troubleshooting Ground Loops in my rig

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ners

ners

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I'm having noise issues with my rig that I'm pretty sure is a ground loop, but can't find a good solution for. Problem resolves itself completely when I stop using the 4 Cable Method, so the issue obviously resides in that (either my EQ or my noise gate...or both).

Squeals: https://recorder.google.com/9661a955-2ea6-4ba7-9846-3cec9f371fd2
  1. High gain amp (Hellion) with guitar volume off, then slowly roll it up
  2. You can hear all the noise while playing and it 100% impacts the tone (almost like its choking out the guitar signal)
  3. Switch to my clean amp (Fender) and still a bunch of noise and impact to tone
  4. Flip through every amp on my switcher with the guitar volume down.
Here is a shotty/simplified drawing of my rig and the signal chain. Between the BLA and the Strymons I think every piece of equipment is on its own isolated power supply.
1741970197939.png


My attenuator (Boss) has ground/lift switches on both the input and output of the FX loop. Using them separately does absolutely nothing, but when lifting both grounds it does improve things...except not all the way. Can't tell if this is just the way it is, or if there is more I can do to clean things up (isolation transformer...somewhere).

My noise gate (Fortin) also gas a ground/lift switch for the guitar in (not FX loop), but I currently have it off my board for troubleshooting purposes.
 
I'm not the expert here and do not have as complicated of a set up as you @ners but I feel I've now eliminated 'most' all extraneous noise from my rig, outside of the what I consider to be normal Dual Rectifier noise. I have a similar set up in that I am ABY on two high gain amps and one operating loop (on splawn) that also has 4 channel noise gate in play.

JBT had similar issues and there are some good answers in this thread below - along with my suggestions, some videos, and recommendations for ISO Transformer.

Similar thread

Good luck.

For me, it was a matter of making sure everything was on 1 single wall outlet, and then putting on a 2 prong (ground lifted) adapter on one of the amps (mesa). What this did was force all ground signal into the splawn and its power connection. So outside of normal amp hum, it is fairly quiet. Didn't listed to your clip - but your explanation was enough.
 
Please don’t use ground lifts on amplifiers. If there’s a fault in a potentiometer or a capacitor and the chassis is floating you’ll become the path to ground. The giant filter capacitors in amps use the chassis as ground reference and without an actual ground strap the caps can be floating at hot potential with no ground OR neutral reference which is very very dangerous. This is even moreso dangerous at gigs where neutral and hot connections can be reversed by accident which means a non grounded chassis that would pop a fuse can be live. You touch a mic that’s grounded on stage and you’re getting shocked and no one will know to help.

Ground the amplifier and lift only one side of the small voltage stuff you connect to it. Use the ground of the amplifier as ground central.

If you have multiple amplifiers, ground them and use isolation buffers into them. Even better is to use power conditioners and regulators to isolate and filter the power sources for the amplifiers but still always be grounded.
 
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glpg80 said:
If you have multiple amplifiers, ground them and use isolation buffers into them. Even better is to use power conditioners and regulators to isolate and filter the power sources for the amplifiers but still always be grounded.
Click to expand...
I have all my amps on a voltage regulator, so they should be good. I'm not really sure how the amp switcher impacts things but I assume it's making only a single amp visible to the guitar signal at one time? The unused amps should just be seeing the switcher's load.

Given the issue occurs only when using the 4CM with my pedals I assume it's somewhere on my board I need to isolate better but not sure how to identify where.

All my pedals are powered by a single power source (well the Zuma + Ojai together) which is using the same outlet as my voltage regulator does for amps. So they should all have a common earth ground already. Which is why I'm confused about the issue or where to place an isolator.
 
ners said:
I have all my amps on a voltage regulator, so they should be good. I'm not really sure how the amp switcher impacts things but I assume it's making only a single amp visible to the guitar signal at one time? The unused amps should just be seeing the switcher's load.

Given the issue occurs only when using the 4CM with my pedals I assume it's somewhere on my board I need to isolate better but not sure how to identify where.

All my pedals are powered by a single power source (well the Zuma + Ojai together) which is using the same outlet as my voltage regulator does for amps. So they should all have a common earth ground already. Which is why I'm confused about the issue or where to place an isolator.
Click to expand...

You can make a simple cable to break ground on one side to see where you need to place an aftermarket buffer. On any instrument cable, snip the ground connection on one side. Use a mini zip tie to add rigidity back. I keep a marked red cable modified like this to find and fix ground loops. You can even flip the cable around to see which ground reference is lower noise.
 
glpg80 said:
Please don’t use ground lifts on amplifiers. If there’s a fault in a potentiometer or a capacitor and the chassis is floating you’ll become the path to ground. The giant filter capacitors in amps use the chassis as ground reference and without an actual ground strap the caps can be floating at hot potential with no ground OR neutral reference which is very very dangerous. This is even moreso dangerous at gigs where neutral and hot connections can be reversed by accident which means a non grounded chassis that would pop a fuse can be live. You touch a mic that’s grounded on stage and you’re getting shocked and no one will know to help.

Ground the amplifier and lift only one side of the small voltage stuff you connect to it. Use the ground of the amplifier as ground central.

