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Optimod-TV 8182 A

Overview

Analog Audio Processor

The 8182A is an integrated signal processing system designed specifically for stereo or mono television. It provides gain riding to compensate for varying input levels, adjustable dynamic range control, loudness control to tame blaring commercials, and patented circuits for transparent peak limiting to prevent overmodulation. Proven over millions of on-air hours by broadcasters around the world, the 8182A combines exceptional audio quality with cost-effective analog technology.

Features

Specifications

Performance

Frequency Response (PROOF mode): Strapped for preemphasized output, follows standard 75us (or 50us) preemphasis curve ±0.75dB, 50-15,000Hz. Strapped for flat output, ±0.75dB, 50-15,000Hz.
Noise: -75dB referenced to 100% modulation, 50-15,000Hz; -81dB typical.
Total system distortion (PROOF mode, deemphasized, 100% modulation): <0.25% THD, 50-15,000Hz; 0.02% typical. <0.1% SMPTE Intermodulation Distortion.
System separation: >50dB, 50-15,000Hz; 60dB typical.

Installation
Audio Input

Configuration: Left and Right.
Impedance: >10k ohm load impedance, electronically balanced by true instrumentation amplifier. Requires balanced source £600 ohms. Common mode rejection >60dB @50-60Hz. Sensitivity: -30dBm to + 10dBm to produce 10dB "Master Band" gain reduction @ 1kHz.

Audio Output

Configuration: Left and right or sum and difference, selectable with internal jumpers; preemphasized or flat, selectable with internal jumpers. Impedance: 370 ohm source impedance, independent of OUTPUT ATTEN setting, balanced. Recommended load impedance 600 ohms ±20%. Peak Output Level: Adjustable from -infinity.dBm to >+20dBm with 15-turn OUTPUT ATTEN controls. Output clipping level + 26dBm/600 ohms.
Connector: Barrier strip (#5 screw), EMI suppressed.

Remote Control

Function: Selects loudness Controller ON/OFF.
Voltage: 6 to 24V AC or DC, momentary or continuous, optically isolated.
Connector: Barrier strip (#5 screw).

Remote Gain Reduction

Meter Output

Configuration: Negative DC voltage proportional to total master gain reduction. Scale approximately -0.33V/dB, source impedance 8.87k ohms.
Connector: Barrier strip (#5 screw).
Power:115/230 VAC (switch selectable), ±15%, 50-60Hz; 31VA. IEC mains connector with detachable 3-wire "U-Ground" power cord supplied. Leakage to chassis <0.5mA. AC is EMI suppressed.
Ground: Circuit ground is independent of chassis ground; both appear on terminal strip on rear panel for strapping as required.
Dimensions: 19" (48.3cm) W, 7" (17.8 cm) H, 12.5" (31.2cm) D. 4 rack units.
Environmental: Operating temperature range 0-50 degrees Celsius (32-122 degrees F). Humidity 0-95% RH, non-condensing.


