Orban OPTIMOD-PCn 1600 Audio Processing Software

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Orban’s OPTIMOD-PCn 1600 is audio processing software that is available both as a software-only product for Orban-approved Windows® 7 (and higher) computers and pre-installed on a host Windows computer. The host computer can be configured at the factory to run advanced audio processing software (called OPTIMOD-PCn 1600) and MPEG-4 AAC/HE-AACv2/MP3 streaming audio codecs (from Orban’s partner Modulation Index) software natively on its Intel processor. Depending on its ordered configuration, the OPTIMOD-PCn 1600 can run multiple instances of monophonic or stereo processing, and these can be mixed and matched as required. Orban’s exclusive Optimix® stereo → 5.0 surround upmixer can be applied to stereo source material to create “instant surround” with excellent downmix compatibility. The OPTIMOD-PCn 1600 is equally suited for mastering, netcasts and digital radio broadcasting.


  • Optimod-quality digital audio processing, running natively on Intel x86 processors, pre-processes audio for consistency and loudness before it is transmitted or recorded. OPTIMOD-PCn 1600 offers new features never before available in Optimods, as well as a significantly improved high frequency enhancer and stereo enhancer.
  • Applications include netcasting, DAB and other dedicated digital radio services, FMExtra and other digital subcarriers, sound-for-picture, mastering, audio production, and many others.
  • Incorporates modern “target loudness” concepts (including those specified in EBU R128 and ATSC A/85) using the ITU-R BS.1770 loudness model. Allows you to easily set and verify the target loudness of the output.
  • The OPTIMOD-PCn 1600 audio processor runs as a Windows Service on the host computer. A responsive, smooth, easy-to-use graphic control application runs on the host or remote PCs and can control any number of OPTIMOD-PCn 1600 instances, either locally (via a localhost TCP/IP connection) or in other OPTIMOD-PCns on your network via TCP/IP addressing.The Control application allows you complete flexibility to create your own custom presets, to save as many as you want to your local hard drive, and to recall them at will.
  • In hardware bundles, optional sound cards are available for customers needing AES3 or analog hardware I/O.
  • Precisely controls peak levels to prevent overmodulation or codec overload. While primarily oriented toward “flat” media, OPTIMOD-PCn 1600 can also provide preemphasis limiting for the two standard preemphasis curves of 50ms and 75 ms. This allows it to protect preemphasized satellite uplinks and similar channels where protection limiting or light processing is required. It can also be used to process analog television FM aural carriers in television applications because these are usually processed lightly compared to FM radio.
  • Controls audio bandwidth as necessary to accommodate the transmitted sample frequency, obviating the need for extra, overshooting anti-aliasing filters in downstream equipment. OPTIMOD-PCn’s high frequency bandwidth can be switched instantly (typically in 1 kHz increments) between 10.0 kHz and 20 kHz. 20 kHz is used for highest-quality systems. 15 kHz codec bandwidth may help low bitrate lossy codecs sound better than they do when fed full 20 kHz bandwidth audio. 15 kHz is well matched to the codec used the iBiquity® HD-AM system.
  • For specialized purposes like speech processing, a highpass filter switchable from 30 Hz to 200 Hz is available.
  • A DC removal filter with a 0.1 Hz -3 dB low frequency cutoff removes DC offset from source material without introducing overshoot and tilt into low-frequency waveforms.
  • OPTIMOD-PCn 1600 ships with many standard presets, which correspond to different programming formats. There are also special-purpose, no-compromise presets for mastering, studio AGC, pure peak limiting, and low bitrate encoding applications.
  • Audio processing can be smoothly activated and defeated on-air via a delay-matched pass-through mode, allowing programs that can benefit from full dynamic range to pass through OPTIMOD-PCn without dynamics compression except for safety limiting using MX or non-MX limiter modes.
  • A Bypass Test Mode can be invoked locally, by remote control (from either the OPTIMOD-PCn’s GPI port or PC Remote application), or by automation to permit broadcast system test and alignment or “proof of performance” tests.
  • OPTIMOD-PCn 1600 contains a built-in line-up tone generator, facilitating quick and accurate level setting in any system. (See Test Modes on page 3-67.)
  • Silence alarm  and digital audio fault tally outputs are available.
  • Dongle-based copy protection allows the software to be easily moved from one computer to another without elaborate re-authorization procedures.

