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previous: Ricky have any of you seen the amp projec... -- 12/25/1999 9:06 PM

Re: cathode bias cap value

12/26/1999 3:02 AM
Ken Gilbert	Re: cathode bias cap value Switching a bypass cap in and out of the cathode circuit will alter gain IF there is appreciable signal across the shared cathode resistance. If there is no signal voltage across the cathode resistor, then there is no AC to short by the cap. There would be no signal across that resistor IF the output stage is running in class A. Switch over to class AB though and you're gonna get some change in current, which will lead to a change in voltage across the resistor. To answer your other question, you could certainly make only a portion of the cathode bypass cap switchable. In this case it would act like a kind of "thick" control. Ken

12/26/1999 3:02 AM

Ken Gilbert

Re: cathode bias cap value

Switching a bypass cap in and out of the cathode circuit will alter gain IF there is appreciable signal across the shared cathode resistance. If there is no signal voltage across the cathode resistor, then there is no AC to short by the cap.

There would be no signal across that resistor IF the output stage is running in class A. Switch over to class AB though and you're gonna get some change in current, which will lead to a change in voltage across the resistor.

To answer your other question, you could certainly make only a portion of the cathode bypass cap switchable. In this case it would act like a kind of "thick" control.

Ken

Replies:

Bruce q{There would be no signal across t... -- 12/26/1999 7:17 PM