Re:: ¡°The Bass IN/OUT thing could be attributed to the change in gain of the 1st audio amp.? Figure 11, the audio filter curve, shows that the gain is 100+X higher when the bass switch is in the IN position at 60 cycles.? I would not say that the hum is gone in the OUT position, but I would say that it is not easily heard in the speaker.?¡° ??
But ?post #1 says ?¡°When I switch the Bass in, the hum goes away.¡± , from witch I gather there IS a HUM problem in ¡°OUT¡± where the 60Hz gain is lower ,, ???? I was doing mental cartwheels about this and my head is still sore.
You are overlooking an alternative, that nothing is actually wrong.? AFAIK. the radio works well but there is a noticeable hum.? Hum is subjective, if you have listened to solid state audio most of your life you expect to hear no background audio.? If you have listened to tube audio all of your life, you expect some hum.?
