The Two-Band Structure; The Protection Presets - Orban OPTIMOD-FM 5500 Operation Manual

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OPERATION ORBAN MODEL 5500
depending on whether the underlying processing preset is "loud" or "quiet." There-
fore, the appropriate setting of the MPX P O control depends strongly on
OWER FFSET
what preset is in use. Accordingly, each preset has its own setting of the MPX P
OWER
O , which is a processing parameter like any other in a given preset. Hence, ad-
FFSET
justments that affect the multiplex power controller appear in two independent
places in the Optimod: The M P T control is a system setup
ULTIPLEX OWER HRESHOLD
control, while the MPX P is part of the on-air preset.
O
OWER FFSET
Depending on the preset, the MPX P O control's setting can vary from 0
OWER FFSET
dB (no effect) to as much as –9 dB. If you customize a preset in any way (including
using L ), you may wish to trim the MPX P for that preset so
-M O
ESS ORE OWER FFSET
that the multiplex power controller produces 2-3 dB of indicated gain reduction
with typical program material. This will achieve the maximum on-air loudness that
complies with the ITU standard while minimizing the potential for unnatural and
audibly disturbing loudness inconsistencies caused by the operation of the multiplex
power controller.

The Two-Band Structure

The Two-Band structure consists of a slow two-band gated AGC (Automatic Gain
Control) for gain riding, followed by an equalization section, a gated two-band
compressor, a high-frequency limiter, and a complex peak limiting system similar to
the one used in the Five-Band structure. Like the "Two-Band Purist" structure in
Orban's OPTIMOD-FM 8200, the 5500's Two-Band Structure is phase-linear through-
out to maximize sonic transparency.
The Two-Band structure has an open, easy-to-listen-to sound that is similar to the
source material if the source material is of good quality. However, if the spectral
balance between the bass and high frequency energy of the program material is in-
correct, the Two-Band structure (when its BAND COUPLING 2>1 control is operated
toward 0%) can gently correct it without introducing obvious coloration.
The Two-Band structure is mainly useful for classical or "fine arts" programming that
demands high fidelity to the original program source.

The Protection Presets

There are two Protection Factory Presets. Both use the same DSP code as the Two-
Band Purist structure, but the AGC is defeated.
PROTECTION 0DB sets the limiting threshold so that limiting almost never occurs,
while PROTECTION 5DB sets the limiting threshold so that program material at the
maximum normal input level (as determined by a PPM or VU meter monitoring the
input program line) produces an average limiting of 5 dB.
To set up the Protection Limiter, recall preset PROTECTION 0DB if you want limiting
to occur only when the program level exceeds the maximum normal input level as
determined by a PPM or VU meter monitoring the input program line. Recall preset