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Old 31st May 2012, 06:25 PM   #5911
a.wayne is offline a.wayne  United States
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Quote:
Originally Posted by Wavebourn View Post
Do you mean 5W for earbuds is sissy stuff?
Depends, DVV has big ears .., now is this with Nested feedback ..?
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Old 31st May 2012, 06:29 PM   #5912
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Quote:
Originally Posted by a.wayne View Post
Depends, DVV has big ears .., now is this with Nested feedback ..?
Absolutely!

Solid state assisted vacuum tube amp, with nested feedbacks.
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Old 31st May 2012, 06:30 PM   #5913
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I have a Papworth TVA10 valve amp that is a descendant of a design by Tim de Paravicini I believe. When it broke one day I was forced to trace out the circuit diagram in order to fix it. I realised that gain was being thrown away because of a method of stabilising the DC conditions. I re-worked the DC stabilisation with a fairly minor mod which freed up the extra gain. In addition I had to alter the frequency compensation to make it stable. Having done this, the pre clip distortion dropped from 0.1% to 0.046% on the worst channel. McIntosh MC series of valve amps achieve around 0.06% pre clip from looking at Stereophile's measurements. I haven't come across any measurements better than this for a valve amp unless someone informs me otherwise.

Listening to the amp, post fix, it now sounded like my MOSFET one. I was also able to compare it with my TVA50 which is the same topology in a different chassis. I actually prefer the sound pre fix but which is the 'better' amp?
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Old 31st May 2012, 06:41 PM   #5914
dvv is offline dvv  Serbia
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Quote:
Originally Posted by a.wayne View Post
Depends, DVV has big ears .., now is this with Nested feedback ..?
How d'you know, Wayne? You got me cold.

Actually, Wave, of course 5W for earbuds is a lot, but still, I am not amazed or surprised.

Perhaps because I have 15 WPC for the same purpose. As BJT or MOSFET, your choice.
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Old 31st May 2012, 06:41 PM   #5915
a.wayne is offline a.wayne  United States
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@spladski..

You mean which had the nicer distortion ... ?
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Old 31st May 2012, 06:46 PM   #5916
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Distortion profiles basically the same. One just had less.
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Old 31st May 2012, 06:47 PM   #5917
dvv is offline dvv  Serbia
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Quote:
Originally Posted by a.wayne View Post
@spladski..

You mean which had the nicer distortion ... ?
Lay yer money down an' make yer pick, mister.

Actually, you'd probably love 'em, Wayne, because the quite literally double down. Not too hard, given the load impedances and the fact that I use 50 W trannies for the BJT and 70W trannies for the MOSFET, both in SEPP topology.

When you work it out, with a say 2Vrms output, you probably get split eardrums - remember, all headphones tend to VERY efficient, so 1 mW into say 30 Ohms produces 90 dB and upwards SPL.
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Old 31st May 2012, 06:47 PM   #5918
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I'm most impressed with the names he coins (remember the "autocorrelator" in one of the Phase Linear preamps?).
Yes, if I recall a Motrola Gilbert cell mixer and many carbon comp resistors were involved to make a very bad multiplier.
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Old 31st May 2012, 06:51 PM   #5919
a.wayne is offline a.wayne  United States
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Not nested feedback, but you will need an Nest egg to play ...

MARANTZ 7 7C low serial # 10xxx with original documents!! DON'T MISS!!!!!!!!!! | eBay
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Old 31st May 2012, 06:52 PM   #5920
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Where is Carver's double blind test NOW?
John, you use "double blind" as a pejorative as if it immediately discounts the results. As I remember the participants had no complaints as to the protocol, and freely accepted the results as well as being well into the subjectivist camp. I'm sure they went right back to demagnetizing their LP's when it was all over.
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