USB ground loop

I have been putting up with interference on my AI ever since I hooked up my Line6 POD Go and have now discovered that this is down to the AI and POD both being connected to the PC via USB at the same time. ie USB Ground Loop.

So having just discovered that, I know I can circumvent the audio garbage by not playing by disconnecting the POD, when I am not using the POD Edit software on the PC. However, I was wondering if there was another way around a USB Ground Loop, where both devices can be left connected.

If its not possible nowt lost but if any of our tech bods know of a solution, I’d be interested in trying something.

Weird thing is, it doesn’t happen with the Mustang III. That or the interference is a much lower volume.

Thoughts on a postcard please.


Correction - guess the noise is actually on the Windows/PC soundcard not the AI itself. :thinking:

Is it a PC, or laptop?



PC Keith. Just checking out so YT vids on isolators etc but your thoughts appreciated. :sunglasses:

I had a ground loop drama when using an analogue audio cable to connect my audio interface to my headphones. Both my Focusrite & headphones were connected to PC with USB so had a horrible humm.

I used a ground loop isolator on the analog cable and now it works great.

Mustang is powered by AC, and USB is for data, my understanding is ground loops over USB only happen when both devices are powered from the same power source.


My little ground loop isolator.


Yep it sounds pants.

FWIW set up is

L & R POD Go Line outs to Xenyx X1204
Dynmaic Mic to Xenyx X1204
Headphones direct from Xenyx X1204
Both POD and Xenyx USBs to Win PC
AI goes into rear USB port
POD via front panel USB hub

Yes but the Mustang has similar USB connection for using Fuse on the PC.

Hmm, that’s a more complicated setup than mine. I think the analog loop in there would be the “L & R POD Go Line outs to Xenyx X1204”.

What kind of cabling and connectors is it?

1 Like

1/4 jack at the POD end and XLR into the AI

Yeah, that’s analog. You can test if that’s the source of the ground loop by unplugging that cable and seeing if the ground loop goes away - although obviously so will the sound from your POD Go. It would at least confirm it as the source.

My one is this: a really basic one for headphones, because that’s what caused my ground loop.

There are ones like this that might suit you better: AVE Vox-Hum Hum Eliminator - DJ City. I haven’t used that.

1 Like

I think the POD is definitely the source. If I mute the two Line Out XLR input channels on the AI, the interference stops. Same when it is powered off.

I’ll have a look at those two links, so thx. No normal need to keep the POD connected via USB all the time but I’ve been chasing and refining a signal chain for the OM, so its been a bit of a pita have the frequencies whining away while I’ve been tweaking.

1 Like

Found these two at Thomann that may well do the trick.

Second one needs batteries or phantom power which could be provided by the Xenyx.

1 Like

It could be the Pod power supply.

The power supply that came with my Spark amp was dreadful, largely because it wasn’t earthed.

I replaced it with a grounded power unit of the same specifications and it sorted the problem.



1 Like

Thanks Keith, I’ll look into that. Could well be the case as its a standard 2 pin adapter by the looks of it. Off to Thomann for a looksee. Thx.

If I had trouble sourcing one, would that HD400 do the job ?

Wonder if @Kasper or @Rossco01 have experience similar with their Line6 kit ?

Hi Toby,

I’ve had a number of humm/ground loop issues in my home studio setup… and for a time it was driving me batshit crazy! The more gear, the more issues :slight_smile: Luckily I’ve managed to get it all under control now.

First thing was to make sure everything was actually grounded (I had a few power cables that was not) and trying to have most/all audio gear draw power from the same wall socket.

That did not solve the worst offender though - which was the USB cable from my Line6 HW to computer. That’s (if I understand it correctly) not a traditional ground loop, but something called “electrical noise” which is more high pitched and absolutely destroys recording/playing sound quality. Same thing happens when I plug other pedals to the computer via USB. That particular problem I solved with this thing (which got rid of it entirely)

When running an amp in 4 cable method I also have one of these LEHLE P-ISO | LEHLE
connected before the input of my amp (so between the “send” on the Helix and the amp).

This got rid of all loop/electrical noise.

Finally I do use the noise gate in the Helix (the one on the input block works well) when running high gain tones.


That little gizmo might do the trick then. And as you say its the more high pitched interference. Think I could rule out power supply as I don’t get this via headphones connected to the POD or if I just use the amp out and drive that into the Mustang. So its only when both Pod and the Xenyx are connected via USB. Thx.

Oh yes, discovered that very early on :+1:

Have to admit Toby not experienced this but only generally plug my PG into the laptop if backing up the presets or updating the software ( I tend to use the onboard editing for pretty much everything). Output wise I always go via my mixer or zoom r24

1 Like