The 8500 Sound You Trust at a Price You Can Afford
Summary
For years, broadcasters have trusted Optimod-FM 8500 to build audiences and ratings with its big, bold sound. Optimod-FM 8500S now offers the popular 8500 sound in a compact, cool-running 1U package at a more affordable price.
The 8500S provides stereo enhancement, equalization, AGC, multiband compression, low-IM peak limiting, stereo encoding, and composite limiting—everything that you need to compete in your market.
The front-panel display includes a 2×40-character LCD and LED bargraphs that show all metering functions of the processing structure (Two-Band or Five-Band) in use. The metering is always visible while you are adjusting the processor. Navigation is by dedicated buttons, soft buttons (whose functions are context-sensitive), and a large rotary knob.
Ethernet connectivity is standard, as is an easy to use PC remote control application that runs on Windows XP and higher and that can control many 8500S units on a TCP/IP network. Additionally, programmable contact-closure (GPI) control plus ACSII terminal control via the 8500S’s RS232 serial and Ethernet ports together give you total freedom to interface the 8500S with your facility’s remote control infrastructure, whatever it might be. SNMP support offers yet another way to control and monitor the 8500S’s operation via your network.
The 8500S includes a full-featured RBS/RBDS generator at no additional charge. The generator supports dynamic PS. It can be controlled via 8500S presets and an ASCII terminal server that can be connected to automation to support displaying title and artist.
Features
The 8500S is available in two versions: an FM-only version (8500SFM) and a version (8500SHD) that includes simultaneous processing for FM and for digital transmissions like netcasts and HD Radio. Via a purchased upgrade kit, the FM version can be upgraded to the HD version at any time without removing the unit from the rack or disconnecting any wiring. Both versions offer up to 16 seconds of delay in the FM processing chain, which is useful for HD Radio diversity delay or other purposes.
The FM and digital media processing paths split after the 8500S’s stereo enhancer and AGC. There are two equalizers, multiband compressors, and peak limiters, allowing the analog FM and digital media processing to be optimized separately. The bottom line? Processing that optimizes the sound of your FM channel while punching remarkably crisp, clean, CD-like audio through to your digital channel audience.
More than 20 excellent sounding, format-specific factory presets get you started. You’ll find all of your favorite 8500 presets here. Although the factory presets are fully competent “out of the box,” you can customize them with easy one-knob LESS-MORE control or with more than 60 advanced controls whose versatility will satisfy even the most finicky on-air sound designer. If you have created custom presets for Optimod-FM 8500, 8400, 8300, 5500, or 5300, you’ll find that they import perfectly into the 8500S, retaining your carefully designed sound.
If you choose to use the 8500S’s superb DSP-based stereo encoder and composite limiter, be assured that they deliver an FM analog signal that is always immaculately clean and perfectly peak limited, with full spectral protection of subcarriers and RDS/RBDS regardless of the amount of composite limiting.
The 8500S includes a “ratings encoder loop-through” connection. This allows a ratings encoder with an AES3 digital input and output to be inserted between the output of the left/right audio processing and the input of the stereo encoder. This keeps the audio level driving the ratings encoder as high as possible, minimizing the number of “low audio level” alarms that the ratings encoder generates.
For our European customers, a second-generation ITU BS 412 multiplex power controller smoothly and naturally complies with the standard. In addition, the 8500S-HD’s digital radio processing path offers an ITU-R BS.1770-compliant loudness controller and a 4x-oversampled, “true peak” limiter that prevents clipping from occurring at the output of the D/A converter in a consumer receiver or other playback device.
To protect your investment, the 8500S can be upgraded to full 8600S functionality via a purchased upgrade kit. There’s no need to remove the unit from the rack, and you will immediately benefit from Orban’s state-of-the-art MX limiter technology.
Processing for HD Radio
The HD Radio™ system generates a digital carrier that shares a given station’s allocated bandwidth with the normal analog FM carrier. The receiver crossfades between the analog and digital channels to minimize the effect of RF dropouts. This scheme requires audio processing for the two channels to be closely matched in texture to ensure that the receiver’s crossfades are seamless.
