USBC 
 

Thanks, that's exactly what i was looking for.

  Quote:


 If you want uberbright, try www.lsdiodes.com. 
 

Wow, those are REALLY bright. thanks


----------



## ahmose

Quote:


 A good LED resistor calculator can be found here----> http://www.muzique.com/schem/led.htm 
 

MisterX, thanks. This is very helpfull.
 Question: Is supply voltage the bias voltage for the tube in this case ? 
 I plan on using a 24V power supply. 
 So supply voltage should be 12V in this case ?


----------



## Thaddy

I just wanted to toss up a quick teaser picture of the Millet that should be on it's way to me tomorrow. You guys are going to have to wait for impressions, but I will say that it's pretty much maxed out all the way 
	

	
	
		
		

		
			











 All the props belongs to n_maher though, he's the builder responsible for creating this one-of-a-kind masterpiece


----------



## amb

Quote:


  Originally Posted by *ahmose* 
_MisterX, thanks. This is very helpfull.
 Question: Is supply voltage the bias voltage for the tube in this case ? 
 I plan on using a 24V power supply. 
 So supply voltage should be 12V in this case ?_

 

If you wire the LEDs the way I did (as posted in the following thead: http://www.diyforums.org/phpBB2/viewtopic.php?t=12 ), then yes, the voltage would be 12V. It's the heater filament voltage, not the bias voltage. Each LED will have its own resistor.


----------



## ahmose

Thanks amb. Very helpfull response, as usual.


----------



## mrdon

I've been reading reviews of the Millet tending to lack air and life. Not that it is completely lacking in that department but it's not up to the level some of us would like. I want to report that Tangent's TREAD helped resolve this issue a bit as well as putting boutique caps in C7L/R (ELNA Cerafine 470µF/25V) and adding a pair of DIY fine silver interconnects ala Chris VenHaus.


----------



## Blooze

Thanks for the info, mrdon!


----------



## Thaddy

I just wanted to add that today I took delivery of that amazing Millet you can see a few posts up...and *[size=large]WOW[/size]*. 

 If you guys can use the STEPS with your builds, do it. This is a major improvement over the Elpac that I was using with my old Millet.


----------



## en480c4

Quote:


  Originally Posted by *Thaddy* 
_I just wanted to add that today I took delivery of that amazing Millet you can see a few posts up...and *[size=large]WOW[/size]*. 

 If you guys can use the STEPS with your builds, do it. This is a major improvement over the Elpac that I was using with my old Millet._

 

I had a chance to hear your Millett before Nate sent it out, and I would agree whole-heartedly. After getting to know an Elpac-powered prototype from the group buy, I couldn't believe the difference the STEPS made. The improvement in impact and detail is definitely there, but you don't lose any of the good things about the Millett. While I primarily enjoyed the prototype with my 325i's and limited my 650's to PPAv2 & M^3 listening (I felt the 650-Millett pairing was uninspired), I will definitely be enjoying the 650's with my STEPS-powered Millett.

 Enjoy it... it looks great and sounds even better!!!


----------



## Thaddy

Yeah, I heard that you really enjoyed this amp with the HD650's, that's when I got really excited because that's what I'm using 
	

	
	
		
		

		
		
	


	




 By the way, thanks a *ton* for your help on the casework!


----------



## en480c4

Quote:


  Originally Posted by *Thaddy* 
_Yeah, I heard that you really enjoyed this amp with the HD650's, that's when I got really excited because that's what I'm using 
	

	
	
		
		

		
		
	


	


_

 

I really did... the STEPS really brings the Millett to life with the 650's and to helps open things up.

  Quote:


  Originally Posted by *Thaddy* 
_By the way, thanks a *ton* for your help on the casework!_

 

My pleasure... it was a good time. Seriously.
 We must've tried about 5 different variations of that one layout. Glad to hear you're happy with everything.

 But you were right the first time... props really do belong w/ Nate...


----------



## Thaddy

You played a part, so you deserve your props as well


----------



## n_maher

:blushes: Aw, geez, thanks Zack 
	

	
	
		
		

		
		
	


	




. 

 And Ian's a bit modest. His help, with most of the amps I build, is invaluable.

 I'm sure that more details, pictures, impression and the like will be coming from Thaddy in the future as well as the tale of how that amp got built the way that it did, so I'll leave all that nonsense for another thread.

 In terms of general information that may be useful for other builders I simply cannot stress how much of a difference it made (to my ears) moving from the Elpac to the STEPS. If time and budget allows I hope to build two similar amps to compare - one with a TREAD and one with a STEPS to see how those two power supplies compare. I know that they measure similarly in one of Tangent's tests but it should be interesting nonetheless. 

 Nate


----------



## rreynol

I have such a setup (TREAD vs STEPS). My ears are not as critical as others but I couldn't hear a difference. I'd be interested to hear your impressions on the issue as well. That is, if you can ever stop making Millet-Hybrids for others.


----------



## n_maher

Quote:


  Originally Posted by *rreynol* 
_I have such a setup (TREAD vs STEPS). My ears are not as critical as others but I couldn't hear a difference. I'd be interested to hear your impressions on the issue as well. That is, if you can ever stop making Millet-Hybrids for others. 
	

	
	
		
		

		
		
	


	


_

 

 My guess is that my ears will yield similar results. The TREAD should have a significantly lower noise floor compared to stand-alone wallwarts and the Millett doesn't require so much current that it really needs a STEPS. But for the extra $30 that a STEPS costs to build I'll probably stick with it for my "higher" end DIY amps.

 As far as building Milletts for others goes, Thaddy's is the only one I hadn't planned on. The other two that I've built thus far were built as gifts for members of my wedding party (brother and brother-in-law). The only one that I have left to build for someone other than me is for Ian, who was also forced to be in my wedding 
	

	
	
		
		

		
		
	


	




. His board is fully populated and the STEPS is already built so it's merely a matter of deciding what features we want to implement and what we're going to case it with (think wood 
	

	
	
		
		

		
		
	


	




 ). 

 And Thaddy's Millett sort of served as a testing ground for a lot of ideas that I'd wanted to try which is part of why I agreed to build it for him in the first place. But after completing his amp I'm done building amps for others. It was *really* hard to put that amp in a box and send it off to another home.

 N


----------



## cantskienuf

Nate,

 Can you share what you use for a transformer and values for R3 and R4 in your implementation of the STEPS in the Millett Hybrid?

 Thanks,

 John


----------



## amb

Not Nate here, but my STEPS for the Millett has 120 ohms and 2K ohms for R3/R4 and the output adjusted to 27VDC. I am using the Amveco 70062 25VA transformer and the LM338T regulator which are a bit of overkill but I wanted to be able to use the same supply for other amps too. I am also using another identically-configured STEPS for use with my M³.


----------



## n_maher

Quote:


  Originally Posted by *amb* 
_Not Nate here, but my STEPS for the Millett has 120 ohms and 2K ohms for R3/R4 and the output adjusted to 27VDC. I am using the Amveco 70062 25VA transformer and the LM338T regulator which are a bit of overkill but I wanted to be able to use the same supply for other amps too. I am also using another identically-configured STEPS for use with my M³._

 

Mine is similar to AMB's but I used the 70052 15VA transformer and LM317 regulator. I'd have to recheck my notes to see what resistors I used but my guess is that it was 100 ohm and 2.0K.

 HTH,

 Nate


----------



## Blooze

Please excuse this noobie question.

 I was thinking I'd like to put a rotary on/off switch on my Millet. I'm not sure which to use since most of the rotarys are 2 pole with many positions and it seems like a SPST would be the one to get. Does anyone know where I can get a suitable switch that will work?


----------



## derek_lukasik

Hi,

 Just got my board and started the build last night. One thing I noticed that I haven't been able to figure out... There is a position on the board labelled D3 with markings for a diode on the board. Yet, I have not been able to find any reference as to how to populate this position. It looks like the leads coming off of it don't go anywhere??? Anyone know what this is for?

 D3 is located between C1 and C10L right in the center of the board. On the opposite side of the pot.

 Thanks,

 Derek


----------



## n_maher

Derek,

 I'll ask Drew, that position didn't used to be there as far as I can remember.

 I'll get back to you ASAP.

 Nate


----------



## n_maher

Update, just leave D3 unpopulated. It only exists on the most recent batch of Millett boards and serves no purpose. It's already been taken back out 
	

	
	
		
		

		
			





.

 Sorry for the confusion.

 Nate


----------



## derek_lukasik

OK. Thanks a lot for looking into that.

 Derek


----------



## n_maher

That's what I'm here for 
	

	
	
		
		

		
		
	


	




.


----------



## Nisbeth

FWIW, if anyone wants an in-line diode to protect against reverse polarity damage it is possible (with a tiny bit of force...) to fit an 1N400x across the switch pads on the board. You then have to fit the power switch directly on the supply leads of course, but I always do that anyway so it wasn't really a problem for me 
	

	
	
		
		

		
		
	


	





 /U.


----------



## derek_lukasik

Just finished up my Millett. Here are a couple of pics. I've decided I'm the worst case builder in the world.... Listening begins in earnest tonight!!! Can't wait.

 Derek


----------



## Blooze

Quote:


  Originally Posted by *derek_lukasik* 
_Just finished up my Millett. Here are a couple of pics. I've decided I'm the worst case builder in the world.... Listening begins in earnest tonight!!! Can't wait.

 Derek_

 

Looks pretty dang good to me! Let us know how she sounds.


----------



## amb

Quote:


  Originally Posted by *Nisbeth* 
_FWIW, if anyone wants an in-line diode to protect against reverse polarity damage it is possible (with a tiny bit of force...) to fit an 1N400x across the switch pads on the board._

 

There is no need to do that because the self-resetting fuse PF1 and the overvoltage protection diode D1 already perform this function. If the supply voltage is higher than what D1 is rated for, then D1 begins to conduct and acts like a crowbar and will cause PF1 to open. If the supply is connected with the wrong polarity, D1 becomes forward biased and will also acts as a crowbar and cause PF1 to open.


----------



## derek_lukasik

Well, two solid nights of listening and I love it! Man, this thing is really smooooth. I'm a Grado fan, and I think the Millett really complements the Grados well. Smooths out the brightness really well. The midrange on this thing is really beautiful as advertised. Haven't really had much experience with tubes until now. For this application, I think they're great.

 Thanks to all of you folks out there for making this possible! Who woulda thunk that a software guy could build a decent piece of hardware? V=IR is about as much as I can handle... 
	

	
	
		
		

		
		
	


	




 Back to listening.... 
	

	
	
		
		

		
		
	


	













 Derek


----------



## derek_lukasik

Speaking of my lack of EE knowledge....that reminds me....a quick question. So, if I wanted to figure out how much load my cans put on the amp, how would I go about it? Is the bias voltage the one to use to calculate the current? For my Millett, I have the bias at 16V or so I think. So, the max current draw would be something like 500mA for 32ohm Grados. Is that right? And the power would be 8 watts (500mA *500mA * 16V * 2)? That seems way too high for some reason... 
	

