The OPTIMOD 8600 provides the industry’s most consistent sound allowing you to create a sonic signature for your station

The OPTIMOD 8600 can be used for analog FM processing as well as for HD/digital radio/streaming processing at no extra cost. It provides you with Orban’s MX limiter technology which lowers distortion, improves transient punch, and minimizes preemphasis-induced high frequency loss. A special feature unique to the OPTIMOD 8600 and the OPTIMOD 8700i is the Multipath Mitigator phase corrector. It minimizes stereo subchannel energy without compromising stereo separation. The 8600 has a built-in RDS generator with dynamic PS as well as a dedicated low-delay headphone monitor chain that lets you dial in controlled amounts of “FM limiter sound” to match talent preferences. More outstanding features are described in the Key Features section.

The OPTIMOD 8600 delivers the inimitable “Optimod Sound,” proven to attract and hold audiences worldwide. Try it yourself and contact your local supplier for a demo.

User-Friendly Interface

Large (quarter-VGA) active-matrix color liquid crystal display (LCD)
Makes setup, adjustment and programming of the 8600 easy. Navigation is by a miniature joystick, two dedicated buttons and a large rotary knob. The LCD shows all metering functions of the processing structure in use.

Locate joystick
Used to navigate through a menu that lets you recall a preset, modify processing (at three levels of expertise), or to access the system’s setup controls.

Absolute Control of Peak Modulation

Universal transmitter protection & audio processing for FM broadcast
The 8600 provides universal transmitter protection and audio processing for FM broadcast. It can be configured to interface ideally with any commonly found transmission system in the world, analog or digital.

Pre-emphasis limiting
The 8600 provides pre-emphasis limiting for the internationally used pre-emphasis curves of 50 µs and 75 µs. Compared to its predecessor, its new clipping/pre-emphasis-control technology preserves 2.5 to 3 dB more frequency energy while significantly reducing audible clipping distortion at all frequencies. This produces a clean, open sound whose subjective brightness more closely matches the original program.

Tight peak control at all its outputs
The 8600 achieves extremely tight peak control at all its outputs – analog, AES3 (for both the analog FM and HD/digital radio channels) and composite baseband.

Stereo encoder integrated with audio processing
Eliminates the overshoot problems that waste valuable modulation in traditional external encoders.

Two outputs
The stereo encoder has two outputs with independent level controls, each capable of driving 75 Ω in parallel with 47,000 pF, (100 ft / 30 m of coaxial cable).

Stereo encoder
By integrating the stereo encoder with the audio processing, the 8600 eliminates the overshoot problems that waste valuable modulation in traditional external encoders.

Bandwidth limiting & overshoot compensation
The 8600 prevents aliasing distortion in subsequent stereo encoders or transmission links by providing bandwidth limiting and overshoot compensated 15 kHz low-pass filters ahead of the 8600’s audio outputs and stereo encoder.

Internal DSP-based stereo encoder
The 8600 has an internal, DSP-based stereo encoder (with a patented “half-cosine interpolation” composite limiter operating at 512 kHz samplerate) to generate the pilot tone stereo baseband signal and control its peak level. The composite limiter is a unique, “you can only do this in DSP” process that beats composite clippers by preserving stereo imaging while fully protecting the stereo pilot tone, RDS/RBDS and subcarriers.

“Multipath Mitigator” Left/Right Phase Skew Correction
The phase skew corrector maximizes the quality of a mono mixdown or blend that might occur in a receiver.

Built-in RDS/RBDS generator. Loudness and True Peak Control
The digital radio and analog FM processing chains each include an ITU-R BS.1770-3 Loudness Meter and Loudness Controller for use in countries that enforce a BS.1770 loudness limit on digital radio broadcasts. The 8600HD implements “true peak” control in the HD processing chain by oversampling the HD peak limiter’s sidechain at 256 kHz. This allows the 8600 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 to an accuracy of better than 0.5 dB. For typical program material, accuracy is 0.2 dB.

