I built this this bass overdrive:
http://www.sugardas.lt/~igoramps/article16/fx91.gif
Now abuot the problem.
First OP-amp wich reduces the gain, goes to generate. It makes a quite hi tone. When I turn the gain off then noise is gone. But this scheme is for drive, isn't it. :P
I tried to replace capacitor C22 to bigger one, and the noise goes, but it eats, all the drive, and I think the mistake is somewhere els.
Op- amps are TL071
Pin Voltages Taken?
The power supply is assumed here, looks like it has a 1/2 V for the OA + inputs.
Note the pin voltages, post them here if you need comment...and audio probe it.
I used biasing with two resistor to get 4,5 V.
http://www.hot.ee/gravity/bias2
How to probe it?