	
	
		
		

		
		
	


	




 Thanks,

 Derek


----------



## jerb

A quick skim didnt bring up the awnser I needed, what tube is the prefered favorite? I've seen the 12AE6A, 12FM6, and 12FK6 floating around so what is everyones favorite?


----------



## ottopig

Answers to the last two posts:
  Quote:


  Originally Posted by *derek_lukasik* 
_...So, the max current draw would be something like 500mA for 32ohm Grados. Is that right? And the power would be 8 watts (500mA *500mA * 16V * 2)? That seems way too high for some reason..._

 

and 
  Quote:


  Originally Posted by *jerb* 
_A quick skim didnt bring up the awnser I needed, what tube is the prefered favorite? I've seen the 12AE6A, 12FM6, and 12FK6 floating around so what is everyones favorite?_

 

and a lot more can be found on *amb's* site at http://www.ibiblio.org/tkan/audio/millett.html

 See the *Comments* section for the current load at 32ohm and all the tube selection and bias setting info. Ti's posted boatloads of good info for all of us building and tweaking the M-H. You might also be interested in the substitution of OPA551PA for BUF634P and the discrete buffer development work being led by *steinchen* with input from amb and others at http://www.diyforums.org/phpBB2/view...r=asc&start=30

 I don't mean to direct people away from this site and hope to see your comments back here. Cheers,

 ottopig


----------



## Thaddy

Quote:


  Originally Posted by *jerb* 
_A quick skim didnt bring up the awnser I needed, what tube is the prefered favorite? I've seen the 12AE6A, 12FM6, and 12FK6 floating around so what is everyones favorite?_

 

In both Millet's I've owned (one with and one without the STEPS) I've preferred the 12FK6's for the majority of my music. The 12AE6A's see some playing time whenever I'm in the mood for a tad bit extra **oomph** in the low end.


----------



## jerb

Thanks tot he two above reply's, I hadent heard of ambs site, its very nice though.


----------



## CedMan

Quote:


  Originally Posted by *mrdon* 
_FYI, they do work.

 Quote:
 Originally Posted by mrdon
 For C7L/R would Tangent's ELNA Cerafine 470µF/25V caps work? 
_

 

Finished my first Millet, just wondering about this for my second one, I thought the instruction mentioned that it should be at least 35V? Would it be okay to use that or I will be risking something? 

 Thanks!

 -Ced


----------



## n_maher

Quote:


  Originally Posted by *CedMan* 
_Finished my first Millet, just wondering about this for my second one, I thought the instruction mentioned that it should be at least 35V? Would it be okay to use that or I will be risking something? _

 

 To be on the safe side, they should be a minimum of 35V (provided you're using a 24V power supply). The reason for this is to allow some sort of headroom over and above what the power supply _might_ output. In most configurations these caps will see much less voltage (whatever you have the bias set to) but if you've ever experienced an exploding cap you know why it's a bad thing. In the end it's a matter of personal risk, in the audio realm I doubt you'll hear the difference between a 35 or 25V cap. You may have a harder time finding the cap value you're looking for (470/35) but might I suggest taking a peak at this site and seeing if you can find something that'll work 
	

	
	
		
		

		
			





. Disclaimer(s): A. I'm not associated with that site but have used them in the past with decent results, B. I have never used that particular cap in a Millett and its size should be checked for fit before ordering.

 HTH,

 Nate


----------



## SHLim

Hi n_maher,
 What is your R1 and R2 value for Steps? I ordered the board and is now getting the bits for it.

 TIA,
 Sam


----------



## Voodoochile

Quote:


  Originally Posted by *derek_lukasik* 
_Just finished up my Millett. Here are a couple of pics. I've decided I'm the worst case builder in the world._

 

Sorry man, but I've seen plenty worse. 
	

	
	
		
		

		
		
	


	




 You're looking pretty good, I think. 

 You might try trimming the shaft of your volume pot a bit to get the knob closer to the faceplate. An extra-fine hacksaw/jeweller's saw works well. I like to place the pot in a plastic bag, poke the shaft through and grip the shaft in a vise. Then trim it. As you are cased up already... I'd still remove the board from the case- and mount the shaft in a vise, bagging the entire circuit board to protect it from metal filings and debris.


----------



## n_maher

Quote:


  Originally Posted by *SHLim* 
_What is your R1 and R2 value for Steps?_

 

I think you probably meant R3 and R4 as you really shouldn't change R1 or R2 unless you really know what you're doing. The schematic values are the easiest way to go for these. If you did mean R3/R4 I generally use 100/2.0K or 120/2.0K as I feel they give the best range of useable voltages. 

 HTH,

 Nate


----------



## derek_lukasik

Quote:


  Originally Posted by *n_maher* 
_You may have a harder time finding the cap value you're looking for (470/35) but might I suggest taking a peak at this site and seeing if you can find something that'll work 
	

	
	
		
		

		
		
	


	




. Disclaimer(s): A. I'm not associated with that site but have used them in the past with decent results, B. I have never used that particular cap in a Millett and its size should be checked for fit before ordering._

 

I can verify that those caps do in fact work in the Millett. I used the ROA220 (C2), the ROA473 (C7) and the ROA221 (C1, C9, and C10) in the appropriate locations. They work great!

 Derek


----------



## stewtheking

I have just finished my millett, and I am very happy with it, sounds fantastic with my RS-1's. HOWEVER, I did hit a bit of a snag when building. My regulated power supply failed to manage to provide enough power to heat up the tubes, and cut out, beleiving that the circuit was dodgy in some way. This problem was "solved" by adding a small resistor directly in the path from the power supply, thus neatly negating the beneficial effects of a regulated power supply. 

 Any ideas of a way around this? Anybody else encountered a similar problem? My resistor has solved the problem for the time being, but it's hardly an ideal solution!

 Stew


----------



## nikongod

stew, get a more powerfull regulated psu.


----------



## Erik S.

Quote:


  Originally Posted by *stewtheking* 
_I have just finished my millett, and I am very happy with it, sounds fantastic with my RS-1's. HOWEVER, I did hit a bit of a snag when building. My regulated power supply failed to manage to provide enough power to heat up the tubes, and cut out, beleiving that the circuit was dodgy in some way. This problem was "solved" by adding a small resistor directly in the path from the power supply, thus neatly negating the beneficial effects of a regulated power supply. 

 Any ideas of a way around this? Anybody else encountered a similar problem? My resistor has solved the problem for the time being, but it's hardly an ideal solution!

 Stew_

 

Try to connect the psu to the amp, turn on the amp, then connect the psu into the walloutlet. This is what I have to do with my Mascot psu.


----------



## stewtheking

Quote:


  Originally Posted by *Erik S.* 
_Try to connect the psu to the amp, turn on the amp, then connect the psu into the walloutlet. This is what I have to do with my Mascot psu._

 

That worked, but I can't be bothered faffing around with wall-sockets every time i want to listen! 

 Also, Nikongod, would a more powerful psu really be the answer, as opposed to putting, for example, a high-value cap directly in series with the power supply, to supply some of the warm-up current? Seems to me a bit of an ass-about-face way of doing it really, and rather expensive!

 Anyhoo, nobody has any feindishly clever yet alarmingly inexpensive solutions?


----------



## n_maher

Quote:


  Originally Posted by *stewtheking* 
_Anyhoo, nobody has any feindishly clever yet alarmingly inexpensive solutions?_

 

 Sure, put an inline switch between the power supply and the amp. Most of my amps now use a staged power arrangement so that I can turn the amp off idependant of the power supply.

 Nate


----------



## amb

stewtheking, what kind of power supply is this that you're running? Is it a STEPS or TREAD? Or something else?


----------



## Voodoochile

Quote:


  Originally Posted by *stewtheking* 
_That worked, but I can't be bothered faffing around with wall-sockets every time i want to listen! 

 Also, Nikongod, would a more powerful psu really be the answer, as opposed to putting, for example, a high-value cap directly in series with the power supply, to supply some of the warm-up current? Seems to me a bit of an ass-about-face way of doing it really, and rather expensive!

 Anyhoo, nobody has any feindishly clever yet alarmingly inexpensive solutions?_

 

If that worked, you want a switch between the PSU and the powercord (120vac line), and have the amp and PSU wired together all the time. Amp comes on with the PSU, per Erik S's suggestion. It's a workaround, but works.

 It does sound like the initial current demand that the Millett places on your PSU is exceeding it's capacity (charging up the Millett's caps). By connecting the amp and PSU directly, they both power up slowly and steadily, not overwhelming the regulator.

 Off the cuff, it does sound like you need a fatter PSU. What are you using?


----------



## BradJudy

Quote:


  Originally Posted by *Voodoochile* 
_If that worked, you want a switch between the PSU and the powercord (120vac line), and have the amp and PSU wired together all the time. Amp comes on with the PSU, per Erik S's suggestion. It's a workaround, but works._

 

Oooohhhh...you could hook it up to 'The Clapper'.


----------



## Buzzerbro

I might try one of these for turning on/off my equipment. 
	

	
	
		
		

		
		
	


	




Wireless RF Remote-Control On/Off Switch


----------



## stewtheking

Quote:


  Originally Posted by *Voodoochile* 
_Off the cuff, it does sound like you need a fatter PSU. What are you using?_

 

I am using an off-the-shelf power supply, a "mascot" type 2083 
 Specs:
 Input: 230VAC 50-60Hz 120mA
 Output 24VDC max.500mA
 The only modification was to change the power connector to a din plug, so that i could get a locking one that didn't fall out as easily!

 Hmmm.... I may just go on the principle of "if it aint broke, don't fix it!"


----------



## dsavitsk

Quote:


  Originally Posted by *stewtheking* 
_Output 24VDC max.500mA_

 

That's too small. You are starving the amp and straining the PS.

  Quote:


 Hmmm.... I may just go on the principle of "if it aint broke, don't fix it!" 
 

This is a definition of "broke" I am not familiar with.


----------



## Erik S.

According to BrokenEnglish the mascots lack some reversed biased protection diodes, that could help them coming up when there's a lot of capacitance in the amp.

 Use the Mascot 2083 myself and own the 2183 which is 1A, I find no difference between them with the Hybrid. So there's no point in buying the 2183 which I did.


----------



## slindeman

Quote:


  Originally Posted by *dsavitsk* 
_That's too small. You are starving the amp and straining the PS._

 

That's not true. The amp draws under 200mA at idle. In my amp, with 470uF PS caps on the board, the inrush current at turn on reaches over 400mA, but quickly settles. I ran my first Millet amp (which I've since sold) with the Elpac 24V 330mA wal-wart without ever having a single problem.


----------



## sharshan

I'll have to agree with slindeman. I just built mine, and I have no issues with it running a stock Tangent PSU running at 24V output. Sounds great and no power issues.


