Lexicon PCM 81 - REV 2 - Section 3: Algorithms and Parameters; About the Algorithms; The 4-Voice Algorithms

3-2
Algorithms and Parameters
Lexicon
The PCM 81 uses 17 algorithms to create different types of effects.
Each algorithm includes an uncompromised stereo reverb effect, as
well as several voices of additional stereo effects. When you select
any effect, the name of the algorithm from which it was derived
will appear on the upper display line. Pressing Edit will display the
last edited parameter in that algorithm's parameter matrix.
There are three general classes of algorithm: 4-Voice, 6-Voice and
Pitch. The 4-Voice algorithms: Concert Hall, Plate, Chamber,
Inverse and Infinite each combine a specific type of reverb with a
4-voice, general purpose stereo "effect toolbox" which we call the
Reverb Shell. These algorithms also provide "post-processing" for
the reverb. The 6-Voice algorithms: Glide>Hall, Chorus+Rvb,
M-Band+Rvb, Res 1>Plate, and Res 2>Plate each combine a
specific type of reverb with a specialized 6-voice stereo effect. The
Pitch algorithms: Quad>Hall, Dual-Chmb, Dual-Plt, Dual-Inv,
Stereo-Chmb, VSO-Chmb and Pitch Correct each offer a unique
type of pitch shifting, combined with an uncompromised Lexicon
reverb.
In this chapter, diagrams and descriptions of the Reverb Shell,and
of the 4 and 6-Voice algorithms are presented first, along with
pictures of each edit matrix. The diagrams are followed by a
glossary of parameter descriptions, organized alphabetically by
matrix row name. Within each matrix row, parameters are
organized as far as possible in the sequence in which they appear
in the row. The Pitch algorithms, most of which make use of a
dedicated Submixer incorporated into each algorithm, are
described in the following section along with operational tips on
pitch shifting in general and the submixer in particular.
THE 4-VOICE ALGORITHMS
Each of the 4-Voice algorithms share a common set of controls and
parameters built around one of five stereo reverb effects: Concert
Hall, Plate, Chamber, Inverse and Infinite. The diagram below
shows these common controls and parameters as they are
structured around a reverb effect. We call this structure the Reverb
Shell. (Individual reverb effects are described on the following
pages.)
Chorus +Rvb
P0 0.0 Prime Blue
The algorithm name appears on the upper line of the display
whenever an effect is selected.
Press Edit to access the parameter matrix.
Up
Program
Banks
Register
Banks Edit Control Tempo
EFFECT MIX
Left
Input
Right
Left
Right
ABOUT THE ALGORITHMS
Most PCM 81 algorithms share the same general structure, shown
below. The shaded area of the diagram is detailed in the individual
effect descriptions that follow.