"Uptown Audio" wrote in message news:yK50c.79648$4o.103084@attbi_s52...
There are plenty of components that have "balanced
inputs", etc but are not fully balanced amplifiers. That is why you
see "fully balanced", and "true balanced", etc used in descriptions.
[snip]
I have heard
gear that had balanced circuitry, but sounded better SE as the
amplifiers were not fully balanced all the way through. It is common
practice to have balanced inputs and then convert to SE and then back
again, just as you would with a A/D and D/A device.

The idea of "true balanced" or "fully balanced" equipment (actually
better termed differential) being necessary to appreciate the value of
balanced interconnections is just one of those audiophile myths that
seem to endure. The entire point of balanced interconnection is to
cancel common-mode noise induced on both conductors as near the input
of the component as possible. Once common-mode noise makes it inside
the component, it is very difficult to get rid of it, and it can be
easily converted to differential mode noise and cause more problems.
True balanced components that try to maintain separate amplification
paths for each balanced phase are a waste of money if they don't do
the balanced cancellation at some point, because they'll just amplify
and pass along any common-mode noise riding on the signal. There are
valid reasons for having a differential amplification topology, but
exploiting balanced interconnections isn't one of them.

A useful side effect of balanced interconnection is that they can be
immune from ground loops, because unlike RCA single-ended
interconnection, they separate the function of signal ground from
chassis ground (assuming no pin-1 problems in the interconnected
components). This, to me, is the most valuable reason to use balanced
interconnections, especially in today's fairly complicated
multichannel/HT systems with multiple boxes and the resultant
goobledygook of grounding topologies.

As for shielding degrading a balanced interconnection's ability to
reduce CM noise, this isn't anything new. When Belden came out with
MediaTwist many years ago, they found that shielding degraded the
matching of the cables, because of asymmetrical parisitic effects.
MediaTwist maintains a very precise geometry through bonding of the
two conductors --- I wouldn't be suprised if the cable under
discussion was just repackaged MediaTwist.

Of course, this assumes that your balanced I/O is up to the
capabilities of the cable --- balanced cancellation of CM noise is
directly proportional to how balanced the input common mode impedances
are. If you have messed up balanced inputs or outputs that aren't
very well designed, a fancy cable isn't going to do much for you, as
something that's already the least of your problems becomes even less
significant.

--Andre