Orban Optimod-TV 8685

Orban Television Audio Processing — Sound That Keeps Audiences Listening

The 8685 is Orban's second-generation surround/2.0 processor. In addition to the effective automatic loudness control of its predecessor, the 8685 offers new input/output capabilities that include support for SDI and HD-SDI and for Dolby E. Dual redundant power supplies help ensure maximum uptime. In addition to surround processing, the 8685 can simultaneously provide up to four channels of 2.0 processing, allowing it to provide all the audio processing necessary for a typical ATSC broadcast with multiple subchannels.

Like the 8585, the 8685 is dialnorm-aware. Loudness control is excellent when measured by the ITU BS.1770-2 and EBU R-128 standards or by the 8685's built-in CBS Loudness Meters, allowing stations to comply effortlessly with the requirements of the CALM act. An included logging application allows time-stamped indications of the 8685's built-in BS.1770-2 short-term and integrated loudness meters to be written to a Windows PC’s local or network storage.

Experience has shown that the mass television audience wants two things from television audio: dialog should be comfortably intelligible and commercials should not be irritatingly loud compared to program material. Home theater owners may want the opportunity to watch feature films while hearing a wide dynamic range signal. However, even these viewers usually consume television in a much more passive way when viewing garden-variety programs. To be an acceptable part of the domestic environment, television sound cannot overwhelm household members not interested in viewing (not to mention neighbors, particularly in multi-family dwellings). For a variety of reasons, the dynamic range of sound essential to the intelligibility of the program should not exceed 15 dB in a domestic listening environment. Underscoring and ambient sound effects will, of course, be lower than this.

The issue of loud commercials is particularly important. In the U.S., it is against Federal Communications Commission rules to broadcast irritatingly loud commercials. Because of viewer complaints, the FCC has periodically investigated the problem ever since 1965.

Orban understands such issues well. Since 1980, we have provided analog television broadcasters with industry-standard dynamics processors: Optimod-TV 8180, 8182, 8282, and 8382. In 1998, we introduced Optimod-DAB 6200 — two-channel processing specifically tailored for digital channels using lossy compression like Dolby’s AC-3, which is used for ATSC transmissions. Our 6300, introduced in 2006, is a second-generation two-channel processor for digital channels, including DTV, DAB, and netcasting.

In typical analog television practice, all audio is applied to a single transmission audio processor that automatically controls the average modulation and the peak-to-average ratio while smoothing out transitions between program elements. Simple compression and peak limiting cannot do this effectively. Starting with the 8182, all Optimod-TV processors have incorporated the CBS Loudness Controller™.

Developed after 15 years of psychoacoustic research at CBS Laboratories, the CBS Loudness Controller accurately estimates the amount of perceived loudness in a given piece of program material. If the loudness exceeds a preset threshold, the controller automatically reduces it to that threshold. The CBS algorithm has proven its effectiveness by processing millions of hours of on-air programming and greatly reducing viewer complaints.

In ITU parlance, the CBS Loudness Controller relies on a "short-term" loudness measurement that takes into account the human ear's loudness integration time — approximately 200 milliseconds. The CBS algorithms attack time is fast enough to prevent audible and irritating loudness overshoots — blasts of sound that have viewers scrambling for their remote controls. Loudness control is always smooth and unobtrusive. Unlike "long-term" loudness measurement and control technologies, the CBS Loudness Controller recognizes that a piece of program material whose average loudness seems acceptable according to a long-term loudness measurement may nevertheless have short sections whose loudness should be reduced because it is extremely annoying. While main purpose of this processing is to control the loudness of commercials, other exuberantly mixed elements can also benefit. A good example is applause with whistling.

Optimod-Surround 8685:
Effective Automatic Loudness Control
for Up to 7.1 Channels

For many years our television customers have been asking for Optimod-quality surround sound processing along with the ability to process the local insertion of news, weather and sports independently. Our customers know that there is no substitute for the smooth, natural-sounding control that only Optimod provides, particularly with speech material.

Orban's response is the 8685. This next generation Optimod provides the functionality and control necessary for up to nine audio streams simultaneously. It can help you achieve the highest audience satisfaction in digital audio broadcasting, digital television, and netcasting.

The 8685 features Optimod-quality two-band and five-band audio processing for surround sound broadcasting and netcasting. Thanks to versatile compression ratio controls and a mastering-quality look-ahead peak limiter, the 8685 is also ideal for mastering audio in broadcast productions as well as productions intended for media such as DVD and Blu-ray.

The 8685 starts with the technology of Orban's popular Optimod 6300 and takes it to the next level with surround processing that reflects the latest psychoacoustic research into loudness perception. The 8685's CBS Loudness Controller works in both two-band and five-band modes. Third generation improvements reduce annoyance better than simple loudness control alone, doing so without audible gain pumping.