Audio Processing

  • OPTIMOD-PCn 1600 can increase the density and loudness of the program material by multiband compression and sophisticated peak limiting, improving the consistency of the station’s sound and increasing loudness and definition remarkably, without producing unpleasant side effects.
  • Automatic left/right phase-skew corrector eliminates comb-filtering artifacts in a mono downmix.
  • Bass can be made monophonic, with crossover frequencies of 80 or 100 Hz.
  • Two-Band automatic gain control with a phase-linear crossover, adjustable band coupling, and window gating compensates for widely varying input levels. The AGC rides gain over an adjustable range of up to 25dB, compressing dynamic range and compensating for operator gain-riding errors and for gain inconsistencies in automated systems
  • Five-Band compression with selectable phase-linear and allpass crossover topologies can provide a consistent, “processed” sound, free from undesirable side effects.Band-coupling controls allow the gain differences between adjacent bands of the five-band compressor to be constrained to any desired value, allowing you to preserve as much of the frequency balance of the original program material as desired unless doing so would otherwise cause objectionable spectral gain intermodulation artifacts. Combined with the phase-linear crossover, this functionality can be used in lieu of the two-band compression found in earlier Optimods.Parametric soft-knee compression curves with adjustable ratio allow you to fine-tune the audio to your exact requirements and make OPTIMOD-PCn 1600 an excellent mastering processor.
  • Stereo Enhancer is based on Orban’s patented analog 222 Stereo Enhancer, which increases the energy in the stereo difference signal (L-R) whenever a transient is detected in the stereo sum signal (L+R). Gating circuitry prevents over-enhancement and undesired enhancement on slightly unbalanced mono material, complements the Optimix upmixer, increasing the sense of envelopment and space while maintaining excellent downmix compatibility.
  • Shelving bass equalizer and three-band parametric equalizer let you color the audio to your exact requirements.
  • Dynamic High-Frequency Enhancer constantly monitors the ratio of HF to broadband energy in the incoming audio and can automatically re-equalize it to achieve a target balance between broadband and HF energy.
  • Subharmonic Synthesizer creates energy one octave below program energy in the range of 50-90 Hz when such energy is not present at the input and when music is detected. If input program material below 50 Hz is present, the subharmonic synthesizer automatically reduces the level of the synthesized subharmonics to prevent excess build-up of energy below 50 Hz. This process effectively modernizes the bass sound of older, bass-shy material in a way that sounds punchy, natural, and musical.
  • First introduced in Optimod-FM 8600 and applied to “flat” transmission channels for the first time in OPTIMOD-PCn 1600, Orban’s exclusive MX peak limiter technology uses a psychoacoustic model to achieve an unprecedentedly favorable tradeoff between loudness, transient punch, and distortion artifacts.For applications where target loudness is below approximately -12 LKFS/LUFS, you can reduce CPU load by approximately 50% without compromising audio quality (compared to full MX limiter operation) by defeating the MX limiter and instead using Orban’s smooth, low-IM look-ahead limiter for the very light peak limiting required at these low loudness levels. This is the normal mode of operation for sound-for-picture applications, where target loudness is typically -23 LUFS or -24 LUFS and peak limiting rarely occurs at all.

    In all modes of operation, the peak limiter offers “true peak” control by oversampling the peak limiter’s sidechain at 192 kHz or higher. This allows OPTIMOD-PCn 1600 to prevent clipping in a playback device’s analog signal path by predicting and controlling the analog peak level following the playback device’s reconstruction filter.Without true peak control, analog clipping can occur even if all peak values of the digital samples are below 0 dBFS. This phenomenon has also been termed
    0 dBFS+.”Thanks to true peak control, sample rate conversion, unless it removes high frequency program energy or introduces group delay distortion, cannot cause sample peaks to increase more than 0.5 dB. For example, sample rate conversion from 48 kHz to 44.1 kHz is highly unlikely to cause sample peak clipping in the 44.1 kHz audio data.Accuracy is typically 0.15 dB even with heavy peak limiting, so the output level can be set to -0.2 dBFS without true peak levels exceeding 0 dBFS.
  • Second-generation Optimix stereo → 5.0 surround upmixer provides uncolored automatic upmixing, plus phase correction that ensures that the center channel is always crisp, free from comb-filtering artifacts, 5.1-compatible, provides excellent downmix compatibility, can wrap the virtual soundstage around the listener (put the listener “in the middle of the band”) or place the stage primarily in the front (put the listener “in the audience”). It effectively creates “instant surround” that is compatible with the MPEG4 HE-AAC Parametric Surround codec.
  • Orban Stereo Synthesizer can create an attractively spacious stereo or surround output from mono program material, has excellent downmix compatibility: the mono downmix sum is equal to the mono input. “Wide” and “narrow” modes (based on Orban’s classic analog 275A Stereo Synthesizer), synthesis can be invoked manually, or activated automatically by sensing silence in the right channel input.
  • BS.1770-3 and CBS Loudness Meters measure the subjective loudness of the OPTIMOD-PCn’s output and are displayed in the OPTIMOD-PCn 1600’s control application meter window.
  • OPTIMOD-PCn 1600 includes third-generation CBS Loudness Controllers that are particularly suited for video and news/talk applications. The third-generation improvements reduce annoyance more than simple loudness control alone, doing so without audible gain pumping. Attack time is fast enough to prevent audible loudness overshoots, so the control is smooth and unobtrusive. Material processed by the CBS Loudness Controller has been shown to be well controlled when measured with a long-term loudness meter using the BS.1770 standard.
  • A BS.1770 Safety Limiter follows the CBS Loudness Controller, When activated, it can further improve the measured performance using the BS.1770 meter and which was added for the benefit of organizations with strict objective limits on the indication of a BS.1770 long-term loudness meter. It can be used with or without the CBS Loudness Controller to ensure that broadcasts and netcasts are always constrained to a specified BS.1770 target loudness.
  • A pure peak limiting preset is available. It allows OPTIMOD-PCn 1600 to perform very high quality peak limiting in mastering applications.
  • OPTIMOD-PCn 1600 can be used as a studio AGC (including peak limiting) to protect a studio-to-transmitter link (STL), optimally using the STL’s native dynamic range.
  • Uses “multirate” digital signal processing. Internal processing occurs at sample rates from 48 kHz to 256 kHz and provides 20 kHz audio bandwidth (unless specifically constrained by the user-adjustable lowpass filter).
  • Uses 32-bit or 64-bit floating-point arithmetic as appropriate.


