Section 6 Technical Data; Specifications; Performance - Orban OPTIMOD-FM 8500S Operating Manual

OPTIMOD-FM DIGITAL
Section 6
Technical Data

Specifications

It is impossible to characterize the listening quality of even the simplest limiter or
compressor based on specifications, because such specifications cannot adequately
describe the crucial dynamic processes that occur under program conditions. There-
fore, the only way to evaluate the sound of an audio processor meaningfully is by
subjective listening tests.
Certain specifications are presented here to assure the engineer that they are rea-
sonable, to help plan the installation, and make certain comparisons with other
processing equipment.

Performance

Except as noted in the text, specifications apply for measurements from analog left/right in-
put to stereo composite output and to FM analog left/right output.
Frequency Response (Bypass Mode): Follows standard 50µs or 75µs pre-emphasis curve
±0.10 dB, 2.0 Hz–15 kHz. Analog left/right output and digital output can be user-
configured for flat or pre-emphasized output.
Noise: Output noise floor will depend upon how much gain the processor is set for (Limit
Drive, AGC Drive, Two-Band Drive, and/or Multi-Band Drive), gating level, equalization,
noise reduction, etc. The dynamic range of the A/D Converter, which has a specified
overload-to–noise ratio of 110 dB, primarily governs it. The dynamic range of the digital
signal processing is 144 dB.
Total System Distortion (de-emphasized, 100% modulation): <0.01% THD, 20 Hz–1 kHz,
rising to <0.05% at 15 kHz. <0.02% SMPTE IM Distortion.
Total System L/R Channel Separation: >50 dB, 20 Hz – 15 kHz; 60 dB typical.
Polarity (Two-Band and Bypass Modes): Absolute polarity maintained. Positive-going signal
on input will result in positive-going signal on output when HD Polarity and FM polarity
controls are set to P
Processing Sample Rate: The 8500S is a "multirate" system, using internal rates from 64
kHz to 512 kHz as appropriate for the processing being performed. Audio clippers oper-
ate at 256 kHz (and are anti-aliased), while the composite limiter operates at 512 kHz.
Peak Control at HD Output: The peak limiter is oversampled at 256 kHz, yielding a worst-
case overshoot of 0.5 dB at the analog output and for all output sample rates. (To
achieve this performance at 32 kHz output sample rate, it is necessary to set the
8500S's HD lowpass filter cutoff frequency to 15 kHz.)
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OSITIVE
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TECHNICAL DATA