I built a few of PedalPCBs Parentheses Fuzz. great clone of the EarthQuaker Life Pedal. All of the pedals I built seem to have whistling noise/oscillation sound when the Gain and Octave are at 100%. I haven’t played an original Life pedal so I’m not sure if it has this same issue.
The noise sounds like noise you get with anything high gain when the gain and volume are all the way up. When the octave is engage the noise turns into an oscillation that sounds like whoosh in a wind tunnel. You don’t hear it when you’re playing but the sound is pretty egregious when you’re not playing.
Again, this was with the Gain and Volume at 100% which you’re unlikely to use. And the worst of the noise happens when the octave is also on at 100%. Your likely to play with the octave 100%, Gain 100% and volume at 50%. Here the noise is there not as loud but noticeable.
The best I could figure was the sound came from the op-amp but had some interaction with the power supply. I did not use an original LM308 and instead used 741 type op-amps. These are cheaper and easier to get. They sound good.
The best solution I could come up with was swapping C15 with larger value. Using values of 33n and larger the noise was completely gone even with the gain all the way up and volume all the way up. Bringing the value down starts to reveal the noise/oscillation. The larger values make for a darker sounding pedal as this cap limits the gain of high frequencies. The larger this cap is the lower the range of frequencies it limits.
I settled on 15n which seems like a drastic change but it sound pretty good. The noise/oscillation was brought to a negligible level.