I have a Marshall Plexi, Powerstation and GPDI-IR setup in the suggest method based on a diagram I found here from a Team Fryette poster.
My Marshall in is setup with the “To Amp Input” from the GPDI-IR. The problem is that when I barely turn the amp up I get a high pitched squeal. I have tried the following:
Switch the Ground lifts on both the PS and GP — they change the hum slightly but doesn’t eliminate it or even decrease it
Plug the Guitar directly into the Marshall — eliminates the hum (still routed through the GP and PS as the diagram showed.
Insert a Passive DI box in front of the marshall input — eliminates the hum but muddles the guitar tone significantly
Also tried a Morley Hum Eliminator, on the power strip, on just the GP and on just eh PS — no effect
If the GPDI-IR is very close to the amp, try moving it first; sometimes there can be feedback for this reason (like when pickups are too close to an amp).
Do you have anything in your FX loop, unplug it completely. Does the squealing problem go away? If so, then this is telling you where you need to break the loop.
I suggest getting hold of an audio isolator and trying it in different places.
Isolated power supply would help too, and connecting everything to a single wall socket (via extension cord).
I also have a Cyclops but I’m hoping to return that and use the GP switching. Is there even a way to route that into my system? Before I had the GP I had that setup and it worked fine with no hum switching with a Friedman IR-D.
But the thing I want to do with the GP is to route everything back into it’s 1 watt section for sending to my computer, so I’m not sure how I would connect a Cyclops into the loop and TBH I’d prefer the simpler approach than more wires.
Any tips on volume matching the Ext Amp out with the direct GPDI-IR output? I can do it by changing the Master volume knob and the IR Volume but the IR clipping light starts flashing. Thanks.
