3-46
OPERATION ORBAN MODEL 8685
sum/difference MATRIX mode, this control determines the maximum
amount of width change in the stereo soundfield.
Master Delta Threshold (2.0 processing only) allows you to set the difference be-
tween the compression thresholds of the sum and difference channels. (This control
is only useful when you set the AGC
MATR IX to SUM/DIF.) By setting the threshold of
the difference channel lower than the sum channel, you can have the AGC auto-
matically produce more gain reduction in the difference channel. This will reduce
the separation of material with an excessively wide stereo image (like old Beatles re-
cords). To make this work, you must set the M
AX DELTA GR control away from zero.
For example, to limit an excessively wide image while preventing more than 3 dB
difference in gain between the sum and difference channels, set the M
AX DELTA GR
control to 3.0 and the M
ASTER DELTA THRESHOLD control to some positive number,
depending on how much automatic width control you want the 8685 to perform
Bass Delta Threshold
(2.0 processing only) works the same as MASTER DELTA
THRESHOLD, but applies to the bass band. You will usually set it the same as MASTER
DELTA THRESHOLD.
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 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 anywhere between 0 dB and 6 dB below the threshold of the look-
ahead limiter, depending on the setting of the L
ESS-MORE control in the parent pre-
set upon which you are basing your Advanced Control adjustments and depending
on how much look-ahead limiting the preset causes with typical program material.
This provides headroom for contributions from the other four bands so that bass
transients don’t smash against the look-ahead limiter, causing audible intermodula-
tion distortion between the bass and higher frequency program material.
The threshold of the bass clipper is user-adjustable to trade off bass punch against
Distortion Control Adjustments
Name Range
AGC Final Limit Drive –10.0 … +12.0 dB
Multiband Final Limit Drive –20.0 … +24.0 dB
Bass Clip Shape 0.0 … 10.0
Bass Clip Threshold –6.0 … +6.0 dB, OFF
Center Bass Clip Threshold (surround only) –6.0 … +6.0 dB, OFF
Speech Bass Clip Threshold (2.0 only) –6.0 … +6.0 dB, OFF
Transient Enhance 0…10 ms
Dialnorm –31…–11 dB, Global
Table 3-6: Distortion Control Adjustments
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