Orban Optimod-TV 6585

Artifact-Free Automatic Loudness Control Requires
Much More Than Just “Processing for the BS.1770 Meter.”

Orban's value-priced Optimod 6585 surround/stereo television loudness controller builds on Orban's 30+ year experience in television audio processing to provide audibly transparent automatic loudness control and dialog intelligibility control for one surround program (up to 7.1) or four stereo (stereo) programs. The stereo processing can operate in dual-mono mode, so it can process four subchannels in stereo or eight subchannels in mono. Put in-line and operated correctly, the 6585 will ensure that loudness meets the requirements of the CALM Act and EBU R-128.

The 6585 features 3G HD-SDI and AES3id input/output, plus comprehensive handling of metadata. The 6585 is Dialnorm-aware and can re-author metadata as needed. Seamless switching between processing and pass-through modes (where both audio and metadata are passed through without further processing) allows the 6585 to pass pre-qualified material without modification—you can use the 6585's transparent-sounding loudness control only when needed. This makes it easy to comply with the requirements of network program providers who preprocess their audio feeds to comply with Recommendations A/85 and R-128.

For each logical processing channel (surround or stereo), the 6585 has one loudness controller and two loudness meters. The short-term meter uses second-generation CBS Technology Center loudness metering technology with an integration time of 200 ms, which is slightly faster than a standard VU meter. The long-term meter, which has an integration time of several seconds, is switchable between the ITU-R BS.1770-1 and 1770-2 standards (i.e. ungated or gated). Its readings can be logged for up to a week in the 6585's internal memory and for an essentially unlimited time via the included 6585 PC Remote Software for Windows®. This allows you to retain proof that your transmissions have complied with the CALM Act.

6585 front panel info

The 6585 controls loudness smoothly and unobtrusively without the unnatural-sounding gain pumping, noise breathing, harshness, stereo image shifts, and compromised dialog intelligibility that can result from naive designs whose only goal is to make a BS.1770 loudness meter look good. Only experienced human listeners can assess these artifacts; the BS.1770 meter cannot indicate them.

Since 1980, Orban has sold thousands of Optimod-TV processors and these have processed millions of hours of on-air programming. No other manufacturer can make this claim. Over the decades, we have constantly refined and polished our loudness control algorithms to provide audibly transparent loudness control that never annoys audiences. Instead of using BS.1770 as a simplistic internal model that determines how loudness is controlled, we use a much more sophisticated multiband psychoacoustic model to do this. This model is based on years of research at CBS Laboratories and CBS Technology Center and was further refined by us. This model allows the 6585 to control both short-term and long-term loudness. The only purpose of the 6585's built-in BS.1770 meter is to verify that our model controls long-term loudness effectively according to the BS.1770 standard. Thousand of hours of subjective listening tests have verified that our model controls loudness without irritating audiences. The 6585 meters the processing; it doesn't process for the meter.

Automatic loudness control is just the beginning. Because not all program material is mixed perfectly, we have designed the 6585 to re-equalize and de-ess dialog and will automatically correct the balance between dialog and other program elements as necessary.

In surround mode, the 6585 provides a simultaneous stereo downmix that is loudness-controlled, peak-controlled, and pre-emphasis aware, so it can drive an analog TV transmitter in countries that simulcast digital and analog signals. In stereo mode, the four stereo processors can be made pre-emphasis aware, allowing the 6585 to be purchased for immediate use with analog transmitters with the assurance that it will provide no-compromise processing for digital transmissions when the need arises. A second use for the stereo processors is processing up to four different languages in DTV program streams.

In addition to standard HD-SDI I/O and AES3id I/O, the 6585 optionally supports Dolby-E streams from and to the AES3id and SDI I/O via plug-in Dolby-manufactured modules. The 6585 can accept and emit Dolby-E metadata via RS485 serial (per SMPTE RDD 6-2008), Dolby-E-encoded streams (when the Dolby-E decoder option is fitted), and SDI [per SMPTE 2020-2-2008 (Method-A) and SMPTE 2020-3-2008 (Method-B)].


Dual redundant power supplies with independent AC line inputs help ensure maximum uptime.


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.


Frequency Response (Bypass Mode): ± 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.

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 6585 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 9 Freescale (formerly Motorola) 250 MHz DSPB56724 dual-core 24-bit fixed-point DSP chips.

Delay: The minimum available input/output delay is approximately 20 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.) HD-SDI I/O provides video delay of up to 11 frames to compensate for the delay of the 6585's loudness processing (approximately one frame) and optional Penteo® upmixer (approximately seven frames).

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 automatically.

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 AES 3 Status Bits.