If you have multiple amplifiers, ground them and use isolation buffers into them. Even better is to use power conditioners and regulators to isolate and filter the power sources for the amplifiers but still always be grounded.
Click to expand...
Good point. I should not be so reckless. Not the best long term solution granted. Still good for troubleshooting noise. If you put one on and the noise is still there then you can rule that out. I have mine on my splawn - so I'm confident until I find a better solution. I will caveat in the future :cheers:
 
I use a suhr buffer/splitter and split my signal before the gate. One input goes to the key input on my gate and the other input then goes on to my drive pedals and front of amp. It broke the loop for me. Then I followed the rest of the chain from my gate out to my fx loop
 
PiggySmallz said:
I use a suhr buffer/splitter and split my signal before the gate. One input goes to the key input on my gate and the other input then goes on to my drive pedals and front of amp. It broke the loop for me. Then I followed the rest of the chain from my gate out to my fx loop
Click to expand...
So while I can do this, my EQ pedal has 2 I/Os where I put one in front and one in the loop which also causes the issue.
 
ners said:
So while I can do this, my EQ pedal has 2 I/Os where I put one in front and one in the loop which also causes the issue.
Click to expand...
Missed that part. I just keep an EQ in my loop because I can change some EQ settings on my drive pedals. If you can get away with a single EQ in the loop that is likely the easiest solution.
 
I bought a cheap pyle two channel passive hum eliminator on Amazon that fixed my issue.
 
I bought the Lehle isolator and still can't really solve my problem...not exactly sure why I need it given the amount of ground lifts my rig has.
  • KHE ACS has a ground lift, not sure if it's before or after the selected amp (or after attenuator loop)
  • Boss TAE has ground lifts at both ends of the FX loop
  • Fortin Zuul+ has a lift at the Key input (so before the amp)
Should the placement of the isolator be different? Not sure if the transformer works differently than a lift.
 
ners said:
I bought the Lehle isolator and still can't really solve my problem...not exactly sure why I need it given the amount of ground lifts my rig has.
  • KHE ACS has a ground lift, not sure if it's before or after the selected amp (or after attenuator loop)
  • Boss TAE has ground lifts at both ends of the FX loop
  • Fortin Zuul+ has a lift at the Key input (so before the amp)
Should the placement of the isolator be different? Not sure if the transformer works differently than a lift.
Click to expand...
if you tried it between pedalboard and amp, then you did it right. Ground lifts don't solve the issue. they CAN mask it effectively. Are you returning pedal, or did you buy used?
 
What you using to power your effects? I had a power supply once that was causing me problems. Once I trashed it I was fine.
 
JackBootedThug said:
What you using to power your effects? I had a power supply once that was causing me problems. Once I trashed it I was fine.
Click to expand...
Strymon Zuma, which is also powering 2 Strymon Ojai's (designed to be linked together like that).

I finally managed to solve this with the isolator, so I don't think its the power supply (but maybe still and the isolator is masking the root cause?).
 
Smash said:
if you tried it between pedalboard and amp, then you did it right. Ground lifts don't solve the issue. they CAN mask it effectively. Are you returning pedal, or did you buy used?
Click to expand...
Turns out I didn't try between my board and amp, so I just did and that solved it!

Bought it new off Amazon (think it came from Sweetwater though, didn't know they sold via Amazon), so I can still return it. Now the question is, is $150 for an isolator a reasonable price?

I love how small and passive the Lehle is, I was able to just tuck it into my rack and just a small patch cable to insert it right before my amp switcher. Is there anything comparable size/quality wise for less money? Or does design & component choice matter for these things an I should just keep the Lehle (I'm so unfamiliar with them)?
 
I just tried to set up my stereo rig again and damn it sounds like dog shit. Ground loop hum and some weird oscillating sounds sometimes… got it figured out now though….
 
ners said:
Turns out I didn't try between my board and amp, so I just did and that solved it!

Bought it new off Amazon (think it came from Sweetwater though, didn't know they sold via Amazon), so I can still return it. Now the question is, is $150 for an isolator a reasonable price?

I love how small and passive the Lehle is, I was able to just tuck it into my rack and just a small patch cable to insert it right before my amp switcher. Is there anything comparable size/quality wise for less money? Or does design & component choice matter for these things an I should just keep the Lehle (I'm so unfamiliar with them)?
Click to expand...
Glad you found the issue.

If you haven’t already returned it, keep the Lehle. It will come in handy sometime soon.

My experience with still running a TC G-System 4CM, stereo or W/D/W is I’ve learned Lehle make excellent products and you’ll need their products again.

Other products I use to help my setup is both Ebtech HE-8, Lehle Dual SGOS for multiple amps and Tripp Lite LCR2400 or equivalent.
 
glpg80 said:
Please don’t use ground lifts on amplifiers. If there’s a fault in a potentiometer or a capacitor and the chassis is floating you’ll become the path to ground. The giant filter capacitors in amps use the chassis as ground reference and without an actual ground strap the caps can be floating at hot potential with no ground OR neutral reference which is very very dangerous. This is even moreso dangerous at gigs where neutral and hot connections can be reversed by accident which means a non grounded chassis that would pop a fuse can be live. You touch a mic that’s grounded on stage and you’re getting shocked and no one will know to help.

Ground the amplifier and lift only one side of the small voltage stuff you connect to it. Use the ground of the amplifier as ground central.

If you have multiple amplifiers, ground them and use isolation buffers into them. Even better is to use power conditioners and regulators to isolate and filter the power sources for the amplifiers but still always be grounded.
Click to expand...
Great life enhancing advice!

Two weeks ago I bought a Randall RG80ES used locally on a whim that at the time of the demo, couldn’t work out a deal with the seller. Seller called me as I was driving home from the demo to strike a deal and subsequently already unpowered the amp and packed the amp, tucking the power cord tightly around itself on the back panel. I didn’t think to check because I was already on a time crunch to get home. When I got it home, I went to plug it in and saw the ground prong had been snapped off. Easy fix of course within the day of getting parts at the local hardware store but a small lesson learned for me when buying used and I got experience changing out a 3 prong end. I did message the seller to see if he knew it was running without the ground and he said he’s never had any issues with it become live. Didn’t want to take the chance and neither should you. Again, great advice from glpg80
 
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