Orban OPTIMOD-FM 5500 Operation Manual page 164

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OPERATION ORBAN MODEL 5500
point beyond which increasing density (with faster settings of the 2B R control)
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will no longer yield more loudness, and will simply degrade the punch and defini-
tion of the sound.
When the 2B R control is set between 8 and 1 dB/second (the slowest settings), the
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amount of gain reduction is surprisingly non-critical. Gating prevents noise from be-
ing brought up during short pauses and pumping does not occur at high levels of
gain reduction. Therefore, the primary danger of using large amounts of gain reduc-
tion is that the level of quiet passages in input material with wide dynamic range
may eventually be increased unnaturally. Accordingly, when you operate the 2B R
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control between 8 and 2 dB/second, it may be wise to defeat the gain-riding AGC
and to permit the two-band compressor to perform all of the gain riding. This will
prevent excessive reduction of dynamic range, and will produce the most natural
sound achievable from the Two-Band structures.
With faster 2B R control settings (above 8 dB/second), the sound will change sub-
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stantially with the amount of gain reduction in the two-band compressor. This
means that you should activate the gain-riding AGC to ensure that the two-band
compressor is always being driven at the level that produces the amount of gain re-
duction desired. Decide based on listening tests how much gain reduction gives you
the density that you want without creating a feeling of over-compression and fa-
tigue.
Release in the two-band compressor automatically becomes faster as more gain re-
duction is applied (up to about 10 dB). This makes the program progressively denser,
creating a sense of increasing loudness although peaks are not actually increasing. If
the gain-riding AGC is defeated (with the on/off control), you can use this char-
AGC
acteristic to preserve some feeling of dynamic range. Once 10 dB of gain reduction is
exceeded, full loudness is achieved — no further increase in short-term density oc-
curs as more gain reduction is applied. This avoids the unnatural, fatiguing 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 5500 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