Ground loops and 4CM using FX8 with tube amp(s)

MRH

MRH

Member
My apologies for the possible redundancy on creating a new thread on this subject.
A quick Forum search seems to suggest there already are many that deal with this subject in one way or another. Please feel free to redirect to an existing thread if appropriate.

I have a very clean/quiet two-channel Fuchs ODSII head
with a 2x12 Feiten cabinet.
Channel 1 = clean to slight-OD
Channel 2 = slight-OD to high-gain OD (cascaded pre-amp gain stages)

Been using my FX8 (just upgraded to a MarkII) and I am having very disappointing (and it seems sporadic) issues with hum.
The noise is definitely associated with the connection of the two devices.
I am using humbuster cables for:
FX8-->Preamp In; and FX8-->series effects loop Return. (All properly wired.)

I have tried various power configurations.
For example, problem occurs when using both amp and FX8 powered though a power conditioner such as
Monster Power Center Pro2500. And, interestingly enough, when both FX8 and head are plugged into the same wall outlet (no power conditioning), the problem seems less severe, but still rather noisy for such a clean amp.

The worst scenario is when I engage several of the ODSII's boost relays (gain, drive and mid-boost), the higher gain Channel 2 squeals under those functions. (To be clear, this does NOT happen with the amp used on its own.)

Would love to hear what experience other 4CM users are having and get some guidance on possible fixes.

Thanks all.
 
the TRS end of your Humbuster cables are in the FX8, right?

have you tried regular 1/4" instrument cables instead just as a test?
 
I had the same problem with my Splawn Competition. Turned out to be the outlets the amp and FX8 were plugged into. I had them on the same outlet as my computer, through a Belkin battery backup/power conditioner. I moved the amp to a different outlet and it reduced the noise/hum by about 50 percent, moved the FX8 to the same outlet as the amp and it dropped again but only slightly. Unplugged the USB from the FX8 and it reduced the noise by about another 20 percent. Much better and more acceptable, I expect a little noise when dealing with multiple cable runs so I can live with 10-15 percent of what the noise was.

I don't seem to have as much of a problem live but I am using other amps for gigging which is why it never occurred to me that the amp wasn't the problem.
 
Sonofiam said:
I had the same problem with my Splawn Competition. Turned out to be the outlets the amp and FX8 were plugged into. I had them on the same outlet as my computer, through a Belkin battery backup/power conditioner. I moved the amp to a different outlet and it reduced the noise/hum by about 50 percent, moved the FX8 to the same outlet as the amp and it dropped again but only slightly. Unplugged the USB from the FX8 and it reduced the noise by about another 20 percent. Much better and more acceptable, I expect a little noise when dealing with multiple cable runs so I can live with 10-15 percent of what the noise was.

I don't seem to have as much of a problem live but I am using other amps for gigging which is why it never occurred to me that the amp wasn't the problem.
Click to expand...

Thanks. I am hoping to find some fix(es) to get the noise-level as low as possible. Not sure why there should be any noise at all if it is truly a ground-loop situation, they are usually fixable.
 
Chris@AxeFxTutorials said:
the TRS end of your Humbuster cables are in the FX8, right?

have you tried regular 1/4" instrument cables instead just as a test?
Click to expand...

Yes. TRS ends at FX8, TS at amp side.
I have used regular TS-TS (originally), and just retried to compare. The humbuster approach is much better, so it is clear that
that is working within its means.
 
Get an Ebtech HumX

It's totally worth it and I carry one around all the time. Now if I could just remember where I put mine... :D

My only gripe (aside from issues with one drive model) about the FX8 is that you MUST use Humbuster cables or you WILL have ground loop issues. That's a pain in my backside because I have a perfectly good PedalSnake and one other set of cables that I routinely use for 4CM that are worthless with this device.
 
  • Like
Reactions: MRH
Karl Houseknecht said:
Get an Ebtech HumX

It's totally worth it and I carry one around all the time. Now if I could just remember where I put mine... :D
Click to expand...

Update: Found my HumX...right where I left it in my gig bag. :)

Doesn't help with ground loops between amp and FX8 at all. The ONLY thing that works is Humbuster cables. I'm a little ticked off at that because it has to be an intentional design decision, but I'll suck it up and buy an extra set of Humbuster cables.

As a point of comparison, my Helix doesn't have ground loop issues. Nor does my GT-100.
 
Karl Houseknecht said:
What about the Helix?
Click to expand...

I don't own one so I don't know. I've read reports on TGP that some Helix users have ground loop hum issues in 4CM. It looks like it is AC powered, and it's therefore required to have a chassis ground. So if you don't get any noise in 4CM using standard cables and no ground lifts or eliminators, more power to ya!
 
You must log in or register to reply here.
Back
Top Bottom