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Sales price $23,227.50
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  • Description
  • Reviews

Orban’s flagship OPTIMOD TV 8685 surround/stereo television loudness controller builds on Orban’s 30+ years experience in television audio processing to provide audibly transparent automatic loudness control and dialog intelligibility control for one surround program (up to 7.1) and four stereo programs simultaneously.


  • Frequency Response (Bypass Mode): Surround Processing: ±0.10 dB, 20 Hz-20 kHz for 44.1 kHz or higher input/output sample rates. At 32 kHz input and/or output sample rate, the passband is reduced to approximately 14.7 kHz. 2.0 Processing: Depending on settings, is flat or follows standard 50 µs or 75 µs pre-emphasis curve ±0.10 dB, 20 Hz-20 kHz (except at 32 kHz). Output can be user-configured to be flat or pre-emphasized. (Pre-emphasis limiting allows any of the 8685’s 2.0 processors to drive an analog television transmitter that uses an preemphasized FM aural carrier. This function is particularly useful when used with 2.0 processor #4, which can emit a loudness-controlled and peak-limited downmix of the surround audio. Preemphasis limiting is also useful for certain older analog studio/transmitter links.)
  • 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.
  • Polarity (Bypass Mode; Operate Mode when
    processing chain is configured for linear phase): Absolute polarity maintained.
    Positive-going signal on input will result in positive-going signal on output.
  • Internal Processing Sample Rate: 48 kHz. We
    believe this provides maximum audible transparency by minimizing numerical
    ?noise? in the equalizers and filters while still preserving a pure,
    transparent sound. The double-precision equalizers and crossover filters used
    throughout the 8685 produce at least 6 dB lower noise and nonlinear distortion
    than they would at 96 kHz.
  • Processing Resolution: Internal processing has
    24 bit (fixed point) or higher resolution; uses nine Freescale (formerly
    Motorola) 250 MHz DSPB56724 dual-core 24-bit fixed-point DSP chips.
  • Delay: The minimum available input/output
    delay is approximately 33 ms with look-ahead limiting active and 6 ms with
    look-ahead limiting bypassed. This can be padded to exactly one or two frames
    of 24, 25, 29.97, 30, 50, 59.94, or 60 frames/second video up to a maximum
    delay of 60 ms. (Two frames are required for 59.94/60 fps progressively scanned
    video.) The HD-SDI connection provides video delay of up to 11 frames to
    compensate for the delay of the 8685?s loudness processing (approximately one
    frame), Optimix® upmixer (approximately five frames) and optional Dolby
    Digital® (AC3) encoder (185 ms).
  • Surround Processing Stereo Coupling: All
    channels of the AGC and compressors are coupled using RMS summation. The user
    can select whether or not the LFE channel contributes to the RMS sum in the AGC
    and compressor control sidechains. Peak limiters in the multiband compressor
    limiter and look-ahead limiters all operate uncoupled to prevent transients in
    a given channel from causing audible loudness modulation in other channels. In
    additional, the compressors acting on the center channel can be uncoupled from
    the remaining channels within a user-selectable window, allowing the processing
    to correct the balance between dialog and remaining program elements
  • 2.0 Processing Stereo Coupling: Stereo or
    dual-mono. In dual-mono mode, both processing channels have the same subjective
    adjustments (as determined by the active preset) but are otherwise independent,
    making this mode appropriate for dual-language transmissions. In stereo mode,
    the user can set the maximum permitted gain difference between the channels in
    each band of the multiband compressor/limiter. 2.0 Stereo/Dual-Mono operating
    mode can be set via GPI, Ethernet and serial connections, internal clock-based
    automation, and AES3 Status Bits.
  • Loudness Level Meters (x5 or x9): One set of
    meters for the surround processor and one set of meters for each of the 2.0
    processors. In dual-mono mode, each mono channel has one set of meters. Meters
    can be displayed on the 8685’s front-panel screen and on PC Remote software. A
    set of loudness meters includes a BS.1770-4 meter and a CBS meter, which are
    displayed side-by-side. The ITU BS.1770 meter displays Short-term and
    Integrated Loudness simultaneously on the same scale. The integrated loudness
    measurement shows the loudness of the previous 10 seconds of program material
    with equal time-weighting and gating per BS.1770-2. The CBS meter?s display
    time constants are matched to the loudness integration time of the human ear,
    reaching steady-state level in approximately 200 ms and having a decay time
    constant of approximately 300 ms. The short-term meter uses the Jones &
    Torick algorithm developed at CBS Technology Center. (B. L. Jones & E. L.
    Torick: “A New Loudness Indicator for Use in Broadcasting,” J. SMPTE,
    September 1981, pp 772-777.)
  • Peak Control: As recommended in ITU-R
    BS.1770-4, the peak limiter is oversampled at 192 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
    8685?s lowpass filter cutoff frequency to 15 kHz.)
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