SET Asylum

RE: Class D gain

192.161.70.66

tube wrangler

M

In Reply to: RE: Class D gain posted by Ralph on October 22, 2021 at 11:06:50

Thanks, Ralph! An excellent discussion,
as usual.

I break rules whenever I think that it
might work-- maybe it won't work.

I have been lazy in that regard because
I always wanted to play with a high-gain
solid-state device, and run it Class A, with zero FBK..

Everyone I ever talked to on this said mostly
the same thing-- it won't work with solid-state
devices-- they're not tubes-- they require all that
FBK.

Someday I think I'll try it anyhow-- I just want
to know for myself--- hah!

Who knows what that will sound like!

-Dennis-

Follow Ups:

There are zero feedback class D amps- some are getting very good comments too. nt - Ralph 09:36:31 10/25/21 (0)
-
RE: Class D gain - morricab 02:59:11 10/25/21 (1)
I have some idea on this because I had in the past an amp from the company NAT out of Serbia.

The amp was the Symbiosis SE, which was a single ended hybrid that had a tube input, tube driver and an output stage with a single large MOSFET that was strapped to the bottom of a huge heat sink...per channel. There were two other heat sink towers that also had a single MOSFET that were regulating the output of the other MOSFET. Being single ended it was pure Class A where it consumed 800 watts even at idle.

This amp in some ways was the most amazing sounding amp I ever heard...if you could wait 2 hours for it to fully warm up (it was 155lbs. so there was a lot to warm up). It got spookily transparent...like an OTL and yet had much of the tonality of a good SET. It didn't quite have the same inner resolution and holography of a top SET but it wasn't absent either.

Of course there was not Feedback on this amp at all and it sounded that way. The most interesting part was that it actually put out 100 watts into either 8 or 4 ohms and was 2 ohm capable.

So, while a MOSFET doesn't sound quite like a triode it could in many ways sound quite convincing when used like a triode.

The only reason I sold it was the very long warm up to where it sounded almost psychedelically good...before that it was kind of like you knew it could do much better so it was a bit disappointing until it really came on song.
- RE: Class D gain - tube wrangler 12:57:48 10/25/21 (0)
  Most interesting, and confirms some of
  my suspicions about it.
  
  The question for me is-- is that long warmup
  a function of zero FBK, or is it just power supplies,
  etc., finally getting warm enough to clean-up.
  
  I suspect that, but don't know it, so I'll just
  have to build one. Mine would be much simpler--
  maybe I'll get away with something-- it could work.
  
  Thanks! -Dennis-

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