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In Reply to: RE: Class A posted by Paul Joppa on August 03, 2014 at 15:21:43
"...current-source cathode loads on both output and driver stages, forcing a truly constant current."
Can you explain that for me? Shouldn't the cathodes of the output stages be held at as nearly constant a voltage as possible (as though a voltage source were attached)? Guess I don't understand your meaning...
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Follow Ups:
I was thinking of cascaded "long-tail pair" differential amp stages. With a current source the "tail" does not need to be so long and inefficient.
The LTP is sometimes used as a phase splitter. Sometimes the common (shared) cathode resistor in a P-P output stage is left unbypassed; you might call that a short-tail pair diff amp. :^)
Or this.Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Edits: 08/03/14
I've built an amp with that type output stage, using 2A3 and chokes in place of the CCSs.
I like it a lot. Rest of the amp is 1/2 of a 6n6p direct-coupled to a triode-connected 6w6gt driving a center-tapped autoformer phase splitter.
Regards,
John
I like this one even better and have a pair of OPT's that would allow for this type hook up.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
I tried it both ways. In my case, it both measured and sounded better the other way -- this way had increased 3h versus the other way.Regards,
John
Edits: 08/04/14
Interesting.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
I seem to remember proposing the same concept some years ago on this forum. The only difference was that I used chokes as CCSs. Guess I wasn't the first to think of it. :)
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Buy Chinese. Bury freedom.
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