Flexible Configuration

Single Sideband
Because of broadcaster interest in this topic, we have implemented an experimental compatible single sideband/vestigial sideband mode in the 8600’s stereo encoder. SSB/VSB operation suppresses the upper sideband of the stereo subcarrier above 38,150 Hz, which reduces the occupied bandwidth of the FM-modulated RF signal. In SSB/VBS mode, the subchannel modulator acts as a pure SSB generator for L-R material in the frequency range of 150 Hz to 17 kHz and as a vestigial sideband generator below 150 Hz.

Analog & AES3 digital inputs & outputs
OPTIMOD 8600 is supplied with analog and AES3 digital inputs and outputs. The digital input and the two digital outputs are equipped with sample rate converters and can operate at 32 kHz, 44.1 kHz, 48 kHz, 88.1 kHz and 96 kHz sample rates. The pre-emphasis status and output levels are separately adjustable for the analog and digital outputs. Each output can emit the analog FM processed signal, the analog FM processed signal with diversity delay applied, the digital radio processed signal or the low-delay monitor signal.

Analog & AES3 digital inputs & outputs
A loop-through connection is provided to enable a ratings encoder (such as Arbitron®) to be inserted at the output of the AGC (before the analog-FM and HD processing paths split) or between the output of the audio processing and the input to the stereo encoder.

Defeatable diversity delay
A defeatable diversity delay can delay the FM analog processing output up to 16.2 seconds. Delay can be trimmed in intervals of one sample of 64 kHz to match the analog and digital paths in the HD Radio system, eliminating the need to use the delay built into the HD Radio exciter and permitting the 8600’s internal stereo encoder and composite limiter to drive the analog FM exciter. Each output (Analog, Digital 1, Digital 2, Composite(analog and digital)) can be independently configured to emit the delayed or undelayed signal.

AES11 sync input
An AES11 sync input allows you to synchronize the output sample rate of either (or both) AES3 outputs to this input. You can also synchronize the outputs to the AES3 digital input or to 8600’s internal clock. The sync source of each AES3 output is independently selectable.

Transformerless, balanced 10 k Ω instrumentation-amplifier circuits
The analog inputs are transformerless, balanced 10 kΩ instrumentation-amplifier circuits. The analog outputs are transformerless balanced and floating (with 50 Ω impedance) to ensure highest transparency and accurate pulse response.

Two independent composite baseband outputs
The 8600 has two independent composite baseband outputs with digitally programmable output levels. Robust line drivers enable them to drive 100 feet of RG59 coaxial cable without audible performance degradation.

Two subcarrier inputs
The 8600’s two subcarrier inputs are mixed with the output of the 8600’s stereo encoder before application to the composite output connectors. One input can be re-jumpered to provide a 19 kHz pilot reference output. Both inputs have internal level trims to accommodate subcarrier generators with output levels as low as 220 mV.

Precise control of the audio bandwidth
The 8600 precisely controls the audio bandwidth of its analog FM processing to 16.5 kHz. This prevents significant overshoots in uncompressed digital links operating at a 44.1 kHz-sample rate or higher and prevents interference to the pilot tone and RDS (or RBDS) subcarrier. The bandwidth of the 8600’s digital radio output is adjustable in 1 kHz increments between 15 kHz and 20 kHz.

Defeatable multiplex power limiter
The 8600 has a defeatable multiplex power limiter that controls the multiplex power to ITU-R BS412 standards. An adjustable threshold allows a station to achieve maximum legal multiplex power even if the downstream transmission system introduces peak overshoots into the 8600-processed signal. Because this limiter closes a feedback loop around the audio processing, it allows the user to adjust the processor’s subjective setup controls freely without violating BS412 limits, regardless of program material. The multiplex power limiter acts on all outputs (not just the composite output). In its most common configuration, it reduces clipper drive when it reduces power, simultaneously reducing clipping distortion. However, to accommodate customers who wish to use heavier clipping to achieve a certain sound, the MPX power controller can be configured to reduce gain after the clippers.

