Pre-Fade Listen. A system used within a mixing console to allow the operator to audition a selected channel signal, prior to the fader, and thus independent of the fader setting. Normally used to check the level of the signal through the channel to optimise the gain structure, or to confirm the presence of a signal before fading it up. (See AFL and Solo)

The practice of removing all headroom to maximise the peak level of an audio signal on a particular medium. So all peak-normalised material will have the same maximum peak value, but the perceived loudness is likely to vary between different tracks. The technique became popular and commonplace with the advent of digital formats such as CD, where the signal level was typically engineered to reach 0dBFS. (See also Loudness-Normalisation, Mastering and Loudness Wars)

The maximum instantaneous level of a signal.

Pulse Code Modulation - the technique used by most digital audio systems to encode audio as binary data.

Peripheral Component Interconnect: an internal computer bus format used to integrating hardware devices such as sound cards. The PCI Local Bus has superseded earlier internal bus systems such as ISA and VESA, and although still very common on contemporary motherboards has, itself, now been superseded by faster interfaces such as PCI-X and PCI Express.

A short cable used with patch bays.

A system of panel-mounted connectors used to bring inputs and outputs to a central point from where they can be routed using plug-in patch cords. Also called a Jackfield.

An alternative term for a Program, referring to a single programmed sound within a synthesizer that can be called up using Program Change commands. MIDI effects units and samplers also have patches. (see also Bank)

A loudspeaker which requires an external power amplifier, the signal from which is passed to a passive cross-over filter. This splits and filters the signal to feed the two (or more) drive units.

A circuit with no active elements.