[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.