----------



## rjkdivin

I have finally begun construction of my Head-Fi modified Millet Hybrid. I am wondering why the suggested parts list (Mouser version) lists C3, C4, C5, and C8 as .22uf film caps, but the referenced Mouser part number is for a 0.1uf cap? Does this have any effect....good or bad.....if the lower value is used?

 I looked back through the prior postings, and found no discussion of this issue.

 Refering to the inrush current potentially straining the STEPS PSU, if it becomes a problem, I would suggest changing the regulator to the LM338T which has a 1.5A current rating plus current limiting. I had a problem burning out the LM317 regulators in a STEPS with an M3 when I had them separately switched and ONLY if I switched on the STEPS before I switched on the M3. If they are powered on at the same time, the charging of the power caps is 'gradual' and does not strain the regulator.


----------



## tess

Have a look here link scroll down untill you see the green information. the mouser parts are fine

 Also this link will help link 

 Tess.


----------



## BlueCan

Quote:


  Originally Posted by *rjkdivin* 
_I have finally begun construction of my Head-Fi modified Millet Hybrid. I am wondering why the suggested parts list (Mouser version) lists C3, C4, C5, and C8 as .22uf film caps, but the referenced Mouser part number is for a 0.1uf cap? Does this have any effect....good or bad.....if the lower value is used?_

 

Actually, I'd suggest reading the original Pete Millet article on the amp. He talks a bit about part substitution.

 The design is MADE to be tweaked and MEANT to be an introduction to the "tube sound". Sourcing the exact values of most parts wasn't described as being all that important. I seem to recall it said +/- 200% for many of them. 
	

	
	
		
		

		
		
	


	




 I was a little taken aback earlier in one of the Millet threads where someone said if we're not using BUF634's and ar instead replacing them with discrete buffers we're not following the intent of the design. IMO, the article disagreed when it basically said, "Tweak away! Have fun! That's what this amp is about..."

 -Patrick


----------



## JWFokker

Speaking of discrete buffers, I wonder how their design is progressing. It's been a while since we heard about the diamond buffers being worked on.


----------



## nikongod

Quote:


  Originally Posted by *JWFokker* 
_Speaking of discrete buffers, I wonder how their design is progressing. It's been a while since we heard about the diamond buffers being worked on._

 

diamonds are a girls best friend. if i can ever get off my lazy arse, and FINISH my millet, that will likely be my first mod.


----------



## steinchen

Quote:


  Originally Posted by *JWFokker* 
_Speaking of discrete buffers, I wonder how their design is progressing. It's been a while since we heard about the diamond buffers being worked on._

 

as mentioned before, the development of discrete buffers is discussed at the forum of DIYforums.org
 atm the boards are in beta test stage, I hope to hear the first impressions from the beta testers the next days. I'm confident that they become available in October.

 due to the group-buy status of head-fi there won't be any promotion for the buffers here, hopefully I didn't break a rule by mention the "Millet-forum". To be on the safe side I'd like to discuss any aspect of the buffers at diyforums exclusively.


----------



## JWFokker

I've been gone a while so I had no idea. Off to diyforums.org then.


----------



## Voodoochile

Quote:


  Originally Posted by *stewtheking* 
_I am using an off-the-shelf power supply, a "mascot" type 2083 
 Specs:
 Input: 230VAC 50-60Hz 120mA
 Output 24VDC max.500mA
 The only modification was to change the power connector to a din plug, so that i could get a locking one that didn't fall out as easily!_

 

From a current capacity standpoint, that PSU IS fine; however I am not aware of any 'Mascot PSU'-specific concerns. Inrush current and soforth are dealt with differently by some PSUs, and demands vary depending on how you have your Millett configured. Pete's original parts list is not demanding at all of the PSU. His wallwart is actually pretty poor spec, but it's also far away from the amp, so at least the physical separation helps.

 The amp has low drain, as slindeman pointed out, and also, it has the polyswitch on it which cuts out above 500mA. But that is mainly there to cut out if you either send more than 30v to the amp, in which case the transient diode will breakdown, shorting the amp and causing the polyswitch to open, or if there is another short, causing a lower voltage PSU to deliver a sustained flow of more than 500mA, in which case the polyswitch will also open. It is not instant, like a typical glass fuse, it takes some 4 seconds to heat up and open, depending on the overcurrent situation.

  Quote:


  Originally Posted by *BlueCan* 
_Actually, I'd suggest reading the original Pete Millet article on the amp. He talks a bit about part substitution._

 

Great idea! It used to be more difficult, as you had to buy the back issue, but it's all on Pete's website now for free download. Many of the questions asked here are answered there, though there is nothing wrong with polling for opinion, either. He explains the full operation of the transiend protection diode and polyswitch there, and the setup does indeed protect against reverse polarity, overvoltage, and overcurrent. The guy knows what he's doing.

 He also describes the reason for laying out this little amp, and states it is not intended to be any world-class amp, but that he himself was also pleasantly surprised by the very good qualities that the amp demonstrates. It also allows the new builder to experiment with tube bias and it's effects on sound quality as it relates to distortion and harmonics. He discusses bias setting, both higher than half the supply voltage, and less than half the supply voltage. In the original Millet I built, I was running a 28v PSU, and had the amp biased at around 18.5 volts with 12AE6 tung-sol tubes... after much fiddling around.


----------



## Voodoochile

Speaking of polling for opinion, I have a few questions.

 1: Has anyone experiemented with different plate loading? The article suggests using the 0.56mA CRD, and also Pete says he tried a 1mA part and got slightly higher distortion. I'm wondering if anyone has tried a bit lower than 0.56, or something between 0.56mA and 1mA?

 2: _I have a question regarding what folks are settling on for coupling, but will post it in another thread_ so it does not get lost in this mammoth thread. Other thread is linked here.


----------



## cantskienuf

OK, so I'm a little late to the game. I wasn't even into headphone amps - my interest in building tube pre's and SE tube amps dragged me into this, but I have to say I'm quite impressed. I've only got a few hours on the device, but it sounds amazingly good. Used 330uF Blackgates in C7, Auricaps for C4, Multicaps for C6, Nichicons in the remaining electrolytic cap positions and WIMAs in the remaining film cap positions, Vishay Dales in RLED and 1w Holcos in the remaining resistor positions. Used an Alps pot, but now I wish I had taken it more seriously and built a ladder attenuator. Used 4N silver-in-teflon for input and output wiring and 18awg solid-core copper to connect the PS, pot and tubes. It is powered by a fully-populated STEPS v1.2. I'm running RCA 12AE6A tubes biased at 13.5v and single BUF634s (no stacking yet). Even though both Blackgates and Auricaps take quite a while to sound their best, I really like what I hear. Built it on a plexiglass topsheet with chassis-mount tube sockets wired to the PCBs, which are downward suspended via 3" stand-offs. The topsheet is then dropped onto an 11" x 9" x 4" red-oak base finished with tudor brown Briwax. I like my tubes right up on top and fully visible, and this layout matches my other tube gear. Playing it through an inexpensive pair of Sennheiser 202 headphones (remember, I wasn't into headphones - just wanted to build the amp) but I'm really surprised at the quality of the sound. You guys did a great job. Guess I'll have to turn off the horns and think about this headphone stuff a bit more seriously. Thanks for all the design work on the boards and the implementation in the thread.

 John


----------



## Vladco

I’ve got unusual question because I got on hand case 6” by 9” by 2.5”. Could I cut board down to fit the case to include board and PC in. I’m using outboard pot. If yes how much 1/2” to ¾” or other length I could cut without penalizing myself. I don’t understand obsession with eurocard size.
 Vlad.


----------



## n_maher

The facination with euro card sized boards, well in this case Drew and I picked it so that it'd be easy for folks to pick what cases might work (same as the PPA). Other than that we couldn't go much smaller without cramping things seriously so that's that. 

 As to trimming the board, yes it's possible to do so and not destroy anything. I had to cut a bit off of two of the prototypes that I built (picked a case that didn't work wouldn't ya know 
	

	
	
		
		

		
			





) and I managed to trim enough to make the boards fit in 6" cases. So yes, again, it can be done but panel component placement gets really tight in a hurry. D1 and the signal trace on the front are probably going to be the things that establish how much you can cut.

 Best of luck, and be careful.

 Nate


----------



## Vladco

Actually I’m thinking about another side - pot side. Its looks like I could trim about 7/8” on that side. I’m not planning to use onboard pot.
 Vlad


----------



## BradJudy

John - Sounds like you have put together a very cool amp (and a local guy no less). Now you just need some cool headphones to go with it.


----------



## n_maher

Quote:


  Originally Posted by *Vladco* 
_Actually I’m thinking about another side - pot side. Its looks like I could trim about 7/8” on that side. I’m not planning to use onboard pot.
 Vlad_

 

You may be able to trim this much if you jumper the R/L_POT_1/2 pads but like I said, that doesn't leave you much room to put stuff.

 N


----------



## Vladco

I’ve got three different transformers: toroid 18vac with 22dc after lm317, ecore 24vac 400ma which got pretty warm after ½ hr of use and bigger toroid 28vac. Which you recommend to use with amp
 Vlad


----------



## rjkdivin

Quote:


  Originally Posted by *Vladco* 
_I’ve got three different transformers: toroid 18vac with 22dc after lm317, ecore 24vac 400ma which got pretty warm after ½ hr of use and bigger toroid 28vac. Which you recommend to use with amp
 Vlad_

 

Vlad....what power supply are you using these transformers with....STEPS? If so, I recommend using a transformer with vdc output very close to the desired psu output so that the regulator doesn't have to drop very much voltage. If you want to output 24vdc, the Amveco 70062 is perfect at 12v + 12v at 25VA total output, or close to 1.0A output. If you want to output 27 volts, I would go up to the 15v + 15v model.


----------



## nikongod

woot, my final parts are ordered. and too think i waited 2 months to order 4 resistors, and the 2 trimpots after spending about $50 on my caps....

 well, i neaded some other parts too...


----------



## matthew-s

Hi All,

 I am very new to this board. I am fascinated by this build. I currently have no means to listen to headphones through my home rig, so in looking for alternatives, I found this board. Very cool.

 I am fascinated by this amp. I am curious to hear if anyone has compared the sonics of a point-to-point wired Millett Hybrid, over the PCB Millett.

 If there is no difference, I would go PCB. But if there is noticeable improvement for P2P, then I'll take the dive. The only pro's & con's I have seen discussed re: P2P for the Millet are related to cost (of PCB) and speed (extra effort for P2P).

 As an aside, I've built a Bottlehead Seduction, which I could not be happier with. I considered doing the S.E.X preamp as a headphone amp, but don't want to invest that much money in a headphone project. . . .yet!

 Thanks,

 Matt


----------



## dsavitsk

Quote:


  Originally Posted by *matthew-s* 
_I am curious to hear if anyone has compared the sonics of a point-to-point wired Millett Hybrid, over the PCB Millett._

 

There shouldn't be a difference.


----------



## nikongod

the p2p of a millet should not be terribly difficult.
 someone actually made one before the millet boards were "cut" check it out. i think the pictures are still up in the builds pictures thread.

 as for which would sound better: eeh, who knows for sure. any fair comparason would require IDENTICAL parts. otherwise, part "quality" will likely play a decent factor.