Loudness Level Meter (x4): One meter for the surround processing or four meters for the four 2.0 processing channels, all meters realized in software. For a given processing chain, two meters operate simultaneously: a long-term loudness meter displays loudness over an ungated 3-second integration time or 10-second integration time using the ITU-R BS.1770-2 algorithm (per ATSC A/85 and EBU R 128) and a short-term loudness meter uses the Jones & Torick algorithm developed at CBS Technology Center in 1981. The Jones & Torick meter's display time constants are matched to the psychoacoustic 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. Hence, this meter can indicate the momentary loudness of transient events like pistol shots, which may be annoying to viewers but which the BS.1770-2 meter ignores because of its longer integration time. (B. L. Jones & E. L. Torick: “A New Loudness Indicator for Use in Broadcasting,” J. SMPTE, September 1981, pp 772-777.)

One ITU BS.1770-2 meter is always displayed on the 6585's front-panel; it indicates the Surround loudness when the 6585 is in Surround mode and it indicates the 2.0 loudness of one of the four 2.0 processing channels (user selected) when the 6585 is in 2.0 Mode. In 6585 PC Remote software, all four loudness meters are displayed simultaneously when the 6585 is in 2.0 mode.


HD-SDI Input/Output

SD-SDI (per SMPTE 259M ), 1.5 Gbit/s HD-SDI (per SMPTE 292M; up to 720p and 1080i), and 3.0 Gbit/s single-wire HD-SDI (per SMPTE 424M; 1080p). Input and output are on BNC connectors. A bypass relay is provided.

Unless the bypass relay is directly connecting the HD-SDI input to the HD-SDI output (which is true when no AC power is applied to the 6585), the HD-SDI input is internally terminated with 75Ω .

Audio Channel Support: Supports SDI and HD-SDI audio channels 1 through 8.

Delay for A/V Sync: Includes up to 11 frames of video and metadata delay to preserve AV-sync. Normal 6585 loudness control processing requires one frame of delay; the Penteo upmixer requires an additional 261 ms of delay.

Dolby E Metadata Support: Supports Dolby-E metadata received through HD-SDI and RS485 interfaces per SMPTE RDD 06-2008. The metadata in the HD-SD stream must be embedded the HD-SDI VANC data per SMPTE 2020-2-2008 (Method-A) or SMPTE 2020-3-2008 (Method-B).

Digital Audio Inputs (x4)

Configuration: Each of four hardware inputs accepts two audio channels per AES3id standard, 24 bit resolution. Internal programmable routing switcher allows any of the 10 physical input channels to be routed to the LF, RF, C, LB1, RB1, LFE, LB2, RB2, STEREO L, or STEREO R inputs of the audio processing. For the 2.0 processing, unit can detect Stereo or Two-Channel status bits appearing at Input #1 and switch the 2.0 processor between stereo and dual-mono modes. Input #4 can also be used as a sync input, accepting wordclock or AES11id sync. In addition to the ability to receive and emit program audio, the AES3id I/O can be configured as a loop-through to support Orban's external Penteo upmixer.

User Bits: Unit can pass AES3id User Bits from Input #1 to Output #1.

Sampling Rate: 32, 44.1, 48, 88.2, or 96 kHz, automatically selected.

Connector: BNC, female, shell bypassed to chassis via 1000 pF capacitor, EMI-suppressed. 75Ω impedance, terminated.

Input Reference Level: Variable from -30 dBFS to -10 dBFS.

Filtering: RFI filtered.

Digital Audio Outputs (x3)

Configuration: AESid. Internal, remote-controllable routing switcher allows sending LF, RF, C, LB1, RB1, LFE, LB2, RB2, STEREO L, STEREO R, DOWNMIX L, and DOWNMIX R to any hardware output channel.

Sample Rate: Internal free running at 32, 44.1, 48, 88.1 or 96 kHz, selected in software. Can also be synced to the AES3id Input #1,or to the sync input (which supports AES11id and wordclock) at 32, 44.1, 48, 88.1 or 96 kHz, as configured in software. (Passband is limited to approximately 14.7 kHz when using 32 kHz input and/or output sample rate.)

Word Length: Software selected for 24, 20, 18, or 16-bit resolution. First-order highpass noise-shaped dither can be optionally added, Dither level is automatically adjusted to complement the word length.

Connector: BNC, female, shell bypassed to chassis via 1000 pF capacitor, EMI-suppressed. 75Ω impedance, terminated.

Output Level (100% peak modulation): -20.0 to 0.0 dBFS software controlled.

Filtering: RFI filtered.

Audio Reference Input

Configuration: Can accept wordclock or AES 11id (75Ω ) sync, automatically detected.

Connector: Female BNC.

Termination: Internally terminated with 75Ω .

Analog Audio Outputs

Configuration: One pair of outputs, which can be configured in software to emit LF, RF, C, LB1, RB1, LFE, LB2, RB2, STEREO L, STEREO R, DOWNMIX L, DOWNMIX R, LF/RF, C, LB1/RB1, LB2/RB2, STEREO L/R, and DOWNMIX L/R signals.

Source Impedance: 50Ω, electronically balanced and floating.

Load Impedance: 600Ω or greater, balanced or unbalanced. Termination not required or recommended.

