I made a certain modification to DMM that was quite cool, but wasn’t as cool as I wanted it to be. I changed an Ernie Ball volume pedal to have the same value pot as the Feedback control on the DMM. It gave the user a great amount of control over the amount of feedback during play.

Originally, I had intended to replace the direct out jack with a TRS input and a mathching TRS on the expression pedal. But that didn’t work. (I’m not an electrical genius, I only know enough to be dangerous.) I figured this was because the expression pedal was not grounded to the DMM. So, I hard-wired up the pedal directly to the pcb. This worked great until some other bad stuff happened, which I posted elsewhere. But I don’t think this modification caused the issue.

So, what I’m trying to find out is, if I were to do this mod again, how could I implement my first idea of being able to connect the expression pedal to the DMM via a TRS or some other kind of cable?