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Bijou All Tube Futterman Headphone Amplifier - Page 159

post #2371 of 3976
3/17/09 at 11:27am
Shunt regulators, you say?

Very soon, very small, pretty simple, so, may yet follow the Bijou philosophy, even if they were designed for the uber stat amp.
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post #2372 of 3976
3/17/09 at 8:20pm
Yes, those were my design goals when I did the Bijou design. And it is a remarkably simple tube amp for how good it sounds.

But diyers being what they are, there are always some who find it a challenge to squeeze out the last bit of better. I don't know if removing the O/P caps here would change the SQ, but it might - to some ears.

In any case, there are many projects to work on right now. This one will have to wait. Thanks for your most generous comments on the sound of this amp. It was this SQ of the proto version that convinced me to make an effort to make the amp more widely available. It is always great to hear from someone who is happy with theirs.
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post #2373 of 3976
3/17/09 at 8:21pm
Quote:
Originally Posted by pabbi1 View Post
Shunt regulators, you say?

Very soon, very small, pretty simple, so, may yet follow the Bijou philosophy, even if they were designed for the uber stat amp.
Pabbi1, you are teasing us.
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post #2374 of 3976
3/17/09 at 10:18pm
Nah, it is just taking for freaking ever, but looks like it is coming around the bend... over on Diyaudio.
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post #2375 of 3976
3/17/09 at 11:49pm
Ah, I see. But with the schematics that I saw (and I did not poke around a lot), it's not a high voltage regulator. Is there a HV version?
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post #2376 of 3976
3/18/09 at 12:00am
HV version - though I am NOT as well read on this one.
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post #2377 of 3976
3/18/09 at 1:24pm
Thanks for the links Pabbi1...
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post #2378 of 3976
3/18/09 at 1:41pm
N/p - it is a big world, and just amazing how things cross pollinate.
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post #2379 of 3976
3/19/09 at 11:37am
Could someone please enlighten me as to why C1 is an electro? I'm no expert on the finer points of the Futterman design but it looks to me like its in the signal path & therefore may have a significant influence on the amp's sound. Is it this critical? Would there be any benefit in replacing it with a HQ film cap of same or similar value I happened upon a discussion about this some time ago but can't find it again.

Thanks.
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post #2380 of 3976
3/19/09 at 11:52am
When I did the design my goal was a high performing tube amp at as low cost as possible and as easy as possible for those builders who had never built a tube (and HV) amp before. I used the simplest choices for components wherever possible knowing that upgrades could be made by anyone who had a mind to. I also wanted to keep the footprint (boards) as small as possible.

That said, you are absolutely correct. The return cap is in the signal path and there will be some benefit to using a non-electrolytic cap here.
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post #2381 of 3976
3/19/09 at 8:56pm
runeight

Thanks for the clarification. My main concern was, given that an electro had been specified for C1, using a film cap in this position would not compromise performance. I have been running a Mundorf M-Cap (15uF) for some time, with no ill effects that I can detect, but recently had a moment of uncertainty. Hence the question.

BTW, dropped the bypass (C6) off the 200uF Tubecap (C5) a few days ago & I cannot detect a significant change in sound quality. In the spirit of the project, simpler is better, so I'll leave it off. The most significant change between the 200uF Tubecap & 470uF electro is a slight contraction in the amazing bass extension that the amp possesses (this may be due the smaller capacitance value??), but the overall sound is tighter & more focussed. Not a bad trade-off, IMO.
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post #2382 of 3976
3/19/09 at 9:04pm
Yes, I think that's exactly right. With the smaller cap the bass will roll off a bit faster but it should clarify a bit also.
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post #2383 of 3976
3/20/09 at 6:25am
That should sound quite good Rolotube, with bass heavy phones like the senns. It would tame their boominess possibly for some configurations of the Bijou. I hadn't considered output coupling with a low-value high-quality film cap, Bravo!

Well the lathe came today, and here's some pics after cleaning off the cosmoline red packing grease, and lubing it with lithium grease and paraffin oil.......



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post #2384 of 3976
3/21/09 at 6:03am
Here's what I've done so far. I stuck to the stock caps except the Rubycon's Thanks Pabbi1 for them. I was thinking about ordering Sonicaps and hearing the difference before and after. Amphead I'll be your first customer. I need some Volume knobs. :P You guys have a good forum going here. Glad I joined.
Sorry for Blurred PIC best I can do with Camera phone. Will take better pics once done.
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post #2385 of 3976
3/21/09 at 10:33am
Looks like progress to me.

When do you fire it up?
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