DISCONTINUED Orban Optimod-FM 8400 Audio Processor

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Since its introduction in 1991, Orban’s OPTIMOD 8200 has achieved a reputation as the industry’s best sounding FM transmission processor, as well as the first successful FM processor based on DSP technology. Now Orban introduces its new, second-generation flagship FM digital processor—the 8400. With five times the DSP power of its predecessor, the 8400 refines and improves Orban’s world-class sound while adding a plethora of new features designed to add value and to make the 8400 the preeminent FM processor at the start of the new century.


Easy To Use: The 8400 retains and builds upon the 8200’s ease of use and user friendliness. A new pointing device and large color LCD display make it even easier to navigate through the 8400’s menus. The Quick Setup wizard walks you through the initial setup, step by step, to get you on the air fast. Once you’re on the air, dozens of excellent-sounding presets let you quickly customize the processing for your format and target demographic. If you want to fine-tune a preset, an easy, one-knob LESS-MORE adjustment lets you trade off loudness against processing artifacts.
Versatile: The 8400 offers the same basic processing structures as the 8200. Five-Band is the flagship sound for competitive broadcasters with popular music and talk formats. It gives you an unmatched combination of loudness and consistency. Two-Band is a phase-linear structure ideal for classical music and jazz, where natural, uncolored sound is an absolute requirement. Protect is designed to be operated below threshold most of the time, and allows the 8400 to be used as a protection limiter to retain the original dynamics in the highest quality classical broadcasts. (The Two-Band Normal structure was eliminated because almost all customers prefer the Five-Band structure for popular music and talk formats.)

Clean and Loud: The 8400’s back end—its peak limiting system—is the most advanced ever offered in an Orban processor. New distortion cancellation techniques and overshoot compensation for the 15 kHz lowpass filters yield spectacularly clean and tight control. This powerful back end can be pushed hard to achieve highest loudness with minimum artifacts. All clipping occurs at 256 kHz sample rate, and the clippers are fully anti-aliased. The 8400 burns DSP MIPS to achieve unparalleled performance!
Feature-Rich: In the 8400, two user-selectable “flavors” of stereo enhancement are standard. One emulates Orban’s analog 222A, while the other emulates a popular “max”-type processor. The 8400 has rich, versatile equalization facilities with three bands of analog-sounding parametric, a sweepable bass shelf with 6, 12, or 18dB/octave slopes, and a program-adaptive dynamic shelving equalizer. A new composite processor allows you to limit in the composite domain while still protecting your pilot tone and subcarriers, and without compromising stereo imaging.
Controllable: The 8400 offers TCP/IP networkability as well as Orban’s traditional dial-up PC Remote control. The new PC Remote Management software allows you to control the 8400 via a direct serial connection, a pair of modems, or Ethernet.
Easy to Install: Like all digital OPTIMODs, the 8400 is a plug-and-play solution that works correctly in any plant, whether the 8400 is located at the studio or at the transmitter. It offers flawless control over its baseband spectrum and peak modulation. It protects all subcarriers, including RDS, superbly well. It protects the stereo pilot tone by 60dB, allowing maximum stereo coverage even in areas with substantial multipath. It is fully compatible with 32 kHz sample-rate uncompressed STLs without the need for distortion producing overshoot compensation schemes. In short, it was designed to work right, the first time, effortlessly, using industry-standard connections.

The Digital Advantage, Times Five

Thanks to a new generation of Motorola Digital Signal Processing (DSP) chips, we’ve been able to give the 8400 over five times the power of its predecessor at lower cost. This has allowed us to improve on its predecessor’s basic processing, and also to add features that many Orban customers have requested over the years.

Stereo Enhancement: DSP-based stereo enhancement is now standard. We’ve built a DSP emulation of Orban’s analog 222 Stereo Enhancer, which has developed a reputation for subtle, tasteful, musical enhancement that increases brightness and transient definition while broadening the stereo soundstage. The 222 does not try to “remix the record,” so it doesn’t increase reverberation to levels unanticipated by the original recording artists and producers.

A second type of enhancement is also available. It’s similar to the popular “max”-type unit used by many broadcasters. This can provide a more obvious, but less controlled, amount of enhancement. With the 8400, the choice is yours.

Improved AGC: A newly-improved two-band AGC adds features based on the legendary Gregg Labs five-band analog processor. One new feature is “target zone” gating. As long as the output level of the AGC is within a selectable window, the AGC’s gain freezes, so the AGC does not add to the density of the sound. This can achieve maximum transparency in smooth jazz and similar formats that depend on long time-spent-listening.

A big change is the availability of dual-mono operation. Some broadcasters like the sound of operating the left and right processing without stereo coupling because they feel that it maximizes loudness and widens the stereo image.

