Lexicon DC-1 Supplementary Manual page 31

DC-1 Theory
and Design
THX Enhancements
THX with Lexicon Stereo Surround 5-
channel decoding combines full Pro Logic
decoding with stereo surrounds.
28
The LFE channel delivers deep bass information for special effects and
music soundtracks, but is not always used. Recordings made without the
LFE channel are referred to as "5.0" soundtracks.
Home THX Cinema is designed to present film viewers with the same audio
impressions perceived by the film director on the "dubbing stage" — the
studio in which the final mix of the soundtrack is established. These stages
feature a large screen for viewing the picture and a massive audio console
for controlling every aspect of the soundtrack. THX attempts to precisely
reproduce the experience intended by the director in a home environment.
In general, this requires not only considerations of the characteristics of a
small room (as opposed to a large dubbing stage), but many specific system
performance requirements. A complete THX system for accurate transla-
tion of dynamic motion picture soundtracks requires a specific array of
speakers which are designed to produce the soundtrack's full frequency
response and dynamics without distortion, amplifiers which meet exacting
specifications for distortion, noise, stability and dynamic power, and a
Dolby Pro Logic controller with electronic enhancement.
As a complete discussion of the theory of THX design is beyond the scope
of this booklet, we refer you to LucasArts for detailed information on all
aspects of the Home THX Cinema system. (LucasArts Entertainment Com-
pany, THX Division, P.O. Box 2009, San Rafael, California 94912 Telephone:
415-662-1900) Here, we will limit our discussion to the advantages of the
DC-1 as a THX controller.
The main requirements of any THX controller are:
Dolby Pro-Logic Surround decoding
Subwoofer Crossover
Re-equalization
Surround Decorrelation
Surround Timbre-Matching
Dolby Pro-Logic decoding is not only necessary to decode soundtracks
which are encoded in a matrixed surround sound format such as Dolby
Stereo or Ultra*Stereo, but enables all motion pictures (including the more
than 5000 made in matrix stereo) to be reproduced as they were heard in the
film studio dubbing stage — no matter what delivery system is used. The
DC-1 is a completely digital, Dolby Pro Logic decoder with patented
automatic correction of inter-channel phase and channel-balance errors.
With this technology, home theater speakers not only reproduce the appro-
priate audio information, but correct errors which occur in the multiple re-
recording processes of most video software releases.
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