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. Therefore, 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 reasonable, to help plan the installation, and make certain comparisons with other processing equipment.
Except as noted, specifications apply for measurements from the analog left/right input to the analog #1 and analog #2 output.
Performance Frequency Response (Bypass Mode): ±0.2 dB, 50 Hz–9.5 kHz, or as determined by user-settable high-pass and low-pass filters.
Noise: Output noise floor will depend upon how much gain the processor is set for (Limit Drive, AGC Drive, Two-Band Drive, and/or Multiband 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 9.5 kHz. <0.02% SMPTE IM Distortion.
Polarity: The processing employs phase rotation to maximize loudness. Therefore, the polarity is frequency-dependent.
Processing Sample Rate: The 9300 is a “multirate” system, using internal rates from 32 kHz to 128 kHz as appropriate for the processing being performed. Audio clippers operate at 128 kHz.
Processing Resolution: Internal processing has 24 bit (fixed point) or higher resolution; uses Motorola DSP56362 DSP chips.
Low-Pass Filter: 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, or 9.5 (NRSC) kHz as set by user. Unit can be set up to comply easily with ITU-R and NRSC spectrum masks. Lowpass filter shape is parametric and can be set to be –0.1, –3, or –6 dB down at the cutoff frequency.
High-Pass Filter: Constrained by user settable fifth-order “quasi-elliptical” highpass filter to 50, 60, 70, 80, 90, or 100 Hz. All filters have equal-ripple (Chebychev-like) passbands and a 25 Hz notch for transmitter protection.
Channel Configuration: Processing is monophonic.
Installation Analog Audio Input Configuration: Stereo (Configurable to drive the processing selection with mono from left, mono from right, or mono from sum).
Nominal Input Level: Software adjustable from -9.0 to +13.0 dBu (VU).
Maximum Input Level: +27 dBu.
Connectors: Two XLR-type, female, EMI-suppressed. Pin 1 chassis ground, Pins 2 (+) and 3 electronically balanced, floating and symmetrical.
A/D Conversion: 24 bit 128x oversampled delta sigma converter with linear-phase anti-aliasing filter. Converter outputs 64 kHz sample rate, which the 9300 then decimates to 32 kHz in DSP using an ultra-high-quality image-free synchronous sample rate converter.
Filtering: RFI filtered, with high-pass filter at 0.15 Hz (-3 dB).
Analog Audio Output Configuration: Two monophonic outputs, capable to driving two transmitters. The two outputs have independent level controls.
Source Impedance: 351Ω (includes the third-order output EMI suppression network), electronically balanced and floating. The user can specify the output load in software to calibrate the output level accurately into a bridging or 600Ω load.
Load Impedance: 600Ω or greater, balanced or unbalanced. Termination not required or recommended.
Output Level (100% peak modulation): Adjustable from -6 dBu to +20 dBu peak, into 600Ω or greater load, software-adjustable.
Signal-to-Noise: ≥ 90 dB unweighted (Bypass mode, de-emphasized, 20 Hz - 9.5 kHz bandwidth, referenced to 100% modulation).