Main Bus Compressor - Solid State Logic Duality Fuse Operator's Manual

Main Bus Compressor

Using the same classic design as found on the original SL 4000 Series console,
themain 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 contribute to the side chain, or not. A further
button, S/C ∑ , defeats the 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.
Duality Fuse Operator's Manual
Console Operation
-20 +20
THRESHOLD
LFE
TO S/C
1 3
.3
10
.1
30
ATTACK - mS
SRND
TO S/C
3 4
2
5
1.5 10
RATIO
F/B A
0
+20
MAKE-UP
S/C SUM
.3 .8
.2
1.2
.1 AUTO
RELEASE - S
IN
F/B B
2-21