Optimum peak limiting for the two channels is very different. The analog channel requires state-of-the-art preemphasis limiting to achieve competitive loudness and minimize preemphasis-induced high frequency loss. This usually implies use of sophisticated distortion-cancelled clipping. The digital channel, on the other hand, has no preemphasis but is heavily bit-reduced with the HDC perceptual codec. The highest available rate is 96 kbps and many broadcasters are now multicasting with two 48 kbps channels.
This limited bit rate creates an entirely different set of requirements: the peak limiting must not use clipping because there is no bit budget available to encode clipping-induced distortion products. However, preemphasis limiting is unnecessary. The best technology for peak limiting the digital channel is look-ahead limiting, which can perform very clean peak reduction on flat channels, but which is unsuitable for pre-emphasized channels.
Optimod-FM 8500S is an excellent solution to his dilemma because its AGC and stereo enhancement are shared between the two channels, while equalization, multiband compression/limiting, and peak limiting are independent.
The analog FM path provides 8500-style distortion-cancelled clipping, overshoot compensation, stereo encoding, and composite limiting using Orban’s patented “Half-Cosine Interpolation” algorithm. The limiting is anti-aliased and uses sample rates as high as 512 kHz. Meanwhile, the HD output receives low-IM look-ahead “true-peak” peak limiting. This look-ahead limiting is optimized to make the most of the limited bit-rate codecs used digital radio and netcasting channels. By eschewing any clipping, the HD processing prevents the codec from wasting precious bits encoding clipping distortion products, allowing the codec to use its entire bit budget to encode the desired program material.
For convenience, it is possible to couple the equalizer, HF enhancer, and multiband compressor/limiter setup controls of the two paths, allowing them to be matched easily. This is convenient in HD Radio installations where the station’s goal is to minimize the audibility of analog/digital crossfades at the receiver. However, the ability to adjust the analog FM and digital radio paths separately allows users more latitude to fine-tune their audio. For example, a broadcaster who believes that selling the advantages of HD Radio to the public requires an obvious, audible difference between the analog FM and digital channels can generate this “wow!” factor. Dual-path processing also allows the digital media processing to be independently tuned to minimize artifacts in low bit-rate codecs, like those used in netcasting and HD Radio.
A built-in diversity delay of up to 16 seconds in the analog processing path simplifies installation in HD Radio facilities, freeing you from the need to use the delay line built into the HD Radio exciter. This allows you to use the 8500S’s built-in stereo encoder and composite limiter to drive the analog FM transmitter, ensuring no-compromise analog-channel loudness. The diversity delay can be applied independently to any output emitting the analog-FM processing signal, so some outputs can be delayed while others are not.
The 8500S’s 64 kHz base sample rate allows it to provide up to 20 kHz audio bandwidth at its HD output. The HD bandwidth is user-settable between 15 and 20 kHz to optimize the processing for the codec employed in the digital chain. Many low bit rate codecs operate better when fed 15 kHz audio because this enables them to use their available bit bandwidth most efficiently. This is particularly true for low rates, like 32 kbps. However, at higher sample rates, full 20 kHz bandwidth provides the same bandwidth as typical source material, so the user may prefer to use it for these higher rates.
Most HD Radio exciters require 44.1 kHz AES/EBU audio streams for both their analog-FM and digital inputs. The sample rates for both streams must be identical and must be locked to an external reference. This requires two AES/EBU outputs from a single-box processor. Because the output sample rate on either or both of the 8500S’s AES3 outputs can be locked to either the 8500S’s sync.
Technical Specification
Technical Specification
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.
Performance
Except as noted in the text, specifications apply for measurements from analog left/right input to stereo composite output and to FM analog left/right output.
Frequency Response (Bypass Mode): Follows standard 50µs or 75µs 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.
Noise: 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. 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.
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 L/R Channel Separation: >50 dB, 20 Hz – 15 kHz; 60 dB typical.
Polarity (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.
