My PCB skills are probably not quite the best but I have given it a fair try. It's almost working like a charm. The customer wants footswitchable channels so I've incorporated two dpdt relays for that purpose. (there's one Fender-ish channel and the other is more Marshall-ish). One relay is switching the tone stack, the other is switching the input gain (which half of V1 is used). The relay switching the gain keeps inserting some unpleasant noise/hum (sounds like 100Hz). I have tried to replace the relay, no change. I have tried to move the relay on a separate board over at the free spot at the red board (see picture) (I used shielded wires to/from the relay). No change. If I remove the AC on the input of that relay the hum disappears. Any clues or better solutions to make the preamp switchable..? The schematic is attached, but the pin numberings on V1B and V2B is incorrect.. and there is one wire missing in the tone stack I think, but You'll get the idea
The EQ OUT1 point is where I send the signal to the phase inverter.The relay on the right in the picture is the one making problems. I did not take a picture after i removed and moved it.