In July 2011, the ATSC revised its Recommended Practice entitled Techniques for Establishing and Maintaining Audio Loudness for Digital Television (A/85:2011), which recommends use of the ITU-R BS.1770 long-term loudness meter algorithm to measure loudness. We have verified that the CBS Loudness Controller as implemented in the 8685 (as well as in Orban's two-channel 6300 and 1101 processors) effectively controls long-term loudness as measured by the BS.1770-2, maintaining it within the +2, –5 dB “comfort zone” defined in ATSC A/85 Annex E, thus allowing U.S. broadcasters to comply with the CALM Act. The 8685 also offers a built-in ITU-R BS.1770-2 loudness meter so that users can verify the effectiveness of its loudness control. (BS.1770-2 is based on BS.1770 but adds gating to prevent it from reading too low during material having pauses or silence.)

In our experience, the CBS Loudness Controller and Loudness Meter lock onto the program’s “anchor element” (typically speech) more accurately than the BS.1770 meter, which also tends to over-indicate the loudness of material with low peak-to-RMS ratio (such as promos and commercials with a lot of “artistic compression) by 3 dB or more. Nevertheless, to accommodate organizations that will disqualify an automatic loudness controller if it causes a BS.1770 meter to read higher than a specified threshold, the 8685 now offers a defeatable “BS.1770 safety limiter” that follows the CBS Loudness Controller in the signal path. This limiter can be set to effectively control the indications of a BS.1770-2 gated meter with 10-second or longer integration time. Because gain reduction in the BS.1770 safety limiter is usually triggered by inaccuracies in the BS.1770-2 algorithm itself, we prefer the sound of the processing with this limiter defeated so that all loudness control is performed by the CBS algorithm.

The 8685 is up to nine processors in one, offering four independent 2.0 channel processors plus surround processing for up to 7.1 channels. The 2.0 processing can operate in dual-mono mode, so a given 2.0 processor can process one audio stream in stereo or two audio streams in mono. Each processor includes a CBS Loudness Controller, BS.1770 Safety Limiter, CBS Loudness Meter, and BS.1770-2 Loudness Meter. Additionally, the first 2.0 processor's output can be mixed into the left and right front channels of the surround processing so that the surround processing's Loudness Controller and look-ahead limiters control the loudness and peak level of the mix. Meanwhile, the fourth 2.0 processor can receive a stereo downmixed output from the surround multiband compressor. This downmix application uses only the loudness controllers and peak limiter of the 2.0 processor, allowing the stereo downmix to have dedicated, accurate loudness control and peak levels.

The multichannel and 2.0 processors can operate with separate audio processing parameters like release times. For example, one of the 2.0 processors could be set up for relatively heavy processing to make a newsroom feed more consistent, while the surround processing could be set up more conservatively to correct network material and commercials unobtrusively.

Because the 2.0 processors have their own loudness controllers and peak limiters, another important application is processing subchannels in digital television.

The 8685 is built on Orban's flagship hardware platform. This features a GUI displayed on a quarter-VGA active matrix color LCD, making it easy to do all setup and adjustment from the 8685's front panel. To minimize latency and to achieve highest reliability, the 8685 uses a dual hardware architecture. Freescale 24-bit DSP chips do all audio processing while a separate microcontroller supports the GUI and control functions. Even if this controller malfunctions, the 8685 will continue to process audio normally. Minimum latency of the fully processed signal is 21 milliseconds, which can be padded to exactly one frame of delay for any video standard. The low latency headphone feed (containing all processing except for peak limiting) has a latency of approximately 6 milliseconds.


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; see above). 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.)
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.
(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 12 Freescale (formerly Motorola) 150 MHz DSP56367 DSP chips.
Surround Processing: 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.) The optional HD-SDI I/O module provides video delay of up to 11 frames to compensate for the delay of the 8685’s loudness processing (approximately one frame), optional Penteo® upmixer (approximately seven frames) and optional Dolby-E® decoder and encoders (one frame apiece).
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 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.1770-2 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.)



HD-SDI Input/Output

(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 8685), the HD-SDI input is internally terminated with 75 Ω.
Audio Channel Support:
Supports only SDI audio channels 1 through 8.
Dolby-E® Support:
Sockets exist to accept Dolby-E encoder/decoder modules; unit is field-upgradeable to support Dolby-E.
Delay for A/V Sync:
Includes up to 11 frames of video and metadata delay to preserve AV-sync. Normal 8685 loudness control processing requires one frame of delay; the Penteo upmixer requires an additional seven frame delay; Dolby-E requires one frame for decoding and one frame for encoding.
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)

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.
BNC, female, shell bypassed to chassis via 1000 pF capacitor, EMI-suppressed. 75 Ω impedance, terminated.
Input Reference Level:
Variable from -30 dBfs to -10 dBfs.
RFI filtered.

