42
Lexicon
PCM Effects and Parameters
LOW FREQ WIDTH allows you to apply low-frequency spatial correc-
tion to the signal. Positive values of LOW FREQ Width indicate that the
difference signal (L-R) has additional energy below 500Hz, while the
sum (L+R) has correspondingly less. Negative settings of LOW FREQ
WIDTH can compensate for recordings with too much of this property.
This control can add needed spaciousness and warmth to classical
recordings made with coincident or near-coincident microphones.
MAIN LEVEL controls the level of the mono signal that is reproduced by
the main speakers. When a center speaker is part of the configuration
many films may sound better when this control is set between 6-12. This
spreads the film sound out around the screen and can be more pleasant
than restricting the dialog and much of the other film sound to the center
speaker.
MID RT (midrange reverberation time) is the time required for midrange
sounds to decay 60dB in level.
PRE-DELAY
increases the delay between the direct sound and the
onset of reverberation. Because some pre-delay is inherent in the
program material, a value of 0 is usually a good starting point. Increasing
the pre-delay value will make the hall sound larger.
RE-EQUALIZER equalizes the left, center, and right channel outputs to
match the overall frequency balance of the original recording. Without
this re-equalization, many films and some television programs will
sound too bright.
REAR DELAY adjusts the amount of time between the appearance of
a signal in the front channels and its emergence from the rear. Gener-
ally, the correct delay is about 16 milliseconds, but the setting depends
on speaker set-up and source material. In general, the delay should be
low enough so that the rear sound does not become identifiable as a
distinct source. The settings also affect the side outputs.
REAR DELAY OFFSET is an additional delay added to the rear
channels. This delay increases the apparent size of the listening space
by increasing the rear delay time. Feel free to experiment to find the
setting that works best.
REAR LEVEL controls the volume level of the rear speakers. Although
we have selected a default value, the correct setting will vary with each
recording, the room, and your personal taste.
REAR ROLLOFF sets the frequency above which the rear-channel
sound is attenuated. The appropriate setting will vary with the program
material. It should be set high enough to give presence and airiness to
the rear sound without placing distracting instrumental overtones or
other sounds behind you. The settings also affect the side outputs.