newbie question concerning DIY: about balanced cables, is the cable any different than the regular ones or the "balanced" thingy is produced by the connectors (TRS, for example)? I mean, does a "balanced" cable have some sort of different shielding?
Balancing is actually sending an inverse of the same signal down a separate wire. What that does is that any noise introduced will affect both signals the same way. So when the inverse and original signal are combined, the noise cancels out.
Also since there is leakage through the insulation, the wires in a balance cable tend to be twisted. So they are a twisted pair. Electrically this actually boosts the signal with each twist. An example is network cable, the CAT number (ie. CAT 5, CAT 6) is how many twists per distance. The more twists the better, but only if the signal is balanced (the inverse is sent on the second wire of the pair).
So the connectors have nothing to do with it, but you need three connections, a ground which is also the shield, the + or regular signal, and the - or inverted signal.
Headphone cables are also TRS, but the cable is actually two individual coax wires (single + wire with a shield). They are also not twisted to prevent bleed between the left and right.
XLR's can also be used for power and often are used in lighting control systems. But the cable is completely different.
Shielding is just a wrap around the outside. Some are spiraled, some braided. Foil is the best and cheapest but moving it will cause tears and problems. But it is a great way to save on permanent installs. They tend to be same between coax (guitar cables) and mic cables (twisted pair). This essentially is a capacitor, so that is why length and capacitance measurements matter to some degree depending on the impedance and signal strength.
When you start building say Mogami+Neutrik, your cost will be the same and often even lower than the super cheapo cables.
If you are determined not to solder, or don't have time (ie. I need 40 cables tomorrow) then check out Audiopile.net, I have had really good luck with their cables. I have a couple from Orange County Speaker repair, their connectors are Neutrik clones and the cable is very flexible and sounds fine. They have been holding up for a few years now, so I can't complain.
Redco brand cable (not their mogami and canare and such) is nice cable. But they use rope for strain relief which I have trouble working with, very minor gripe.
