Lexicon PCM 80 - Manual (Page 94)

Lexicon
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PCM 80 User Guide
The Reverb Time row, available in every algorithm, contains parameters that
affect the time-based aspects of the reverb effect.
Mid Rt and Low Rt
Mid Rt sets the reverb time for mid-frequency signals. Because low frequency
reverb time (Low Rt) is a multiplier of Mid Rt, Mid Rt acts as a master control for
the reverb time.
Low Rt sets the reverb time for low-frequency signals, as a multiplier of the Mid
Rt parameter. For example, if Low Rt is set to 2X, and Mid Rt 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.
Low Slope and Mid Slope
These parameters are only available in the Inverse algorithm. Low Slope
determines the shape of the reverb envelope for low frequencies. When set to
0, the level of low reverb remains unchanged over its Duration, then cuts off
abruptly (depending on the amount of diffusion in use). Setting Low Slope above
0 causes the level of low-frequency reverb to rise smoothly from soft to loud until
the sound is cut off. The greater the slope, the softer the initial reverberation and
the more pronounced its rise. With negative values, the low frequency reverb
drops from its initial level to a quieter one before cutoff. The lower the slope, the
more pronounced the dropoff.
Mid Slope is similar to Low Slope, but applies to middle and high frequencies.
The actual frequencies affected are determined by Crossover.
Crossover
Crossover sets the frequency at which the transition from Mid Rt to Low Rt takes
place. This control should be set at least two octaves higher than the low
frequency you want to boost. For example, to boost a signal at 100Hz, set
Crossover to 400Hz. (This setting works well for classical music.) Crossover
works best around 400Hz for boosting low frequencies, and around 1.5 kHz for
cutting low frequencies.
Rt HC
Rt HC sets the frequency above which a 6dB/octave low-pass filter attenuates
the reverberated signal. It does not attenuate the reflections. High frequencies
are often rolled off with this parameter, resulting in more natural-sounding
reverberation.
Pre Delay
Pre Delay adjusts an additional time delay between the input of signal and the
onset of reverberation. The maximum range is 930ms. This control is not
intended to mimic the time delays in natural spaces. In real rooms, the build-up
of reverberation is gradual, and the initial time gap is usually relatively short.
Natural spaces are best emulated by adjusting Spread for the desired effective
predelay.
Infinite
In the Infinite algorithm, this control is provided to turn the infinite effect On or Off.
Rvb Time