I made a custom pedal board. I have a 1/4" input jack for the guitar on the right side. The jack is connected via patch cable to the first pedal in the chain.
If I plug my guitar directly into the first pedal in the chain (i.e., bypass the jack on the side), all is well.
However, whenever I use the jack, the patch cable goes loudly microphonic, as do all the other patch cables between the pedals. There is also a loud hum. Do I need to put a filter on the jack? Is the jack itself functioning as some kind of bad buffer? Or is this a symptom of some other problem?
Originally, I had the input jack, plus a wireless receiver. Using a DPDT rocker switch, I could choose which signal (jack or receiver) I could feed into the first pedal. However, any time I switched to the jack input, I got the loud cable microphonics and hum. For now, to make it simple, I completely removed the switch & receiver from the circuit. The point I'm at now is just trying to get the jack to play nicely, period.