RFI-suppressed connections
All input, output and power connections are rigorously RFI-suppressed to Orban’s traditional exacting standards, ensuring trouble-free installation.

International safety and emissions standards
The 8600 is designed and certified to meet all applicable international safety and emissions standards.

Adaptability through Multiple Audio Processing Structures

Processing structure
A processing structure is a program that operates as a complete audio processing system. Only one processing structure can be on-air at a time, although all are active simultaneously to permit mute-free switching between them. The 8600 realizes its processing structures as a series of high-speed mathematical computations made by Digital Signal Processing (DSP) chips.

Featuring six processing structures
The 8600 features six processing structures. Four of these are the same as OPTIMOD-FM/HD 8500: Five-Band (or “Multiband”) for a consistent, “processed” sound with 17 ms delay (typical), Low-Latency Five-Band (12 ms delay), Ultra-Low-Latency Five-Band (3.7 ms delay) and Two-Band (17 or 22 ms delay) for a transparent sound that preserves the frequency balance of the original program material. A special Two-Band preset creates a no-compromise “Protect” function that is functionally similar to the “Protect” structures in earlier Orban digital processors.

“MX” structures
The 8600’s two latest “MX” structures (five-band and two-band) are similar to their 8500 counterparts except that they use the 8600’s new peak limiting technology to decrease distortion while achieving substantial improvements in transient punch and high frequency clarity. This advanced technology requires more input-to-output delay than the older structures, so it is impractical for talent to monitor these structures off-air with headphones. The 8600 offers a special low-delay monitor output for this purpose.

The 8600’s Two-Band processing structures can be made phase-linear to maximize audible transparency.

Rides gain
The 8600 rides gain over an adjustable range of up to 25 dB, compressing dynamic range and compensating for both operator gain-riding errors and gain inconsistencies in automated systems.

Increase density and loudness
The 8600 can increase the density and loudness of the program material by multiband compression, limiting and clipping – improving the consistency of the station’s sound and increasing loudness and definition remarkably, without producing unpleasant side effects.


Remote control
The 8600 can be remote-controlled by 5 – 12V pulses applied to eight programmable, optically isolated GPI (general-purpose interface) ports.

Serial port #1
The 8600 is equipped with a serial port to interface to an WIndows® computer running Orban’s PC Remote software. The connection can be either direct or through an external modem.

Serial port #2
The 8600 has a second serial port that allows the user to set up security and communications parameters through a simple ASCII terminal program running on any PC.

Built-in 100 Mbps Ethernet port
The 8600 can be connected through its built-in 100 Mbps Ethernet port to a TCP/IP network.

The SNMP (Simple Network Management Protocol) features allow you to monitor the 8600’s status and to send Alarm notifications via the 8600’s Ethernet connection to your network.

Telnet client
The 8600 includes a Telnet client that allows presets to be recalled via batch files using the free PuTTY and Plink applications. The commands are simple ASCII strings, facilitating interface to automation systems that can emit such strings through an Ethernet or RS232 serial connection.

PC Remote control software
8600 PC Remote software is a graphical application that runs under Windows 2000, XP, Vista, 7, 8 and 10. It communicates with a given 8600 via TCP/IP over modem, direct serial and Ethernet connections. You can configure PC Remote to switch between many 8600s via a convenient organizer that supports giving any 8600 an alias name and grouping multiple 8600s into folders. Clicking an 8600’s icon causes PC Remote to connect to that 8600 through an Ethernet network, or initiates a Windows Dial-Up or Direct Cable Connection if appropriate. The PC Remote software allows the user to access all 8600 features and allows the user to archive and restore presets, automation lists and system setups (containing I/O levels, digital word lengths, GPI functional assignments, etc.).

