HELP! Grounding issue is driving me nuts

Does it go away when you switch off your IEM transmitter?

 

The only long distance suggestion I have is to disconnect devices one at a time to see if you can isolate the problem. In the alternative, take the whole thing apart (sorry) and connect it one device at a time to determine which connection is causing the problem. Be methodical and change strictly one thing at a time. Also, make sure each individual link in the chain works normally with known working gear. Good luck!

 

Is it possible that the problem was not your gear but something external to your rack?

 

I'm talking about the PA or input wiring to the PA.

 

Possible that the headroom and galvanic isolation of transformer-based DI might work where the (presumably) active-DI does not.

 

It’s because of the 15” & 4x10” cabs. The setup makes interference through the ethers with the beliefs of the TBers and causes static buzz.

No, seriously I had such a thing and it was one 1/4” plug not fully plugged in back in the rack.

 

I am not a rack guy, so don't take my advice over others. The suggestion to isolate components is probably the best, to identify exactly where the problem stems from.
Are you using isolated power supplies/power conditioner?
This was a problem for my pedal rig, easily solved by investing in a quality, albeit more costly power supply.
Lastly, and correct me if I am wrong fof suggesting this, but could you add a noise gate in the signal chain? I don't know if that would solve the problem, but it could be a cheap and quick fix until you can isolate the problem.

 

where are the DI & monitor feeds coming from? how are you running to both heads? FX loop or in the Inst. input?

 

This could easily be caused by the PA being on a different electrical circuit from your rig. Try it at home. If it happens not at home but only at the gig, run your rack power to the same outlets as the PA.

 

To test, ground lift your whole rack. Be careful and I don’t suggest playing that way but often the grounds are tied through the chassis and lifting a single unit won’t do anything.

Sounds like the PA power and rig power aren’t wired the same.

 

I as well suspect something related to power supply.
Lol did the guy have the phantom power on your channel?

 

No fluorescent or corkscrew lamps nearby?

 

This is exactly what I thought.

Is this the only time it's happened?

 

Sometimes isolation transformers can be helpful.

https://www.sweetwater.com/store/de...MIid7p0fr94QIVTv_jBx0ATQFkEAQYAyABEgJfx_D_BwE

 

I had this issue with an Ampeg SVT 1000 and DI to FOH and ended up making a short XLR cable with a hard wired ground lift on the amp end of the cable and the problem stopped. This was per Jerrold Tiers (Ampegs Engineer) who suggested many of these amps with an electronic balanced out aren't as good as a transformer balanced out. Of course this did not fix the actual problem but it eliminated the hum.