----------



## sbelyo

So... I'm going to use Riken Carbon comp 1% resistors to see what kind of change this makes.

 In theory this will be my 3rd millett. My first one was with the diycable board(I used wima, blackgate, and vishay dale). My second was the redesigned millett proto (Nichicon Muse KZ, wima, solen on the output and Vishay dale). Between the two I don't really notice a huge difference.

 Now my third, after much thought will use the following. Silmic II's in all except for C7 (blackgates in there). Riken for all the resistors, and Solen for all the film caps. R4 will be jumpered. 

 I also have enough Holco's for the resistors as well. So I am not sure if some positions will benefit from the precision of the holco's or not 

 What do you guys think?


----------



## dsavitsk

Quote:


  Originally Posted by *sbelyo* 
_So... I'm going to use Riken Carbon comp 1% resistors to see what kind of change this makes.

 In theory this will be my 3rd millett. My first one was with the diycable board(I used wima, blackgate, and vishay dale). My second was the redesigned millett proto (Nichicon Muse KZ, wima, solen on the output and Vishay dale). Between the two I don't really notice a huge difference.

 Now my third, after much thought will use the following. Silmic II's in all except for C7 (blackgates in there). Riken for all the resistors, and Solen for all the film caps. R4 will be jumpered. 

 I also have enough Holco's for the resistors as well. So I am not sure if some positions will benefit from the precision of the holco's or not 

 What do you guys think?_

 

I don't think the precision will matter much. Match the Rikens and they should be fine. Rikens don't have the same drift problems as something like an AB.

 As for position, since you are not using the output resistors, I would think the difference won't be huge. I use Kiwames there and it added a little bit of lushening/softening to the sound. It is worth a try in the pther spots, but will be difficult to know what to attribute any changes to.


----------



## sbelyo

Quote:


  Originally Posted by *dsavitsk* 
_It is worth a try in the other spots, but will be difficult to know what to attribute any changes to._

 

That's what I was thinking, I just wanted to hear the sonic difference of carbon comp over metal film. I suspect I'll have it working in 2 weeks or so. I actually had all the parts ready to go minus the rikens, so now I'm waiting on partsconnecxion to ship. I'll just use this time for case work


----------



## n_maher

Quote:


  Originally Posted by *sbelyo* 
_ I'll just use this time for case work_

 

Well, you might want to wait just a bit longer. I've gotten permission from Head-Fi managment to post information about an upcoming group buy for drop in diamond buffers for the DIY Modified Millett Hybrid PCBs. While I'm not prepared to post the full details of the project at this point the final prototyping should be complete by the end of the month. Any and all discussion of the buffers should be held until the group buy is real as we don't want to clog the DIY forum with posts and threads of this nature, but I wanted to post something so that folks didn't think that I'd totally abandoned this project. 

 And please, no PMs about it either - I won't reply to them. Just know that we're working hard and in the final stages. 

 Nate


----------



## Jaypetermen

Has anyone used the 470µF/100v ELNA ROB Capacitor for C7?

 How does it compare to Cerafine or Muzes for this purpose?


----------



## sbelyo

Quote:


  Originally Posted by *n_maher* 
_Well, you might want to wait just a bit longer._

 

You're funny Nate 
	

	
	
		
		

		
			





 I've waited sevral months to actually build the production version, so what a few more weeks....


----------



## blueworm

Trying to get a parts list together RS-amidata.
 Having problems deciding on C3/C4/C5/C8 (0.1-0.22 mF caps).
 Choices are 166-6487 0.1mF Vishay MKP 1.21 EURO each (seems expensive).
 or 116-644 0.1mF wima MKS-4 0.36 EURO each.


----------



## Teerawit

Quote:


  Originally Posted by *blueworm* 
_Trying to get a parts list together RS-amidata.
 Having problems deciding on C3/C4/C5/C8 (0.1-0.22 mF caps).
 Choices are 166-6487 0.1mF Vishay MKP 1.21 EURO each (seems expensive).
 or 116-644 0.1mF wima MKS-4 0.36 EURO each._

 

Do you mean uF? cuz mF is quite a bit of capacitance


----------



## steinchen

Quote:


  Originally Posted by *blueworm* 
_Having problems deciding on C3/C4/C5/C8 (0.1-0.22 mF caps).
 Choices are 166-6487 0.1mF Vishay MKP 1.21 EURO each (seems expensive).
 or 116-644 0.1mF wima MKS-4 0.36 EURO each._

 

the 0.1uF Vishay MKP are polypropylene caps and better specced than the MKS (polyester). I doubt you hear the difference for power rail bypass caps (c3 / c5 / c8), MKS should be sufficient there. You may try the MKP cap in the signal path (c4).


----------



## CedMan

Hello all,

 I've been trying to build a Millet as a pre-amp (built and sounds great btw) and use it was my Charlize T-amp as a mini system, so today I am trying to complete the casing for both and I was just wondering, hmm ... would it be nice to be able to put a sub output somewhere ....

 So here's my questions to all experts out here ... is there a way to add a sub output from my millet? can I just "split" the output and wire it that way?? Will it destroy anything? or is there a better way to do that?

 Any help would be greatly appreciated.

 Thanks!

 -Ced


----------



## Blooze

Quote:


  Originally Posted by *sbelyo* 
_So... I'm going to use Riken Carbon comp 1% resistors to see what kind of change this makes.

 In theory this will be my 3rd millett. My first one was with the diycable board(I used wima, blackgate, and vishay dale). My second was the redesigned millett proto (Nichicon Muse KZ, wima, solen on the output and Vishay dale). Between the two I don't really notice a huge difference.

 Now my third, after much thought will use the following. Silmic II's in all except for C7 (blackgates in there). Riken for all the resistors, and Solen for all the film caps. R4 will be jumpered. 

 I also have enough Holco's for the resistors as well. So I am not sure if some positions will benefit from the precision of the holco's or not 

 What do you guys think?_

 

Does R4 just adjust the impedence? Since I messed up, read the warning for ordering R4 schematic value, and then propmptly wrote down 22K instead of 22 ohm when I ordered my Kiwames, then can R4 just then be jumpered? I could put a metal film in there for now, but kinda defeats the purpose, and this is the only parts I lack now to finish populating the board. I hate to place an order for just a couple of resistors, so if anyone has a couple extras see my WTB in the For Sale section.


----------



## sbelyo

Yes, You can jumper R4. It just protects the buffers from momentary shorts (like when you pull the headphone plug out while the amp is on) The TI buf634 have this protection built in.


----------



## Blooze

Thanks. I'm using the OPA551 as I messed around and didn't get a BUF634.


----------



## Blooze

Breadboarded up all the jacks and switches to the board and the amp worked first try! Happened to have 2 12FK6's that worked (unfortunately I don't have a set of 12FM6 or 12AE6E where both work). Adjusted the bias to 12V and everything sounded great through my POS test phones, some hiss with no input past 1/2 volume, but it's probably the low grade resistor I put in R4 as it's pretty balanced out of both sides. I don't notice it with music playing.

 One question: I have the TREAD running to the board, then the power switch running to the pads on the board. Would it be better to put the power switch between the DC jack and the TREAD, or just leave it where it is?


----------



## GregVDS

Hello,

 I finished my M³, hence, now Millet Hybrid.

 I read the DIYforum page about it. This is my first tube atempt, so I have some questions:

 - First, I tried to understand better the pcb, comparing it with the schematic. Is there not an incoherence between both? I think, but as I just begin this, let me know if I did not catch something, VT1 and VT2 should be exchanged or in the schematic, or on the silkscreen of the pcb, no? This is based on the Pin3 and pin4 connection to 24V, in between, and to ground.

 - Can I use the mod Linkwitz filter (high z around 2kohm) in front of this amp?

 - I will use grado 325i on it, so 32ohms, can I go for a 1000µF 50v for C7? is it still 1/(2*pi*(C7+C4)*R3) that gives the cut-off frequency? How the impedance of the headphones influences this?

 - I built a STEPS 24.77V for the M³, I can use it directly right?

 - I don't want to use a power switch on the millet (cleaning the design). Can I just connect everything, and then switch on the STEPS, or current inrushs or other will be a problem?

 - Nichicon ok? better/worse than Silmic II?

 - How can I customize a little bit values of capacitors to further match with grado impedance?

 - Warning, don't take this badly at all, this is not a critic! Why the pcb layout does not present a higher symmetry between the two channels? Some components are in the same relative places, others are 90° rotated, other are completely differently layouted. Is there a cryptic reason I don't catch?

 - Is it possible to have a rough estimate of the total height of tube and socket above pcb?

 - Is the Alps rk27 shaft exactly centered on the pcb, as the tubes?

 - At the moment, pf1 does not seem to exist at all in Mouser?! Buf634 seems also absent, and OPA551 too... Where can I find them?

 - the Intersil, is it HA2-5003, or HA3-5002? Both exist on the webpage.

 - I intend to deport the testpoints and R2 trimpots on backside of the box. Long wires are not a problem?

 Ok, this is the beginning 

 Many many thanks, and all the best to you all,

 GregVDS


----------



## steinchen

Quote:


  Originally Posted by *GregVDS* 
_- Can I use the mod Linkwitz filter (high z around 2kohm) in front of this amp?_

 

yes


  Quote:


  Originally Posted by *GregVDS* 
_- I will use grado 325i on it, so 32ohms, can I go for a 1000µF 50v for C7? is it still 1/(2*pi*(C7+C4)*R3) that gives the cut-off frequency? How the impedance of the headphones influences this?_

 

the higher the headphone impedance the lower the cutoff frequency and vice versa. 470uF are enough even for 32 ohm cans, go for capacitor quality and not for excessive capacitance


  Quote:


  Originally Posted by *GregVDS* 
_- I built a STEPS 24.77V for the M³, I can use it directly right?_

 

yes


  Quote:


  Originally Posted by *GregVDS* 
_- I don't want to use a power switch on the millet (cleaning the design). Can I just connect everything, and then switch on the STEPS, or current inrushs or other will be a problem?_

 

yes, no problem


  Quote:


  Originally Posted by *GregVDS* 
_- Nichicon ok? better/worse than Silmic II?_

 

depends on the nichicon line you are going to pick. The best Nichicon line(s) should be on the same level with the Silimic II


  Quote:


  Originally Posted by *GregVDS* 
_- How can I customize a little bit values of capacitors to further match with grado impedance?_

 

no use for further customization, just pick a high quality 470uF cap


  Quote:


  Originally Posted by *GregVDS* 
_- Is the Alps rk27 shaft exactly centered on the pcb, as the tubes?_

 

yes, but if you are going to have a frontpanel done by FPE add at least 1mm to the pot drill diameter, you never solder the pot perfectly straight to the pcb


  Quote:


  Originally Posted by *GregVDS* 
_- At the moment, pf1 does not seem to exist at all in Mouser?! Buf634 seems also absent, and OPA551 too... Where can I find them?_

 

they seem to be out of stock world wide with a lead time of 12+ weeks. You may start a trade/buy thread if you are in a hurry. PM me if you can't get any, I think I have 2 spare


  Quote:


  Originally Posted by *GregVDS* 
_- the Intersil, is it HA2-5003, or HA3-5002? Both exist on the webpage._

 

the Harris / Intersil buffers got a different pinout than buf634 and don't fit the MH (no drop in replacement)


----------



## GregVDS

Thanks,

 now there are places for intersil buffers too, look at the diyforum website.

