Another great sounding overdrive
Quite a few people have had issues with the circuit oscillating with presence and gain maxed. This has been known to happen more easily with some pickups, while there hasn’t been an issue with others. Usable cure has been to put a buffer in front of the circuit to isolate the circuit from the pickups and to give higher input impedance. I drew this layout to add a buffer from tubescreamer to the circuit input. IT IS EXPERIMENTAL AND CURRENTLY TOTALLY UNVERIFIED. So please do not build it, unless you know what you’re doing. I’ve been it over a few times and couldn’t see anything wrong with it. However, if you build it (or notice something wrong) let me know if it works…
Please note! With the transistor buffered version, there have been reported cases with the squeeling still there. If you experience this behavior, try replacing the 1M resistor from VRef to 1µ/10K with another 10K resistor. This should fix the issue. If it does, please let me know and i’ll fix the layout accordingly… (P.S. 1M -> 10K works for the original layout too. It just changes the signal impedance maybe a bit too much to be viable fix.)