[Dan H]

My DIY Pete Millett low power tube amp is done. I understand a quality power supply is needed for good sound. What should I be using? What have you had good results with?
Thanks Dan

 

[jamont]

I use a Power One 24V open-frame PS that I got from Brigar Electronics. This supply is noticeably quieter than the CUI wall wart suggested in the AudioXpress article.

 

[Voodoochile]

That sounds good, jamont. I do not have a copy of the article yet, but have all but 7 of the caps for my millett.

Also, I have a similar power supply, only it's a +28v. Too much, or passable?

Looking forward to hearing your impressions, dan h.

 

[Serow]

28V is fine, as long as it is regulated tightly. The BUF634 max is 30V. The tubes may not last quite as long as they would on 12V heaters, but they are cheap!

 

[Voodoochile]

That sounds good, serow. It's very tightly regulated, and quiet.

I just looked at it, and there is also an output trimmer. I may be able to bring it down a bit without making it run too hot. The reg is in a TO3 package, very heavily sinked. I suppose I could also feed a second 24v regulator with the 28 volts from the ps.

As cheap as the tubes are, they are still in a finite supply.

 

[Dan H]

The tubes are designed to work from 10 to 16 volts. Pete sugests a 24 volt unregulated unit. And says anything between 20 and 28 volts will work fine.
Anyone have a part number of a quality PS from Digi-Key or someplace that would be quiet (RF) and not too expensive?

Voodoochile;
After this thing breaks in I'll post best resistor values for R4, R9. I use high impedance headphones, Sennheiser HD 600's. What do you use?

 

[Voodoochile]

Thanks, guys. I'm using HD575s right now, pricipally. I am at the threshold of buying some 580 or 600s, but keep flip-flopping over possibly getting some Grado 225s.
Which would change everything... so I plan at this point to go with high impedance.

Regarding the PS- I'd build my own if I were you. I'm not a fan of wall-warts. Yes, I think some of them are very good. But I just don't like them (unreasonable mode off).
This 28v linear Condor I have was $16. shipped from ebay stores. I was thinking of possibly a bench supply at the time.

 

[jamont]

I think the Condor would be ok VC, you will be adjusting the bias on the tubes anyway. BTW, is it a HB28-1-A+? I got one of those in todays mail, $14 on ebay.

I use Senn HD580 and Philips HP890 with mine, both work well.

 

[Voodoochile]

Yes, that's the same one. In fact, I remember discussing this in another thread now! Mine was $14, also. It was 8.99 I think, plus $5 for shipping. An unbeatable deal.

 

[Voodoochile]

Been listening to my Millett Hybrid for a few hours now...

I like it pretty well so far, it's different from straight solid state, for certain. Right now it is adjusted to a 19v bias (as Jamont and Pete have done), and I did end up using the 28v open-frame linear. I got the article finally just today, and see that Pete's wall-wart was running at around 26 or 27 volts anyway. I used Nichicon Muse KZ caps, and Panasonic Polypropylenes, vs the Cerafine and Wima poly caps from Welborne. The little cost column in Pete's parts spreadsheet needs some updating! DIY wants $40, not $20 for the board, and Welborne's cap prices have roughly doubled. Yet the board is dated Nov of 2002! Oh well. The board I would have made myself, in hindsight, adn the Muse/Panasonic caps saved me probably $18. alone.

Anyway, this is quite a nice little amp for the money, and it was a good foray into lightweight tube. I actually built it last night (all but the seven 100uf/100v caps, which arrived today from Percy). It was very simple and straightforward assembly, only taking a couple hours. Turned it on, fiddled with bias for a few minutes, let it warm up, and adjusted it further.

Right now, it's in the little serpac case that the board was designed for, but I'm thinking about maybe a small wooden box-type (chassis style

) base for it, that would enclose the power supply.

More to come later, I'm sure.

 

[Dan H]

I think the Condor would be ok VC, you will be adjusting the bias on the tubes anyway. BTW, is it a HB28-1-A+? I got one of those in todays mail, $14 on ebay.

I used a 20 v wall wart for two weeks while I was looking for a good deal on a better quality PS. I ended up buying a new 24 volt Condor from Digi-Key at $30.00, Ouch! Thanks for the tip on the open frame Condor you guys. The amp sounds much better now. I'm using a 40 Ohm resistor for the Sennheiser 600's and have set bias to 19v.
I'm curious if better caps would help.
More tubes coming next week will post then..........Dan

 

[Voodoochile]

What caps are you using, Dan?

 

[jamont]

Glad you like the new PS, Dan, I thought it was a very worthwhile upgrade. About the resistor, did you start with 22 ohms? And if so, what difference did you hear when you changed it?

 

[Dan H]

Voodoochile;
All stock caps per Petes list now. Am thinking of replacing signal caps with some higher quality, don't know what yet.


jamont;
Thanks again for the worthwhile PS tip.
I installed 44 Ohm resistors, will try 100 ohm later this week. My only headphone is Sennheiser HD600 so I'm thinking the 44 ohm would be correct.
Am waiting for more tubes to arrive next week then will start rolling tubes. So far of two tube values (12AE6A and 12AJ6) I like Philco 12AE6A best.
This has been a fun project for me, easy and not too $$$$. The sound quality is not bad.

 

[Voodoochile]

If you mean stock as in Wimas and Cerafines, that'll be tough to beat without going nutty...

I'm not sure if the rest the Millett amp is ready for Blackgates or Auricaps