Technical Specification

  • Audio Processors: Each Processor in OPTIMOD-PCn realizes a mono, stereo, or surround
    audio processor. Except for mono, each processor consists of the following cascaded
    processing elements: Internal Processing: Input > Left/Right Phase Skew Corrector
    > Mono Bass > Stereo Synthesizer > Stereo Enhancer > Two-Band defeatable
    AGC with window gating > Equalizer/HF Enhancer > Multiband Compressor > Optimix
    ® upmixer > Peak Limiter > Automatic Loudness Controller > Output. In surround
    processors, Optimix is located just before the AGC, and all dynamics processing
    operates on the upmixed signal when Optimix is active. See Figure 3-2: OPTIMOD-PCnDigital Signal Processing Block Diagram on page 3-12.
  • Number of Audio Processors: Software is priced according to the total number of Processors
    permitted to run simultaneously on a given computer. The number of Processors
    realizable on a given computer depends on the processing features used and the power
    of the computer’s CPU. Plan your installation by using the information in CPU starting on
    page 1-4.
  • Frequency Response: ±0.1dB, 2-20,000Hz (Bypass software running).
  • Input/Output Delay: Typically 1.0 to 1.6 seconds. Varies according to the number of processing
    features that are activated.
  • Internal Filters: 10, 11, 12, 13, 14, 15, and 20kHz can be used to provide additional antialiasing
    for low sample rate services.
  • Internal Sample Rate: 48-256 kHz, as appropriate.
  • Internal Resolution: 32-bit or 64-bit floating point, as appropriate for the processing being
  • Input/Output Resolution: 16-bit or 24-bit fixed point. If the output is configured for 16 bits,
    First-order noise-shaped dither can be applied prior to truncation to 16 bits from 32-bit
  • Peak Control: Peak limiter is oversampled at 192 (non-MX mode) or 256 kHz (MX mode),
    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
    OPTIMOD-PCn’s lowpass filter cutoff frequency to 15 kHz.)
  • Phase Response: Linear-phase (constant group delay) or allpass, user selectable.
    AGC (Automatic Gain Control): ±12dB/24dB gain range, Two-Band, Gate and Window
  • Stereo Enhancer: Orban-developed L−R dynamic expansion triggered by L+R transients.
    Equalizers: Shelving Low Bass EQ, selectable 6 dB, 12dB or 18dB/octave. Three-band Parametric
    EQ with analog-style bell-shaped curves. Program Adaptive HF Enhancer.
  • Multiband Compressors: 25dB gain reduction range, Five-Band.
  • Limiter: >12dB gain reduction range. Two modes available: low-IM look-ahead (to minimize
    CPU usage) and MX (to achieve highest performance). Moreover, the MX limiter’s overshoot
    compensator can be operated in Soft mode (for lowest distortion) or Hard mode
    (to achieve highest loudness without audible gain pumping).
  • Loudness Controller: Constrains subjective loudness to a user-adjustable threshold via
    the 1981 Jones & Torick CBS Technology Center algorithm, as further refined and developed
    by Orban. The algorithm also drives a subjective loudness meter, which is displayed
    on the 1600’s GUI. In dual-mono mode, there are two independent loudness controllers
    and meters.
  • BS.1770 Safety Limiter: Constrains Integrated BS.1770-2 (and higher) loudness to preset
    value, with an attack time of 10 seconds and a release time of 3 seconds.
    Pass-through mode: Delay-matched to active processing. Gain adjustable from −10 dB to
    +10 dB.
  • Number of Factory Presets: More than 50, each with 19-step LESS-MORE control. Presets
    are fully customizable.
  • Number of User Presets: Essentially unlimited. User presets can be saved on the host
    computer’s hard drive or on other storage devices.

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