Ground Loops with 4CM - Already using Humbuster Cables

Ryan Pullin

Ryan Pullin

Member
Hey y’all, so I’m dealing with ground loop issues with my Axe Fx 3 going into my amps 4CM. I’m already using humbuster cables and I’m not sure what else to do.

I’ve gone through the extent of plugging my amps into different outlets and different power conditioners to see if the source of the power was the issue, but after several combinations it still didn’t resolve the issue.

I’m using all humbuster cables already. With my EVH specifically, turning off the effects loop removes all of the excessive noise so I know it’s in the effects loop. I have the same issue with my Friedman, so I know it’s not isolated to one amp.

The effects loop part of my signal is utilizing In and Out 4. I confirmed the TRS is in the axe fx and TS in the amp.

What other solutions would there be at this point? I’m skeptical of some of those cheap plug in ground loop killers or modifying any power cables to remove the ground plug.
 
Never defeat the ground connection on a tube amp. If something goes wrong in the amp, you can then become the path to ground through your guitar. It's rare, but not worth the risk. Even vintage amps with two wire power cords should be retrofitted to properly ground the chassis.

Transformer based hum isolators can help in some situations.

Have you tried physically isolating your devices from each other if they are all in a rack? Sometimes the rack itself can lead to ground loops between devices. Humfrees tabs can sometimes help with that.

Do you have any cables bundled together going to and from the amp or a pedalboard? Make sure your signal and power cables are not running closely parallel to each other.

I'd try swapping different cables around as well just in case one is maybe not shielded properly or something.
 
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Ryan Pullin said:
I’m using all humbuster cables already.
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Ryan Pullin said:
The effects loop part of my signal is utilizing In and Out 4. I confirmed the TRS is in the axe fx and TS in the amp.
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“cables”?

You didn’t say exactly where you are using the Humusters. The 1/4” out for OUT 4 is a Humbuster, but IN 4 is balanced, so you can’t use a Humbuster there. Only the 1/4” Output jacks support it.

Which of the suggested setups in Section 4 of the manual is closest to your configuration?
 
muudrock said:
Do you have the humbuster cable ends oriented correctly?
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“I confirmed the TRS is in the axe fx and TS in the amp.
mr_fender said:
Have you tried physically isolating your devices from each other if they are all in a rack? Sometimes the rack itself can lead to ground loops between devices. Humfrees tabs can sometimes help with that.
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The Axe FX is in its own headshell. Nothing else is in contact with the rails that the Axe FX is mounted
mr_fender said:
Do you have any cables bundled together going to and from the amp or a pedalboard? Make sure your signal and power cables are not running closely parallel to each other.
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That could be an issue, I have basically all of the cables alongside each other for cable management. However I used to have my Friedman on the other side of the room, so really only 4 cables total were running to it (input, two effects loop cables, and the power cable) and still had the issues. Is that really a possibility?
mr_fender said:
I'd try swapping different cables around as well just in case one is maybe not shielded properly or something.
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I haven’t gone as far as completely swapping cables around, but I have swapped the humbuster cables in the In and Out 4 L & R with each other. It seems unlikely that four cables would be bad unless QC was horrible at the time I ordered them.
 
Greg Ferguson said:
“cables”?

You didn’t say exactly where you are using the Humusters. The 1/4” out for OUT 4 is a Humbuster, but IN 4 is balanced, so you can’t use a Humbuster there. Only the 1/4” Output jacks support it.

Which of the suggested setups in Section 4 of the manual is closest to your configuration?
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Why are you quoting “cables”? You know Fractal makes humbuster cables right? lol

I said I’m using all humbuster cables so I’m not sure what you’re asking lol. Humbuster cables are going from all the I/O of the Axe FX to the amps, and then I’m using a Planet Waves American Stage cable for the instrument cable to the front input. Not sure how else to explain it lol.

I’m using the setup on page 28. I overlooked that the Inputs do not have the humbuster feature so I’ll try TS to TS cables and see if that makes a difference. If the jack for the Inputs aren’t stereo though for Humbuster, does that really make a difference? Wouldn’t it just not make contact with the ring? I see that the Inputs are balanced, is it possible that a TRS cable in a balanced jack with a TS going to a mono jack could create a ground loop?

I also don’t have the Input 4 set to “left only”, my setup is running L and R respectively to two separate amps and I leave everything connected at the moment.

I’ll make adjustments to match the manual and try it with one amp first to see if the extra noise goes away.
 
