Orban OPTIMOD-FM 8600, Operating Manual

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3-62
OPERATION ORBAN MODEL 8600
The
Fast
setting is used only for the
TALK
and
SPORTS
factory pro-
gramming formats. Processing for this sound keeps the levels of an-
nouncers and guests consistent, pulls low-grade telephone calls out of
the mud, and keeps a proper balance between voice and commercials.
Voice is the most difficult audio to process, but these settings result in a
favorable trade-off between consistency, presence, and distortion.
The Factory Presets for this sound are quite different from the other
three release time settings. The amount of gain reduction in the multi-
band compressor is substantially lower (so that it operates more like a
limiter than like a compressor) and the release time of the gain-riding
AGC is speeded up (so that it provides compression and some increase of
density). We made these trade-offs to prevent excessive build-up of den-
sity.
It is possible to experiment with this sound for music-oriented program-
ming as well. However, even with these settings, your sound is getting
farther away from the balance and texture of the input. We think that
this is as far as processing can go without causing unacceptable listener
fatigue. However, this sound may be useful for stations that are ordinari-
ly heard very softly in the background because it improves intelligibility
under these quiet listening conditions. Stations that are usually played
louder will probably prefer one of the slower release times, where the
multiband compressor takes more gain reduction and where the AGC is
operated slowly for gentle gain riding only. These slower sounds are less
consistent than those produced by the
F
AST
setting. Using
S
LOW
preserves
more of the source’s frequency balance, making the sound less dense and
fatiguing when the radio is played loudly.
The
S
PEECH
MB R
ELEASE
control overrides the
MB R
ELEASE
control when the 8600
automatically detects speech (page 3-70). You may wish to set the
S
PEECH
MB
R
ELEASE
control faster for speech (to maximize smoothness and uniformity) and
slower on music (to prevent excessive build-up of density).
MB Gate Thresh (Threshold) control determines the lowest input level that will be
recognized as program by OPTIMOD-FM; 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 8600. The first affects the AGC and
the second affects the multiband compressor
.
Each has its own threshold control.
V2.0 software sets the multiband compressor’s gating threshold with respect to the
signal driving the multiband compressor/limiter, which follows the AGC. Meanwhile,
the AGC gating threshold remains set with respect to the AGC’s input, as it was in
V1.x software. Driving the MB gate detector after the AGC allows the AGC to do its
work of slowly correcting the drive level to later processing, including the multiband
gate.
When the AGC produces 10 dB of gain reduction, the calibration of the MB GATE
control in V2.x software is the same as it was in V1.x software. When upgrading
from V1.x to V2.x, it should thus be unnecessary to change the MB GATE setting in