(gcx) 2 amps + gsp1101 played by 1 gtr & reamp same time

[JohnClark]

The only place you should be routing the Hum Eliminators is just before the inputs of the amplifiers. Try connecting things as I previously described but now inserting the hum Eliminators between the Output of a GCX Loop and the Input of at least two of the amplifiers.

Not all buzzing is a ground loop! The Return jacks on the GCX are all ground lifted. In order for the signal from the laptop to reference ground correctly it must be routed through one of the front panel jacks before being split to the individual loops. Take it one step at a time then report the findings, I can only help you if I know all connections are as I suggested.

[Midicity]

Yes I did everything as you suggested first. It did have hum with it connected as you recommended in the test. It even hums when the laptop rig is not powered on. Anyime I activate those loops it hums loudly with or without the hum eliminators right before the amp from the 2 amplifiers loop outs. I even tried 2 different hum eliminators (1 for amp A and 1 for amp B) Same hum. I have tried several different cables as well just to make sure its not the cable. All types of cables from Mogami to voodoo amps to george l to rapco etc. I think I tried everything except an isolator as you mentioned unless you consider the ebtech hum eliminator an isolator? Not sure if thats what it does or not? Could you recommend an isolator for my issue? Thanks. ALMOST THERE lol

[JohnClark]

With the Hum Eliminators in place before the inputs to the amps, try isolating the GCX from the rack rails. You can test this by unscrewing the rack screws and sliding the GCX out of the rack a little so it is not touching any other metal pieces in the rack.

[Midicity]

I am using humfrees and also have rubber pads between the 2 gcx units

I did just unscrew the gcx and pushed it out a bit. Still humming the same.

[JohnClark]

Well then it is time to simplify the setup in order to find where the buzz is coming from. Start by removing the laptop connection from the GCX front panel Feedthru, and also remove the 3 way split cable from the rear panel Feedtru and GCX Loop Return jacks. This will leave only the Guitar connected to the Guitar In, the 3 way split from the Guitar Out to the Input of three GCX Loops, the GCX Loop Outputs running to the amplifiers with at least two of them running through a Hum Eliminator first.

[Midicity]

Ok

[Midicity]

Ok I now completely removed the laptops cables from the gcx and no hum. Meaning even from the returns of the gcx

[Midicity]

So where do we go from here? Should I run the latop signal to 3 other loops and run the outputs of all the loops into a merge of some sort then to the amps?

[JohnClark]

Now try running the output from the laptop directly to the Input of Loop 1. Listen for any buzz with the loop off then again with the loop on.

[Midicity]

I left everything plugged in the same except I unplugged the gtr from loop 1 input and replaced it with the laptops signal. It has no hum but when I turn loop 1 it hums loud.

I just tried putting the gtr into loop 1 return and laptop into loop 1 in. This loops output goes to my Randall. When I toggled the loop (1) on and off it would have hum when the guitar signal was engaged. I think it is my returns giving me the issue? Anything that is on the returns hums when used in this setup. I am going to try and plug a second guitar into the return of loop 1 instead of the laptop and see what happens?