User Guide

P
F
S
Slow RMS Detector active
Fast RMS Detector active
Peak Detector active
A Detector Compare circuit immediately follows the three detectors of the Dynamics
section. The function served by the comparison circuit is to determine how the dynamic
range will be affected in subsequent processing blocks. At this stage, the Crest Factor
controls--both Fast and Peak--determine at what level the dynamic range will be altered
for the corresponding control signals from the RMS Detectors. These "weighting
factors" allow the comparison circuit to vary the amount of dynamic range alteration
applied to the VCA. These controls may actually be seen as a type of predictor to
determine the resultant crest factor (signal peak vs. RMS) of the output signal. Higher
values of Crest Factor (clockwise potentiometer rotation) will result in more transient
preservation at the output, all other factors being equal. Interestingly, the crest factor
value for the Slow RMS Detector is fixed in the detector comparison circuit.
The most complex and difficult aspect of the operation of the Model 2020 Dynamics
section involves the interrelationship of the Ratio and Threshold controls. It is best to
conceptualize these sections in terms of two different units, each with the same control
circuitry as described above, but with distinct operational characteristics thereafter.
In terms of straightforward operation, the Soft Knee operation mode is simplest to detail.
Operation under this condition emulates the operational principle similar to that found in
La2-style compressors, wherein the Threshold control behaves as a conventional
threshold control to determine the dB threshold value for the dynamic range controller,
while the Ratio control remains in the "Soft" position. The signal is unaffected until the
threshold is surpassed, then compression begins at a moderate ratio and increases
automatically, according to a prescribed compression characteristic. Continued signal
levels increasing above the threshold result in higher compression ratios such that the
further a signal goes beyond the threshold, the more severely compressed it becomes.