Can someone remind me about ground/lift

[Ryan.]

on a DI?

 

It has been a while since I used mine and at a recent party I played some music over my system and found in one of the speakers an annoying hum. I thought about switching the ground/lift on the DI but couldn't really remember whether it was safe or not.

 

would that have possibly solved my problem?

[Miko Man]

Lifting the audio ground on a DI is safe.

 

It might have stopped a hum. Whether it would have stopped the hum you had is an open question.

 

Mark C.

[fdew]

The ground lift removes the connection between Pin 1 of the XLR (Shield) and the DI box and 1/4 in connector body.

 

Neither the shield on the 1/4 in jacks nor the shield connected to pin 1 of the XLR are safety grounds. they are for audio shielding only.

 

Use the DI with the ground lift switch in what ever position gives the least hum.

 

BTW On some DI boxes if the XLR connector plugged into the DI has it's shell connected to Pin 1 then the ground lift switch is defeated.

[rrrredrvr]

Also thought I'd throw this in. Depending on where you're getting your mains power, sometimes duplex outlets at venues are not wired correctly, or have poor grounds between circuits. We always run ONE heavy extension to the mixer cabinet where we have a power conditioner, and then run another heavy extension to the back of stage with multiple outlets (found a 12-gauge Christmas Light extension with outlets every 3 feet or so that was perfect). That way, the power for ALL the amps comes from one, clean, protected source. Our problems with occasional hums and picking up errant radio stations have disappeared. We always run the lighting off a separate circuit (our lighting system has no connection to our sound systems) as with both running on the same circuit, a 15A breaker can pop. At a recent gig, one amp was humming, and found that it wasn't plugged into our clean line, but another, different wall outlet. Moved it over to the clean line, and problem solved.