This refers to a system where three wires are used to carry an audio signal: one is the ground (the 0 volt reference), the second carries the audio signal as it varies above and below 0v, and the third carries an inverted copy of the audio signal that goes negative while the original is going positive. This system helps reject noise that might appear along the length of a cable, as outside noise would be the same on both the normal and inverted wires. When these get to their destination, the inverted wire is inverted again and added together with the original signal wire, effectively cancelling out the induced noise.
Balanced audio usually implies a reference signal level of +4dB (higher than line level; still lower than most modular synths), although microphone signals – much weaker by comparison, and therefore more susceptible to outside noise – are almost always balanced as well.
Modular synths tend to use unbalanced audio for their internal signals. If you require a balanced output (or input), you need a special module that converts between balanced and unbalanced audio, plus does any necessary level matching.« Back to Glossary Index