King of Tone-Both Channels Engaged

[dfx_pedalpcbs]

Anybody used the original diodes (1S1588 & MA856) and have that high pitched whine when the gain is maxed out when both channels are engaged?
is there something that can be done to eliminate this?

[MikeA]

The diode choice shouldn't cause a whine, I've used the ones you mention with no problem.  For this circuit, there's a lot of gain with both sides engaged, maybe you need more separation between your low-level and high-level signal path wiring? (input jack>>foot switch>>PCB input being low level, PCB output>>foot switch>>output jack being high level.)  You can open it up and reposition the wires to see if that changes the noise, sometimes a half inch matters.  Using shielded wire on the input runs can also help.  Could also be oscillation of an active component, but I've used lots of different op amps in this circuit without any problem, including those that are sensitive to output capacitance. 

[dfx_pedalpcbs]

ok thanks mate