GUIDE TO INSTALLATION AND OPERATION
30
| AMX-1901
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. Its effect is visible on the Input (LUFS) display to make the adjustment easier.
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).
Response Time
Outside of the
Fast
and
Transient
modes ranges, the ALC performs loudness correction slowly, following the
Response Time
. Response time values are : 5 sec, 10 sec, 15 sec, 20 sec, 30 sec, 45 sec, 1 min, 5 min, 10 min, 15
min, 20 min.
Freeze Threshold
The
Freeze Threshold
sets the threshold below which the ALC will not increase loudness This prevents quiet
portions of programs (and noise) from being unintentionally boosted. If the input program loudness is under the
Freeze Threshold
for more than 30 seconds, the ALC will smoothly return to 0 dB of loudness correction.
Limiter Threshold
The
Limiter Threshold
will limit the output loudness under the selected threshold. This avoids unintentional clipping
of loud portions of programs. If the input program loudness is over the
Limiter Threshold
, the ALC will reduce the
loudness very quickly, in 1 millisecond.
5.9 Loudness Panel
The AMX-1901 allows the user to measure the loudness of audio streams passing through it. The measurement
process is flexible:
•
All major loudness standards are supported.
•
The measurement standards can be customized if desired.
•
Up to eight programs can be measured at once.
•
Segment markers can be inserted from two triggers.
•
Log files of the measurements can be stored externally, for analysis using Miranda’s Audio Loudness Analyzer.