You can now choose to operate the processing either coupled or independent. In Independent mode, you can set the maximum amount of gain difference between the left and right channels on a band-by-band basis, thereby controlling the maximum amount of image shift. We’ve also allowed you to operate the AGC in either left/right or sum-and-difference modes. Sum-and-difference can give a different style of stereo enhancement than the 8400’s other stereo enhancers. It can also control material with excessive stereo separation (like old Beatles records).

Powerful Equalization: The 8400 provides three bands of fully parametric bell-shaped equalization, with control over the amount of EQ (± 10dB), center frequency, and the bandwidth. These curves accurately emulate the shapes of the curves in Orban’s vintage studio parametric equalizers, so they don’t have the usual “digital equalizer” sound.

The 8400 also has a sweepable bass shelving EQ that improves on the bass shelving EQ present in its predecessor. You have your choice of 6, 12 and 18dB/octave slopes, while the +3dB frequency is sweepable from 80 to 500Hz.

To add even more color to the palette, we included a dynamic, program-adaptive high-frequency shelving equalizer. First introduced in Orban’s popular OPTIMOD-FM 2200, this equalizer helps you achieve a bright sound without over-equalizing material that is already sufficiently bright.

Output band mix controls in the five-band structure provide still more control over the spectral balance. The various equalizers together provide an almost infinite variety of tone, allowing you to customize your sound to your exact requirements.

Look-ahead compression and a high-performance back end maximize loudness: On-air loudness is constrained by the amount of peak limiting you can do for a given amount of perceived distortion. The 8400 allows you to reduce distortion with look-ahead compression. By delaying the audio until the attack waveform in its control signal has fully developed, this system minimizes overshoot for a given attack rate. So you can have the solid, punchy sound characteristic of slower attack rate while minimizing the resulting overshoot. In turn, this minimizes the amount of clipping necessary for peak control, allowing you to drive the clippers harder to achieve highest loudness.

Because some transient material sounds punchier when it is controlled by clipping instead of look-ahead compression, we also offer an “auto” mode that activates the look-ahead compression on speech (to lower distortion) while seamlessly defeating it on music (to increase transient punch).

Orban’s exclusive embedded bass clipper system has been significantly improved. You now have your choice of hard, medium, or soft bass clipping. Medium and soft have greatly reduced clipper distortion.

The look-ahead compressor and low-distortion bass clipper are complemented by Orban’s new back-end processing. Improved distortion cancellation and a low-distortion overshoot compensator complement a 256 kHz sample frequency for the clippers. This prevents any significant overshoot due to the peaks’ “slipping between the samples.”

To gild the lily, the clippers are now anti-aliased so they sound completely “analog.” Based on extensive listening tests, we never believed that “digital grunge” was audible with program material in a well-designed processor like the 8200. But we’ve eliminated it in the 8400, providing extra comfort for the folks who feel that “digital grunge” might otherwise have a negative effect on the sound.

DSP-Based Stereo Encoder and Composite Processor: The 8400’s stereo encoder (generator) is realized in DSP to achieve the ultimate in stability and high performance. Two composite outputs are provided, each with programmable gain. For convenience, one composite output can be configured to provide a pilot reference signal for RDS encoders. These outputs use accurate, robust drivers and can drive over 100 feet (30m) of coaxial cable into a 75-ohm load.

For composite clipping fans, we have developed a completely new technique (patent pending) for composite processing in the digital domain. It uses a short look-ahead, but without the usual gain reduction that can cause pumping. It protects the SCA region and pilot tone to –80dB, and achieves better than 60dB stereo separation up to 3dB processing depth. It operates at 512 kHz sample rate and adds another finely honed tool to the 8400 user’s competitive arsenal.

Tunability, for Beginners and Experts

Part of the fun of owning a digital processor is being able to make your own custom presets. The 8400 is tunable on three levels:

BASIC CONTROL is all most people will ever need. It’s a one-knob less-more control that allows you to effortlessly trade off loudness against distortion, based on tables created by Orban’s experienced processing experts.

INTERMEDIATE CONTROL is one step beyond less-more. It allows you to make your own trade-offs, adjusting parameters like clipping level and multiband drive. Most of these controls are only moderately risky, providing few program-dependent surprises when they are misadjusted.

The 8400 adds a third level: ADVANCED CONTROL. This is designed for audio processing experts, and makes available controls that require considerable experience and sophistication to adjust correctly. Consultants will love this! Included for the first time in Orban processors are compressor threshold, attack rate, and multiband clipping threshold controls. You can also custom-tune the multiband compressor release time in a band-by-band basis. The Advanced Control screen allows you access to the same level of control that the factory programmers had when they were creating the 8400’s presets.

Regardless of the level at which you make your adjustments, you can name your custom preset and save it to one of 32 user preset locations, recalling it by remote control or by internal clock-based automation.

