Grass Valley AMX-3981 2014 - Manual (Page 39)

GUIDE TO INSTALLATION AND OPERATION
AMX-3981 | 33
Target Loudness
Sets the target output loudness. This value sets the average output loudness, which means that due to the program
dynamics, the output loudness will move around the selected target. The units of measurement and the nominal
value, as well as the window size for the measurements (not shown on this panel) are set by the Mode pulldown in the
Config tab.
Although the nominal Target Loudness is reset according to the table above when the Mode is changed, the user may
change the value at any time using the pulldown, where the available range is -10 to -31 for all modes.
Here’s the time-domain response of the ALC:
ALC Pre-Amp Level
A pre-amp stage is available in front of the ALC to compensate for programs having an input loudness out of the ALC
tracking range (very low or very high input loudness). The pre-amp level ranges from -20 dB to + 20 dB, in steps of 1
dB.
Fast Mode Response
The Fast Mode Response is optional and is enabled by checking the Enable box.
The ALC Fast Mode Response kicks in whenever the input loudness goes over the Fast Mode Threshold and
loudness is reduced, in a few milliseconds. The Fast Mode Threshold is given in dB with respect to the target
loudness and ranges from 2 to 12 dB, in dB steps.
Transient Mode Response
The Transient Mode Response is optional and is enabled by checking the Enable box.
The ALC Transient Mode Response kicks in whenever the input loudness goes over or under the Transient Mode
Threshold. The Transient Mode Threshold is symmetric with respect to the target loudness and ranges from 2 to 12
dB, in dB steps. When the input loudness is over the Transient Mode Threshold , loudness is reduced following the
rate set by the Speed pull-down. When the input loudness is under the Transient Mode Threshold, loudness is
increased, again following the Speed pull-down, which ranges from Slow (up to 15 seconds) to Fast (up to 4
seconds).
Limiter Threshold
Fast Mode Threshold
Transient Threshold
Transient Threshold
Gate Threshold
Output Target
Fast
Time
Transient
Time
ALC Response Time
Transient
Time
ALC
Response
Time
ALC
Response
Time
Freeze
INPUT
OUTPUT