Optimod-FM 8500
Optimod-FM 8500

Optimod‐FM 8500

FM and Digital Radio Optimod Audio Processor

Featuring versatile five-band and two-band processing for analog FM transmission, the 8500 provides consistent sound, track-to-track and source-to-source. This consistency allows you to create a sonic signature for your station with the assurance that your signature will stay locked in, uniquely branding your sound. There are two versions of Optimod-FM 8500. Model 8500HD is the full FM and Digital Radio version and the analog FM-only version is 8500FM.
The 8500 provides stereo enhancement, equalization, AGC, multiband compression, low-IM peak limiting, stereo encoding, and composite limiting everything that even the most competitive major market station needs to stand out on the dial.
More than 20 excellent sounding, format-specific factory presets get you started. Although the factory presets are fully competent "out of the box," you can customize them with easy one-knob LESS-MORE control in Basic Control, with 50 parameters Intermediate control or with more than 120 in the Advanced controls, whose versatility will satisfy even the most finicky on-air sound designer.

Absolute Control of Peak Modulation

The 8500 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.
The 8500 provides pre-emphasis limiting for the internationally used pre- emphasis curves of 50µs and 75µs. Its pre-emphasis control is seldom audibly apparent, producing a clean, open sound with subjective brightness matching the original program.
The 8500 achieves extremely tight peak control at all its outputs. Analog, AES3 (for both the analog FM and HD channels), and composite baseband.
The 8500 has an internal, DSP-based stereo encoder 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.
The stereo encoder has two outputs with independent level controls.

Multiplex Power (ITU-R BS412)

The 8500 has a de-featable 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 8500-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). It reduces clipper drive when it reduces power, simultaneously reducing clipping distortion.

Independent Processing

The 8500 HD ("Digital Radio") output is designed to feed streaming, netcasting, and digital satellite or cable radio channels, which can be Eureka 147, DRM, DAB + or the iBiquity® HD Radio system (formerly known as "IBOC"—"In-Band On-Channel") approved for use in the United States.
The equalizer and five-band compressor/limiter in the HD processing chain have their own sets of user-adjustable audio controls that are independent of the controls in the FM analog transmission chain's equalizer and five-band compressor/limiter. This allows you to optimize the HD processing for the higher fidelity sound provided by the digital channel while giving you the flexibility to process the analog channel.

Diversity Delay

For Digital Radio broadcasters who prefer using a separate processor for the digital channel, the 8500FM's built-in delay (up to 16 seconds) in the analog processing path vastly improves installation versatility in HD Radio facilities, freeing you from the need to use the delay line built into the Digital Radio exciter. This allows you to use the 8500FM's built-in stereo encoder and composite limiter to drive the analog FM transmitter, ensuring no-compromise analog-channel loudness.


An intuitive user interface round out the package. Features include an easy-to-use joystick, knob, and button navigation system and a bright, active-matrix color LCD that makes it easier to program the 8500 from its front panel.
Ethernet connectivity is standard, as is an easy to use PC remote control application that can control many 8500s on a TCP/IP network. In addition, RS232 serial control and programmable contact-closure (GPI) control give you total freedom to interface the 8500 with your facility's remote control infrastructure, whatever it might be.


There are two versions of Optimod-FM 8500. Model 8500HD is the full digital radio version and the analog FM-only version is 8500FM. Both models can be upgraded to Optimod-FM 8600 functionality. The upgrade kits can be installed in the field. Orban offers three versions of the upgrade kit at prices that are commensurate with the features that a given kit adds. These three versions upgrade 8500FM to 8600FM, 8500FM to 8600HD, or 8500HD to 8600HD. A given kit is compatible with all versions of 8500 hardware and includes a V2 DSP board. If your 8500 has a V2 board already installed, upgrading is more convenient (there is no need to remove the 8500 from the rack) and you may retain the DSP board in the upgrade kit as a spare.




return to top