www.megadrum.info

I noticed some peculiarities while I was testing my drum head tension.

Basically, I pressed on one of my toms (input 20) and I get rapid hits of the snare rim midi note (input 5).

If I swap the cables around, the problem remains on input 20 (whereby it triggers input 5) no matter what drum it's connected too. So it's not the drum, and it's the reason I've named it as "hardwired crosstalk"

If I remove the cable from snare end, leaving the cable attached to input 4/5 on megadrum; the gain is massively increased. Meaning I can now trigger consecutive snare rim hits, just by touching a drum stick on the surface of the tom head. If I remove the cable completely from input 4/5, the problem stops immediately.

Here's where it starts getting confusing...

I plug one end of the cable back into input 4/5 and unplug the tom connected to input 20/21. Now input 16/17 shows the same symptoms as input 20/21 = touching it lightly triggers lots of snare rim hits (note 40 in this case - not important, as I can change it)

So I unplug input 16/17, now the symptom moves to input 8/9, so on and so fourth etc.

Just what is happening electronically here?

The important thing is, when everything is plugged in and setup, there are no issues. I just want to understand a more clearly about this so-called, hardwired crosstalk.

FYI - this all started when I wanted to improve my rim triggering response from my snare drum - seems I messed up something in the process.

If I understood your description correctly you are connecting a cable to MegaDrum without a pad at the other end.
In that case a cable acts like an antenna and picks up all the electromagnetic noise. So if there is nothing connected to an input it is better to disable this input by setting its Note to 0.