Thanks for the tip. Unfortunately it has little to no effect.
I've practically rebuilt that cell from scratch now, even matched the other transistor pair. I'm wondering if it's being adversely affected by other circuits around it though the fact that I've got two identical gain cells built onto a piece of strip board in the same M-class module would suggest that's not the case.
For reference, the M-class module is a custom one that I made for a client (his scheme, my design) which includes:
CGS96 Triple Comparator
CGS84 Peaks and Troughs
CGS90 Phaser
CGS60 Stompbox Adapter
The gain cells are to replace the input parts of the CGS60 to give more gain and CV control so I'm only using the output side of that circuit.
On 23 July 2015 at 19:50, ghpicard@... [cgs_synth] <cgs_synth@yahoogroups.com> wrote:It looks like an HF oscillation. You could try enhancing the decoupling of the power supply input. Ceramic 10nF capacitors between the power legs of the ICs (+ and -) and ground can help. They must be soldered directly on the pins to avoid spurious inductance. Also, try not to route the output wires near the input section.
HTH