Specifications
DigiRack Plug-ins Guide68
Compressor/Limiter III
The Compressor/Limiter plug-in applies either
compression or limiting to audio material, de-
pending on the ratio of compression used.
About Compression
Compression reduces the dynamic range of sig-
nals that exceed a chosen threshold by a specific
amount. The Threshold control sets the level
that the signal must exceed to trigger compres-
sion. The Attack control sets how quickly the
compressor responds to the “front” of an audio
signal once it crosses the selected threshold. The
Release control sets the amount of time that it
takes for the compressor’s gain to return to its
original level after the input signal drops below
the selected threshold.
To use compression most effectively, the attack
time should be set so that signals exceed the
threshold level long enough to cause an increase
in the average level. This helps ensure that gain
reduction does not decrease the overall volume
too drastically, or eliminate desired attack tran-
sients in the program material.
Of course, compression has many creative uses
that break these rules.
About Limiting
Limiting prevents signal peaks from ever ex-
ceeding a chosen threshold, and is generally
used to prevent short-term peaks from reaching
their full amplitude. Used judiciously, limiting
produces higher average levels, while avoiding
overload (clipping or distortion), by limiting
only some short-term transients in the source
audio. To prevent the ear from hearing the gain
changes, extremely short attack and release
times are used.
Limiting is used to remove only occasional
peaks because gain reduction on successive
peaks would be noticeable. If audio material
contains many peaks, the threshold should be
raised and the gain manually reduced so that
only occasional, extreme peaks are limited.
Limiting generally begins with the ratio set at
10:1 and higher. Large ratios effectively limit the
dynamic range of the signal to a specific value
by setting an absolute ceiling for the dynamic
range.
Compressor/Limiter III