Network and Remote-Control Ready

The 8400 has two PC Card slots, one on the front panel and one on the rear panel. The front panel slot accommodates a memory card that permits you to save user presets.

The rear panel slot accommodates an Ethernet network card. The 8400 ships with PC Remote Control software that allows you to control one 8400 at a time from a PC using a direct serial cable connection, a dial-up connection, or an Ethernet network.

The software allows you can do virtually everything that you can do from the 8400’s front panel, including making custom presets. The Remote Management Software also allows you to load and save presets, and to share custom presets between various 8400 units.

Compatible With Industry Standards, for Hassle-Free Installation

Like other Orban FM digital processors, the 8400 uses industry-standard AES/EBU digital inputs and outputs. (Line-level balanced analog inputs and outputs are also provided.) The digital output can emit 32, 44.1, and 48 kHz sample rates, while the digital input can accept any sample rate between 32 kHz and 96 kHz.

The 8400’s basic sample rate is 32 kHz, with internal sample rates as high as 512 kHz for certain processing. We believe that the basic 32 kHz sample rate perfectly complements the 15 kHz audio bandwidth limitation of the FM stereo system, allowing us to effectively protect the stereo pilot tone and RDS subcarriers from the interference typically caused by the excessive, uncontrolled audio bandwidth typical of 96 kHz sample rate systems. Unlike such systems, we don’t need to use additional, distortion-producing overshoot compensation to force our signal through 32 kHz uncompressed digital STLs while preventing overshoot. Instead, the 8400’s output is perfectly bandlimited and can pass through such STLs with bit-for-bit transparency. The 8400’s design guarantees a minimum-hassle installation through industry-standard connections. The result is a louder, cleaner sound that’s overshoot-free and that prevents interference to subcarriers and the stereo pilot tone.


The 8400 offers clock-based automation with timebase accuracy considerably improved over the 8200. Using either the 8400’s front panel or remote management software, you can program up to 99 events to occur on a one-time, daily, or weekly basis.

ITU-R 412 Compliance

ITU-R 412 requires the “average multiplex power” to be limited to a standard value. The 8400 contains a defeatable feedback multiplex power limiter that constantly monitors the multiplex power according to ITU-R 412 standards. The power controller automatically reduces the average modulation to ensure compliance. It allows you to set the “texture” of the processing freely, using any preset. If a given processing setting would otherwise exceed the multiplex power limit, the power controller automatically reduces the drive to the peak limiting system. This action retains the compression texture but reduces distortion while controlling multiplex power.

The 8400 gives you control over the multiplex power threshold. This allows you to compensate for overshoots in the signal path upstream from the 8400, preventing excessive reduction of the multiplex power.

Unlike some other processors, the ITU controller works with all outputs (not just the composite output), allowing you to use any STL you want while still controlling the multiplex power.

Orban Quality

Like all OPTIMODs, the 8400’s design has been exhaustively tested for EMI immunity and emissions and meets all applicable international standards. It is designed to operate at a conservative internal temperature to ensure long life for critical components. Because its sound depends on programs running in high-speed DSP chips, its sound is not subject to drift over time, unlike analog boxes. Every aspect of its design and operation has received detailed attention from our engineers, project managers, and test department. In short, you’re probably already familiar with OPTIMOD quality, and Orban is determined to make the 8400 live up to the reputation of its predecessors.

Progress and Processing Delay

The important DSP improvements we’ve put into the 8400 have required that we increase its total input/output time delay to about 21 milliseconds (starting with 8400 version 2.0 software; earlier versions had substantially higher delay). The 8200, on the other hand, had only 2.7 ms delay. Fortunately, the 8400’s higher delay is nevertheless below the threshold that causes a distinct echo, so off-air monitoring through headphones is still practical without confusing talent.

The increase in delay is the inevitable price of progress—doing cool things in DSP that were impossible in analog usually requires look-aheads or other digital processing having intrinsic time delay. These delays are not caused by lack of raw DSP processing power (The 8400 has more than enough power to compute the relevant algorithms in real time); they’re inherent in the algorithms used and would be present even if an infinite amount of processing power were available.

Why Do I Need One?

The 8400 sound is a big step beyond 8200 version 3.0. We’ve been able to exploit the huge increase in DSP power to achieve clearly audible improvements in cleanliness and loudness by comparison to the best we could do with the 8200’s DSP “engine.” We then surrounded this improved processing engine with auxiliary processing—stereo enhancement, versatile equalization, and advanced composite processing—that either previously required outboard boxes, or was simply unavailable. Finally, we made it available to you at a fair price.

The 8400 is the choice for any major market station that has to remain competitive by using state of the art processing. It’s also the right choice for any station that has budgeted for new processing and that wants to select the processor that provides the best sound, highest reliability, and easiest installation. For over 25 years, OPTIMOD has provided this to the broadcast industry, and the 8400 continues this proud tradition.