Circuitry
Input Conditioning

Highpass filter: Third-order Chebychev with 30Hz cutoff and 0.5dB passband ripple; -0.5dB @ 30Hz, -10.5dB @ 20Hz, -31.5dB @ 10Hz.
Phase Scrambler: Allpass network makes peaks more symmetrical to best utilize the symmetrical peak overload characteristics of the FM medium.
Crossover
(US Patent No. 4,249,042)
Control: 6dB/octave, 200Hz.
Program: 12dB/octave, 200Hz, in unique "distributed crossover" configuration.
"Master Band" Compressor
Attack Time: Approximately 1 ms.
Release Time: Program controlled; varies according to program dynamics and amount of gain reduction. Process can be scaled fast or slow with continuously variable RELEASE TIME control. Employs delayed release for distortion reduction.
Threshold of compression: Controlled by left and right input attenuators.
Operation: Gains of left and right channels track to avoid stereo perspective shift.
Total harmonic distortion (at VCA output, OPERATE mode, RELEASE TIME control centered): <0.1%, 200-15,000Hz, +10 to -15dB gain reduction.
Available gain reduction: 25dB.
"Bass Band" Compressor
Attack Time: Program controlled.
Release Time: Program controlled. Employs delayed release for distortion reduction.
Operation: Gains of left and right channels track to avoid stereo perspective shift.
Total Harmonic Distortion (At VCA output, OPERATE mode): <0.1%, 50-200Hz, +10 to -20dB gain reduction.
Available Gain Reduction: 30dB.
Bass Coupling (US Patent No. 4,249,042): Enables gains of "Bass Band" to track gain of "Master Band" to any degree, from identical tracking to fully independent operation. Adjustable with BASS COUPLING control.
High Frequency Limiter
Attack time: Approximately 5ms.
Release time: Approximately 20ms. Employs delayed release for distortion reduction.
Threshold of HF limiting: User-adjustable over 3dB range to meet user requirements.
Operation: Left and right channels operate independently to prevent high frequencies in one channel from causing audible timbre modulation in opposite channel.
Hilbert-Transform Clipper
(US Patent No. 4,495,643)
Bandwidth: 15.4kHz.
Distortion Characteristics:<2.5% THD produced by individual frequencies 30-4,000Hz when driving Hilbert-Transform clipper to 6dB beyond threshold of limiting. Further distortion cancellation assures that, for any input including program material, distortion components in the frequency range 0 to 2,200Hz are canceled better than 30dB below overshoot compensator threshold. With drive frequencies above 4,000Hz, characteristics revert to those of a "hard" clipper.
Amount of Clipping: User-adjustable over 6dB range.
Frequency-Contoured Side-Chain (FCS) Overshoot Compensator
(US Patent No. 4,460,871)
Operation: The FCS circuit is best thought of as a "bandlimited safety clipper." It operates like a hard clipper, but without producing out-of-band frequency components. It is followed by a safety clipper, aligned so that it is almost never active, fully preserving the bandlimiting provided by the FCS circuit.
Peak Modulation Control: Within ±2% on typical program material; ±3.5% worst-case.
Sinewave modulation ability: 93% modulation (0.6dB below maximum overshoot level) at all frequencies.
"Proof" Test Mode
Compressor: Defeats "Master" and "Bass" gain reduction control; switches "gate" ON to force unit into 10dB gain reduction (0dB on GR meter).
Limiter: Defeats HF limiter, Hilbert-Transform Clipper, FCS Overshoot Compensator, and safety clipper.

Warranty

One year, parts and labor. Subject to limitations set forth in Orban's Standard Warranty Agreement.

Specifications subject to change without notice.

Notes

The Quality Standard for Mono or Stereo TV Audio

 

Quality and Consistency

Television audio presents a particularly difficult challenge due to the varying quality of different sources: live studio, live remote, satellite feeds, videotape, and film-to-tape transfers. All of these signals must be controlled to achieve consistent loudness, pleasing spectral balance, and high intelligibility on TV receivers of all types and sizes. This should be accomplished without introducing any audible artifacts.

Orban has applied over two decades of experience in broadcast audio processing to solving the problems of TV audio. The solutions are incorporated in a single, fully-integrated television audio processor: OPTIMOD-TV 8182A.

Four Level Control Functions

Master control operators tend to concentrate on video and often neglect audio levels. The 8182A addresses this with gentle gain riding over a 25dB range to achieve consistent sound quality on air.

The 8182 also provides adjustable control of dynamic range to maintain an ideal dynamic range between loud and soft passages. This produces intelligible and natural-sounding results on small portable sets, yet maintains a remarkably open and natural sound for home theater systems.

The 8182A's Automatic Loudness Controller effectively restrains commercials that are perceived as annoyingly loud even though actual measured level would not indicate a problem. The sophisticated circuits that handle this task are based on over 20 years of psychoacoustic research at the CBS Technology Center.

Finally, the 8182A incorporates Orban's patented Hilbert-Transform Clipper and FCS Overshoot Compensator to provide effective peak limiting with absolutely no audible artifacts.

The Result

With OPTIMOD-TV, home viewers enjoy sound that is consistently natural and pleasant, no matter the source. Local news is more intelligible over dinnertime noises, movie soundtracks have more impact, and fewer commercials are totally silenced by remote controls. OPTIMOD-TV contributes to a total TV viewing experience that often translates, over the long term, into positive ratings trends.