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Ground loop master thread
Old 4 weeks ago
Here for the gear

Ground loop master thread

So I've been doing studio work for a while now and I'm now moving to live work. I usually dealt with noise on instruments by attaching a wire to the bridge or any other place attached to the circuitry of the instrument or cable to mine or the player's skin. I know about instrument shielding and grounding and have a general idea about grounding but it's all still sorta magical nonsense to me. Now that I'm moving into live sound on a cheap mixer, the ground loop thing is getting on my nerves because there are alot of opposing opinions all over the place so I came here to ask for some help. Here's what I want to know. Anyone with knowledge of electricity and dealing with ground loops and such, I'd be very grateful were they to chime in because I'd like to know the science too, not just how to fix it but anyone, feel free to help, talk about your experiences and so on. I'm desperate.
So here goes:
1) Starting from the building's source of power and circuit breaker. I've heard that studios usually ask power companies for an isolated line to remediate 'dirty' power. Obviously this isn't always practical for someone doing live sound but I'd like to know what that's about. I also read about these devices called GFCIs that I think attach to circuit breakers and there are some that are shrunk and in a different form as to attach directly to an outlet. Do GFCIs in a circuit breaker help with ground loops?

2) At the outlet side of things, the outlet version of GFCIs, Power Conditioners with RFI and EMI filtering, 'Ebtech's Hum Canceller', what should we employ here when the buildings power quality is beyond control?

3) After the outlet, moving on to the mixer and audio cables and so on. DI boxes and hum eleminaters on everything? Pseudo balanced cables on some things? Shielded cables help right? Why are audio gear manufacturers so DUMB ABOUT WIRING. There's a compliance standard right? I feel like that's never followed. Found this white paper (a term for something that's well established and could be called a standard) on interconnection between audio gear. Showed all the wiring that should be employed and a sigh of relief came as years of confusion over gear and microphones that misbehaved with mixers.

4) Beyond all guitars being shielded, grounded and having working, noise free equipment (depending on their inherent designs ofcourse [noise cancelling bass pickups anyone? Glenn Fricker taught me that one]), if there's anything past this point that's important I may have missed, feel free to mention.

Thank you to anyone who even read this far whether you have advice or stories to give.
Old 4 weeks ago
Here for the gear

Old 6 days ago
Here for the gear

Found solutions to the problem but will someone please explain this for us normies
Old 6 days ago
Lives for gear
avare's Avatar

Originally Posted by GoldenH2O View Post
Found solutions to the problem but will someone please explain this for us normies
Why do you not at least identify the white paper so we know your level of knowledge?

Put your questions clearly, not buried in paragraphs.
Old 5 days ago
Gear Maniac

1. Find the source/sources of the noise

2. Come up with a solution to fix the noise.

3. don't attach anything to peoples skin. FIX the issue don't bandade it.

There are ALL kinds of reasons you can have issues. If you are doing livesound with your own gear and noise issues pop up at different locations then the issues if probably something in your gear.

Just recently I was working with a church that had 2 issues.

1. Ground loop via laptop connection and
2. RF noise via VGA projector cable

A DI box with ground lift fixed the loop and a new hdmi cable with sheilding fixed the noise issue, now the sound is pristine!

SO step one is to figure out where the noise is coming from.

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