Gain Reduction Metering; About The Processing Structures - Orban OPTIMOD 8400 Operating Manual

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OPERATION

Gain Reduction Metering

About the Processing Structures

Unlike the metering on some processors, when any OPTIMOD-FM gain reduction meter
indicates full-scale (at its bottom), it means that its associated compressor has run out of
gain reduction range, that the circuitry is being overloaded, and that various nastinesses
are likely to commence.
Because the various compressors have 25 dB of gain reduction range, the meter should
never come close to 25 dB gain reduction if OPTIMOD-FM has been set up for a sane
amount of gain reduction under ordinary program conditions.
To accommodate the FM pre-emphasis curve, Band 5 of the Five-Band
Structure is capable of 30 dB of gain reduction.
Further, be aware of the different peak factors on voice and music—if voice and music
are peaked identically on a VU meter, voice may cause up to 10 dB more peak gain re-
duction than does music! (A PPM will indicate relative peak levels much more accu-
rately.)
If you want to create your own User Presets, the following detailed discussion of the
processing structures is important to understand. If you only use Factory Presets, or if
you only modify them with
but it is not necessary to understand it to get excellent sound from the 8400.
In the 8400, a processing structure is a program that operates as a complete audio proc-
essing system. Only one processing structure can be on-air at a time. Just as there are
many possible ways of configuring a processing system using analog components (like
equalizers, compressors, limiters, and clippers), there are several possible processing
structures that the 8400's DSP hardware could realize. Unlike an analog system, where
creating a complete processing system involves physically wiring its various components
together, the 8400 realizes its processing structures as a series of high-speed mathemati-
cal computations made by Digital Signal Processing (DSP) integrated circuit chips. In the
8400, both structures operate simultaneously so there is no delay in switching between
them, which is done with a smooth cross-fade.
There are two basic structures: Two-Band and Five-Band.
Two-Band is a purist, phase-linear structure. When correctly configured it can be used
for protection limiting, and we provide two presets that use it for this. It is also the basis
for the
CLASSICAL-2 BAND
Five-Band is the basic structure used for popular music in its many variations. Because it
provides effective automatic re-equalization of program material, it is also used for news,
talk, and sports.
, then you may still find the material interesting,
Less/More
presets.
ORBAN Model 8400