Re: [english 100%] [Nature Recordists] Re: technical advice on long

["Avocet" madl74]

> Why shouldn't the shell be connected?
> I always connect mine and I haven't had any problems so far. Was
> that a grave mistake?

Volker,

No, but on long runs it can form a "ground loop" if the shells touch
the ground, a mic stand or each other. A ground loop forms where a
circuit is double grounded. I had a problem with outside cables with
connected shells when they were grounded indoors by the mixer to the
company ground connection and outside by earth or touching. The golden
rule is to ground everything only once to a single point.

Even a small voltage difference across the ends of a ground loop can
produce quite a high current conpared to the mic signal and this can
produce a hum which is difficult to trace. (Took me about a day) If
you insulate the shells, it's OK but it is easier just to leave the
shells floating.

David

David Brinicombe
North Devon, UK
Cogito cogito ergo cogito sum - Ambrose Bierce