inSync reader David N. comes to us with another grounding issue:

In an old building where I occasionally play keyboards, if I keep my keyboard properly plugged into the ground, it doesn't matter if I lift the audio ground or not, the mixer (plugged into a different AC circuit I'm pretty sure) gets a mix of AM radio+keyboards on my channel. To get quality sound I have to use a 3-2 adapter on my keyboard and plug into the grounded input on the direct box that goes back to the mixer. Why doesn't the ground lifted direct box input give me the same effect (Note the keyboard, snake, mixer, etc. all work fine in other buildings with better wiring)?

For the answer we go once again to our resident "figure it out" guy, Mark (McGyver) Phillips:

You have a "Ground Quality" issue. The AC Safety ground is only required, by code, to save your life. (In the event of an AC wiring failure; either a short circuit to chassis or the loss of the AC common return path, the equipment will not kill you.) The AC Safety Ground is often good enough to also be used as a connection to Earth for audio cable Shielding but sometimes it is not. There are many "potential" reasons why the Safety Ground is not a good Earth shield.

When you use a 3/2 AC adapter you are risking your life. The Safety Ground becomes your audio cable shield. Audio cable shields are usually Aluminum foil with a 26GA wire. It makes a great audio SHIELD and a lousy SAFETY GROUND. Your signal cables are designed to carry signal, they are NOT designed to be able to pop a 15 amp circuit breaker!

Solution: AC Power distribution. Plug all of your audio equipment (guitar amps, keyboards, mixer and PA amps) into the same AC source. This doesn't need to cost a fortune and your life depends on it. Usually the Stage draw is small compared to the PA. Buy a quality, grounded, 12Ga Extension Cord with a quad box. Plug the stage equipment and the mixing gear into the same power source as the PA power amps. Live long and prosper!