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RE: Cathode bypass cap removed and I like it

Posted by megasat16 on January 10, 2017 at 17:17:41:
Tre,

Are you saying the quoted RCA or any datasheets for the plate resistance is measured with the cathode bypass capacitor in place for A or AB circuits for the tubes such as 2A3? I meant the plate resistance is usually given in the data sheet and you can assume that plate resistance base on the operating parameter and use an appropriate cathode bias resistor and load the tube with a transformer with equal or a little higher primary Z.

Cathode bypass restores the degenerative feedback lost by the cathode bias resistor. AC flows through the resistor just as well as DC. The AC current is fed back into the GND so the feedback current is considerable reduced. The cathode bypass cap somewhat restores that lost current by acting like a buffer for the AC current.

My understanding is that you can safely remove the cathode bypass cap without effecting the plate resistance. The damping factor may be effected as it is calculated on the output from the amp and the amp without the cathode bypass cap has lesser (Volt or Power) output than the one with it. But this damping factor shouldn't matter much in the High Efficiency world when less than 1W of power is required for daily listening.