| Charlie Richmond - Richmond Sound Design - Skype: charlierichmond |
| http://www.RichmondSoundDesign.com "Performance for the Long Run" |
| -- Free! - SoundMan-Designer - Show & Sound Control Software -- |
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| - King Lear |

---------- Forwarded message ----------
Date: Sun, 16 Mar 2008 21:42:30 -0700 (PDT)
From: Dan Monti <sndguy@...>
Reply-To: EntertainmentElectricity@yahoogroups.com
To: EntertainmentElectricity@yahoogroups.com
Subject: Re: [EntertainmentElectricity] Isolated Ground

In my equally NSHO, Isolated grounds are quite
good/fantastic if done properly. This means planning,
lots of it and EVERYONE is on board with what, why and
how. That said, they are good only if you can control
their use, ie radio stations, recording studios... In
a large multi-use space, I agree, waste of time and
money.
Also, isoground systems should be as small in
geography as possible. Distance yields resistance and
that means voltage drop and hum. More copper, lower
resistances, but cha ching $$$. I think the studio I
was at ran zero gauge or larger between rooms to keep
things equal. That is 70' at the longest. In a huge
space that would just get stupid.
ISO-Grounding is not so much isolated as it is bonded
in one place only.

-D

--- cpz@... wrote:

> In a flurry of recycled electrons, Pip Schulte
> wrote:
>
>> One of the things they are trying
>> to figure out is whether or not to put in any
> isolated ground plugs
>> around the building.
>
> Don't do it....
>
>> From what I understand, in the sound amp room and
>> the main control room they will have some isolated
> ground.
>
> Isolated from what? (and for how long?)
>
>> But he also
>> has need to be able to plug a sound mixer in
> different parts of the
>> building and patch into the system. So should he
> install some isolated
>> ground plugs around the building or will plugging
> into any outlet be
>> fine without getting that ground hum?
>
> In general, and IMNSHO, isolated ground outlets are
> worthless. They're
> hard to install properly, tend to be installed for
> the wrong reasons,
> are hard to troubleshoot when something goes wrong,
> and... the moment that
> the case of the mixer (or anything related, really)
> touches some other
> metal, it becomes grounded through that, too. Which
> creates another ground
> loop.
>
> If he's concerned about ground loops, use proper
> audio wiring techniques
> and isolation transformers as needed and leave the
> power/protectice ground
> alone. (Some web searches for ground loop
> prevention will provice
> some valuable info. Or search the forum at
> mikeholt.com for "isolated
> ground".)
>
> (In the steel mill where I worked, about once a year
> when -everything-
> was out of service, the electricians would
> disconnect each iso ground
> wire from the main bus and test it. About one in
> four showed continuity
> back to the bus, and this is in a facility where you
> have trained
> personal doing the work.)
>
> Not that I have a strong opinion about it :-).
>
> z!
>




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