 Thanks for comment about the shaft hole size, I noticed that already with M³ (need of some tolerance). By the way, FPE sell also angle profile and side profiles that can replace easily segor electronics box, at least if you intend to have top, bottom, front and back done by FPE!

 Nichicon UPW series, as given in the BOM of the website, good enough?

 Thanks for the comments,

 All the best,

 GregVDS


----------



## steinchen

Quote:


  Originally Posted by *GregVDS* 
_now there are places for intersil buffers too, look at the diyforum website_

 

oops, correct, I forgot they were added with the second generation of boards

  Quote:


  Originally Posted by *GregVDS* 
_By the way, FPE sell also angle profile and side profiles that can replace easily segor electronics box, at least if you intend to have top, bottom, front and back done by FPE!_

 

I imagine you get a decent and solid enclosure this way, though pretty expensive, too :/


----------



## rreynol

Quote:


  Originally Posted by *steinchen* 
_the Harris / Intersil buffers got a different pinout than buf634 and don't fit the MH (no drop in replacement)_

 


 <== works for harris. intersil (which apparently is a harris spinoff) is right across the street.


----------



## blueworm

I recieved my pcb today it is a newer revision.
 What buffers should I get?
 opa551 = 5.71 EURO
 HA3-5002 = 5.49 EURO
 BUF634P = 10.70 EURO
 Which will sound better?


----------



## n_maher

Quote:


  Originally Posted by *blueworm* 
_I recieved my pcb today it is a newer revision.
 What buffers should I get?
 opa551 = 5.71 EURO
 HA3-5002 = 5.49 EURO
 BUF634P = 10.70 EURO
 Which will sound better?_

 

At those prices I'd go for the OPA551 - I haven't heard them yet (they're on the way to me now) but most reports are that they sound as good as the BUF's. From what little I've read about the intersils some like them in the DIY Millett, some don't.

 Also, at some point in the not-to-distant future you're going to have another buffer option as well 
	

	
	
		
		

		
			





.

 Nate


----------



## blueworm

Ok Thanks nate.
 So many options such little money


----------



## dsavitsk

Quote:


  Originally Posted by *n_maher* 
_Also, at some point in the not-to-distant future you're going to have another buffer option as well_

 

Is this other option going to be a universal buf634 drop in replacement, or is it amp specific?


----------



## rjkdivin

Quote:


  Originally Posted by *n_maher* 
_At those prices I'd go for the OPA551 - I haven't heard them yet (they're on there way to me now) but most reports are that they sound as good as the BUF's. From what little I've read about the intersils some like them in the DIY Millett, some don't.

 Also, at some point in the not-to-distant future you're going to have another buffer option as well 
	

	
	
		
		

		
		
	


	




.

 Nate_

 

I agree that the OPA551 is a good option. I have played both the BUF634P and the OPA551 in my Millett, and cannot hear any difference. I haven't gotten around to stacking the BUF634s yet to see how that compares, but I have a few extras and am planning to do that.

 If you go to AMBs Millet page and scroll down to the bottom, you will find his comparitive RMAA tests between the two. He found slightly less distortion with the OPA551:

http://www.ibiblio.org/tkan/audio/millett.html


----------



## n_maher

Quote:


  Originally Posted by *dsavitsk* 
_Is this other option going to be a universal buf634 drop in replacement, or is it amp specific?_

 

 It's amp specific as it was impossible given all of the configurations that could be possible with this chip to design a one-size fits all replacement. From the beginning we laid out the Millett board with ample space around the buffer sockets so that this type of thing would be possible. But one look at say, Tangent's PIMETA, and you know the two solutions would be radically different. Plus, as with all of the Millett DIY things, there was a goal to keep it simple and doable for newish DIYers. 

 The schematics and files for the buffers will certainly be posted so if someone was so inclined they could make their own version to fit other amps. 

 Nate


----------



## Clutz

Quote:


  Originally Posted by *n_maher* 
_Also, at some point in the not-to-distant future you're going to have another buffer option as well 
	

	
	
		
		

		
		
	


	




._

 

you're always so coy Nate


----------



## n_maher

Quote:


  Originally Posted by *Clutz* 
_you're always so coy Nate 
	

	
	
		
		

		
		
	


	


_

 

Just trying to play by the rules my friend.


----------



## Angelic

Sorry for a bit stupid question, but are 6N1P ar 6n30P tubes are compatible with this amp?


----------



## n_maher

Quote:


  Originally Posted by *Angelic* 
_Sorry for a bit stupid question, but are 6N1P ar 6n30P tubes are compatible with this amp?_

 

Not as far as I can tell, both of those appear to be high-voltage tubes.

 Nate


----------



## Nisbeth

Quote:


  Originally Posted by *Angelic* 
_Sorry for a bit stupid question, but are 6N1P ar 6n30P tubes are compatible with this amp?_

 

No.


 /U.


----------



## Angelic

thanks for quick replays.


----------



## Dougigs

What are your thoughts on adding a servo?


----------



## Jaypetermen

How would the 0.18uf/600V Solen polypropylene capacitors compare to the 0.10uF Wima MKP10 capacitors for C4L/R?

 I have a couple extras and they look like they could be squeezed in.


----------



## dsavitsk

Quote:


  Originally Posted by *Jaypetermen* 
_How would the 0.18uf/600V Solen polypropylene capacitors compare to the 0.10uF Wima MKP10 capacitors for C4L/R?_

 

Probably won't make a difference one way of the other. Give it a try, though, to see what happens.


----------



## Dougigs

Let me bump that question: Has anyone tried using a DC servo on this amp? I can't find it mentioned in threads (but I didn't search too hard). It seems a good candidate for a servo, though you'd have to fabricate a bipolar supply for the op amp (not too hard, since there are plenty of decent rail-to-rail op amps)...

 Now, I know that some people feel that a servo creates far more audio troubles than a huge output cap does (in essence, a poorly designed servo can act like a compressor). But have the various merits and disadvantages been weighed for this amp?


----------



## rickcr42

why not just do the experiment then report the results ?

 Just keep in mind you want to use an opamp with good low frequency response so check the data sheets for the 0.1-10hz graphs and band limit the servo itself so any effects are strictly in the low bass area (like 10 hz down)


----------



## jerb

ok, I finally got around to assembling the millet and now I have everything wired up, one problem... there is no sound, not even hiss

 Using a 24v wallwart I plugged it in and the tubes dont glow, no sound comes through. I made sure I have power and sure enough I do. nothing gets warm, Ive check orientation of all diodes.

 I think its a bias problem, when use my DMM set to VDC I go from the spot labeled "left Bias" to ground and get 385 mV and 69 mV on the right channel. Rotating the varible ressitors does nothing.


 What did I do wrong, I see no solder bridges

 EDIT- Ive traced the sound I get: From the In on the board (both L and R) I can hear the signal to the pot, after the pot, and upto the tube but no noise after that.


----------



## nikongod

jerb: your psu may (likely) not be up to the task of "starting" the tube heaters & "filling" all of the psu caps. they require some serious current to get going, probably more than the psu can provide. 

 i have found un-pluging the dc side of the wallwart fromt eh back of the unit, and re-inserting it quickly sometimes works, or you could just get a more powerfull psu


----------



## jerb

I tried using an Eplac 24V 330mA Wallwart... is that enough current?


----------



## n_maher

Quote:


  Originally Posted by *jerb* 
_ok, I finally got around to assembling the millet and now I have everything wired up, one problem... there is no sound, not even hiss

 What did I do wrong, I see no solder bridges_

 

I'm afraid that without some pictures (maybe start a new thread) and a bunch more information that I'm not able to determine what the problem might be. I'm tempted to run down the "D'OH!" list: buffers installed? the right way? tubes installed correctly? is the LED lighting? Is the power at the tube socket? And on and on. But, if you're getting signal to the tube but no power that's obviously where we need to start. Have you tried check the voltages at the tubes? It's pretty easy to look at the bottom of the board and see which traces lead from the power to the tubes. My WAG is that you've got a cap in backwards or something. 

 One other visual cue - does the LED brightness change at all when you power up the amp (dimming after intial brightness) - this is a sure sign of a short with this amp as the power protection kicks in. Carefully check if the fuse is getting hot as well. I've built a lot of Milletts the wrong way and can't say I've come accross this particular issue.

 Bottom line, I think we need more information.

 Nate


----------



## n_maher

Quote:


  Originally Posted by *jerb* 
_I tried using an Eplac 24V 330mA Wallwart... is that enough current?_

 

Barely, depending on your configuration - and it still could be the problem if the startup current is overloading it. Use your DMM to measure the current draw and see if it's maxing out the supply. Just snip the + lead to the board and insert your meter there and measure.

 Nate


----------



## Blooze

Read the voltage between pins 3 and 4 on the tubes to see what voltage you're getting to the heaters if your tubes aren't even lighting up. Drewd reminded me that these tubes run between 10-15.9V on the heaters and even with my 24VDC wart going through a TREAD I'm only putting about 10.25V on each tube (wart actually puts out 23.9VDC). Have you tried swapping the tubes, always an easy check. I had one tube that wouldn't work at all and another that the heater warmed up on, but you couldn't adjust the bias--tested with practically no emission after the fact.


----------



## Blooze

Okay, this is what I have so far. Case is made from Bamboo, but I need to get knobs and make a top for it. I was thinking a black metal top, or even taking some plexi and laminating some thin copper sheet to it. Any and all ideas are welcome!

Click on Stereo Stuff Album


----------



## Teerawit

Quote:


  Originally Posted by *Blooze* 
_Okay, this is what I have so far. Case is made from Bamboo, but I need to get knobs and make a top for it. I was thinking a black metal top, or even taking some plexi and laminating some thin copper sheet to it. Any and all ideas are welcome!

Click on Stereo Stuff Album_

 

Nice case!! Where would one be able to obtain such a bamboo case (if it isn't custom)?


----------



## Blooze

Quote:


  Originally Posted by *Teerawit* 
_Nice case!! Where would one be able to obtain such a bamboo case (if it isn't custom)?_

 

If you promise not to tell anyone that I had to suffer through Bed, Bath, and Beyond 
	

	
	
		
		

		
		
	


	




 ----that's where I picked it up ($7). I planned on making a custom purpleheart/paduak case to match my headphone stand, but just don't have the time right now (future case possibly) and refused to let it sit all strung out on the bench! You could make a custom one out of bamboo though as the stuff is relatively easy to get as flooring.


