Re: Pleasantly surprised - amp modification
CCS as a cathode bias for output valves is theoretically a bad idea, although undeservedly popular. For PP an unbypassed CCS enforces current balance, but it also enforces fixed average current when what you actually want for low distortion is fixed quiescent current. For single-ended, a bypassed CCS can create LF phase problems in addition to fixing the wrong current. The LF phase problems can then encourage motorboating.
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