Re: Amp wired. Squealing under some conditions, Cathode-follower FX driver still suspected Full amp schematic included! Warning - nonpolitical.

Thank you Steve,

Really, a CF should be driven by a CC stage before it, DC
coupled... most folks do it that way. Or, copy the 1983
Twin Reverb II... it does the buffered effects loop right.

I checked that schematic out. So they do use a separate power supply
decoupling section for the loop. Oh well, I can put one in tonight (a
euphemism for whenever I come home from work and don't feel too tired
to do it) and see what happens.

And if you think it'll calm things down I can put a few 1M resistors
on the straight-to-pot-wiper grids. Got plenty of those.

About the thumping - heck why don't I just hook up the Gain switch to
the plate of V1A as well as to the plate of V1B? That way it'll
always have about 150V charged up there. Much less thumping.





The question is, is the squeal coming in through the +55V, or is it
coming through the plate? Where does it come from, where does it go?
How can I track it down?

It comes through the power supply, is my guess... that's
usually the case with oscillation.

Any time you put a grid leak through a wiper you are
flirting with noise. Relying on a switch to be
an infinite reactance can also bite you... it's not, it
has a minimum reactance at certain frequencies, even
when 'off'. This could be a problem with FXBypass.
__
Steve
.

True. That is scary. But yes, if V2B's output feeds back to V2A's
input via the FXBypass switch, that would suck a whole lot. Probably
create a little phase-shift oscillator there. And who knows what
would happen if I jammed actual effects into that loop! I had better
try lifting wires from that switch and see what happens.

Thank you so much for your help. I'll post as soon as I try some of
these things.

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