Bypass Test Mode
A Bypass Test Mode can be invoked locally, by remote control (from the 8600’s GPI port, its PC Remote application, or ASCII API), or by automation to permit broadcast system test and alignment or “proof of performance” tests.

Built-in line-up tone generator
The 8600 contains a built-in line-up tone generator, facilitating quick and accurate level setting in any system.

Versatile real-time clock
The 8600 contains a versatile real-time clock, which allows automation of various events (including recalling presets) at pre-programmed times. To maintain accuracy, this clock can be automatically synchronized via the Internet to a reference time source.


Frequency Response(Bypass Mode; Analog Processing Chain)
Follows standard 50µs or 75µs preemphasis curve ±0.10 dB, 2.0 Hz – 15 kHz.

64 kHz to 512 kHz, depending on processing being performed.

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. It is primarily governed by the dynamic range of the A/D converter, which has a specified overload-to–noise ratio of 110 dB. 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 15 kHz. <0.02% SMPTE IM Distortion.

Total System Separation
> 55 dB, 20 Hz – 15 kHz; 60 dB typical.

Polarity (Two-Band and Bypass Modes)
(Two-Band and Bypass Modes): Absolute polarity maintained. Positive-going signal on input will result in positive-going signal on output when HD Polarity and FM polarity controls are set to POSITIVE.


Defeatable Analog FM Processing Delay
0.27 to 12.0 seconds. Delay adjustments of less than ±1.3 seconds are applied to the HD path to prevent FM analog artifacts.

Minimum Processing Delay
3.7 ms to 270 ms, processing structure dependent. Multipath Mitigator delay = 146 ms.

Analog Audio Input


> 10kΩ load impedance, electronically balanced1.

Nominal Input Level
Software adjustable from –4.0 to +13.0 dBu (VU).

Maximum Input Level
+27 dBu.

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.

RFI filtered, with high-pass filter at 0.15 Hz.

Analog Audio Output

Stereo. The analog output can emit the analog FM processed signal, the digital radio processed signal, or the low-delay monitor signal. The FM processed signal can be flat or pre-emphasized (at 50μs or 75μs), software-selectable.

Source Impedance
50 Ω, electronically balanced and floating.

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

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

≥ 90 dB unweighted (Bypass mode, de-emphasized, 20 Hz – 15 kHz bandwidth, referenced to 100% modulation).

≤ -70 dB, 20 Hz – 15 kHz.

≤ 0.01% THD (Bypass mode, de-emphasized) 20 Hz – 15 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.

Digital Audio Input

Stereo per AES3 standard, 24 bit resolution, software selection of stereo, mono from left, mono from right or mono from sum.

32 kHz, 44.1 kHz, 48 kHz, 88.2 kHz, and 96 kHz.

XLR-type, female, EMI-suppressed. Pin 1 chassis ground, pins 2 and 3 transformer balanced and floating, 110 Ω impedance.

Input Reference Level
Variable within the range of -30 dBFS to -10 dBFS.

J.17 De-emphasis

RFI filtered.

Digital Audio Output

Two outputs, each stereo per the AES3 standard. The outputs can be set independently to emit the analog FM processed signal, the digital radio processed signal, or the low-delay monitor signal. The FM processed signal can be configured in software as flat or pre-emphasized to the chosen processing pre-emphasis (50μs or 75μs). The digital radio processing chain receives the output of the multiband limiter and processes it through a look-ahead true peak limiter that operates in parallel with the main FM peak limiting system. The DR and FM signals are always simultaneously available. Each output can apply J.17 pre-emphasis if desired.

Internal free running at 32 kHz, 44.1 kHz, 48 kHz, 88.2 kHz, or 96 kHz, selected in software. (Use 44.1 kHz or higher for best peak control.) Can also be synced to the AES3 SYNC input or the AES3 digital input at 32 kHz, 44.1 kHz, 48 kHz, 88.2 kHz, and 96 kHz, as configured in software.

