Lexicon LEXICON480LV4 Owner's Manual page 97

SPREAD
SPREAD works together with SHAPE to control the
contour of the overall ambience of the sound created
by the 480L. SPREAD controls the duration of the initial
contour of the reverberation envelope (SHAPE con-
trols the envelope). Low SPREAD settings result in a
rapid onset of reverberation at the beginning of the
envelope, with little or no sustain. Higher settings
spread out both the buildup and sustain.
SPREAD and SHAPE control the rate at which rever-
beration builds up, and how the reverberation sustains
as it begins to decay. When DECAY OPT is in Reverb
mode, SPREAD is linked to SIZE, and the actual value
for SPREAD depends on the selected SIZE. Parame-
ters are unlinked in Effect mode.
SIZE
SIZE sets the rate of buildup of diffusion after the initial
period (which is controlled by DIFFUSION). It also acts
as a master control for RT MID and SPREAD. For this
reason, the SIZE control can be used to vary a reverb
sound from very large to very small. Generally, you
should set the SIZE control to approximate the size of
the acoustic space you are trying to create. The size in
meters is roughly equal to the longest dimension of the
space. Moving SIZE while a signal is present momen-
tarily mutes the reverb signal.
The apparent size of the space created is actually a
combination of the settings of the SIZE, SHAPE, and
SPREAD controls. Small acoustic spaces are charac-
terized by a rapid buildup of diffusion. However, both
small and large spaces frequently have an uneven
buildup of initial reverberation. This uneven buildup is
what is controlled by the SPREAD and SHAPE con-
trols.
HF CUTOFF
HF CUTOFF sets the frequency above which a 6 dB/
octave low-pass filter attenuates the processed signal.
It attenuates both preechoes and reverberant sound.
High frequencies are often rolled off with this parame-
ter, resulting in more natural sounding reverberation.
PREDELAY
PREDELAY adjusts an additional time delay between
the input of signal and the onset of reverberation. The
control is not intended to mimic the time delays in
natural spaces. In real rooms the build-up of rever-
beration is gradual, and the initial time gap is usually
relatively short. Natural spaces are best emulated by
setting SHAPE at a middle value and adjusting
SPREAD for the desired effective pre-delay.
Banks 11-12: the Random Halls and Spaces Program
Additional delay added with the PREDELAY control
can increase the initial time gap slightly, emulating a
situation where reverberant pick-up microphones are
located much further from the source than the main
microphones. If less than about 30ms of pre-delay is
added, this additional delay can add clarity with some
music, but it can also sound unnatural. Large pre-
delays can be useful for slap-echo effects.
Note: Very high values of PREDELAY limit the amount
of SPREAD available. The display, however, does not
reflect this.
Page Two
BASS MULTIPLY
BASS MULTIPLY sets the reverb time for low-fre-
quency signals, as a multiplier of the RT MID parame-
ter. For example, if BASS MULTIPLY is set to 2X, and
RT MID is set to two seconds, the low frequency reverb
time will be four seconds. For a natural-sounding hall
ambience, we recommend values of 1.5X or less.
CROSSOVER
CROSSOVER sets the frequency at which the transi-
tion from LF RT to RT MID takes place. CROSSOVER
should be set at least two octaves higher than the low
frequency you want to boost. For example, to boost a
signal at 100 Hz, set the CROSSOVER to 400 Hz (This
setting works well for classical music). CROSSOVER
works best around 400 for boosting low frequencies,
and around 1.5 kHz for cutting low frequencies.
RT HF CUT
RT HF CUT sets the frequency above which sounds
decay at a progressively faster rate. It filters all the
sound except the preechoes. When set relatively low,
it gives a darker tone to the reverberation, simulating
the effect of air absorption in a real hall. This also helps
keep the ambience generated by the program from
muddying the direct sound.
DIFFUSION
DIFFUSION controls the degree to which initial echo
density increases over time. High settings of DIFFU-
SION result in high initial buildup of echo density, and
low settings cause low initial buildup. After the initial
period (in which echo buildup is controlled by DIFFU-
SION) density continues to change at a rate deter-
mined by SIZE. To enhance percussion, use high
settings of diffusion. For clearer and more natural
vocals, mixes, and piano music, use low or moderate
settings of diffusion.
10-3