2.1
Cinema-style surround sound from 2 speakers and a subwoofer. Front left and right channels deliver dialogue and on-screen sounds, and also surround effects normally reproduced by separate surround speakers. The LFE (Low Frequency Effects) channel provides low frequency bass at certain points for sound effects such as explosions. 5.1 sound can be “downmixed” by a 2.1 system.
5.1
Very precise cinema-style surround sound from 5 speakers and a subwoofer. Front left centre and right channels deliver dialogue and on-screen sounds, while twin left and right surround channels provide the surround effect. Both Dolby Digital and DTS are forms of 5.1 surround sound.
All-in-one
A unit containing surround sound decoding, amplification and multiple speakers.
Centre speaker
A loudspeaker which generally sits above or below your TV and reproduces dialogue and other front-oriented sound effects.
Coaxial digital cable
A lead used to connect a DVD player to a home cinema surround system. Carries the 5.1 signal to be decoded by the receiver.
Dolby ProLogic
A technology which decodes audio encoded in two-channel Dolby Surround for four-channel playback. The channels consist of Front Left/Right, Centre (mainly for speech) and Rear (for sound effects), combining to offer superb three-dimensional sound. Good sources of Dolby Surround material include TV broadcasts, video games, or DVDs of older films (which don’t carry 5.1 audio).
Dolby Digital
This sound format is more advanced than Dolby ProLogic. The surround speakers output full-range stereo sound, and a subwoofer channel for deep bass is provided. The format is also referred to as 5.1 with the subwoofer designed as the 0.1 channel. All six channels are recorded separately for superior channel separation, which ultimately leads to greater steering of sound effects around the room.