Word Length
Software selected for 24, 20, 18, 16 or 14-bit resolution. First-order highpass noise-shaped dither can be optionally added, dither level automatically adjusted appropriately for the word length.

XLR-type, male, EMI-suppressed. Pin 1 chassis ground, pins 2 and 3 transformer balanced and floating, 110 Ω impedance.

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

Frequency Response through Digital Radio Processing Chain
For output sample rates of 44.1 kHz and above, the frequency response from input to DR-configured output is ±0.10 dB, 2.0 Hz – 20 kHz; flat or with J.17 pre-emphasis applied. The user may specify lowpass filtering to constrain the bandwidth to 15, 16, 17, 18, or 19 kHz.

Relative Time Delay between FM and HD Outputs
Depends on setting of analog processing channel diversity delay; up to 16 seconds is available. Once set, this delay is constant regardless of processing preset in use.

Digital Sync Input

Used for synchronization of either or both AES3 signals to an external reference provided at this input.

32, 44.1, 48, 88.1 and 96 kHz, automatically selected.

XLR-type, female, EMI-suppressed. Pin 1 chassis ground, Pins 2 and 3 transformer balanced and floating, 110 Ω impedance.

RFI filtered.

Digital Sync Input

Accepts 1x wordclock or 10 MHz reference signals, automatically selected. The DSP master clock can be phase-locked to these signals, which in turn phase-locks the 19 kHz pilot tone frequency, facilitating singe-frequency network operation. The digital output sample frequency can also be locked to these signals.

Unit will lock to 1x wordclock and 10 MHz squarewaves and sinewaves having a peak value of 0.5 V to 5.0 V.

BNC female, grounded to chassis, non-terminating to allow reference signals to be looped through via an external BNC “tee” connector (not supplied).

Composite Baseband Output

Number of Outputs
2 x analog; 1 x AES3 (MPX hardware only)

Subcarrier Modulation Mode
Standard double sideband mode or compatible single sideband/vestigial sideband mode with SSB/VSB crossover at 150 Hz. SSB/VSB mode adds approximately 12 ms of delay to the composite output signal.

Two outputs, each with an independent software-controlled output level control, output amplifier and connector.

Source Impedance
0Ω voltage source or 75Ω, jumper-selectable. Single-ended, floating over chassis ground.

Load Impedance
37Ω or greater. Termination not required or recommended.

Maximum Output Level:]
+12.0 dBu (8.72 Vp-p).

Minimum Output Level
–12 dBu (0.55 Vp-p) for 0.5 dB adjustment resolution.

Pilot Level
Adjustable from 6.0% to 12.0%, software controlled.

Pilot Stability
19 kHz, ±0.5 Hz (10 degrees to 40 degrees C).

D/A Conversion

Signal-to-Noise Ratio
<= 85 dB (Bypass mode, de-emphasized, 20 Hz – 15 kHz band- width, referenced to 100% modulation, unweighted).

<= 0.02% THD (Bypass mode, de-emphasized, 20 Hz – 15 kHz bandwidth, referenced to 100% modulation, unweighted).

Stereo Separation (analog outputs)
At 100% modulation = 3.5Vp-p, > 60 dB, 30 Hz – 15 kHz. At 100% modulation = 1.0 – 8.0 Vp-p, > 55 dB, 30 Hz – 15 kHz.

<= –80 dB, main channel to sub-channel or sub-channel to main channel (referenced to 100% modulation).

<= –80 dB, main channel to sub-channel or sub-channel to main channel (referenced to 100% modulation).

38 kHz Suppression
> = 70 dB (referenced to 100% modulation).

76 kHz & Sideband Suppression
> = 80 dB (referenced to 100% modulation).

Pilot Protection
60 dB relative to 9% pilot injection, ±250 Hz (up to 2 dB composite processing drive).

