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SECTION 1INTRODUCTION1.1 The SDU4
The Dolby SDU4 is designed for reference monitoring of Dolby encoded
film formats or Dolby Surround program material in broadcast, audio-for-
video, and music recording applications. The unit contains a reference 2:4
matrix decoder, like that used in the Dolby monitoring equipment found in
film production centers. The 2:4 decoder takes a two-track matrix encoded
signal as its input and generates four output signals (Left, Center, Right and
Surround). The SDU4 is designed for monitoring rooms where the electro-
acoustical response conforms to international standards for wide-range
audio monitoring. The input program material can originate from any two-
channel, reasonably phase-stable source, such as video tape, video disk,
motion picture film, or stereo broadcast.
Broadcast applications include evaluation of air-masters of program material
originally recorded for theatrical Dolby release. Using the SDU4, the
engineer can check for compatibility in mono, conventional stereo, or in a
fully decoded surround playback. Music studios will find the SDU4
invaluable when monitoring material intended for integration into Dolby
film soundtracks as it provides accurate reproduction of two-channel
material in its final dimensional perspective. The SDU4 can also derive a
center output signal for monitoring the mono compatibility of conventionally
produced stereo material.
An internal calibrate mode, using channel-sequenced pink noise, allows
easy verification of monitor levels and equalization. Internal logic allows
the correct reproduction of program material either with or without a center
loudspeaker. Other features include extended monitor functions, balanced
inputs and outputs at professional levels, monitor level control, remote
control of all functions and external interface capability.
The SDU4 is designed for use with a Dolby Surround encoder, the SEU4. A
first step in equipping a post-production facility for future surround
productions should be the installation of the SDU4 and the establishment of
a correct monitoring environment.
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