Output Level (100% peak modulation): Adjustable from -6 dBu to +24 dBu peak, into 600Ω or greater load, software-adjustable.

Signal-to-Noise: ≥ 100 dB unweighted (Bypass mode, 20 Hz-20 kHz bandwidth, referenced to 100% modulation).

Distortion: ≤ 0.01% THD (Bypass mode, de-emphasized) 20 Hz-20 kHz bandwidth.

Connectors: Two XLR-type, male, EMI-suppressed. Pin 1 chassis ground, Pins 2 (+) and 3 electronically balanced, floating and symmetrical.

D/A Conversion: 24 bit 128x oversampled.

Filtering: RFI filtered.

Audio Sync Input

Configuration: Can accept wordclock or AES 11id (75Ω ) sync, automatically selected.

Connector: Female BNC, shell grounded to chassis.

Termination: Internally terminated with 75Ω .

Video Sync Input

Video Sync input (per SMPTE 274M and SMPTE 296M ) can be used as a reference for the output audio sample rate and to correctly align Dolby metadata frames with video per Dolby's requirements (SMPTE RDD 6-2008 and Dolby Labs published specifications) in cases where HD-SDI is not in use. When HD-SDI is in use, frame sync is obtained from the HD-SDI input stream.

The video reference input is on a female BNC connector and is internally terminated with 75Ω .

Remote Computer Interface

Configuration: TCP /IP protocol via direct cable connect, modem, or Ethernet interface. Modem is not supplied.

Serial Port 115 kbps RS-232 port DB-9 male, EMI-suppressed.

Ethernet Port 100 Mbit/sec on RJ45 female connector.

RS-485 Serial Interface (x2)

Hardware: 115 kbps RS-485 port DB-9 male, EMI-suppressed.

Compatibility: Designed to be hardware-compatible with Dolby Digital® hardware that sends and receives Dolby Digital metadata per SMPTE RDD 06-2008.

Conveying and Re-authoring Dolby Metadata

The 6585 can, via an SMPTE RDD 06-2008 -compliant RS-485 serial connection or via an HD-SDI connection, automatically convey its active surround metadata value to a downstream Dolby Digital encoder like the Dolby DP-569, which must be set up according to its operating instructions to receive and act upon this input. This reduces the possibility that operator error will cause the wrong value of surround metadata to be transmitted to consumers.

To emit an RDD 06-2008-compliant signal, the 6585 must be receiving a valid input stream that is compliant with RDD 06-2008—this is necessary to synchronize the output metadata to video frame boundaries per the Dolby specification. When a valid input stream in present, the 6585 passes this stream unchanged to its output except for the following modifications:

•  When using any preset other than Pass-through, the ac3_dialnorm word in the output metadata stream is reauthored so it is the same as the 6585's active Dialnorm value. When Pass-through is active, the Dialnorm value in the input metadata is passed through to the 6585's output.

•  The ac3_dynrnge word in the output stream is set to 0, indicating that the downstream AC3 encoder must reauthor the line-mode DRC metadata, following the level compression profile found in the ac3_dynrng1 word in the input metadata.

•  The ac3_compre word in the output stream is set to 0, indicating that the downstream AC3 encoder must reauthor the RF-mode DRC metadata, following the level compression profile found in the ac3_compr1 word in the input metadata.

Remote Control ( GPI ) Interface

Configuration: Eight (8) inputs, opto-isolated and floating.

Voltage: 6-15V AC or DC, momentary or continuous. 12 VDC provided to facilitate use with contact closure.

Connector: DB-25 male, EMI-suppressed.

Control: User-programmable for any eight of user presets, factory presets, bypass, test tone, stereo or mono modes, analog input, digital input.

Filtering: RFI filtered.

Tally Outputs

Circuit Configuration: Two NPN open-collector outputs.

Voltage: +15 volts maximum. Do not apply negative voltage. When driving a relay or other inductive load, connect a diode in reverse polarity across the relay coil to protect the driver transistors from reverse voltage caused by inductive kickback.

Current: 30 mA maximum

Indications: Tally outputs can be programmed to indicate a number of different operational and fault conditions.


Voltage: 100-264 VAC, automatically selected, 50-60 Hz, 75 VA.

Connector: IEC, EMI-suppressed. Detachable 3-wire power cord supplied.

Configuration: Two independent power supplies with independent IEC input connectors. Power supply health is monitored and the good supply is automatically connected to the load should one supply fail.

Safety Standards: ETL listed to UL standards, CE marked.



Operating Temperature: 32 ° to 122 ° F / 0 ° to 50 ° C for all operating voltage ranges.

Humidity: 0-95% RH, non-condensing.

Dimensions (W x H x D): 19" x 3.75" x 15.5" / 48.3 cm x 8.9 cm x 39.4 cm. Two rack units high.

Humidity: 0-95% RH, non-condensing.

RFI / EMI: Tested according to Cenelec procedures. FCC Part 15 Class A device.

Shipping Weight: 40 lbs. / 18.1 kg

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