see Back Electret.

An additional dedicated mixer input channel, usually with minimal facilities, designed to accommodate the output from an external effects unit. (cf. Aux Return)

An interface system, usually involving separate send and receive connections, which allows an external signal processor to be connected into the audio chain. (cf. Insert Point)

A treatment applied to an audio signal in order to change or enhance it in some creative way. Effects often involve the use of delays, and include such treatments as reverb and echo.

The initial sound reflections from walls, floors and ceilings following a sound created in an acoustically reflective environment.

A variant of the SATA interface, called eSATA (with the 'e' standing for 'external'), permits the connection of external hard drives -- see SATA.

A modular synthesizer format developed by Doepfer in the mid-1990s for its A‑100 system, but which has since become a standard format embraced by most modular synth manufacturers. It uses 3U high panels to accommodate standard Eurocard-size electronics, with 3.5mm plugs for patching and a +/-12V dual-rail power supply (sometimes with a separate 5V rail) connected via a ribbon cable.

Describes the polar response of a microphone or loudspeaker that is equally sensitive both front and rear, yet rejects sounds coming from the sides. Also called Bipolar.

The accuracy or precision of a reproduced acoustic sound wave when compared to the electrical input signal.

A form of audio compressor in which an FET is used to provide variable signal attenuation. FET compressors are fast-acting in comparison to opto-compressors.