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Re: Roland R-26 handheld recorder and noise

Subject: Re: Roland R-26 handheld recorder and noise
From: "Avocet" madl74
Date: Tue Sep 20, 2011 3:29 pm ((PDT))
> Is there an electrical engineering reason you have the XLR shell & 
> shield connected?

Scott,

Yes, but it is theory, not practice. Theoretically, the conductors in 
side the XLR are not shielded, but in practice with a balanced line 
this is not a problem. The cable screening is of course insulated, 
which prevents ground loops, but the XLR shell is not. My mistake.

There is a theoretical solution which is to connect the shell through 
a 100 ohm resistor which reduces any ground loop current, but the 
practical solution of leaving the shell floating is the best.

When I made an unbalanced-to-floating transformer box for my Brinibox 
rig, I grounded everything to the left cable shield only. I always get 
a classic ground loop if I double ground any mics at the far end. I've 
measured volts between earth and ground, so there must be quite a 
current flowing through the landscape around here.

David

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







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