Orban OPTIMOD 6300 Operating Manual page 163

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OPTIMOD 6300 DIGITAL OPERATION
In the 6300, a processing structure is a program that operates as a complete audio
processing system. Only one processing structure can be active at a time. Just as
there are many possible ways of configuring a processing system using analog com-
ponents (like equalizers, compressors, limiters, and clippers), the 6300's DSP hard-
ware could realize several possible processing structures that. Unlike an analog sys-
tem, where creating a complete processing system involves physically wiring its vari-
ous components together, the 6300 realizes its processing structures as a series of
high-speed mathematical computations made by Digital Signal Processing (DSP) in-
tegrated circuit chips.
There are two basic structures: 2-band and 5-band. To select a structure, choose a
factory preset having the desired structure, and, if you wish, edit it to create a user
preset. To put a given structure on the air, recall a factory or user preset associated
with that structure.
Both structures have a CBS Loudness Controller available (see Loudness Control on
page 3-11).
5-band: The 5-band structure is very flexible, enabling you to fine-tune your sound.
There are several basic Factory Presets for the 5-band structure. Each of these presets
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can be edited with the L control.
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This control affects the sound-for-picture-oriented presets differently than it does
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the music presets. When a sound-for-picture-oriented preset is on the air, the L
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ORE control adjusts the average amount of gain reduction by adjusting the drive
level to the 5-band structure's input. This also adjusts the idle gain—the amount of
gain reduction in the AGC section when the structure is gated. (It gates whenever
the input level to the structure is below the user-adjustable threshold of gating.)
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When a music preset is on the air, the L control sets the amount of overall
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processing, making optimum tradeoffs between loudness, brightness, and distor-
tion. In sound for picture, there are no loudness wars; for music presets, there is
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probably never a need to advance the L control beyond 5.
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The stereo enhancer, AGC, equalizer, and look-ahead limiter are common to both 2-
band and 5-band processing and therefore stay the same when the 6300 switches
between 2-band and 5-band operation. However, different controls appear in the
screens containing dynamics processing controls, as appropriate for 2-band or 5-
band multiband compression. The meters also change functionality to display the 2-
band or 5-band gain reduction.
Both the 2-band and 5-band multiband compressors always operate in the back-
ground. Switching between 2-band and 5-band therefore occurs with a seamless
cross-fade. Unlike some older Orban processors, no DSP code gets reloaded and no
audio mute occurs, although switching can sound obtrusive if the loudness normally
produced by the 2-band and 5-band presets are very different. It is usually possible
to eliminate audibly obtrusive switching artifacts by tweaking one (or both) of the
presets to make them sound closer to each other and saving the results as user pre-
sets.