Advice, help, and stuff - GCX/FX loop noise

Q & A for building and interfacing your rack gear with Ground Control Pro and GCX-based systems.
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Donnie St. James
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Joined: Sat Feb 01, 2014 2:29 pm

Advice, help, and stuff - GCX/FX loop noise

Post by Donnie St. James » Wed Feb 25, 2015 6:53 am

So I finally got my rack put together. I have a GCX, Furman M-8x2, 5150 - 50 watt, GCP, and the following pedals:

In the amps FX loop - Eventide Timefactor, TC Electronics Spark mini (two of these, one for a lead boost and one for the clean channel boost so there isn't the notorious volume jump between the channels)
In front of the amp - Eventide Modfactor, Digitech Whammy V

I have an Eventide Powerfactor 2 (plugged into the Furman) powering the two Eventide pedals and the two Spark minis. I have the Whammy's power supply plugged into the Furman, along with my amp and power to my pedal board.

When powering up everything I get a radio station and loud hum/hiss noise. I tracked it down to this: when powering the two spark mini pedals with the Eventide Powerfactor I get the radio station. When powering the sparks with separate power supplies the radio station is gone. Annoying, but an easy fix as I can get a One Spot and power them that way.

When only using one spark there is no hum/hiss. When using both (either plugged into the GCX or chaining them together into the amps FX loop) I get the noise.

I have removed the two sparks from the shelf and used different cables to connect them to the FX loop, completely bypassing the GCX. No luck. This makes me believe that it isn't a cabling issue. I have removed the GCX completely from the equation - again no luck. It's obviously having the two sparks in the FX loop together that is giving me the noise.

Unfortunately in order for me to be able to use all 3 channels on my amp I need to have something to boost the volume of the clean channel. I do not believe the problem is with my amp's FX loop.

Does anyone know of a way around this or maybe a programmable boost pedal that allows you to create presets controllable via MIDI?

I'm going a little crazy about all this.


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Re: Advice, help, and stuff - GCX/FX loop noise

Post by nyteowl » Thu Feb 26, 2015 9:19 am

If you could provide a diagram of how all your gear is wired up, that would be a big help to anyone trying to trace the cause of your problem.

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Re: Advice, help, and stuff - GCX/FX loop noise

Post by JohnClark » Thu Feb 26, 2015 12:36 pm

If running just the two pedals directly into the effects loop alone makes noise then I'm not really too sure what can be done. Do you get the noise when both pedals are connected, but bypassed?

Simplifying to the most basic setup is the best starting point. Run your guitar directly to the amp, with only the two boosts in the amp's effects loop and test if different cables or different power methods for the pedals help to cure the radio noise.

I hope that helps!
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Donnie St. James
Posts: 34
Joined: Sat Feb 01, 2014 2:29 pm

Re: Advice, help, and stuff - GCX/FX loop noise

Post by Donnie St. James » Thu Mar 05, 2015 12:47 pm

Hey guys, thanks for the replies. I'm not sure what it was but after unplugging everything and plugging them all back in it seemed to have fixed itself. I also did install Humfrees (man those are not fun to install) and I ended up getting an Ebtech Hum Eliminator as well and placed it in the FX Loop. All good.

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