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Wired Up
Devin DeVore

Unbalanced | Balanced
Unbalanced connections have two conductors, one at ground potential and the other carrying signal. Equipment operating at -10 dBv invariably uses unbalanced connections.

Balanced connections use two conductors, each which carries the same signal but with the polarity of one reversed with respect to the other. Balanced connections may or may not be referred to ground. If not, they are referred to as floating connections. A balanced connection referred to ground requires three conductors, the third having ground potential.

Why use balanced connections?
In sound reinforcment and recording evironments, balanced connections are preferable to unbalanced because they are far less susceptible to interference. Also many feel that the redundancy of two signal conductors carrying audio yields better quality audio.

Good cables and connectors
Not all cables and connectors are the same. Good connectors will have low contact resistance and well supported strain relief. Products like Whirlwind, Switchcraft and Neutric have been the industry standard for years. All brands offer quality products for equipment interfacing.

So what about cables? Cables can play a big roll on the quality of your audio signal. Even if the diameter, wire gauge, and general construction are similar, two cables may have significantly different electrical and physical properties such as resistance, capacitance between conductors, inductance between conductors, over all flexibility, shielding density, durability, ability to withstand crushing or sharp bends, tensile strength, jacket friction, and so forth.
The best shielding you can use is foil shield, but such cables are not particulary strong and the shielding can deteriorate if they are flexed too much. Foil shielding is most often used in permanent installs and within racks where cable movement is minimal. Braided and wrapped cable is most often used for mic and instrument cables. Braided is preferred over wrapped because wrapped tends to open when flexing. This only degrades the shielding density and can also cause microphone noise.
If the cable capacitance changes when you flex it, this can change the induced noise level, and the cable is said to be microphonic. This can be a big problem with phantom power in mic cables, it can happen in any cable though. Avoid this problem by using cables with stable dielectric (insulating) material, and with a tightly braided shield that is well-trapped by the outer jacket so the shield itself doesn't open up as the cable is flexed.

Unshielded cable
Shielding adds capacitance, bulk, weight, and cost to a cable, but never consider using unshielded cable for instruments or microphones.

Speaker signal is different. The signal level is so high in speaker cables that electromagnetic noise is insignifcant in comparison so unshielded cable is fine. In fact, the higher reactance of shielded speaker cables can induce deleterious parasitc oscillation.

Additional infomation provided by Yamaha


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