Orban OPTIMOD-PC 1100, Руководство по эксплуатации

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3-38
OPERATION ORBAN MODEL 1100
lower than the sum channel, you can have the AGC automatically produce more
gain reduction in the difference channel. This will reduce the separation of material
with an excessively wide stereo image (like old Beatles records). To make this work,
you must set the
M
AX
D
ELTA
GR control away from zero. For example, to limit an ex-
cessively wide image while preventing more than 3 dB difference in gain between
the sum and difference channels, set the
M
AX
D
ELTA
GR
control to 3.0 and the
M
ASTER
D
ELTA
T
HRESHOLD
control to some positive number, depending on how much
automatic width control you want the 8500 to perform.
Bass Delta Threshold works the same as M
ASTER
D
ELTA
T
HRESHOLD
, but applies to
the bass band. You will usually set it the same as
M
ASTER
D
ELTA
T
HRESHOLD
.
Distortion Control
The distortion control adjustments are common to the Two-Band and Five-Band
structures except as noted in the descriptions on the following pages.
Bass Clip Threshold controls Orban’s patented embedded bass clipper. The
S
PEECH
B
ASS
C
LIP
T
HRESHOLD
control overrides the B
ASS
C
LIP
T
HRESHOLD
control
when OPTIMOD-PC automatically detects speech (page 3-5).
The bass clipper is embedded in the multiband crossover so that harmonics created
by clipping are rolled off by part of the crossover filters. The threshold of this clipper
is ordinarily set between 0 dB and 6 dB below the threshold of the look-ahead lim-
iter, depending on the setting of the
L
ESS
-M
ORE
control in the parent preset upon
which you are basing your Advanced Control adjustments. This provides headroom
for contributions from the other four bands so that bass transients don’t smash
against the look-ahead limiter, causing audible intermodulation distortion between
the bass and higher frequency program material.
Some OPTIMOD-PC users feel that the bass clipper unnecessarily reduces bass punch
at its factory settings. To accommodate these users, the threshold of the bass clipper
is user-adjustable. The range (with reference to the look-ahead limiter threshold) is
0 to –6dB. (You can also turn the bass clipper off.) As you raise the threshold of the
clipper, you will get more bass but also more distortion and pumping. Be careful
when setting this control; do not adjust it casually. Listen to program material with
heavy bass combined with spectrally sparse midrange material (like a singer) and
listen for IM distortion induced by the bass’ pushing the midrange into the look-
ahead limiter. Although the low-IM technology in OPTIMOD-PC’s look-ahead limiter
substantially reduces this distortion, overdriving the limiter hard enough can still
cause problems.
In the Five-Band structure, the sum of band 1 and 2 drives the clipper. In the Two-
Band structure, the Bass band drives the clipper.
Bass Clip Shape allows you to change the knee of the input/output gain curve of
the bass clipper. It allows you to control the shape of the “knee”—the transition
between no clipping and flat topping. “0” provides the hardest knee, where the