A
little History
When
I was growing up in the '70's, there were two competing standards
for noise reduction in music; Dolby and dbx.
Our perception was that dbx was the newcomer and considered
to be the audiophile's choice while Dolby "B" was
the everyday choice.
Dolby "B" was the consumer version of its Dolby
"A" technology introduced in the late 60's. Dolby
"A" treated the soft signals only, leaving the loud
signals that naturally mask noise untouched. Eventually, Dolby
took over the consumer market while dbx was relegated to the
professional recording markets. Dolby "B"'s premise
was rather simple; record music with amplified high frequencies
and during playback, reduce the high frequencies by the same
value. By doing this, noise from the magnetic particles on
the tape would be reduced as well. Dolby "C" followed
in 1980 offering 20 dB of noise reduction above about 1,000
Hz, fully doubling the amount given by "B"-type.
Because most cassette decks were already equipped with Dolby
"B" circuitry, Dolby "C" never gained
the stature of its older brother. In 1982, Dolby developed
the HX Pro (HX was intorduced in 1979 but didn't gain much
attention) system for increasing the high frequency response
during the recording process. Also during that time was XDR
which increased the overall dynamic range of the recorded
material. Neither HX Pro nor XDR required anything special
for playback.
Ray
Dolby was not content with just the cassette market,however, and began
exploring ways to improve film sound. In 1975, Dolby Labs
introduced Dolby Stereo and motion pictures were never the
same. In the space allotted to the conventional mono optical
soundtrack of films were now two soundtracks carrying not
only left and right information, but also, information for
a third center-screen channel and a fourth surround channel
for ambient sound and special effects. For backward compatibility,
the new track was configured to allow mono playback too, requiring
only one kind of release print.
Realizing
untapped potential, Dolby went after the home theater market.
In 1982 Dolby introduced Dolby Surround, a consumer extension
of the Dolby film sound project. This was followed by Dolby
Surround Pro Logic, a technology that made it possible to
decode the center channel as well, and to take advantage of
advanced circuitry developed originally for theatrical playback.
Dolby's
reputation as a leader in audio technology was greatly enhanced
in 1986 with the introduction of a powerful new system, Dolby
SR (spectral recording), intended to bring analog recording
into the digital age. Dolby SR improved film sound significantly,
both in the mixing of soundtracks and in the soundtracks themselves.
Today the Dolby SR encoded analog optical soundtrack, with
its ultra-low noise and distortion, is the state-of-the-art
of analog film sound, and is used for the vast majority of
releases, including those that also have digital soundtracks.
Out of Dolby SR came a more powerful NR system for consumer
cassette recording, Dolby "S". Dolby "S"
promises CD quality recording.
During
this time, Dolby was researching digital audio. The first
Dolby digital coding system, Dolby AC-1, was introduced in
1984. A more sophisticated version, AC-2, was released in
1989. Dolby ADC-3, now simply called Dolby Digital, was introduced
in 1992.
Fast
forward to 2001 and it looks to be quite a year for Dolby
and ultimately, the consumer.
