I have built a distortion pedal with 3 variable controls: gain, tone and volume. R8 is my gain control (it will be a potentiometer with 50k to 500k resistance.) R5 is the tone control, (low pass filter.) It is a potentiometer with 1k to 10k resistance. R6 is volume, again a potentiometer with 10k to 100k control.
The output at the op-amp seems perfect, it shows a distorted sine wave oscillating about my biased voltage (7.5V.)
When I probe beyond C5 (at the C4, R5 and R6 node,) the voltage becomes very small and even negative.
Does anyone have any idea as to why this happens? How can I go about fixing it?