Talk About Balanced vs Unbalanced Systems

The idea of a balanced system is one that has confused even the most experienced audiophile. The actual application of balanced systems are further confused by relating them to the characteristics of low vs. high impedance. A balanced system is unique in that it possesses an electrical characteristic called common mode rejection. If one can grasp the idea of common mode rejection, then a balanced system can be easily understood. The fact that a system is balanced or unbalanced has nothing whatever to do with its impedance level, although usually balanced systems are low impedance, but do not necessarily have to be. To begin with however, let's start with an unbalanced system, which is so called because it is simply not balanced. Whenever separate chassis are used for different parts of an audio chain-such as a separate mixer and power amplifier, the signal must be patched through some connector and cable system. The most common connector used is the telephone plug and jack developed by Mа Bell many years ago. These are simply called a "phone" plug and jack, but other type connectors will work equally well. The cable used must be some sort of shielded type, required to reduce stray pickup of extraneous hum and noise and R.F. signal always present around us. An unshielded cable should never be used in this application. Such a system is shown in figure 1.

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