Processing Sample Rate: The 8500S is a “multirate” system, using internal rates from 64 kHz to 512 kHz as appropriate for the processing being performed. Audio clippers operate at 256 kHz (and are anti-aliased), while the composite limiter operates at 512 kHz.
Peak Control at HD Output: The peak limiter is oversampled at 256 kHz, yielding a worst-case overshoot of 0.4 dB at the analog output and for all output sample rates. (To achieve this performance at 32 kHz output sample rate, it is necessary to set the 8500S’s HD lowpass filter cutoff frequency to 15 kHz.)
Processing Resolution: Internal processing has 24 bit (fixed point) or higher resolution.
Installation
Delay
Defeatable Analog FM Processing delay: 0.27 to 16.384 seconds, adjustable in one-sample increments at 64 kHz sample rate to allow the delays of the analog and digital paths in the HD Radio system to be matched at the receiver output.
Minimum Processing Delay: Processing structure dependent. Typically 17 ms for normal latency Five-band, 13 ms for low-latency Five-band, 3.7 ms for ultra-low-latency Five-band, and 17 or 22 ms for 2-band, depending on crossover structure chosen. MX presets have approximately 270 ms delay.
Analog Audio Input
Configuration: Stereo.
Impedance: >10kΩ load impedance, electronically balanced. (No jumper selection is available for 600Ω. Surface-mount pads are available on I/O module for user-installed 600Ω termination.)
Nominal Input Level: Software adjustable from –9.0 to +13.0 dBu (VU).
Maximum Input Level: +27 dBu.
Connectors: 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.
Filtering: RFI filtered, with high-pass filter at 0.15 Hz.
Analog Audio Output
Configuration: Stereo. Flat or pre-emphasized (at 50µs or 75µs), software-selectable.
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: >= 90 dB unweighted (Bypass mode, de-emphasized, 20 Hz–15 kHz bandwidth, referenced to 100% modulation).
L/R Crosstalk: <= –70 dB, 20 Hz–15 kHz.
Distortion: <= 0.01% THD(Bypass mode, de-emphasized) 20 Hz–15 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, with high-pass filter at 0.15 Hz (–3 dB).
Filtering: RFI filtered.
Digital Audio Input
Configuration: Stereo per AES3 standard, 24 bit resolution, software selection of stereo, mono from left, mono from right or mono from sum.
Sampling Rate: 32, 44.1, 48, 88.2, or 96 kHz, automatically selected.
Connector: XLR-type, female, EMI-suppressed. Pin 1 chassis ground, pins 2 and 3 transformer balanced and floating, 110Ω impedance.
Input Reference Level: Variable within the range of –30 dBFS to –10 dBFS.
J.17 De-emphasis: Software-selectable.
Filtering: RFI filtered.
Digital Audio Outputs
Configuration: Two outputs, each stereo per the AES3 standard. The outputs can be independently set 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 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.
Sample Rate: 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.
Connector: XLR-type, male, EMI-suppressed. Pin 1 chassis ground, pins 2 and 3 transformer balanced and floating, 110Ω impedance.
Output Level (100% peak modulation): –20.0 to 0.0 dBFS software controlled.
Filtering: RFI filtered.
Frequency Response [Digital Audio Output (from 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. Once set, this delay is constant regardless of processing preset in use.
Wordclock/10 MHz Sync Reference
Configuration: 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.
Level: Unit will lock to 1x wordclock and 10 MHz squarewaves and sinewaves having a peak value of 0.5 V to 5.0 V.
Connector: BNC female, grounded to chassis, non-terminating to allow reference signals to be looped through via an external BNC “tee” connector (not supplied).
AES3id Input
Configuration:The Wordclock/10 MHz Sync Reference can also be configured as an AES3id digital audio input to drive the input of the stereo encoder. This facilitates a “ratings encoder loop-through” connection, where the input of the ratings encoder is driven from one of the 8500S’s AES3 outputs and the encoder’s output is returned to the AESid input. When not being used in ratings encoder loop-through mode, this input can receive an AES3id or AES11id sample rate reference signal to which the 8500S’s digital outputs can be locked.