Digital Audio Outputs (x3)

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.
BNC, female, shell bypassed to chassis via 1000 pF capacitor, EMI-suppressed. 75 Ω impedance, terminated.
Output Level:
(100% peak modulation): -20.0 to 0.0 dBfs software controlled.
RFI filtered.

Audio Reference Input

Can accept wordclock or AES11id (75 Ω) sync, automatically detected.
Female BNC.
Internally terminated with 75 Ω.

Analog Audio Outputs

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 Impedence:
50 Ω, electronically balanced and floating.
Load Impedance:
600 Ω or greater, balanced or unbalanced. Termination not required or recommended.
Output Level:
Adjustable from -6 dBu to +24 dBu peak, into 600 Ω or greater load, software-adjustable.
(100% Peak Modulation)
≥ 100 dB unweighted (Bypass mode, 20 Hz - 20 kHz bandwidth, referenced to 100% modulation).
≤ 0.01% THD (Bypass mode, de-emphasized) 20 Hz - 20 kHz bandwidth.
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.
RFI filtered.

Audio Sync Input

Can accept wordclock or AES11id (75 Ω) sync, automatically selected.
Female BNC, shell grounded to chassis.
Internally terminated with 75 Ω.

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-E 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 provided that the HD-SDI input complies strictly with SMPTE 299M 5.2.1 (CLK [audio clock phase data]).

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

Remote Computer Interface

TCP/IP protocol via direct cable connect, modem, or Ethernet interface. Modem is not supplied.
Serial Port:
115 kbps RS232 port DB-9 male, EMI-suppressed.
Ethernet Port:
100 Mbit/s on RJ45 female connector.

RS485 Serial Interface (x2)

115 kbps RS-485 port DB-9 male, EMI-suppressed.
Designed to be hardware-compatible with Dolby Digital® hardware that sends and receives Dolby Digital metadata.

Conveying and Re-authoring Dolby Metadata

The 8685 can, via an SMPTE RDD 06-2008-compliant RS-485 serial connection, via an HD-SDI connection (when the optional HD-SDI module is installed), or via embedded Dolby-E metadata (when the optional Dolby-E modules are installed in the HD-SDI module), 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 greatly 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 8685 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 8685 passes this stream unchanged to its output except for the following modifications:

  • The ac3_dialnorm word in the output metadata stream is reauthored so it is the same as the 8685's active Dialnorm value.
  • 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

Eight (8) inputs, opto-isolated and floating.
6-15V AC or DC, momentary or continuous. 12 VDC provided to facilitate use with contact closure.
DB-25 male, EMI-suppressed.
User-programmable for any eight of user presets, factory presets, bypass, test tone, stereo or mono modes, analog input, digital input.
RFI filtered.

Tally Outputs

Circuit Configuration:
Two NPN open-collector outputs.
+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.
30 mA maximum.
Tally outputs can be programmed to indicate a number of different operational and fault conditions.


100-264 VAC, automatically selected, 50-60 Hz, 75 VA.
IEC, EMI-suppressed. Detachable 3-wire power cord supplied.
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.


HD Dolby-E Decoder.

  • Base configuration with the addition of a Dolby-E Decoder module.
  • Can accept a Dolby-E bitstream from HD-SDI or AES3id inputs and decode it to PCM for 8685 audio processing or for direct AES3id and HD-SDI outputs.
  • Supports Dolby-E metadata received through HD-SDI and RS485 interfaces per SMPTE RDD 06-2008. The metadata in the HD-SD stream can be embedded in a Dolby-E encoded bitstream (typically using audio channels 1 and 2) or in the HD-SDI VANC data per SMPTE 2020-2-2008 (Method-A) or SMPTE 2020-3-2008 (Method-B).

HD Dolby-E Encoder.

  • Base configuration with the addition of a Dolby-E Encoder module.
  • Can encode PCM outputs from the 8685 audio processor or PCM received from HD-SDI or AES3id inputs into the Dolby-E bitstream.
  • Can emit Dolby-E metadata from an RS485 serial port and through HD-SDI.
  • Can receive Dolby-E metadata through HD-SDI VANC or RS485.

Dolby-E Decoder and Encoder.

  • Base configuration with the addition of Dolby-E Decoder and Encoder modules.
  • Accepts and emits Dolby-E bitstreams from the HD-SDI and AES3id I/O.
  • Supports Dolby-E metadata through HD-SDI and RS485 serial ports.


Operating Temperature:
32 to 122 °F / 0 to 50 °C for all operating voltage ranges.
0 - 95% RH, non-condensing.
Dimensions (W x H x D):
19" x 5.25" x 15.5" / 48.3 cm x 8.9 cm x 39.4 cm. Depth shown indicates rack penetration; overall front-to-back depth is 17.75" / 45.1 cm. Three rack units high.
Tested according to Cenelec procedures. FCC Part 15 Class A device.
Shipping Weight:
40 lbs. / 18.1 kg

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