Re: arsclist Ground Impedance for Sound Studio

["Richard L. Hess" <arclists@xxxxxxxxxxxxxxx>]

At 08:10 AM 10/25/2001 -0400, José Llufrío wrote:

This happens to be an area that I have spent some time studying. In order 
to get you in the correct frame of mind for what follows, remember 
satellites work fine without being grounded. Think about the image of 
geostationary satellites with 22,300 mile long ground conductors! Ok now on 
to what we're trying to do.

When we say grounding, we mean a lot of things. There is bonding 
(connecting everything together to form an equi-potential plane) and 
grounding (connecting that equi-potential plane to the center of the earth).

The actual grounding is really only important so that you don't fry 
yourself as you step from the real world into the facility.

Everything else is bonding. The goal here is to minimize the potential 
difference among all the points that are connected together. The design 
here is very dependent on the power system design and the overall building 
design.

If you have a central computer room using an access floor the #2 copper 
wire grid  (signal reference grid) is a very useful way of achieving a good 
equi-potential plane.

Is RF present? If so, then surface area is more important than cross 
sectional area. Copper strips are often used (and mis-used) as ground 
references.

Don't be afraid of ground loops. In fact, a ring ground around the 
perimeter of the building is often a very good place to start.

I'm sorry there is no one answer, and answering the question of what 
"impedance" ground is only really useful to determine if the power 
utility's circuit breakers will trip if there is a ground fault on the 
incoming feeder.

The most important function of a ground is personnel safety. Bonding helps 
equipment work better.

Also, there are papers for the "pin one problem" that describes common 
impedance sharing. The noise voltage's drop across the common impedance 
becomes superimposed on the signal.

Hope this helps.

Cheers,

Richard

> Hello, everybody.
>
> Sorry for any duplicates/cross-posting.
>
> In a posting a couple of month past, at ARSCLIST, Graham Newton replied to
> Kurt Nauck:
> "Be sure there is a heavy contiguous ground wire available that goes
> directly to a
> solid earth ground at the electrical entry to the building.  Ground all your
> equipment to this."
>
> I am now involved in the design/construction of a sound recording and mixing
> studio for one of our production units (animated films).
>
> There's much discussion going on among our engineers, about the correct
> impedance for grounding the equipment. Recording and mixing will be mostly
> digital, but analog equipment will be eventually used too.
>
> What would be the right way to ground the sound studio?
>
> If the DAWs are networked with the rest of the computers in the building,
> should everything be connected to a common ground, or should they have
> separate grounding with different impedances?
>
> What is the acceptable impedance for grounding sound equipment?
>
> Is the ground to be independent from the grounding in the electrical mains
> feed (transformer chamber belonging to the power company)?
>
> I plead to the many experienced people on the list.
>
> Thanks very much in advance.
>
> José E. Llufrío
> llufrio@xxxxxxxxxxxx
> Technical Advisor
> ICAIC Cuban Film Institute
> Havana, Cuba
>
>
>
> -
> For subscription instructions, see the ARSC home page
> http://www.arsc-audio.org/arsclist.html
> Copyright of individual posting is owned by the author of the posting and
> permission to re-transmit or publish a post must be secured
> from the author of the post.