Word For The Day Archive

Balanced

In audio, the opposite of Unbalanced. For us balanced refers to a type of AC electrical signal having two "legs" independent of ground. One is generally considered positive (+) and the other negative (-) in voltage and current flow with respect to ground. Unlike unbalanced audio lines there is no "signal" carried in the shield or ground connection unless there is a fault. The main benefit is that any noise that gets induced into the line will be common to both the positive and negative sides and thus canceled when it arrives at its destination, assuming the destination is balanced. This phenomenon is called "Common Mode Rejection" and basically just means that any signals common to both the positive and negative legs of balanced lines get canceled. This happens because when the receiving device looks at the signal the common noise actually shows up as out of phase with itself, and gets cancelled. Think of it as if the negative (-) signal gets inverted to positive (+) before use, which puts the desired audio signal in phase with the already positive other leg and at the same time causes the undesired common noise to become out of phase with itself. Clear as mud? Balanced lines are generally much better for long cable runs due to their ability to reject induced noises. XLR and TRS type cables are designed to transmit balanced audio from one balanced device to another. A standard 1/4-inch guitar cable is an example of an unbalanced cable. Another (newer) application of balancing that is becoming popular in audio systems is the idea of balanced power systems. Fundamentally the concept is the same. There is a positive and negative (with respect to ground) leg of electricity at every electrical outlet. The idea is that the power supply of any devices connected can then reject any noise induced on the AC line and thus will produce cleaner audio. We'll talk more about balanced AC systems in the future.