...it is amazing how tubes can fool human perception!
During the last concert I've discovered one 6P3S in my amp has glowing anode. It turned to be I've overbiased them, so evaporated anode metal shorted the path between grid and cathode so only -1V of bias voltage left in one shoulder (2 tubes in parallel)... Actually, it was a single ended kind of an amp as the result with much less output power and higher distortions if to measure them, but people kept saying it sounds brilliant... Go figure...
...so... what if to use a push-pull transformer with a FET current source?
The cheapest way to get a decent class A power amp!
During the last concert I've discovered one 6P3S in my amp has glowing anode. It turned to be I've overbiased them, so evaporated anode metal shorted the path between grid and cathode so only -1V of bias voltage left in one shoulder (2 tubes in parallel)... Actually, it was a single ended kind of an amp as the result with much less output power and higher distortions if to measure them, but people kept saying it sounds brilliant... Go figure...
...so... what if to use a push-pull transformer with a FET current source?
The cheapest way to get a decent class A power amp!
Twice as much power and still giving SET sound using a P-P transformer:
(could just skip the cascode part and use a high voltage Mosfet like the FQP2N90)
https://www.diyaudio.com/community/...omplementary-current-triode.56916/post-638668
Don
(could just skip the cascode part and use a high voltage Mosfet like the FQP2N90)
https://www.diyaudio.com/community/...omplementary-current-triode.56916/post-638668
Don
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