----------



## Teerawit

Quote:


  Originally Posted by *Blooze* 
_If you promise not to tell anyone that I had to suffer through Bed, Bath, and Beyond 
	

	
	
		
		

		
		
	


	




 ----that's where I picked it up ($7). I planned on making a custom purpleheart/paduak case to match my headphone stand, but just don't have the time right now (future case possibly) and refused to let it sit all strung out on the bench! You could make a custom one out of bamboo though as the stuff is relatively easy to get as flooring._

 

That's cool, thanks for the info. I just came back from the university metal shop today. I got quoted $360 for a 12x8x3 aluminum case....yeah right...


----------



## Nospam

I figure I should keep Millet questions in this thread, so...

 Just came back from my vacation, all ready to start putting my Millet together (finally). Well, being the impatient idiot that I am, I failed to read the parts list carefully, especially the part that says to use 1/4W RN60 resistors. My entire stock of resistors, which I was hoping to use, are all 1/8W RN55.

 I recall another thread that said the 1/8W RN55 is capable of handling 1/4W (something about them being over-speced). If so, can I still safely use them for the Millet? Considering all the money I've thrown at parts so far, I suppose ordering some more resistors won't kill me, but I'd rather not, if possible.


----------



## amb

Nospam, no resistor in the Millett comes close to dissipating 1/8W, so RN55s will work just fine.


----------



## Nospam

Thanks!

 Good to know, but now I have to ask, just because I'm that way 
	

	
	
		
		

		
			





 Why are 1/4W resistors called out in the parts list, if 1/8W are OK?


----------



## Clutz

Quote:


  Originally Posted by *Nospam* 
_Thanks!

 Good to know, but now I have to ask, just because I'm that way 
	

	
	
		
		

		
		
	


	




 Why are 1/4W resistors called out in the parts list, if 1/8W are OK?_

 

Probably cause they are the most commonly available.


----------



## amb

Quote:


  Originally Posted by *Nospam* 
_Why are 1/4W resistors called out in the parts list, if 1/8W are OK?_

 

The board is laid out to accept the bigger RN60 series resistors. There are some who claim that the RN60 sounds better than the RN55, but I am not a believer.


----------



## diskostu

Do I need to connect the alps pot to the alps ground pad on the original revised millet board?


----------



## n_maher

Quote:


  Originally Posted by *diskostu* 
_Do I need to connect the alps pot to the alps ground pad on the original revised millet board?_

 

Odds are that if you do not you will have a grounding problem with the metal pot shaft of the alps. It will likely buzz when you are touching it. In my opinion it's safer to ground it as I've never had a problem by doing this, but I've certainly had issues when I did not.

 My 2¢,

 Nate


----------



## diskostu

Quote:


  Originally Posted by *n_maher* 
_In my opinion it's safer to ground it as I've never had a problem by doing this, but I've certainly had issues when I did not.

 My 2¢,

 Nate_

 

Did you used the top left screw on the back of the alps for the ground connection (like wrapping the wire around the screw)?

 Thanks

 -David


----------



## Blooze

Quote:


  Originally Posted by *diskostu* 
_Did you used the top left screw on the back of the alps for the ground connection (like wrapping the wire around the screw)?

 Thanks

 -David_

 

Yep, that's the place I did mine and it cured that buzz you get Nate was talking about. Just wrapped it around the screw and soldered the other end to the pad for ground.


----------



## jerb

quick question: it's my understanding that the gain in this amp is pretty much set and not much can be done to change that, however I find my volume is way too sensitive right now. what can be done to change that? right now I listen to the amp with the volume knob around 7 to 8, Id like to have a little more range of motion in the ALPs pot.... what should I do?


----------



## dsavitsk

The 12FK6 has a gain of about half that of the 12ae6a (12fm6 is right between them) so you might switch tubes. Other than that, the 12ae6a datasheet says that a 1M grid resistor will cut the gain from 17 to 15, which is probably not so useful.


----------



## nikongod

any thoughts on using the 1m ohm grid resistor on the 12fk6's?


----------



## diskostu

I built up two boards: one that uses the BOM from diyforums.org and the other uses the same BOM with the exception of C7, which Elna Cerafine 470 uF. I'm powering them with the Elpac power supply, it's rated at 24C, 0.75A from the same BOM.

 When I try to turn on either boards the power supply dies. It goes from 24V to ~2V and the LED's flicker. I think the inrush current is tripping some protection circuit in the power supply. If I take the tubes out it powers up fine and the LED's light up. Has anyone else had the same problem?











 -David


----------



## n_maher

David,

 What are the details of your power supply, specifically it's rated maximum current? I have used 24V/450mA supplies without a problem but I wouldn't go much below that.

 Nate


----------



## diskostu

Nate,

 I'm using the Elpac FW1824 from the diyforums BOM. It's rated at 24V, 0.75A max. I figured out that it is the inrush current that's shutting down the power supply. If I leave the tubes out and turn the amp on the LED's flicker until the circuit has stablized (caps charged). If I leave the tubes in the LED's flicker and the power supply outputs ~2V. Here's the catch, if I first power on the amp without the tubes then put in the tubes the amp works.

 Once I get the two Millets cased, I need to build a couple of Steps. It'll be a couple of months till I get them cased up.

 -David


----------



## busta

Hey guys, I have a quick question that I'm sure has been asked many times before, but I have not seen an answer to.

 If someone could please roughball an answer as to how much a Millet would cost to build with standard parts (not really premium grade stuff), what would be the figure? I need to do a Senior project for school and I'm debating as to whether I want to build the PPA or the Millet. I would really like to hear the warm sound of the tubes for myself but I want to save money while doing so.

 Thanks!


----------



## dsavitsk

Quote:


  Originally Posted by *busta* 
_Hey guys, I have a quick question that I'm sure has been asked many times before, but I have not seen an answer to.

 If someone could please roughball an answer as to how much a Millet would cost to build with standard parts (not really premium grade stuff), what would be the figure? I need to do a Senior project for school and I'm debating as to whether I want to build the PPA or the Millet. I would really like to hear the warm sound of the tubes for myself but I want to save money while doing so.

 Thanks!_

 

About $100 - 150 for standard stuff.


----------



## busta

Wow!! Definately cheaper than I expected. Is it safe to say that $250 would be sufficient to buy parts to build a "very nice" Millet?

 Thanks for the reply by the way!


----------



## n_maher

Quote:


  Originally Posted by *busta* 
_Wow!! Definately cheaper than I expected. Is it safe to say that $250 would be sufficient to buy parts to build a "very nice" Millet?_

 

That sounds about right, depending on what _very nice_ means to you. Populating the board will run around $80-$90 with decent stuff + the cost of the baord ($20ish or you could point to point wire it) + a power supply ($30-$100) + case, jacks, knobs, blah blah blah ($100ish). So sure, it could be done for $250, browse around the forums and you'll find examples of many Milletts.

 Best of luck,

 Nate


----------



## busta

Thanks a lot Nate. I'm going through the DIYForums right now, there sure is a lot of information there. I see that you've even created a Bill of Materials to make this process easier for the DIY noobs like me.

 Thanks!


----------



## Blooze

Busta - over at the DIYForum you can see a pic of my Millett. I used Cerafines as output caps, Alps Blue Velvet, and a Tread from Tangent. I used standard BOM stuff for populating the board for everything else except for Kiwame resistors. The case I have is a bamboo storage box from Bed, Bath, and Beyond and the wood is zebra wood from woodcraft. I spent right at $200 for everything for mine. About $175 for all the electronics parts.

 "Bloozestringer" over at DIYForums.


----------



## busta

Wow Blooze, that is some case-work you did there! Would you say that the $175 spent on parts was sufficient to build something that to your ears sounds amazing?

 To give you guys a little info on this "Senior Project", it's a nice little thing that my high-school put together for Senior's as a part of our graduation experience. In May, we basically get out of school for a month before the rest of the under classmen. During that month, each student is required to complete a project that he/she decided on earlier in the year. The project requires 100 hours put in over the span of the month off. The project is also monitored by someone that they call a "Sponsor", in my case it will be my Electronics teacher at the Vocational School that I attend. At the end of the month, each student is to come in on the day and time that they are assigned to present their project to a class of their peers and teachers, which will be chosen by the student. The presentations are 15-minutes long, and require complete explanation of how exactly you spent your time off. 

 In my case, I would like to build a headphone amplifier that I can then present to the class. Not only would I simply show them the amplifier and let them demo it, but I would also explain the schematic and the theory behind it. One thing that I am really looking forward to discussing is how transistor and tube amps differ in operation to provide unique sound. I'm sure that they'll all get a kick out of the Millett being a "Hybrid" amplifier being that they are definately familiar with Hybrid cars, which would make explaining things that much easier.

 Anyway, money isn't really an object as I maintain a job along with school and my parents would be happy to cooperate in any way they can to fund my learning experience. The only thing that I didn't tell them was that I was going to have a great time building it, and that it won't even feel like a school assigned project at all 
	

	
	
		
		

		
			





 Anyway, I'm thinking about getting a little head-start on the project. Maybe if I finish my Millett early I can start on the PPA that I wanted to build so I would have even more to show for the presentation.

 As always, I appreciate your guys' input. I didn't mean to de-rail this thread with my childhood story, sorry!


----------



## dsavitsk

Quote:


  Originally Posted by *busta* 
_To give you guys a little info on this "Senior Project", it's a nice little thing that my high-school put together for Senior's as a part of our graduation experience._

 

Neat project. Some background reading that might be helpful to understand what is going on with this circuit are the NEETS manual (http://www.tpub.com/content/neets/14178/) which gives the background on vacuum tubes and pete millett's low mu preamp article from audio express (http://www.pmillett.com/file%20downloadss/ax_lowmu.pdf) as it covers some of the theory of constant current source plate loads.


----------



## Blooze

Quote:


  Originally Posted by *busta* 
_Wow Blooze, that is some case-work you did there! Would you say that the $175 spent on parts was sufficient to build something that to your ears sounds amazing?_

 

More than sufficent for me. I've never heard a PPA or an M3, but I'm assuming they are very nice to listen to. I've just become facinated with tubes and the Millett seemed liked a logical first step (I've got a SOHA off of Headwize breadboarded up that I'm working on now=little step up in voltage). I don't know if amazing is the right word, but I am very, very pleased 
	

	
	
		
		

		
		
	


	




 with the stock result and can listen to it for hours with no problems. Building on the board that Drewd, Nate, and others designed is a breeze and couldn't be simpler to put together. The casework was more difficult for me than the board build because I changed my mind about 1/2 dozen times. 

 About the parts on the BOM. I personally have never been able to hear a big difference in caps, resistors, and such. I did put Kiwames in mine after populating with metal film first and I think the Kiwames made it sound a little smoother to me. But that's a personal preference and may just be my imagination. My recommendation would be to scan through the Millett threads and put high quality parts where they really matter in the circuit and get the good quality BOM parts for the rest. Unless you have something to compare to I would think putting boutique parts everywhere would be money wasted. You can always change parts later and see if the difference was worth the money.


