TC Electronic DB4 MKII - Manual (Page 71)

ALC 5.1
English Manual 67
Fig 7
Slow Window and Freeze parameters.
Gain corrections happen more slowly when pro-
gram level is already within the Slow Window.
The loudness has to drop below the Freeze
Level for the duration of the Freeze Hold setting
before unity gain is gradually reinstated.
In the illustration, parameters are set like this:
Target Level = -22
LFS = -22
LKFS = -22 LUFS
Slow Window = 12 dB
Freeze Level = -24 dB (relative to Target Level)
Average Rate
Sets the speed by which gain changes as a re-
sult of loudness variations. The rate adapts to
the signal, and takes the Slow Window into ac-
count, so this parameter shows an average num-
ber.
Note how a fast Average Rate is more asymmet-
rical than a slow rate: The DB becomes faster at
turning down than turning up because listeners
typically object more to obtrusively loud sounds
(promos, commercials) than to audio becoming
soft.
Slow Window
Sets a window around the Target Level inside
which gain changes happen more slowly. Use
this parameter in combination with Average
Rate. See Fig 7, parameter no 2. (6 dB = ±3 dB
from target)
Loudness Measure
Controls which loudness model is used for the
measurement. Select between TC Grid and the
ITU-R BS.1770 standard model.
ALC5.1 algorithm – Limit page
ALC5.1 algorithm – Limit page. The Limiter in
ALC5.1 uses true-peak detection as specified in
BS.1770.
In this example, the Limit Threshold has been
set at -10 dBFS. Note limit indication above the
output meters.
Center Trim
Static gain control for the Center channel after
the ALC section, but before the output limiter.
The range of the Trim parameter is -18 to +18 dB.
Because DB4 and DB8 use 48 bit processing, a
positive setting does not create overload, even if
the signal is already at full scale.
Lateral Trim
Static gain control for all the Main channels, ex-
cept for Center, after the ALC section, but before
the output limiter. The range of the Trim param-
eter is -18 to +18 dB. Because DB4 and DB8 use
48 bit processing, a positive setting does not
create overload, even if the signal is already at
full scale.
LFE Trim
Static gain control for the LFE channel after the
ALC section, but before the output limiter. The
range of the Trim parameter is -18 to +18 dB.
Because DB4 and DB8 use 48 bit processing, a
positive setting does not create overload, even if
the signal is already at full scale.