Re: ground-loop problems

In article <h0pha3$oa2$1@xxxxxxxxxxxxxxxxxxxxxxxxxx>,
William Sommerwerck <grizzledgeezer@xxxxxxxxxxx> wrote:
This is precisely the kind of discussion I did not want this question to
devolve into.

I don't understand why you think an audio system with components
separated by 20' or more, and connected to different power lines, can be
wired with unbalanced interconnects, on the naive assumption that there
will never be any problems with hum or noise.

Because it is the common domestic way to do it. In the UK at least. You
may well have to take care with cable runs to avoid picking up
interference from mains wiring etc - but then the same applies to balanced
circuits too, although they are more robust.

For what it's worth, all my prior systems had the power amps sitting
next to the preamps. The components were connected with unbalanced
cabling, and I never had problems with hum, noise, etc. Nor did it ever
cross my mind that any of these systems would be "better" with balanced
wiring.

Well they can't be 'better' since you're introducing extra electronics to
balance and unbalance the signal - not many devices are balanced
internally.

My Parasound components -- and the Apogee electronic crossovers -- have
both balanced and unbalanced inputs and outputs, and can be freely
connected as desired. Other than the fact that balanced cables cost
slightly more than unbalanced -- why would anyone in their right mind
use unbalanced cables? Balanced cabling is in every way "superior".

You also have a balanced output radio tuner? Record deck? Etc?

I'm friends with the manager of the Bellevue Magnolia. I'll ask him what
their installation department's opinion on this matter is, and /why/ they
hold that opinion (whatever it might be).

Domestic equipment is fitted with balanced in and out because it looks
professional. Or so it may be used in a pro application, as at the power
amp side of things there is some crossover between them. But not really
with AV stuff.

If your equipment is designed for balanced operation it's quite likely the
unbalanced connections are an afterthought and the screen connected to
mains ground. A simple check with a DVM would confirm this. If this is the
case they ain't suitable for unbalanced connections directly. But that's
their design fault - nothing to do with principles.

I'm not trying to deny that balancing is necessary for long cable runs -
especially with low level signals, like from a microphone. Just that it's
an unnecessary extra expense and complication in the domestic environment.

--
*Don't worry; it only seems kinky the first time.*

Dave Plowman dave@xxxxxxxxxxxxxxx London SW
To e-mail, change noise into sound.
.

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