Whenever you're mixing sound, whether in a studio or a live environment, grounding the mixer is among the most fundamental and easy things you must do. Ground-induced hum can be introduced throughout the signal chain and is one of the most distracting and annoying mishaps that can occur, virtually ruining the resulting sound output. Most every audio mixer, from rack mounts to state-of-the-art studio and concert mixing consoles, have a connection to ground the mixer.
Locate the ground terminal on your sound mixer. If there is no terminal, attaching a grounding wire securely to a metal part of the board chassis will also ground the mixer.
Connect the grounding fork, a U-shaped metal connection on an RCA cable, to the grounding post on the mixer. The grounding post is most often positioned on the back panel of the sound mixer.
Loosen the grounding screw, if the grounding post on the sound mixer is a screw, and slide the grounding fork beneath the screw shaft. A bare wire wrapped around the post will also suffice for grounding purposes if you don't have a particular cable.
Tighten the grounding cable securely to sound mixer and route and attach the other end of the grounding cable to any metal surface that is in contact with the ground.
Turn on the sound mixer to ensure there is no audible hum induced by a lack of grounding.