Lexicon DC-1 Supplementary Manual page 22

DC-1 Digital Controller
these parameters are set for pleasing results with a wide variety of program-
ming, but they can be changed to produce a versatile mode for film sound
— and some music as well.
The Front Steering parameter, which controls the steering among the front
three channels, is preset at Full (the appropriate setting for Dolby Surround
encoded films). Lower settings cause centrally located sounds to be dimin-
ished in the side speakers and vice-versa.
The rear noise reduction parameter (Dolby B NR) is preset to ON, meaning
that the high-frequency sound in the rear channels is being decoded and
frequency limited by the Dolby B circuit. This control may be turned off for
non surround-encoded material, or when full-range surrounds are desired.
The Side Assign parameter can be used to connect the side speakers in
parallel with the front speakers. The resulting wide frontal image can be
effective on a variety of films and music, but for most material, the standard
setting is recommended.
The Re-Equalizer applies the THX main equalization to all the channels.
Stereo surround is also available in this mode.
The Music Surround effect in the DC-1 is designed to optimally play
conventional stereo music through any system which includes side or side-
located rear speakers.
Conventional stereo generally relies on the acoustics of the playback room
to regenerate the important side, or lateral, energy which is present in nearly
all music performance spaces. Speakers which are arranged for film view-
ing, however, often have the front loudspeakers too close together for
optimal reproduction of the spaciousness of the original soundfield. With
the DC-1, additional speakers located near the sides of the listeners can add
to the playback spaciousness. In the ambience and reverb effects (Night-
club, Concert Hall, Church and Cathedral), the DC-1 calculates and gener-
ates the ambient sound from a larger room and presents this sound through
the additional speakers. This works well, but the ambience is generated by
the processor — not contained in the recording. In the surround effects,
surround channel information is extracted from signals encoded on the
recording by the sound mixer — the DC-1 does not add anything to the
sound.
On films, this surround information is intended to be reproduced in
monaural from an array of speakers all around the rear of the listener.
Unless there is enough energy accidentally encoded into the surround
channel to give significant sideways energy, surround speakers won't
contribute very much to the listening experience of ordinary stereo music.
In addition, with all speakers except the fronts reproducing the same
monaural signal, no directional effects are possible. There may be some
DC-1 Theory
and Design
Enjoying Music
in Surround
19