Lexicon DC-1 Supplementary Manual page 15

DC-1Theory
and Design
Panorama can be used with music, films,
or from within the Reverb and Ambience
programs to simulate side speakers if the
listener is inside the effective area be-
tween loudspeakers.
When the front speakers are close to-
gether, the Panorama Effect is less precise
but more dramatic, and it works over a
larger area.
12
Panorama is used in two ways in the DC-1. First, it is designed to reproduce
as closely as possible the sound actually recorded by the engineer. If the
recording has good natural ambience, Panorama will spread that ambience
around the listener, giving a true impression of the original hall.
The Low Frequency Width control provides an important adjustment to the
bass in Panorama. This control is a simple implementation of a Spatial
Equalizer (a function which Alan Blumlein referred to as a "shuffler"). One
of the ways ordinary stereo excites SI is through the out-of-phase low
frequency energy in the recording. The Low Frequency Width control
allows the amount of out-of-phase bass in a recording to be adjusted. Even
when the Effect level of the Panorama control is all the way down, the Low
Frequency Width control is active, allowing the user to experiment with this
property of sound.
Recording engineers have only recently become aware of Spatial Equaliza-
tion and many older recordings are greatly improved by increasing the low
frequency width a little. When the rest of the Panorama mode is not used (by
turning down the Effect control) just turning LF Width up a bit can make
ordinary recordings quite spacious. The user should exercise caution,
however, since some recordings (such as those on Telarc) use microphone
techniques which already contain sufficient out-of-phase low frequency
energy.
The crosstalk cancellation in Panorama increases the low frequency width
as well as the high frequency width of a recording. Recordings in which the
engineer deliberately added large amounts of low frequency width will
sound too wide and phasey when played with either Panorama Normal or
Panorama Wide. Negative values of the Low Frequency Width parameter
can bring the low frequencies back in line with the higher frequencies and
make the playback with Panorama more effective. The Binaural setting of
Panorama greatly increases low frequency width and should only be used
with true binaural recordings, which have very little out-of-phase low
frequency energy. A few compatible binaural recordings are becoming
available, in which the low frequency width has been increased to match the
requirements of loudspeaker playback. These recordings may sound best
when played with the Normal setting.
Panorama is capable of simulating side loudspeakers effectively, but cannot
mimic sound sources to the rear of the listener. So we have added a delayed
Left minus Right signal which can be sent to the side and rear loudspeakers.
The delay is adjustable, as is the treble rolloff.
For a listener in the ideal position, Panorama, with surround (side or rear)
speakers, gives a nearly ideal re-creation of the original recording area.
Lexicon