Voodoo Lab

A loud hum when connecting guitar directly to a GCX loop and the out of that loop directly to the amp is very strange. There is no reason the GCX could make this happen normally. Is this GCX new or is it used and possibly modified in some way? Do you get the same result regardless of the loop used?...

Well I decided to go back to square one based on your feedback and simply take the GCX out of the rack and see what happens. When I plug directly into loop 1, I still have the crazy ground hum when I turn up the volume on the guitar, which was discouraging. However, I decided to go back to plugging ...

UPDATE: I tried plugging the guitar cable directly into the input on loop 1 and the hiss is gone. However now there is major buzzing going on when I turn up the guitar volume that was not there before.

I am hooking my GCX up to a Mark IV. As an example of the problem, I can take the guitar, plug it into a Bad Monkey, and into the amp and I don't have any noise. However if I create just one loop (Loop 1) on the GCX with the Bad Monkey in it...using the same cables it is noisy (verging on "hummy"). ...