Lexicon DC-1 Supplementary Manual page 6

DC-1Theory
and Design
DC-1 Digital Controller
This technique overcomes the limitation of the monaural surround channel
inherent in these formats, while remaining true to the front hemisphere
directional cues. The audio imaging tracks the picture image in a way which
fulfills the intent of the sound mixer. The drama of this effect is most
noticeable with strong stereo music soundtracks, and on films with strongly
panned effects.
For film viewing, the DC-1 also provides effects for expanding monaural
film sound tracks (Mono Logic), general TV viewing (TV Matrix) and, of
course, direct two-channel stereo playback (Two Channel).
The Dolby Digital version of the DC-1 also incorporates Dolby Digital
processing, a film sound format based on Dolby AC-3 technology which has
been used in cinemas since 1992. Dolby Digital processing features five
completely independent channels, each offering full range fidelity, and a
bass-only effects channel, referred to as "5.1 channels". Six of the DC-1's
eight discrete 20-bit A/D converters are dedicated to processing Dolby
Digital encoded signals. Standard AC-3 decoding is available in the Dolby
Digital effect. However Lexicon has gone beyond this decoding with our
proprietary extension of the 5.1 standard to 7 channels, using Logic 7 matrix
technology. This is included in the 5.1 Logic 7 effect, along with some of the
LucasFilm Home THX enhancements. All the LucasFilm enhancements to
the AC-3 standard are available in the 5.1 THX effect, but without the
Lexicon 7 channel technology. The DC-1 also includes the 5.1 Two Channel
effect, which mixes the 5.1 discrete channels of an AC-3 original to two
channels, in such a way that the sound will play back with 5 or 7 channels
of surround when decoded with the DC-1.
The THX and Dolby Digital versions of the DC-1 incorporate Lucasfilm
Home THX Cinema processing. This program compensates for the tonal
and spatial characteristics of film soundtracks mixed for the cinematic
environment. Home THX provides reproduction of film soundtracks
recorded in Dolby Digital or Dolby Pro Logic. In the DC-1, the two channel
input THX Cinema effect includes a parameter which allows it to utilize the
Lexicon 5 channel surround technology, although 7 channel operation is
inhibited if dipole speakers are selected. All matrix decoding algorithms in
the DC-1 (including the original Dolby Pro-Logic effect) utilize a patented,
completely digital surround decoder, the only one with automatic correc-
tion of inter-channel phase and channel-balance errors (the most common
audio problems in currently available video releases of films). The integra-
tion of Lexicon's proprietary digital signal processing with these new
technologies results in a home theater experience that is unmatched in the
industry.
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