Eliminating Ground Loops in a Multi-Amp Rig

[joshoowah]

I was wondering what people's preferred method was for ground loop elimination. I'm considering either several Ebtech Hum-X (one for each AC plug) or an Ebtech Hum Eliminator HE-8 (patchbay), but I'm open to other suggestions.

My signal chain goes guitar>pedals (last acts as splitter)>

Output 1 - Fender Princeton

Output 2 - Kendrick 2410>Kendrick Reverb>Kendrick 2210

With 4 amp chassis needing ground plus the pedals' power supply, I've got some extra noise. The pedals are actually fine, because the Voodoo Labs Pedal Power2 isolates each of them, but you can't daisy chain three amps and a reverb without creating loops unless you don't value your safety, and I'm not disconnecting or lifting any grounds, either by using a 3-to-2 prong adapter or by disconnecting the shielding on one end of an instrument cable. I've had the unpleasant experience of getting zapped by an improperly grounded amp when I touched strings and the amp chassis at the same time. I don't play with grounds after that little lesson.

Advantage of the Hum-X: no additional cables. Disadvantages: eats up power strip space; requires one for each AC plug.

Advantage of the HE-8: No additional power strip real estate needed. Disadvantage: needs a place to sit (I have no other rack gear) and requires a lot of extra cable, since each amp will be separated by one channel of the patch bay.

Thoughts?

[Studio Custom]

Find the offending source through the process of elimination. 

Start with guitar, cable to a single amp and add items until you find the piece causing the issue.  Eliminate its ground.  

[joshoowah]

5 hours ago, Studio Custom said:

Find the offending source through the process of elimination. 

Start with guitar, cable to a single amp and add items until you find the piece causing the issue.  Eliminate its ground.  

It's not a matter of one offending piece. The act of daisy-chaining any two grounded chassis together will create a loop antenna effect, so you either risk shock by lifting (removing) one ground (either by using a 3-to-2 prong adapter or by eliminating the ground connection in the instrument cable connecting them), or they need to be isolated through transformers. Since I run three amps and a reverb unit, there are multiple examples of such a loop, so lifting is out.

[guitaround]

Lehle sells various switchers that 'guarantee' (I have not tested them) no ground loops and some with individual signal levels.

This one might be the right one for you:

https://lehle.com/ES/Lehle-1at3-SGoS

[Studio Custom]

14 hours ago, joshoowah said:

It's not a matter of one offending piece. The act of daisy-chaining any two grounded chassis together will create a loop antenna effect, so you either risk shock by lifting (removing) one ground (either by using a 3-to-2 prong adapter or by eliminating the ground connection in the instrument cable connecting them), or they need to be isolated through transformers. Since I run three amps and a reverb unit, there are multiple examples of such a loop, so lifting is out.

I built rack systems in the 80s and 90s for myself and others, short of star grounding, that is how we did it.  At the height of the lunacy I had four amps slaved, feeding three 4x12s in a W/D/W configuration with two 24 space racks of gear.  We used plastic screws, plastic washers between the rack face and rail, put  pieces of plastic between the units so they would not physically touch. 

 

The bottom line was simple, each unit needed ONE ground.  Often it was the the left audio input wire to keep things simpler to trace later.