[LAU] ground loop hell

Len Ovens len at ovenwerks.net
Wed Feb 11 01:43:39 UTC 2015

On Tue, 10 Feb 2015, Roger wrote:

> These articles may be of interest.
> http://www.rane.com/note151.html
> http://www.rane.com/note110.html

Nothing that I didn't "know", but laid out in a good way so I can practice 
what I know. (If that makes any sense)

> I always try to run all PA and band equipment from the same circuit if 
> capacity is sufficient. The previously

This is where we are at now. The power cable from mixer to stage is about 
100ft(30m) and good heavy size wire.

As an aside... I don't think I will need it at this point, The isolation 
boxes that are easy to get are "DI" boxes tha go from high impedance 
unball to low impedance bal. Would these still work to go from a ballanced 
output to an unballanced input? Or do I need a one to one isolator? Or 
does it depend on the powered monitor? How does this one look:

Having "solved" my problem with a single power source, would it still be 
worth while isolating all stage amps from the mixer? I think I will run 
ballanced audio through the snake and do the cable adapting at the stage 
end anyway. Right now there is a TS plugged directly into a TRS mixer 
output which means the signal minus is grounded. There are two unused 
(unusable) snake lines I could use where we have the DVD and computer 
plugged in as line level.

Hmm, more thought required, the DVD/computer may need changes too.

Len Ovens

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