Two effects in one box - Strange feedback

[juan_felt]

Hi everyone,

I recently built a BSIAB and a LPB1 and I boxed them together. They work fine, two nice effects.
BUT, the other day I was messing around with the controls, and I found that when both are engaged, and both gains are maxed out and the volume on the bsiab is considerably high a sort of feedback starts to sound, and when I move the tone on the BSIAB the feedback changes the pitch.

Is very strange! As well, if I play the feedback disappears.

Any ideas?

Thanks!

[juan_felt]

Also, if I use the distorsion of a different stompbox (BSIAB as well) with the booster, I don't get the same feedback!

HELP PLEASE!

[Mike Burgundy]

They're oscillating - somehow the signal is fed back into the first stage(s).
How that happens is the trick. Could be EM (change the layout, poke wires around), via ground (star grounding!), power, etc.
Sticking two circuits in one box with *lots* of gain makes the game that much more difficult.