Technical Specification

Technical Specification

It is impossible to characterize the listening quality of even the simplest limiter or compressor on the basis of specifications, because such specifications cannot adequately describe the crucial dynamic processes that occur under program conditions. Therefore, the only way to meaningfully evaluate the sound of an audio processor 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.


Specifications for measurements from analog left/right input to stereo composite output and to analog left/right output.

Frequency Response (Bypass Mode):
Follows standard 50 microsecond or 75 microsecond pre-emphasis curve ± 0.10 dB, 2.0 Hz –- 15 kHz. Analog left/right output and Digital output can be user configured for flat or pre-emphasized output.

Output noise floor will depend upon how much gain the processor is set for (LIMIT DRIVE, AGC DRIVE, TWO-BAND DRIVE, and/or MULTI-BAND 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 105 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:
>65 dB, 20 Hz –- 15 kHz; 70 dB typical.

Polarity (PROTECTION, TWO-BAND PURIST, or Bypass Mode):
Absolute polarity maintained. Positive-going signal on input will result in positive-going signal on output.


Analog Audio Input


>10k ohms load impedance, electronically balanced.

Nominal Input Level:
Software adjustable from -9.0 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. Flat or pre-emphasized (at 50 microseconds or 75 microseconds), software-selectable.

Source Impedance:
50 ohms, electronically balanced and floating.

Load Impedance:
600 ohms 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 ohms or greater load, software-adjustable.


³ 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 AES/EBU standard, 24 bit resolution, software selection of stereo, mono from left, mono from right or mono from sum.

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

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

User Bits:
Input user bits are optionally passed through to the output.
Input Reference Level: Variable within the range of -30 dBFS to -10 dBFS.

J.17 De-emphasis:

RFI filtered.

Digital Audio Output

Stereo per AES/EBU standard. Output configured in software as flat, pre-emphasized to the chosen processing pre-emphasis (50 microseconds or 75 microseconds), with- or without J.17 pre-emphasis.

Sample Rate:
Internal free running at 32, 44.1 or 48 kHz, selected in software. Can also be synced to the AES/EBU SYNC input or the AES/EBU digital input at 32, 44.1, or 48 kHz, as configured in software.

Word Length:
Software selected for 24, 20, 16 or 14-bit resolution. 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 ohms impedance.

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

RFI filtered.

Digital Sync Input

Used for synchronization of the Digital Output signal to an external reference provided at this input.

Sampling Rate:
32, 44.1 and 48 kHz automatically selected.

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

RFI filtered.

Composite Baseband Output

Two outputs, each with an independent software-controlled output level control, output amplifier and connector. Output 2 may be configured in software as a pilot frequency reference.

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

Load Impedance:
37 ohms or greater. Termination not required.

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

Pilot Level:
Adjustable from 8.0% to 10.0%, 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 bandwidth, referenced to 100% modulation, unweighted).

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

Stereo Separation:
At 100% modulation=3.5Vp-p, > 70 dB, 30 Hz – 15 kHz. At 100% modulation=1.0 – 8.0 Vp-p, > 60 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:
³ 70 dB (referenced to 100% modulation).

76 kHz & Sideband Suppression:
³ 80 dB (referenced to 100% modulation).

Pilot Protection:
-60 dB relative to 9% pilot injection, ± 250 Hz (no composite processing).

57 kHz (RDS/RBDS) Protection:
-50 dB relative to 4% subcarrier injection, ± 1.0 kHz (no composite processing).

Two BNC, floating over chassis ground, EMI suppressed.

Maximum Load Capacitance:
0.047 microfarad (0 ohms source impedance). Maximum cable length of 100 feet/30 meters RG-58A/U.

RFI filtered.

Remote Computer Interface

TCP/IP protocol via modem or Ethernet interface. Modem (either external or PCMCIA card), Ethernet PCMCIA card, and other external equipment not supplied.

RS-232 port (2) DB-9 male, EMI-suppressed. Ethernet or Modem card supported with PCMCIA rear-panel slot.

Remote Control Interface

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

6-24V AC or DC, momentary or continuous. 9VDC 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.


100-132 VAC or 200-264 VAC, switch-selected on the rear panel, 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 degrees to 122 degrees F / 0 degrees to 50 degrees C for all operating voltage ranges.

0-95% RH, non-condensing.

Dimensions (W x H x D):
19″ x 5.25″ x 16.5″ / 48.3 cm x 8.9 cm x 41.9 cm. Depth shown indicates rack penetration; overall front-to-back depth 18.75″ / 47.6 cm. Three rack units high.

Shipping Weight:
40 lbs. / 18.1 kg

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