Lexicon DC-1 Supplementary Manual page 25

DC-1 Theory
and Design
22
In the 1980's a new movie theater sound system was created under the name
THX. This system addressed, for the first time, the design of a theater
speaker system which could faithfully reproduce the film director's inten-
tions. The THX Sound System complemented and enhanced the playback
of Dolby Stereo, and encompassed standards for power amplifiers, speak-
ers, and the acoustics of theaters themselves, to assure the best possible
reproduction of movie soundtracks. By 1990, this system was available in
over 500 theaters across the country. The recent availability of film on video
tape and laser disc has led to a demand for home audio/video systems
which equal the best theater sound. The Home THX Cinema system was
designed to address this need, and the DC-1 incorporates it into the THX
Cinema effect.
Research at Lexicon has taken the possiblities of THX decoding to a further
level with the introduction of true 7 channel decoding using a stereo
surround process. This option is available via the Surround Effect param-
eter in THX Cinema, and is further refined in the Logic 7 effect. The variety
of DC-1 surround film effects allows you to have the highest possible sound
quality for video material — whether you select classic monaural movies or
the latest releases with all of their special effects — simply by changing
effects.
Dolby Digital began appearing in theaters in 1992. Unlike analog Dolby
surround, with its mono, band-limited surround channel, Dolby Digital has
two completely independent surround channels. As a result, film sound
engineers can implement true stereo surround effects, providing theater
audiences with an expanded sense of depth, localization and overall real-
ism. In 1995, films with Dolby Digital soundtracks were first released on
laser video discs, allowing home theaters equipped with Dolby Digital
playback systems to reproduce the same multi-channel digital sound heard
in cinemas.
Playback of Dolby 5.1 soundtracks in the home also benefits from the Home
THX system. The acoustics, equalization curves and speaker arrays used in
mixing remain the same, whether mixing a four-channel analog Dolby
soundtrack, or a 5.1 digital soundtrack. In the DC-1, the THX 5.1 effect
provides THX Home Cinema enhancements for playback of Dolby Digital
source material. The 5.1 Logic 7 effect incorporates Lexicon enhancements
in addition to some of the THX parameters to reproduce Dolby Digital
soundtracks with a greater sense of spatial realism, creating a more cin-
ematic presentation.
Other delivery formats featuring Dolby Digital are in development. Dolby
Digital has been chosen as the digital audio format for DVD, a new digital
playback medium for film and music, and it has been selected by the Grand
Alliance to provide digital surround for the HDTV system being developed
in the U.S.
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