3-40
OPERATION
ORBAN MODEL 8382
Bx THR
(“Band x Compression Threshold”) controls set the compression threshold in
each band, in units of dB below the final clipper threshold. We recommend making
small changes around the factory settings to avoid changing the range over which
the
MB
CLIPPING
control operates. These controls will affect the spectral balance of
the processing above threshold, but are also risky because they can strongly affect
the amount of distortion produced by the back-end clipping system.
MB GATE
(“Multiband Gate Threshold”) control determines the lowest input level
that will be recognized as program by OPTIMOD-TV; lower levels are considered to
be noise or background sounds and cause the AGC or multiband compressor to gate,
effectively freezing gain to prevent noise breathing.
There are two independent gating circuits in the 8382. The first affects the AGC and
the second affects the multiband compressor. Each has its own threshold control.
The multiband silence gate causes the gain reduction in bands 2 and 3 of the multi-
band compressor to move quickly to the average gain reduction occurring in those
bands when the gate first turns on. This prevents obvious midrange coloration un-
der gated conditions, because bands 2 and 3 have the same gain.
The gate also independently freezes the gain of the two highest frequency bands
(forcing the gain of the highest frequency band to be identical to its lower
neighbor), and independently sets the gain of the lowest frequency band according
to the setting of the
DJ
B
ASS
boost control (in the Equalization screen). Thus, with-
out introducing obvious coloration, the gating smoothly preserves the average
overall frequency response “tilt” of the multiband compressor, broadly maintaining
the “automatic equalization” curve it generates for a given piece of program mate-
rial.
If the
MB
GATE
control is turned
O
FF
, the
DJ
B
ASS
control (in the Equaliza-
tion screen) is disabled.
MB LIM DR
(“Multiband Limiter Drive”) sets the drive level to the multiband distor-
tion controlling processing that precedes the final clipping section. The distortion-
controlling section uses a combination of distortion-cancelled clipping and look-
ahead processing to anticipate and prevent excessive clipping distortion in the final
Band Mix
Full Name
Advanced Name
Range
B2>B1 CPL
B2>B1 Coupling
0 ... 100 %
B2>B3 CPL
B2>B3 Coupling
0 ... 100 %
B3>B2 CPL
B3>B2 Coupling
0 … 100 %
B3>B4 CPL
B3>B4 Coupling
0 ... 100 %
B4>B5 CPL
B4>B5 Coupling
0 ... 100 %
B1 OUT
B1 Output Mix
–3.0 … +3.0
B2 OUT
B2 Output Mix
–3.0 … +3.0
B3 OUT
B3 Output Mix
–3.0 … +3.0
B4 OUT
B4 Output Mix
–3.0 … +3.0
B5 OUT
B5 Output Mix
–3.0 … +3.0
Table 3-9: MB Band Mix Controls
Summary of Contents for Optimod-TV 8382
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