Connector: BNC female, grounded to chassis, terminated with 75Ω. For short cable runs, there is usually no problem in driving this with an AES3 (110Ω) signal. If the cable is long enough to cause digital audio reception errors due to impedance mismatch, a 110Ω/75Ω transformer should be placed in-line.
Composite Baseband Outputs
Configuration: Two outputs, each with an independent software-controlled output level control, output amplifier and connector.
Source Impedance: 0Ω voltage source or 75Ω, jumper-selectable.
Load Impedance: 37Ω or greater. Termination not required or recommended.
Maximum Output Level: +16.0 dBu (13.82Vp-p).
Pilot Level: Adjustable from 6.0% to 12.0%, software controlled.
Pilot Stability: 19 kHz, ±1.0 Hz (10 degrees to 40 degrees C).
D/A Conversion: 24-bit
Signal-to-Noise Ratio: >= 85 dB (Bypass mode, de-emphasized, 20 Hz – 15 kHz bandwidth, referenced to 100% modulation, unweighted).
Distortion: <= 0.02% THD (Bypass mode, de-emphasized, 20 Hz – 15 kHz bandwidth, referenced to 100% modulation, unweighted).
Stereo Separation: >50 dB, 20 Hz – 15 kHz; 60 dB typical.
Crosstalk-Linear: <= –80 dB, main channel to sub-channel or sub-channel to main channel (referenced to 100% modulation).
Crosstalk-Non-Linear: <= –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).
Connectors: Two BNC, shell connected to chassis ground, EMI suppressed.
Maximum Load Capacitance: 0.047 microfarad (0Ω source impedance). Maximum cable length of 100 feet/30 meters RG–58A/U.
Filtering: RFI filtered.
Subcarrier (SCA) Inputs
Configuration: Two subcarrier inputs sum directly into composite baseband outputs; COMPx LVL control settings have no effect on the absolute subcarrier levels.
Impedance: 600Ω
SCA Sensitivity: Variable from <100 mV p-p to >10 V p-p to produce 10% injection assuming 100% modulation = 4 V p-p at the 8500S’s composite outputs. Rear-panel accessible PC-board-mounted trim pots allow user to adjust the sensitivities of the two SCA inputs.
Connectors: Two BNC, shell connected to chassis ground, EMI suppressed.
19 kHz Pilot Reference: SCA2 input can be re-jumpered to provide a 19 kHz pilot reference output.
Remote Computer Interface
Supported Computer and Operating System: IBM-compatible PC running Microsoft Windows® XP or higher.
Configuration:TCP/IP protocol via direct cable connect, modem, or Ethernet interface.
Serial Connector: RS–232 on DB–9 male connector, EMI-suppressed. Uses PPP to provide for direct or modem connection to the 8500S PC Remote application.
Ethernet Connector:Female RJ45 connector for 10 Mbps and higher networks using CAT5 cabling. Native rate is 100 Mbps. Provides for connection to the 8500S PC Remote application through either a network, or, using a crossover Ethernet cable, directly to a computer.
Ethernet Networking Standard: TCP/IP.
Remote Control (GPI) Interface
Configuration: Eight (8) inputs, opto-isolated and floating.
Voltage: 6–15V AC or DC, momentary or continuous. +12VDC 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, including Input: Analog, Input: Digital, Analog Input Silent, AES Input Silent, and AES Input Error.
Power
Voltage: 85–264 VAC, 50–60 Hz, <30 VA.
Connector: IEC, EMI-suppressed. Detachable 3-wire power cord supplied.
Fuse: 2.5A 20mm Quick Acting HBC, mounted on the power supply circuit board.
Grounding: In order to meet EMI standards, circuit ground is hard-wired to chassis ground.
Safety Standards: ETL listed to UL standards, CE marked.
Environmental
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 1.75” x 14.25” / 48.3 cm x 4.5 cm x 36.2 cm. One rack unit high.
Humidity: 0–95% RH, non-condensing.
RFI/EMI: Tested according to Cenelec procedures. FCC Part 15 Class A device.
Shipping Weight: 10 lbs / 4.6 kg
Warranty
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.
