Kurt Nauck:

> We are doing some re-arranging of our studio here at 
> the shop.  We're encountering hum from the audio 
> cables being in proximity of power cables and possibly 
> from florescent lighting (!)  

Are the audio cables balanced?

If not anything you do will be a guesstimate.

With Quadstar balnced cables and properly balanced send and receive
sources and RFI fiters at the inputs then nothing will be heard from any
external unwanted sorce.

> Is there some way to shield audio cables from the 
> influence of power sources? 

In fact line level sources using tightly twisted cables like Media Twist
from Belden does not even have a shield since proper balancing insures
that all common mode interference will be rejected by the receiver.

Unbalanced connections are notorious for picking up all sorts of
interference and are almost impossible to get quiet enough.

> I've read that one 
> should always cross audio and power cables rather 
> than having them run in parallel. 

Unbalanced, yes.

Properly balanced makes no difference at all.

Its alway eye opening to see someone twisting several feet of balanced
cable aroud a big power transformer and cranking the volume fully on and
not hearing a thing.

Do that with an unbalanced connection and the hum is deafening.


Goran Finnberg
The Mastering Room AB

E-mail: [log in to unmask]

Learn from the mistakes of others, you can never live long enough to
make them all yourself.    -   John Luther