ground loops in a studio

[milesdf]

hi everyone this is just a little off topic as I am well trained in live sound and this pertains to a broadcast studio and I am posting it in a recording studio forum, sorry about this, but I thought you might be able to help me, and I am sure most of this carries through to all three fields. i am posting to get clarification on the avoidance of ground loops in a broadcast studio (remote transmitter) which will probablly be completely rewired this summer.

I have been reading alot on the subject of grounding pertaining to audio, and it seems that alot of the advice states that ground loops should be avoided from the start by lifting the ground on the audio cable between two grounded devices at the transmitting end. no ground loops, period. alot of other literature states that grounds should only be lifted if there is a problem, meaning that there are still ground loops around but if theres no audible issue, dont worry about it. my background in live sound tells me that you shouldnt mess with grounds unless there is noise, but in a studio I am thinking that care should be taken with grounding because even a barely audible issue is an issue. what is the correct stance on this in my application?

another issue arises from the power ground in the studio. all the equiptment is currently plugged into power strips, for surge protection and because there arent enough outlets. while there is already a star grounding scheme intact for the outlets in the studio, this is defeated by the power strips, correct? what are your thoughts of me taking one or two of the existing 20 amp circuits and splitting it into about 10 duplex outlets and connecting all the grounds to a central point, possibly the grounding lug on the console (as the console manual recomends), or maybe just in an enclosure somewhere, with only one ground going back to the main panel? would such a grounding system be worth it?

the reasons I want to rewire are that its currently an incoherent mess and nothing is documented, i plan on planning this all out with schematics that can be followed in the future, I have attached an attempt (the note on the line in pair of jacks is a typo). If you were fairly competent, could you understand whats going on here? or is there some standard I should be looking into for these drawings?

thanks for any help or comments.

[Aaronw]

Greetings,

Steve (Knightfly) would probably be able to answer this best, but I'll try and give a few answers here...

I have been reading alot on the subject of grounding pertaining to audio, and it seems that alot of the advice states that ground loops should be avoided from the start by lifting the ground on the audio cable between two grounded devices at the transmitting end. no ground loops, period. alot of other literature states that grounds should only be lifted if there is a problem, meaning that there are still ground loops around but if theres no audible issue, dont worry about it. my background in live sound tells me that you shouldnt mess with grounds unless there is noise, but in a studio I am thinking that care should be taken with grounding because even a barely audible issue is an issue. what is the correct stance on this in my application?

Typically, if you're not getting problems from the grounds, leave them be and not worry about it.

another issue arises from the power ground in the studio. all the equiptment is currently plugged into power strips, for surge protection and because there arent enough outlets. while there is already a star grounding scheme intact for the outlets in the studio, this is defeated by the power strips, correct?

Technically yes, as all equipment doesn't have it's own home run to ground. They're sharing the same ground.

what are your thoughts of me taking one or two of the existing 20 amp circuits and splitting it into about 10 duplex outlets and connecting all the grounds to a central point, possibly the grounding lug on the console (as the console manual recomends), or maybe just in an enclosure somewhere, with only one ground going back to the main panel? would such a grounding system be worth it?

Are there other items sharing the same power, eg: HVAC, refridgerators, or anything with a motor? Could this be source for your noise?

Depending on your console, you may want to consider tightening down ALL of your grounds in the console chasis. (A new trick I recently learned from a tech who commissioned a Neve console for a friend of mine). We tightend down every part of the chasis, and there's no noise.

Does all the audio gear have it's own grounding rod, or are you sharing w/ the rest of the power in the building?

Regarding the outlets, it wouldn't hurt to separate onto additional circuits.

I've been really short on time lately, but hope this may give some help.



Aaron