Extracts four audio channels from either a specially encoded two-channel source or a four-channel source:
Two channels for speakers at the front—left (L) and right (R).
Two channels for surround speakers at the rear—surround left (LS) and surround right (RS). Some newer receivers support the LFE channel.
Describes the early matrixed systems and discrete Quadraphonic surround systems. Source media, usually LP record or tape, is often branded four channel stereo.
Placement: Quadraphonics is a system designed for music only. All speakers should be at an ±45°. All speakers should be above ear height.
