Technical information

McDSP plug-ins
The Knee control can be set from ‘Hard’ at the lowest setting, or to one of a
range of ten gentler knee curves represented by numerical values ranging
from 10 to 100 in increments of 10. Higher settings of the knee control include
the various Modelled Compressor modes: ‘Chan’ (SSL Channel Compressor),
‘Buss’ (SSL Buss Compressor), ‘Brit’ (Neve 33609C), ‘A Soft’ and ‘A Hard’ (API 225
hard and soft modes).
Choosing a Knee mode in the Compressor section resets the ranges of the
attack and release controls to match those ranges found in the modelled unit.
Also the  lter section’s Q and Frequency ranges are adjusted to match the
ranges found in the consoles these modelled compressors are taken from, as
necessary.
The Key Inputs
Both the Expander/Gate and Compressor/Limiter can key from the original
(un- ltered) input, or from the side-chain input, or from the output of the two
 lters. The  lters can take their input from the original input or from the side
chain. The two  lters can also be placed inline so that their e ect on the signal
is heard at the output.
The Filters
Each filter has a selectable slope (up to 24 dB/octave) and lets you select
between two  lter types. Two small Filter Type buttons positioned to the left
of the Freq control let you choose between high-pass (i.e. low-cut)  lter and
notch  lter types in the Low Filter, and between low-pass (i.e. high-cut)  lter
and notch  lter types in the Hi Filter section.
The other Filter Section controls include two Filter Input selector buttons that
allow either the original input or the side-chain input to be routed through the
 lter; a Frequency control that lets you adjust either the centre frequency of
the notch  lter or the cuto frequency of the high-pass or low-pass  lter; and
a Q/Slope control that lets you adjust the width of the notch  lter or the slope
of the high-pass or low-pass  lter.
Feed-Forward vs Feedback Compression
The Channel G Compressor/Limiter can use either the input or the output
of the Compressor/Limiter as the key to trigger the compression. Using
the compressed output – a technique often referred to as feedback
compression– is found in many vintage compressors such as the API 225
compressor. The more common technique found in most modern dynamic-
range processors is feed-forward compression – which uses the input signal
as the compression key.