Subcarrier Protection (60-100 kHz)
> = 70 dB (referenced to 100% modulation; with up to 2 dB composite limiting drive; measured with 800 line FFT analyzer using “maximum peak hold ” display).

57 kHz (RDS/RBDS) Protection
50 dB relative to 4% subcarrier injection, ±2.0 kHz (up to 2 dB composite processing drive)

Analog composite outputs

Two BNC, floating over chassis ground, EMI suppressed.

Maximum Load Capacitance
0.047μF (0Ω source impedance). Maximum cable length of 100 feet / 30 meters RG–58A/U.

RFI filtered.

AES3 Composite Output (MPX hardware only)

One XLR-type, appearing on breakout cable

Sample Frequency>
192 kHz

Extension to Interim Industry Standard:
The composite baseband is internally sampled at 384 kHz and alternate samples are placed on the left and right audio channels. With compatible receiving hardware, this allows the entire baseband frequency range (0 to 99 kHz) to be accommodated without aliasing. If the frequency range of the SCA’ s applied to the digital output is limited to less than 96 kHz, this is fully compatible and interoperable with the existing system adopted by the industry, which uses only the left channel at 192 kHz.

Subcarrier (SCA) Inputs

Non-Digitized Inputs
2 x non-digitized analog are summed into the analog composite outputs but do not appear at the digital composite outputs.

2 x BNC, unbalanced and floating over chassis ground, EMI suppressed.

Number of Inputs
2 x digitized analog. These are summed into the digital composite but do not appear on the analog composite outputs.

16-bit conversion

2 x BNC, appearing on breakout cable.

> 600Ω

SCA Sensitivity (all inputs)
Variable from 220 mV p-p to > 10 V p-p to produce 10% injection. Sensitivity of analog inputs is screwdriver-adjustable by trim pots that are accessible through holes in the rear panel. Sensitivity of digitizing inputs is adjustable in software.

19 kHz Pilot Reference
Analog SCA2 input jack can be jumpered to provide a 19 kHz pilot reference output or to serve as a second analog SCA input. The phase of the reference signal can be set to 0°, 90°, 180°, or 270° with respect to the pilot tone appearing at the composite output. The default is 0°.

Remote Computer Interface

Supported Computer and Operating System
IBM-compatible PC running Microsoft Windows® 2000 (SP3 or higher)/XP/Vista/7/8/8.1.

TCP/IP protocol via direct cable connect, modem, or Ethernet interface. Modem and other external equipment is not supplied.

Serial Connectors
RS–232 port (3) DB–9 male, EMI-suppressed. Serial Connector 1 uses PPP to provide for direct or modem connection to the 8600 PC Remote application. Serial Connector 2 supports communication to a computer or remote control system via simple ASCII commands for administration and recalling presets. Serial Connector 3 is reserved for future developments.

çEthernet Connector
Female RJ45 connector for 10-100 Mbps networks using CAT5 cabling. Native rate is 100 Mbps. Provides for connection to the 8600 PC Remote application through either a network, or, using a crossover Ethernet cable, directly to a computer.

Ethernet Networking Standard:=

Remote Control (GPI) Interface

TCP/IP protocol via direct cable connect, modem, or Ethernet interface.

6 – 15 V AC or DC, momentary or continuous. 9 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 (x2)

NPN open collector.

Maximum Voltage
30 VDC positive. Protected against reverse polarity by a diode; do not exceed 50 mA through this protection diode.

Maximum Current
30 mA; current must be limited externally.


90–240 VAC 50–60 Hz, 50 VA

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

Circuit ground is independent of chassis ground can be isolated or connected with a rear panel switch.

Safety Standards
ETL listed to UL standards, CE marked.


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.

Shipping Weight & Dimensions: 30 lbs / 13.6 kg – 25″ x 24″ x 9″


Five Years, Parts and Service
Subject to the limitations set forth in Orban’s Standard Warranty Agreement. Because engineering improvements are ongoing, specifications are subject to change without notice.

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