LA Audio GCX20 - Manual (Page 11)

Page 11
Fig: 4.3.1 Effect of Ratio control on O/P levels.
A RATIO of 1:1 gives no compression and 20:1 gives no increase in output
level no matter how far the signal increases above Threshold.
The ratio curves shown in Fig 4.3.1 are Hard-knee where the change in
gain is abrupt. The GCX20 has a Soft-knee control system which provides
a gradual change between compression levels.
GAIN
control
Because compression is a gain reduction process, the output of the
compressor is often at a lower level than the normal operating level.
Some way of restoring the signal to its pre-compressed level is required.
The Gain control provides adjustment to restore output level after
compression.
GAIN can also be used to level match between equipment connected to
the GCX20. GAIN range is -20dB to +20dB.
BYPASS
switch
Switches the compressor in and out of the signal path so that comparisons
can be made between compressed and un-compressed signals.
Channel 1 BYPASS switch operates on both channels in LINK mode.
AUTO
switch
The GCX20 compressor has two program dependant Auto Attack/Release
settings -
SLOW mode (switch 'out')
Attack = 10mS to 100mS
Release = 3S
FAST mode (switch 'in')
Attack = 5mS to 70mS
Release = 0.5S
In SLOW mode the compressor reacts to the average level of the input
signal and is the normal setting for most signal types. Fast transient signal
peaks will pass unaffected.
Using FAST attack, the compressor reacts more to signal peaks and will
control all but the fastest transients.
SLOW mode has been tailored for mixed program material. FAST mode is
suitable for solo instruments.
GAIN REDUCTION
meter
The led meter displays the applied gain reduction (GR) in dBs.
In BYPASS the display is dimmed but still displays the amount of gain
reduction which would be applied if the compressor were to be switched in.