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Wootton Bassett, Wiltshire, SN4 8QJ, England Tel: 0793-842100; Fax: 0793-842101; Telex: 44849 WARRANTY INFORMATION: warranty on the product covered by this manual is subject to the limitations and disclaimers set forth in the warranty disclaimer originally shipped with the product and also printed on the back of the invoice. Dolby and the double-D are registered trademarks of Dolby Laboratories Licensing Corporation. ©1994 Dolby Laboratories ISSUE 3 S94/9359/10081 (MAIN) MAIN Part No. 91262 BACKGROUND BACKGROUNDBACKGROUND NOISE NOISENOISE SUPPRESSOR SUPPRESSORSUPPRESSOR DOLBY 430DOLBY 430 DOLBY 430 BACKGROUND NOISE SUPRESSOR T T he Dolby 430 Series is a background noise suppressor system for reducing the broadband noises such as wind or traffic rumble that often mar location recordings. Many mixers in film and television postproduction already rely on Dolby Laboratories’ Cat. No. 43, a background noise suppression unit based on a modified version of Dolby A-type noise reduction. The 430 Series takes this concept further by using a modified version of Dolby SR’s patented combination of fixed and sliding bands to give more stable signal handling and a significantly reduced chance of audible side effects. While superior in performance to the Cat. No. 43, the 430 Series uses fewer controls. Low-and high-frequency faders adjust the amount of noise suppression above and below dominant mid-frequency signals such as dialogue. A pull-to-engage control permits varying the preset operating level for recordings at unusually high or low levels (overall (MAIN) MAIN gain of the unit remains fixed). The 430 Series is a modular system providing from one to six channels of background noise suppression. A single control unit provides power and control signals for up to three single-rackspace frames, each with one or two channels of processing. All operating controls are mounted in a remote control module which may be located up to 15 meters (50 feet) from the control unit. These remote controls have been specifically designed for easy console mounting. Alternatively, a housing is available to allow for standalone operation. 100 Potrero Avenue San Francisco, CA 94103-4813 Telephone 415-558-0200 Fax 415-863-1373 info@dolby.com Wootton Bassett Wiltshire SN4 8QJ, England Telephone (44) 1793-842100 Fax (44) 1793-842101 info@dolby.co.uk (MAIN) MAIN DOLBY NOISE REDUCTION Dolby noise reduction is a family of signal processes that reduce the noise inherent in analog recording media, without affecting the sound being recorded. While they differ in performance and details of operation, all Dolby NR systems are complementary processes that first encode the music when it is recorded, then decode it when it is played back. They also treat soft signals separately from loud ones, and vary the NR action with frequency to avoid the side effects typical of other systems. Dolby A-type noise reduction, introduced in 1965, was originally intended for use by professional recording studios to make quieter master tape recordings. In the early 1970s its use was extended to film studios and motion picture release prints to make films sound better. Dolby SR (spectral recording), introduced in 1986, was designed not only to provide more noise reduction than A-type, but also to enable analog master recordings that equal or surpass 16-bit digital recordings with respect to overall dynamic range. Today, analog with Dolby SR is still a preferred format for some musicians, producers, and recording and mastering facilities, and is the standard format for the analog sound- tracks of virtually all feature films. 430 SPECIFICATIONS Signal Processing Independent low- and high-frequency stages with maximum noise suppression of approximately 16 and 18 dB, respectively Signal Connection 3-pin XLR connectors for audio; 34-way ribbon connector links processing module frames to power supply/control unit; one 15-way D-connector connects remote controls for all channels Operating Controls Operating controls for each channel of processing are mounted on Cat. No. 429 Remote Control module Level: rotary control varies signal level in processing circuitry over a ±6 dB range without changing overall gain of unit In/out: push-button with LED indicator switches processing in and out of circuit HF & LF: fader controls set attenuation of unwanted low-level signals Signal Levels Nominal input and output level +4 dBr1 Input Circuits Electronically balanced, 20 k. input impedance, substantially resistive; common mode rejection better than 55 dB, 50 Hz to 10 kHz; maximum input level +27 dBr balanced, +21 dBr unbalanced Output Circuits Electronically balanced, approximately 20. output impedance; output balance better than 1 dB into a symmetrical 600. load; output float2 better than –40 dB, 50 Hz to 1 kHz; maximum signal level into 600. or greater: +26 dBr balanced, +20 dBr unbalanced; either leg of the output can be grounded for unbalanced operation with no change in leve...