Orban OPTIMOD-FM 8600Si, Operating Manual

Page: 176 / 356

3-10
OPERATION ORBAN MODEL 8600Si
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 8600Si’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 8600Si 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 substan-
tially improved transient impact and high frequency power handling capability com-
pared to the “intelligent” clipping in the non–MX presets. See
Measuring the Im-
provements in Optimod-FM 8600 and 8600Si “MX” FM Peak Limiting Technology
starting on page 3-99.
Speech Mode: You can set many of the processing parameters separately for
speech signals, as detected by the 8600Si’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 8600Si 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 3-71.
DSP-derived Stereo Encoder: The 8600Si’s stereo encoder is derived from algo-
rithms first developed for the high-performance Orban 8218 stand-alone encoder.
The 8600Si’s stereo encoder operates at 512 kHz-sample rate to ease the perform-
ance requirements of the D/A converter’s reconstruction filter, making it possible to
achieve excellent stereo separation that is stable over time and temperature. DSP-
based group delay and magnitude equalizers for the entire composite analog path
further improve separation.