Orban Optimod-PC 1101, Руководство по эксплуатации

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OPTIMOD-PC OPERATION
3-15
iter so that it effectively monitors the loudness at the limiter’s output, not the loud-
ness at the multiband compressor’s output. It does so by scaling its sidechain drive by
two gain factors: (1) the
MB L
IMIT
D
RIVE
control and (2) the 1101’s active
D
IALNORM
value, which is determined either globally or by the active preset depending on the
active preset’s
D
IALNORM
setting. (See Figure 3-3 on page 3-15 and Low-IM Look-
Ahead Limiter on page 3-13.) The
D
IALNORM
value is the same as the “target loud-
ness” as measured by an ITU-R BS.1770-2 loudness meter in units of LKFS (ATSC Rec.
A/85) or LUFS (EBU Rec. R128). Your OPTIMOD-PC contains a BS.1770-2 meter with
an integration time of 10 seconds. To comply with these standards,
D
IALNORM
is cus-
tomarily set to –24 in the United States and –23 in the EU.
The Loudness Controller constrains the loudness of most commercials well enough
to eliminate viewer annoyance. It works by constantly monitoring the subjective
loudness of the 1101's output. The subjective loudness is a single value that repre-
sents the listener’s impression of the loudness in the listening room. It takes into ac-
count the contribution of all stereo and surround channels.
When subjective loudness would otherwise exceed the threshold set by the
L
OUDNESS
T
HRESHOLD
control, the CBS Loudness Controller reduces the gain of mate-
rial above 200 Hz, preventing loudness from exceeding the threshold. To prevent
the loudness controller from causing too much dynamic bass boost, you can use the
L
OUDNESS
C
ONTROLLER
B
ASS
C
OUPLE
control to limit the maximum difference be-
tween the gain of the band below 200 Hz and the band above 200Hz. For example,
when this control is set to
3
DB
and the loudness controller’s gain reduction is 10 dB,
the gain reduction below 200 Hz will be 7 dB. However, if the loudness controller’s
gain reduction is 2 dB, the gain reduction below 200 Hz will be 0 dB because the dif-
ference is now less than 3 dB.
The loudness controller is triggered mainly by program material that has a lot of en-
Figure 3-3: Simplified Block Diagram of Dialnorm Control