----------



## Voodoochile

Quote:


  Originally Posted by *Blooze* 
_The casework was more difficult for me than the board build because I changed my mind about 1/2 dozen times._

 

Isn't that just the name of the game? I have a love/hate relationship with casework!

 [size=xx-small]BTW, love the avatar. 
	

	
	
		
		

		
		
	


	




[/size]


----------



## Predator88

While casework is being mentioned, anyone have any tips for how I can sort of mimic jhawk22's dynalo http://www6.head-fi.org/forums/showthread.php?t=142271
 Yea i should come up with my own design but I love this thing. Basically what sort of confuses me is how to cut the front panel to form fit the neutrik jack, and how or where to buy the tint for the top....or even how ot make that kind of top really (of course with two holes for tubes). Its for sale again on the forums......someone offer to buy the amp board so i can buy the enclosure.......thatd be a miracle (actually i don't even know if thats the right size enclosure or not.)


----------



## Blooze

Quote:


  Originally Posted by *Predator88* 
_While casework is being mentioned, anyone have any tips for how I can sort of mimic jhawk22's dynalo http://www6.head-fi.org/forums/showthread.php?t=142271
 Yea i should come up with my own design but I love this thing. Basically what sort of confuses me is how to cut the front panel to form fit the neutrik jack, and how or where to buy the tint for the top....or even how ot make that kind of top really (of course with two holes for tubes). Its for sale again on the forums......someone offer to buy the amp board so i can buy the enclosure.......thatd be a miracle (actually i don't even know if thats the right size enclosure or not.)_

 

If he's using smoked acrylic (Plexiglass) you can get that about anywhere. Best way to drill the holes for it is using a stepped bit, but I've used a hole saw and smoothed it with a dremel. The square hole for the top plate wouldn't be too bad to do if you had the right equipment or access to somebody with metalworking tools (or is it plastic? that'd make it very easy). You could do it by hand with a dremel and a file if you were very patient. Are you sure that's a Neutrik jack? I've never seen a round one before. I know there are other companies that make a locking jack that is similiar.


----------



## rjkdivin

Quote:


  Originally Posted by *Predator88* 
_While casework is being mentioned, anyone have any tips for how I can sort of mimic jhawk22's dynalo http://www6.head-fi.org/forums/showthread.php?t=142271
 Basically what sort of confuses me is how to cut the front panel to form fit the neutrik jack, and how or where to buy the tint for the top....or even how ot make that kind of top really_

 

Predator88,

 Check out this link for plastics in Buffalo.....it looks similar to retail plastics outlets we have here on the west coast.

http://www.greatlakesplastic.com/

 Generally, these type of retailers will cut to your desired thickness, size and color of plastic. For drilling round holes in plastic, the best bits I have found are called Brad Point bits....they cut around the edge ahead of the center, and this seems to help pevent cracking. Go slow.

 The 1/4 inch headphone jack shown sure looks like a Neutrik, but mounted from the inside...probably with glue since no screws are visible. The diameter of the hole would be very close to 15/16 inch. A stepped drill bit works fairly well for this size hole, but the best way to do it is with a chassis punch. You can find all sizes of chassis punch on ebay. The round part of the Neutrik jack protrudes from the mounting plate by 1/4 inch....just enough to stick throught the front panel as shown.

 Robert


----------



## Predator88

excellent tips guys, thanks.


----------



## busta

I ordered myself a board today, and I should be ordering my parts this weekend.

 Can't wait


----------



## Blooze

Quote:


  Originally Posted by *busta* 
_I ordered myself a board today, and I should be ordering my parts this weekend.

 Can't wait 
	

	
	
		
		

		
		
	


	


_

 


 Great! Keep us updated on how it goes.


----------



## busta

I'm currently setting up my cart on Mouser. Out of curiousity, would building a TREAD be better than using an ELPAC for my Millett? Reason I ask is that the ELPAC on Mouser is $32.56, while I can get a TREAD kit from Tangent for much cheaper.

 Thanks


----------



## Clutz

Quote:


  Originally Posted by *busta* 
_I'm currently setting up my cart on Mouser. Out of curiousity, would building a TREAD be better than using an ELPAC for my Millett? Reason I ask is that the ELPAC on Mouser is $32.56, while I can get a TREAD kit from Tangent for much cheaper.

 Thanks_

 

According to tangent's website, the TREAD measures better than the Elpac. I'm using one for my Millet, and I have no complaints. Nate is using a steps I believe, and has said it does a much better job than the TREAD - but personally, I don't have the money to spend $75 on the PSU a this point.


----------



## busta

I guess I'll use a TREAD. Giving Tangent more business also makes me feel all warm inside, I love his website


----------



## BradJudy

Remember that a TREAD kit doesn't include the transformer/adapter. I'm actually debating what power supply to go with - I might just build a 24v STEPS since it could be used on various amps (PPA, MMM, Millet, etc), so it might be worth building something nice.


----------



## Blooze

Quote:


  Originally Posted by *busta* 
_I guess I'll use a TREAD. Giving Tangent more business also makes me feel all warm inside, I love his website 
	

	
	
		
		

		
		
	


	


_

 

Yeah, Tangent's a good guy. I use a TREAD and got a cheap wall wart to go with it from Mouser for like $10. Only thing is my wall wart actually puts out 24V unloaded, which I think is somewhat unusual. I already had my TREAD built by the time I got the wart so even at max voltage adjustment I only get about 22.4V after the TREAD. I could remove the diodes and gain a couple of volts, but it seems to work fine so I'm leaving well enough alone. The great thing about the TREAD is that you can adjust the voltage-- if your wart puts out more than whats required for the amp.


----------



## busta

So after completion, is it basically the Wall-Wart coming out of the AC, into a DC jack in the back of your Millett which is connected to the TREAD? Is an advantage of using the Wall-Wart with the TREAD further regulation of the signal?


----------



## n_maher

Quote:


  Originally Posted by *Clutz* 
_According to tangent's website, the TREAD measures better than the Elpac. I'm using one for my Millet, and I have no complaints. Nate is using a steps I believe, and has said it does a much better job than the TREAD - but personally, I don't have the money to spend $75 on the PSU a this point. 
	

	
	
		
		

		
		
	


	


_

 

I used to be using a STEPS 
	

	
	
		
		

		
		
	


	




 and then I went crazy 
	

	
	
		
		

		
		
	


	




... My Millett will most likely be fed from a hybrid Jung super regulator design, assuming of course that I finish my own amp some day 
	

	
	
		
		

		
		
	


	




 .

 To my ears using your basic, stock Elpac is ok, the TREAD is much better and the STEPS is very, very nice. I can't honestly say that I've done strict back to back testing or anything so scientific but in my head it all starts with the power supply. All any amp is doing is manipulating that power so to feed it with the cleanest power possible only seems to make sense. 

 Nate


----------



## Blooze

Quote:


  Originally Posted by *busta* 
_So after completion, is it basically the Wall-Wart coming out of the AC, into a DC jack in the back of your Millett which is connected to the TREAD? Is an advantage of using the Wall-Wart with the TREAD further regulation of the signal?_

 


 Well, the TREAD regulates and smooths the DC (or will rectify AC from an AC/AC wart) and will do a better job of it than the Elpac from what I hear. This allows you to buy a cheap, non-regulated wallwart instead of spending $35-100 on a regulated linear one.


----------



## NeilR

Quote:


  Originally Posted by *busta* 
_So after completion, is it basically the Wall-Wart coming out of the AC, into a DC jack in the back of your Millett which is connected to the TREAD? Is an advantage of using the Wall-Wart with the TREAD further regulation of the signal?_

 

You can power the Tread with an AC-AC wallwart. That way you save the redundant cost of the rectifier/filtering parts in the wart. That is probably the cheapest way to do it and there is no compromise on quality. Mouser has a 24V 500ma wart for about $6 (412-224054). So, for about $23 (plus shipping ), you get clean power with well under 0.1mv ripple. 

 One advantage of using the wart is that the transformer (in the wart) is physically isolated from your amp and the power supply. Plus, you don't have to worry about 120/220 VAC running around in your project.


----------



## americandreaming

hey all,
 just found the time to pull my millett board and my bag of goodies from digikey and mouser and found that all the resistors i purchased were the RN55 series. am i SOL or will these work?

 alternatively, would anyone like to trade a bunch of RN55 series resistors for a bunch of RN60?


----------



## Clutz

RN55s should work just fine. The answer tangent always gives about them is that RN55 are 1/8th watt, only because of the temperature specs for them, but that at the temperatures that you'll be using them for, that they're 1/4.


----------



## n_maher

The above answer is fine for 95% of the Millett, however the resistor for the LED either needs to be a value higher than 1k or an RN60. An RN55 flowing that kind of current will likely get very hot and probably not last as long as it should. Just switch the value to 2k or 10k for that matter and you'll be fine. 

 HTH,

 Nate


----------



## americandreaming

thanks clutz and nate. i will give it a go with the little resistors and hope for the best!


----------



## americandreaming

does the orientation of the caps in c3, c4, c5, and c8 matter? it appears from the pcb that it does but when i look at this picture it seems that c5l is backwards. i am using wima .1uF MKPs.

 also i can't seem to find 22Ohm resistors (or anything close) -- are they necessary? i remember reading that they could be jumpered, but i am using grados with this amp.

 thanks again.


----------



## n_maher

Quote:


  Originally Posted by *americandreaming* 
_does the orientation of the caps in c3, c4, c5, and c8 matter? it appears from the pcb that it does but when i look at this picture it seems that c5l is backwards. i am using wima .1uF MKPs._

 

Orientation does not matter, but there is a correct way to place the caps. If you look at the board you will see that three of the 4 pads go to ground and the other is to a trace. You need to make sure that you have one leg of the cap in the "trace hole" and the other will naturally fall in a ground hole. 

  Quote:


 also i can't seem to find 22Ohm resistors (or anything close) -- are they necessary? i remember reading that they could be jumpered, but i am using grados with this amp. 
 

You can jumper that position if you like, regardless of headphone used. However, if you haven't already ordered all of your parts this link should send you right to a 22ohm resistor.

 HTH,

 Nate


----------



## n_maher

Just wanted to let folks know that a limited number of Diamond Buffer PCBs are available in the Group Buy Forum. 

 Happy listening,

 Nate


----------



## 2426

What are the recommended cases for the Millett? I'm not looking to spend much, just to get the job done so I don't need any uber-expensive cases. Also, so from what I hear, it would be best to get a TREAD over a ELPAC right? If so, could you please recommend me a wall-wart to go with the TREAD. Thanks.


----------



## NeilR

The Hammond 1455160x case is listed on the BOM on the main Millet page. That case will exactly fit the board. A Tread is a little better than an Elpac, and a Steps is a little better than a Tread. If you go with the Tread and the 1455160x case you will have to figure out where to put the Tread because it will not fit in that case with the Millet board. You could get the longer Hammond case (8" long) and you may be able to fit the Tread in the back.

