Orban OPTIMOD-FM 8600, Operating Manual

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3-10
OPERATION ORBAN MODEL 8600
However, a high frequency limiter causes additional gain reduction in band 5 when
band 5 multiband clipping alone would be insufficient to prevent HF distortion. The
HF limiter uses a sophisticated analysis of the signal conditions in the 8600’s clipping
system to do this.
Except in MX presets, a clipper, embedded in the crossover, protects bands 1 and 2
from transient overshoot. This clipper has a shape control, allowing you to vary the
“knee” of its input/output transfer curve from hard (0) to soft (10). Instead of a clip-
per, MX presets use a sophisticated bass pre-limiter located immediately before the
system’s main distortion-controlled clipper.
In non-MX presets, the multiband compressor/limiter offers look-ahead compression
to minimize overshoot and its associated clipping distortion. This look-ahead func-
tionality can be turned on or off manually, or the 8600’s speech/music detector can
activate it automatically.
The Ultra-low Latency structure does not offer compressor lookahead.
“Intelligent” Clipping: In non–MX presets, the 8600 prevents excess clipping dis-
tortion by dynamically reducing the drive level to the clippers as required, using an
intelligent analysis of the clipping distortion produced in the final clipper and over-
shoot compensator.
Note that, in the interests of minimizing latency, the Ultra-low Latency
structure does not have this feature. This is the principal reason why it
achieves less on-air loudness that the optimum-latency and low-latency
processing for a given amount of distortion.
MX presets use an advanced peak limiting structure that uses additional “intelli-
gence,” novel processing structures, and other strategies to produce lower perceived
distortion with “difficult” program material. This peak limiter also offers substantial-
ly improved transient impact and high frequency power handling capability com-
pared to the “intelligent” clipping in the non–MX presets.
Speech Mode: You can set many of the processing parameters separately for
speech signals, as detected by the 8600’s speech/music detector. This allows you to
tune the processing separately for speech and music.
A
S
PEECH
D
ETECT
control allow you to force the 8600 into Music mode, overriding
the Speech/Music detector. This control is contained in the processing preset. In five-
band presets, it is found in the Speech Mode screen (Advanced Modify 6) and in
two-band presets, it is found in the Two Band screen (Advanced Modify 4).
Note that the speech detector will detect most speech mixed with music
as “music” unless the music is at a very low level compared to the speech.
Speech must also be centered in the stereo sound field to be detected as
“speech.”
By using the
S
PEECH
D
ETECT
control, you can override the speech/music
detector. See To Override the Speech/Music Detector on page 3-70.
DSP-derived Stereo Encoder: The 8600’s stereo encoder is derived from algo-
rithms first developed for the high-performance Orban 8218 stand-alone encoder.
The 8600’s stereo encoder operates at 512 kHz-sample rate to ease the performance