I use a Westminster Effects micro expression wheel with my MC6. Functionally, it works great. Over time, however, it’s caused more and more pronounced clicking from what I assume is some sort of ground loop. For a long time, I thought the problem was one of my other pedals. I recently narrowed it down to the expression wheel instead. When I disconnect it, my rig is completely quiet. When I reconnect it, the clicking comes back as soon as I press a button on the MC6. Anyone else have experience with an expression wheel causing this? Any suggestions on how to solve the issue? The wheel sit right against the MC6 in my setup. I could space them out a bit. Alternatively, I’m considering a DOD mini expression pedal. Anyone use it successfully? Thanks so much.
Doubt that a passive device would create a ground loop.
Obviously it’s involved in noise in some way, but I suspect it’s only part of the problem.
What’s the entire setup look like? How’s it wired for midi, audio, and power?
Audio signal chain is as follows: Source Audio EQ2 → JHS Morning Glory → Jackson Audio Broken Arrow → Goodwood Audition → Dunlop mini volume → Walrus Audio Monument → Swindler Effects Gulf → HX Stomp => Strymon Timeline => GFI Specular Tempus
MIDI signal chain is as follows: Morningstar MC6 → Source Audio EQ2 → Disaster Area Designs MIDI Box 4 → HX Stomp → Strymon Timeline → GFI Specular Tempus. Additionally, from the MIDI Box 4, separate TRS MIDI to Broken Arrow and Gulf
Everything is powered by Cioks DC7 and 4 Expander. All on separate isolated outlets.
Micro expression runs directly into Exp 1 of the MC6. Exp 2 is unused. Temple Trio 21 pedalboard with Temple 4X mods for ins/outs. Audio and power run under the board with only connectors above. MIDI runs on top of the board.
I’d appreciate your thoughts and can share a picture if that would be helpful. Thanks so much.
I had a lot of trouble with ground loops, slowly tested and found all of them except the last one was a real pain and it was coming from my Source Audio EQ2. Fixed it by switching from true bypass to buffered bypass. Hope that helps.
Also, I bought a DOD mini expression pedal and found it to be sort of clunky and not put together that well. Saved up for a Lehle and it’s so much better.
I appreciate the insight on the DOD pedal. I’ll be skipping that one. I tried switching the buffer on my EQ2. Seemed like the problem was solved, but it came back. 
Damn. Well my only other suggestion is to get a midi box with more outputs (like the morningstar midibox) and run as few things as possible in a loop and as many as possible isolated from the box. For example I got rid of most of my clicks (except the EQ2) by only having a loop betwen my MC8 and midibox, then everything else from the midibox. It took me ages to figure out so I feel your pain! Good luck.
Try taking out the midi connections one at a time.
Sounds like you did this and concluded it was the mini expression which still amazes me. Perhaps try a test with another expression pedal (the volume pedal plus an insert cable can act as an expression pedal)? Can you move the expression pedal in the unlikely event it’s picking something from a nearby device.
TRS midi devices are most likely to skip opto isolation circuit so I’d focus on those.
Well, I’m back for another try. My problem continues. Whenever my expression wheel is plugged into an omniport on the MC6, I get a ground loop MIDI click. When I unplug it, it stops.
I recently also wired my board with three USB B cables out of my MC6, my Specular Tempus, and my HX Stomp. They all run to a small USB hub on the underside of my board. That then runs to a panel mount USB connector on the side of my Temple Trio 21. Doing this allows me to connect my computer to any of the three USB-connected devices without having to move a cable around from device to device where space is tight on the pedalboard. It all works great…with the exception that now even a USB cable connected to the MC6 causes a MIDI signal loop (the same clicking sound as the expression wheel) as well once a preset is engaged. If I unplug the USB cable the click goes away. Very frustrating. Anyone have any suggestion? Thanks for your help.