XLR or RCA?

I used a new pair of balanced cables into a decidedly non balanced but XLR friendly power amp, and they sounded like crap. Seriously...replaced them with much better XLR cables and all is well (although in this case I could be using single ended cables I do prefer the XLRs anyway). I noticed some substantial differences between brands of ACTUALLY balanced cables when mixing sound with headphones from a live feed (TV show production). Even with truly balanced signals I can say that better cables can sound much better. Who knew?

****************02-23-14: Ferrellms
For long runs, rule of thumb being 50 feet, XLR will pick up less interference (less noisy), but in general there will be no real (measurable), as opposed to perceived, (subjective) difference. *****************

This is nonsense. It is an intentional distortion of the following statements from a whitepaper published by Rane, Inc. (in coordination with the Bill Whitlock of Jensen Transformers, Inc.) used by equipment and cable manufacturers who do not offer differentially-balanced products:

"Since the input stage is not balanced, induced noise on the signal conductors is not rejected. If you must use an unbalanced input, use as short an input cable as possible. This reduces the induced noise. There's a reason it's hard to find and buy unbalanced RCA cables longer than 12 feet. Figure 5i shows both ends of the cable shield connected to units with chassis-grounded shields. If the units are far apart, the chance of the shield currents inducing noise on the signal conductors is greater. Keeping this cable very short reduces the shield current and therefore reduces the noise that is not rejected by the unbalanced input stage. Most systems may require disconnecting one end of the shield for the Figure 5i case. Even a small current in the shield may prove too much for an unbalanced input stage."

and this:

"Fully unbalanced systems do not provide a 3-conductor connector to enable proper use of a shield. In the unlikely event you run across one, use the wiring in the fourth column (Figure 5m-p). Again keeping cable lengths short will reduce noise problems, with or without a shield."

Read the entire whitepaper for yourself:

http://www.rane.com/note151.html

Further accurate information on the benefits of the correct implementation of differentially-balanced circuits can be found on the pdf link at the bottom of the page of this link.

Dave

@ Dlcockrum, Hi, The last part of your post that your white papers said, Again keeping cable lengths short will reduce noise problems, I have been saying this for the last 25 years!, the fact of the matter, I have said this recently to a few members, It does not matter what I tell them, They believe some manufacturer that says other wise, or believe someone they know, It's to the point of, what do I know, right?, LOL!, I use 6ft speaker cables, all XLR interconnects are 1-meter length, no rca cables at all, all componets are true balanced from in-put to out-put that I use, been doing audio for 35 years, this a very long time, again, what do I know!

Noise gets in by direct capacitive coupling or electromagnetic pickup. In case of capacitive coupling shield can be very effective. Electromagnetic pickup is a little more complex. Shield is made of aluminum or copper - a non magnetic material and cannot protect against electromagnetic waves, but because of skin effect induced noise currents flow on the outside of the cable - shield. Skin effect works at higher frequencies but at low frequencies cable becomes effective antenna when length of the cable approaches 1/10 of offending signal wavelength. It means that if your cable is very long it will pick-up all sorts of electromagnetic interference in spite of shield. Balanced cable not only allows to reject common mode noise by being balanced but also by twisted wires inside - very effective against noise pickup (capacitive or electromagnetic) by exposing both wires to fields evenly causing same noise currents in both conductors producing cancellation. Keeping cables short is extremely important. My IC is 0.5m XLR.

Fully balanced signal is what makes live sound reinforcement buzzless and clean (except for electric guitar players with noisy single coil pickups)...with 100 foot (or more) snakes. You can take an unbalanced signal cable from a live musician's instrument pickup, stick that cable into an active "direct box" that changes it into the balanced signal the mix needs, and the result is clear as a bell. Also, the "future" is wireless live mixing (use an iPad).
When I play electric guitars I end up using long runs of unbalanced guitar cables (all the stomp boxes with an input cable and out to the amp) and have to apply small "micro amp" boost in there to unload the pickups and retain a modicum of fidelity. Nothing quite like a modicum of fidelity.