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With an Ampeg VL here, there is just a touch too much noise (not hum). Yes, I tried going into the effects loop thus it is the output. Before I replace the the PI and bias caps is there anything to check? This is the first time I've had to focus on the output stage as opposed to the preamp for an issue like this.
NB, I just replace the first bank of filter caps with larger JJs and the amp is equipped with a hefty choke with which I rotated to test for hum but it made no difference so the stock position was (thanks Ampeg) fine.
edit: I posted the rectifier section after reading another thread that mentioned the bleeder/stabilizing resistors which are absent here.
I am thinking of replacing the 12ax7 with a 12ay7 or 12au7 with 33K-47K plate resistors. Would this still provide enough voltage swing for a KT88 swap with the required bias adjustment (420 volts on the plates)? The amp has the standard long tailed/Marshall PI.
Another question: if the hum balance has a too narrow of a sweet spot, how can that be "widened"? Thanks.
NB, I just replace the first bank of filter caps with larger JJs and the amp is equipped with a hefty choke with which I rotated to test for hum but it made no difference so the stock position was (thanks Ampeg) fine.
edit: I posted the rectifier section after reading another thread that mentioned the bleeder/stabilizing resistors which are absent here.
I am thinking of replacing the 12ax7 with a 12ay7 or 12au7 with 33K-47K plate resistors. Would this still provide enough voltage swing for a KT88 swap with the required bias adjustment (420 volts on the plates)? The amp has the standard long tailed/Marshall PI.
Another question: if the hum balance has a too narrow of a sweet spot, how can that be "widened"? Thanks.
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