Balanced cables

Audiozen 2-27-2018
... just about all high end mono amps have both RCA and XLR inputs as well as dual mono stereo designs in a single chassis. So if a balanced dual mono/stereo preamplifier has both XLR and RCA outputs, and both outputs from XLR or RCA or moving signal from a separate mono channel for left and right, then in essence their both balanced cables doing the same thing.

They are both doing the same thing in that they are conveying, or at least attempting to convey, the same information from one component to the other. But they are doing it in very different ways, with results that are unlikely to be identical.

A balanced interface by definition has two signal lines which have the same impedance between each of the signal lines and ground, at least to a **very** close approximation. That equality of the impedances between the two signal lines and ground is a necessary condition for a balanced interface to provide the noise rejection it is known for. It is also frequently the case that those signal lines carry a pair of signals that are of equal amplitude but opposite polarity, which can provide additional advantages such as improved signal-to-noise ratio, reduction of certain forms of distortion, and minimization or elimination of cable effects (if the criteria Ralph has described are met).

Components whose internal signal paths are balanced but which provide RCA connectors in addition to XLR connectors typically convert the unbalanced signal provided to the RCA connector or received from the RCA connector to or from a balanced pair of signals that is processed internally, with the conversion often being accomplished via either an active stage or a transformer. Or in some cases the RCA connector is simply connected to one of the two signals in the balanced signal pair, with the ground shell of the RCA connector being connected to circuit ground.

An interface which conveys a single signal and a ground connection is not balanced, both by definition and as a practical matter.

Regards,
-- Al

Shadorne.....thanks, but I sent the mid and trweeter drivers to Vandersteen who tested and deemed them fine.

The only reason James Cannon designed the XLR is for very long cable runs beyond 25 feet. A very well designed solid state preamp is quiet as a tomb and its redundant to use a 1 meter pair of XLR's since there is no noise to deal with. To create this myth that XLR cables have an effect on the quality and quantity of the music signal is outright fraud. The quality is in the recording itself whether its vinyl or CD and has nothing to do with the wire or the connector. If its a very bad recording its going to sound like crap regardless what cable your using, XLR or RCA. Now if you have a poorly designed preamp with a high level of cross talk and noise than the XLR will help to flush out the noise at the output. Its just wire with a good ground, its not a "mini preamp, a "processor", or a buffer like many
in the high end retail continue to perpetuate to make more money. David Belles who makes the finest solid state and tube preamps in the country in their price range, whose always off the radar, could care less about XLR's with his top preamps, soild state or tube. His pieces are dead quiet, all single ended, and when you listen to his model's, "balanced" cables will be the last thing on your mind.   

Just wanted to reiterate that if designer lays out his signal path to be more direct to the XLR and the gain is set higher to that output it will always sound better which is the intention, if the opposite is done to the RCA out, it will always sound better as well. 

+1 audiozen! Thank you for your cogent explanation and debunking of the "superiority" myth of XLR (Cannon) connectors!