Sonnox Oxford Dynamics - Manual (Page 23)

4.8 CompressorTimingLaws 4 COMPRESSOR
4.8.1 Exponential/dB timing(NormalandClassictypes)
The Exponential/dB curve is by far the most popular law used in a great many
well-respected compressors, and is the natural result of more recent analogue units
employing logarithmic sidechains and resistor/capacitor time constants.
The Exponential/dB law has some interesting characteristics. First, the time taken to
complete a compression event tends to stay the same however large the dynamic signal
excursion is. Also since the peak rate of change of gain increases with dynamic excursion,
the resulting harmonic content due to compression tends to follow the loudness of the
programme in a way the ear expects. This helps to mask the effects of the compression,
and thus provides the most forgiving solution, being tolerant to differing timing settings
and programme material. This makes it the best choice for general compression use and
overall dynamic control of complex musical programme material.
10 dB gain reduction (scaled)
30 dB gain reduction
The diagrams above illustrate the action of the exponential law. The first shows 10 dB
gain reduction (scaled for comparison) and the second one shows 30 dB. As can be seen,
the initial rate of change is much increased in the attack period and the total time for
attack is similar despite the increased level transition.
The CLASSIC type selection is a subset of the NORMAL type, with timing controls fixed
to nominal values to match a range of popular legacy units. All other controls behave as
the
NORMAL type. This type selection is quick to set up and is most useful as a
general-purpose channel compressor.
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