Preamp WOrkinK

[R.Fahl]

Thanks to all who provided feedback on my preamp problem.

I have figured out what the problems were:

I have two preamps and two envelope followers on one PCB.  I had decoupled
the power rails but the oscillation continued.

After contemplating the situation a bit, I decided to disconnect the
circuit from the others.  That alone improved the noise/feedback problem.
There was still the oscillation when I turned up the volume with no signal
inserted.  In addition, when I tried to insert an instrument into the
second jack there would only be the oscillation at the output, but none of
the input signal.

The situation here was that I had two switching jacks connected in
parallel.  This seems to be where the feedback was stemming from - with no
plug inserted, the output of stage one would be fed through both jacks to
stage two.  Unfortunately, there's a pesky feedback loop.

The reason I used two jacks is so I could have both a 1/4" and an 1/8" mini
for the same input.  I'm trying to figure out a way to still be able to use
both.  If anyone sees an easy solution, please tell me.  I prefer playing
to troubleshooting.

Romeo