Solid State Logic Duality Operator's Manual page 31

Main Bus Compressor
Using the same classic design as found on the original SL4000 series
console, the main bus compressor can be used as a single stereo unit or as
a master 5.1 compressor. The compressor is assigned either to one of the
Mix A, B, C busses or the 5.1 mix bus via the main bus select matrix (see
previous page).
The 'soft' knee point of the compressor, ie. the level at which compression
start to take place, is set by the THRESHOLD control (± 20dB). This is
intentionally designed to change depending on the setting of the RATIO
control; decreasing the RATIO setting lowers the effective threshold, hence
maintaining the perceived 'loudness' of the compressed signal. The RATIO
switch has six settings, 1.5:1, 2:1, 3:1, 4:1, 5:1 and 10:1. ATTACK time is
switchable in six steps between 0.1 and 30 mS, and the RELEASE time is
selectable between 0.1 and 1.2 seconds in five steps. The AUTO release
selection adjusts the release time according to the signal envelope.
The gain MAKE-UP simply acts as a level control to compensate for the
lowered level that is a consequence of compressing the signal. This control
may be set so as not to change the overall output level when the
compressor is switched in. The meter indicates dBs of gain reduction.
In 5.1 mode, two buttons, SRND TO S/C and LFE TO S/C determine
whether the surround and LFE channels are included in the processing of
the side chain gain reduction, or not. A further button, S/C
normal 'loudest-bus-in-the-mix' side chain operation and substitutes a
summing mode so that the gain reduction is proportional to the soundfield
energy as opposed to the loudest individual signal.
All manuals and user guides at all-guides.com
∑, defeats the
Duality Operator's Manual
Master Compressor
COMPRESSOR
dB
C O M PR ESSIO N
SL978
-20 +20
THRESHOLD
LFE
0
TO S/C
+
MAKE-UP
1 3
.3 10
.1 30
S/C
ATTACK - mS
.3 .6
.2 1.2
SRND
.1 AUTO
TO S/C
3 4
RELEASE - S
2 5
1.5 10
RATIO IN
2 - 1 9