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52 Chapter 4 Dynamic
Multipressor
The Multipressor (an abbreviation for multiband compressor) is the epitome of an
audio mastering tool. It’s a pretty complex tool; good sounding settings require quite a
lot of listening experience.
Functional Principle of Multi-band Compressors
The multi-band compressor splits the incoming signal into two to four different
frequency bands before applying compression. These frequency bands are then
compressed independently. After compression, the frequency bands are mixed back
together.
The aim of independent compression of different frequency bands is to reach high
compression levels on the bands that need it, without the pumping effect that is
normally heard at high compression levels.
Much higher Ratios, and therefore, a much higher average volume is possible before
the unwanted artefacts of compression will be heard.
Downward Expansion
Strong multi-band compression allows you to raise the overall volume level—resulting
in a dramatic increase of the existing noise floor. Downward expansion allows you to
reduce or suppress this noise. Each frequency band features a downward expander.
This works as the exact counterpart to the compressor: while the compressor
compresses the dynamic range of the higher volume levels, the downward expander
expands the dynamic range of the lower volume levels. With downward expansion, the
signal will be reduced in level when it is lower than the defined Threshold level. The
effect can be compared to a noise gate, but rather than simply cutting off the sound, it
smoothly fades the volume using an adjustable Ratio.