GCX HUM and ground loop

[ibaneijs]

Hi,

I need some help with my setup:

Guitar-->WIRELESS-->>Dunlop Rack Wah-->>INPUT MESA MKIV
FX-LOOP-->GCX-->MXR Phase-->MXR Flanger-->Rocktron Xpression

Because the Dunlop wah also provides a volume-control I tried putting that in loop 1. However then there is a lot of hum...
I've tried several connections and discovered when using the GCX in front of the amp (there is a lot of hum and unwanted noise. I have isolated the GCX from the rack rails and the hum gets less.

Anyone any ideas about how to better isolate the signal from unwanted noise? (or how to permanently isolate the GCX from the rack rails)

Thanks

MArco

[JohnClark]

Exactly where in the GCX did you connect things... there are 36 jacks, which ones did you use?

[ibaneijs]

OK, I've tried several things and it seems that it has something to do with interference of all the power supplies in the back of the rack.

I started off with putting humfrees in the rack and removing all the gear and power supplies. Basically I now have my MKIV and in the FX-loop the GCX with loop 4 connected to the Rocktron Xpression. Tomorrow I'll start adding some more gear to find out what is causing the hum.

Previously I hooked up as following:

Guitar-->Wireless--> GCX Loop 1-Dunlop Wah-->>MKIV input.
Next was the FXloop of the MKIV connected to loop IV of the GCX (Xpression in loop 4) next to loop 5 with the MXR flanger.

I'll keep you posted.