5.3 Stereo 2 Bands Compressor
The
Comp's Stereo 2-bands dynamic process algorithm is based on a "multi-
band" process concept, splitting the full band of the input signals in 2 "sub-bands"
the low frequencies band and the mid/high frequencies band, so to be able to
differentiate the dynamic processes operating on the low frequencies (with higher
energy content) and on the mid/high frequencies (with lower energy content).
This technique allows to avoid the well know "pumping" effect appearing often
when operating a dynamic process on sound signal.
Once splitted the input signal in 2 "sub-bands",
Comp operate a first limiting
process on the low frequencies band, and after, once recreated the full band,
apply a powerful stereo dynamic process on the two "recombined" channels.
14
A compressor's input/output relationship is often described by a simple graph:
The horizontal axis corresponds to the input signal level, and the vertical axis
is the output level (both measured in decibels) . A line at 45 degrees corresponds
to a gain of one - any input level is mapped to exactly the same output level.
The compressor changes the slope (makes it more horizontal) of that line
above some value called the threshold (which is most often adjustable). The height
of the line defines the dynamic range of the output and the slope of that line is the
same as the compressor's gain.
Input
Output
Level
Detector
Gain
Control
Left
Stereo AGC
Right
ON/OFF
LPF
LPF
HPF
HPF
Limiter
Vol1
Vol2
Vol3
Vol4
Left
Right
Stereo
Compressor
Limiter
