Lexicon CP-1 PLUS V2.0 Owner's Manual page 64

Theory
and
Design
CP-1 Digital Audio Environment Processor
balance and digital steering make the CP-1 superior to any other non-digital
surround decoder, including the professional decoder for theaters. This
allows the CP-1 to remove the dialog completely and feed the left and right
signals (not the surround) to the side speakers. When side speakers are
present this is a marvelous solution. (See speaker configurations 10 and 11,
on page 15.) Much the same effect as separate side loudspeakers can be
provided by simply placing the main loudspeakers near the sides of the
listeners and using the center loudspeaker to fill in the middle of the front
image. If the soundstage becomes too wide, the side speaker on/off control
allows you to defeat the side outputs, narrowing the stereo spread.
Page 59