Orban Optimod-FM 8300 Operating Manual page 160

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OPERATION ORBAN MODEL 8300
sound often produced by processors at high gain reduction levels, and makes
OPTIMOD-FM remarkably resistant to operator gain-riding errors.
2B GATE ("2B Gate Threshold") 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 will cause the AGC or two-band compressor to
gate, effectively freezing gain to prevent noise breathing.
There are two independent gating circuits in the 8300 Two-Band structure. The first
affects the AGC and the second affects the two-band compressor. Each has its own
threshold control.
The two-band gain reduction will eventually recover to 0 dB and the AGC gain re-
duction will eventually recover to –10 dB even when the compressor gate is gated.
However, recovery is slow enough to be imperceptible. This avoids OPTIMOD-FM's
getting stuck with a large amount of gain reduction on a long, low-level musical
passage immediately following a loud passage.
It is common to set the 2B G control to –40. Higher settings are primarily useful
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for radio drama, outside sports broadcasts, and other non-musical programming
that contain ambiance, low-level crowd noise and the like. Slightly higher settings
may increase the musicality of the compression by slowing down recovery on mod-
erate-level to low-level musical passages. When such passages cause the gate to cy-
cle on and off, recovery time will be slowed down by the ratio of the "on-time" to
the "off time." This effectively slows down the release time as the input gets quieter
and quieter, thus preserving musical values in material with wide dynamic range
(classical music for example).
BASS CPL ("2B Bass Coupling") is used to set the balance between bass and the rest
of the frequency spectrum.
The two-band compressor processes audio in a master band for all audio above ap-
proximately 200Hz, and a bass band for audio below approximately 200Hz. The
B C control determines how closely the on-air balance of material below 200Hz
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matches that of the program material above 200Hz.
Settings toward 100% (wideband) make the output sound most like the input. Be-
cause setting the B C control at 100% will sometimes cause bass loss, the most
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accurate frequency balance will often be obtained with this control between 70%
and 90%. The optimal setting depends on the amount of gain reduction applied.
Adjust the B C control until the band 1 and band 2 Gain Reduction meters
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track as closely as possible.
With the 2B R (2B Release) control set to 2 dB/second, setting the B C control
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toward 0% (independent) will produce a sound that is very open, natural, and non-
fatiguing, even with large amounts of gain reduction. Such settings will provide a
bass boost on some program material that lacks bass.
With fast release times, settings of the B C toward 100% (wideband) do not
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sound good. Instead, set the B control toward 0% (independent). This com-
C
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bination of fast release and independent operation of the bands provides the