Balanced Audio - Internally Balanced Audio Design

Internally Balanced Audio Design

Most professional audio products (recording, public address, etc.) provide differential balanced inputs and outputs, typically via XLR or TRS phone connectors. However, in most cases, a differential balanced input signal is internally converted to a single-ended signal via transformer or electronic amplifier. After internal processing, the single-ended signal is converted back to a differential balanced signal and fed to an output. A small number of professional audio products have been designed as an entirely differential balanced signal path from input to output; the audio signal never unbalances. This design is achieved by providing identical (mirrored) internal signal paths for both pin 2 and pin 3 signals (AKA "hot" and "cold" audio signals). In critical applications, a 100% differential balanced circuit design can offer better signal integrity by avoiding the extra amplifier stages or transformers required for front-end unbalancing and back-end rebalancing. Fully balanced internal circuitry has been promoted as yielding 3dB better dynamic range.