 You could get a 24 VAC wall wart from Digikey or Mouser for the Tread. Or you could get a 24 VDC wall wart and leave out the bridge on the Tread. Whatever you do, you will draw 200 - 250 mA from the power supply so you need a decent size transformer. You will probably want to run the supply at up to 27V so you want to over specify the transformer to make sure it will deliver that voltage through the regulator. I used this transformer myself, with a Tread, it is rated at 24 VAC 700ma. You can get a cheaper one from Mouser rated at 400ma or so.


----------



## xSolsticex

The 8.66x4.06x2.09 Hammond case (1455N2201, 1455N2201BK, 1455N2202, 1455N2202BK @ Digikey) will fit both the Millett board and the TREAD board without a problem.


----------



## AndrewTosh

I've seen people reference apuresound.com/ATAT/BoMs.xls, but it 404s. Does anyone know where I can find a mirror?


----------



## ATAT

Hey andrew, that's my BoM.. i think [Ak] might have removed it temporarily, but I can always just email it to you... pm me your email address


----------



## [AK]Zip

Sorry guys its case sensitive.

http://apuresound.com/ATAT/boms.xls

 -Alex-


----------



## peterpan188

Hi, does anyone know the part number for screws and nuts that will fit the Neutrik NJ3FP6 locking 1/4" jack, from either Mouser or digikey? Is there any screws that can be use as subsitute to the ones used in Hammond cases?

 Thank you


----------



## NeilR

Quote:


  Originally Posted by *peterpan188* 
_Hi, does anyone know the part number for screws and nuts that will fit the Neutrik NJ3FP6 locking 1/4" jack, from either Mouser or digikey? Is there any screws that can be use as subsitute to the ones used in Hammond cases?

 Thank you_

 

The Neutrik jacks use 4-40 nuts and screws. RatShack sells an assortment pack if you get desperate 
	

	
	
		
		

		
		
	


	




 The Hammond cases will take a 6-32 if you tap it. If you are going to do that, don't install the supplied self tapping screws if you haven't done that yet. It keeps the holes cleaner.


----------



## peterpan188

Quote:


  Originally Posted by *NeilR* 
_The Neutrik jacks use 4-40 nuts and screws. RatShack sells an assortment pack if you get desperate 
	

	
	
		
		

		
		
	


	




 The Hammond cases will take a 6-32 if you tap it. If you are going to do that, don't install the supplied self tapping screws if you haven't done that yet. It keeps the holes cleaner._

 


 Umm, I am sorry that I didn't quite understand what you mean by "tap". Never really done any sort of hand tools work before. 
	

	
	
		
		

		
		
	


	




 I found some 4-40 screws from McMaster-Carr, 90275A113 and 90760A005, do they look good.


----------



## tomb

Quote:


  Originally Posted by *peterpan188* 
_Umm, I am sorry that I didn't quite understand what you mean by "tap". Never really done any sort of hand tools work before. 
	

	
	
		
		

		
		
	


	




 I found some 4-40 screws from McMaster-Carr, 90275A113 and 90760A005, do they look good._

 

To "tap" means to make female threads in a hole. What Neil is referring to is that the Hammond cases come with 6-32 _self-tapping_ screws. Self-tapping screws use a coarse thread with a low pitch (small number of threads per inch). For instance, instead of "32", it might be "10".

 The advantage to self tapping screws is that you don't need a tap - a special tool that cuts the threads in the hole for the proper screw, such as the 6-32. The disadvantage to self-tapping screws is that the threads are not as robust, and cross-threading is very easy. Often, self-tapping screw threads will not last more than a half-dozen times of screwing/unscrewing the screws - especially if the metal is Aluminum, as in the Hammond case.

 There is no reason that tapped threads with standard screws can't last indefinitely. The tapping tool is actually not much different than a drill bit, and usually a numbered (specific odd size) drill bit is matched/included with a tap. These may not cost much more than a few dollars each in the sizes we're talking about (4-40, 6-32), especially if you go to some place like Harbor Freight.

 Neil is also stating that if you use the self-tapping screws first, you've pretty much "screwed" up the holes for a regular tap. You would have to go to the next larger sized tap, but by that time, there wouldn't be enough metal left around the hole to hold the threads.

 I hope that helped, rather than confused things for you.


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## peterpan188

Quote:


  Originally Posted by *tomb* 
_To "tap" means to make female threads in a hole. What Neil is referring to is that the Hammond cases come with 6-32 self-tapping screws. Self-tapping screws use a coarse thread with a low pitch (small number of threads per inch). For instance, instead of "32", it might be "10".

 The advantage to self tapping screws is that you don't need a tap - a special tool that cuts the threads in the hole for the proper screw, such as the 6-32. The disadvantage to self-tapping screws is that the threads are not as robust, and cross-threading is very easy. Often, self-tapping screw threads will not last more than a half-dozen times of screwing/unscrewing the screws - especially if the metal is Aluminum, as in the Hammond case.

 There is no reason that tapped threads with standard screws can't last indefinitely. The tapping tool is actually not much different than a drill bit, and usually a numbered (specific odd size) drill bit is matched/included with a tap. These may not cost much more than a few dollars each in the sizes we're talking about (4-40, 6-32), especially if you go to some place like Harbor Freight.

 Neil is also stating that if you use the self-tapping screws first, you've pretty much "screwed" up the holes for a regular tap. You would have to go to the next larger sized tap, but by that time, there wouldn't be enough metal left around the hole to hold the threads.

 I hope that helped, rather than confused things for you._

 

I see what you mean, Thanks tomb, thats some great help there.

 I haven't done the casing for my millet hybrid yet, but I had the experience with hammond cases when I built my PIMETA, so I want to use a screw altogether since the screw that came with hammond is very easily busted. 

 For my PIMETA, I have already installed the self-tapping screw that came with case, so does that mean I can't really do much about it, since i need to tap for a larger size, but I don't have enough metal around the hole?


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## NeilR

Peterpan,

 I think you will get different opinions on the issue of tapping the Hammonds after you install the self tapping screws. There may not be an "absolute truth" here. I put the self tapping screws in my first Hammond case and later tapped it after reading the discsussions here. I did not have a problem, but that does not mean I wasn't lucky. It may also depend on the condition of the self tapping threads, meaning that after a number of cycles, a 6-32 tap might not work as well since more metal has been removed. My recollection is that I had not yet stripped the threads when I tapped it.

 Regards,
 Neil


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## mb3k

Tip: When you're tapping, use some WD-40. It makes it easier to tap and puts less stress on the case and tap bit, trust me, I've broken a few at work


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## mb3k

For a question of my own:


 For C7 I will be putting in 470uF caps but I'm unsure of a few things...

 I was thinking of the Cerafine 470uF/35V (ROA473 from WelborneLabs) for C7, which is 0.7 x 1.0 inches (17.78 x 25.4 mm). This will be a size issue, if I'm not mistaken, because it exceeds the max of 16mm diameter.

 So a change in C1 will have to be made: replace C1 with a dimensionally smaller Cerafine 100uf/*35V* (ROA103 instead of ROA104) 0.4 x 0.8 which is approx the size of C2 (ROA220)

 A few questions now. Should I change all of C1, C9, and C10 to the new *35V* 100uF caps, or is it okay to change C1 to 35V and leave C9 and C10 to be *100V* 100uF caps?
 Does anyone know the pin spacing of the new C7 (Cerafine 470uF/35V ROA473 from WelborneLabs)? Hopefully it's still 7.5mm.

 My alternate route is to purchase standard Blackgate 470uF 50V caps (16 x 36 mm) for C7 and leave all the other electrolytics as per the BOM on the main page. 
 Any recommendations?


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## nikongod

woot. 

 i just put in an order for diamond buffer parts.


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## nikongod

Quote:


  Originally Posted by *mb3k* 
_For a question of my own:
 (blah, blah, blah too much to quote, scroll up a couple posts)
 Any recommendations?_

 

stay with a 470uf cap for c7 unless you never want to run 32 ohm headphones... 

 i am pretty convinced that this is the MOST important cap on the board, and that c1 is of very little importance. if you have to "shrink" c1 to accomidate a physically larger case size for your desired c7, DO IT.

 i personally use elna tonerex 470uf/100V here but i have a ver-1 board.

 as an asside, you may want to go with a slightly larger size for the c9&c10's that you mentioned unless you are looking for a moded sound. 220uf is pretty standard. 470 for c9 and 220 for c10 is sweetness.


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## mb3k

Quote:


  Originally Posted by *nikongod* 
_stay with a 470uf cap for c7 unless you never want to run 32 ohm headphones... 

 i am pretty convinced that this is the MOST important cap on the board, and that c1 is of very little importance. if you have to "shrink" c1 to accomidate a physically larger case size for your desired c7, DO IT.

 i personally use elna tonerex 470uf/100V here but i have a ver-1 board.

 as an asside, you may want to go with a slightly larger size for the c9&c10's that you mentioned unless you are looking for a moded sound. 220uf is pretty standard. 470 for c9 and 220 for c10 is sweetness._

 

Great! I never really knew what a ballpark value would be for C9&C10 if I went bigger but now I do. 
	

	
	
		
		

		
		
	


	



 I will stick to the ELNA Cerafine series but I will get them all (C7, C9, C10, C1) 470uF @ 35V because they'll fit just as designed.
 Thanks for the headsup!


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## tdicola

I'd like to build a Millet amp, but it looks like there aren't any sources for PCBs. Has anyone had any luck etching their own PCB for a Millet amp?


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## tomb

Quote:


  Originally Posted by *tdicola* 
_I'd like to build a Millet amp, but it looks like there aren't any sources for PCBs. Has anyone had any luck etching their own PCB for a Millet amp?_

 

tdicola,
 The complete PCB files in Eagle format are available at DIYforums.org - the Millett Hybrid site. The original Pete Millett-designed board is also available for purchase at DIYcable.com. It's a little bigger with a different layout, and the BUF634's are setup for TO-220's with heatsinks. Other than that, it's the same.

 Cire was selling board pairs for $18. I bought two from him, so I can testify to his trustworthiness, but am confused on whether he's still selling these. I thought he only had one pair and I bought them, but then it looked like he purposely kept the notice in his Head-Fi signature afterward.


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## mb3k

Quote:


  Originally Posted by *tomb* 
_tdicola,
 The complete PCB files in Eagle format are available at DIYforums.org - the Millett Hybrid site. The original Pete Millett-designed board is also available for purchase at DIYcable.com. It's a little bigger with a different layout, and the BUF634's are setup for TO-220's with heatsinks. Other than that, it's the same.

 Cire was selling board pairs for $18. I bought two from him, so I can testify to his trustworthiness, but am confused on whether he's still selling these. I thought he only had one pair and I bought them, but then it looked like he purposely kept the notice in his Head-Fi signature afterward._

 

He has/had multiple pairs, I bought two more boards from him.


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