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Separate the power and signal cables going to the amp and see if the hum goes away. Power cables will emit EMI along their whole length. The longer you run them in parallel together, the more of that interference you are likely to get picked up by the signal cable.

Only the Fractal 1/4" output jacks have humbuster circuits on them. Using a humbuster cables for the Axe III inputs does no good. Use either fully balanced TRS to TRS cables (if the device you are connecting has a balanced output) or in your case regular 1/4" instrument cables there for the Fractal inputs.
 
mr_fender said:
Separate the power and signal cables going to the amp and see if the hum goes away.

Only the Fractal 1/4" output jacks have humbuster circuits on them. Using a humbuster cables for the Axe III inputs does no good. Use either fully balanced TRS to TRS cables (if the device you are connecting has a balanced output) or in your case regular 1/4" instrument cables there for the Fractal inputs.
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I’ll try that the next time I get the chance. Thank you for the suggestions!
 
I had the same issue and picked up a radial stage bug- solved the problem. I had an issue going into the front of the amp… installed the stage bug, pressed one of the buttons and noise disappeared. I have a stereo amp setup but I believe radial makes a mono version too.
 
I had decent luck with a furman power conditioner in addition to humbusters following the manual's documentation.

I also had to set the Boost/Pad all the way to kill the noise. You'll see the tip in the manual below the 4CM instructions. This was absolutely crucial.
 
Bryanman37 said:
I had the same issue and picked up a radial stage bug- solved the problem. I had an issue going into the front of the amp… installed the stage bug, pressed one of the buttons and noise disappeared. I have a stereo amp setup but I believe radial makes a mono version too.
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I may check one of those out. Ideally I’d like to run a stereo setup but the EVH with the Friedman doesn’t seem to gel well. I talked to Dave Friedman about it and he said it could be the ground loop creating the issue so I wonder if that would be enough.

Unboxed said:
I had decent luck with a furman power conditioner in addition to humbusters following the manual's documentation.

I also had to set the Boost/Pad all the way to kill the noise. You'll see the tip in the manual below the 4CM instructions. This was absolutely crucial.
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I’m actually running everything through some type of Furman. I have a P-1800 PFR, an M8LX, and an SS-6. I’ve tried every combination of all three and cannot get it to quit.

I haven’t tried the Boost/Pad yet and I did see that tip in there. I’m glad that worked for you, I’ll definitely need to try that.
 
It may be that you’re not only getting noise from ground hum but you may also be having a phasing issue when you run stereo. If I run one of my EVHs with one of my Engl’s that can happen for me too. The stage bug helped there as well. There are various phase settings in the AxeFX which I may have played with to fix the phasing issue but I’d have to look.
 
Is your Axe3 sat on top of the amplifier? Sometimes proximity to the transformers can add hum to the signal, even when using humbuster cables.
 
Orvillain said:
Is your Axe3 sat on top of the amplifier? Sometimes proximity to the transformers can add hum to the signal, even when using humbuster cables.
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Yes it’s on top of one amplifier but I have the same issue with the other amplifier that’s not as close in proximity. The noise level is close to identical so I believe it’s something to do with a ground loop between the I/O 3 & 4 and the effects loops.
 
Bryanman37 said:
It may be that you’re not only getting noise from ground hum but you may also be having a phasing issue when you run stereo. If I run one of my EVHs with one of my Engl’s that can happen for me too. The stage bug helped there as well. There are various phase settings in the AxeFX which I may have played with to fix the phasing issue but I’d have to look.
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I messed around with some phase stuff but was addressing the noise issue first before I diagnosed and addressed possible phase issues.
 
I inserted an EBTECH Hum Eliminator XLR within the 4CM routing of my FM3 in combination with Humbuster cables per the owner’s manual and it removed all hum and noise. Works perfectly. The EBTECH properly and safely gets rid of ground or cable related hum.
 
Roxy said:
I inserted an EBTECH Hum Eliminator XLR within the 4CM routing of my FM3 in combination with Humbuster cables per the owner’s manual and it removed all hum and noise. Works perfectly. The EBTECH properly and safely gets rid of ground or cable related hum.
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I’ll check that out, I’m not familiar with that.
 
I have no experience doing this with any Fractal product, but I have put together many racks systems over the years and ground loops are inevitable. I, too, keep Ebtechs around to isolate things. The Ebtechs work great as long as you follow the rules. They are passive so they don't have the complication of their own power supply but that means they have input and output impedance requirements that have to be met to work properly.
 
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