Orban OPTIMOD 5750 Operating Manual page 50

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Orban 5750 Technical Manual Operation
The 5750's bass, midrange, and high frequency parametric equalizers have curves that were modeled on the curves
of Orban's classic analog parametrics (like the 622B), using a sophisticated, proprietary optimization program. The
curves are matched to better than 0.15 dB. This means that their sound is very close to the sound of an Orban analog
parametric. They also use very high quality filter algorithms to ensure low noise and distortion.
The 5750 HF Enhancer is a program-controlled HF shelving equalizer. It intelligently and continuously analyzes the
ratio between broadband and HF energy in the input program material and can equalize excessively dull material
without over-enhancing bright material. It interacts synergistically with the five-band compressor to produce sound
that is bright and present without being excessively shrill.
Subharmonic Synthesizer: The subharmonic synthesizer generates subharmonics of fundamental frequencies in the
50-90 Hz range or 60-120 Hz range depending on the setting of the SUBHARMONIC CUTOFF FREQ control. The
subharmonics are one octave below the frequencies from which they are generated (i.e., 25-45 Hz or 30-60 Hz) and
track the levels of their generating frequencies.
If input program material below 45 or 60 Hz is present, the subharmonic synthesizer automatically reduces the level
of the synthesized subharmonics to prevent excess build-up of energy below 45 or 60 Hz.
To prevent introducing unnatural coloration in male speech. the subharmonic synthesizer is defeated when the
automatic speech/music detector detects speech. This is particularly important when the SUBHARMONIC CUTOFF
FREQ control is set to 120 HZ.
Multiband Compression: The multiband compressor/limiter can be operated in fiveband or two-band mode. The
5750 controls high frequencies with distortioncanceled clipping and, in all but 5-band MX presets, with a high
frequency limiter as well. The clipper operates at 256 kHz-sample rate and is fully anti-aliased.
Usually, the gain reduction in band 5 is slaved to the gain reduction in band 4 (as determined by the setting of the
B4 > B5 COUPLE control); these bands are only independent from the viewpoint of the downward expander and
multiband clippers. 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 5750'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 clipper, 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 functionality can be
turned on or off manually, or the 5750's speech/music detector can activate it automatically.
The Ultra-low Latency structure does not offer compressor look-ahead.
"Intelligent" Clipping: In non–MX presets, the 5750 prevents excess clipping distortion 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 overshoot compensator.
To minimize 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.