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Multi-Channel Music & Cinema Systems
Theory and Design
The goal of the film surround effects is to maximize viewer involvement and
to faithfully reproduce the director’s intentions for the soundtrack in your
own listening environment. Before explaining the way each of the film
surround effects (Mono Logic, Pro Logic, THX Cinema, TV Matrix, and
Logic 7) accomplish this goal, it is important to understand something about
the way film soundtracks are made and presented in the theater.
In the early 1940’s, large movie studios owned their own theaters and took
responsibility for their own quality standards. During this period, movie
theaters had the best sound reproduction heard anywhere — each major
studio had a master sound engineer to ensure that the sound systems in that
studio’s theaters performed properly. A decade later, the studios were
forced to sell off their theater holdings in an anti-trust action, and quality
became the responsibility of independent theater owners. Since each the-
ater could choose films from any studio, it was no longer practical, or
feasible, for the studios to monitor the quality of each theater. At the same
time, the impact of television caused a decline in theater attendance which
left little money for individual theater owners to reinvest in their facilities.
As a result, sound technology in theaters froze. Despite the advances being
made in recording and in home music systems during this period, film
sound remained essentially unchanged through the 50’s and 60’s. In fact, by
the end of the 1960’s the average teenager had a music system at home
which was considerably superior to theater systems.
This situation began to change in the 1970’s with the introduction of Dolby
Stereo. This technological breakthrough, which allowed four channels of
sound to be recorded onto the two available optical soundtracks of a 35mm
movie print, yielded spectacular results — and created a demand for
improved film sound tracks, and for better-sounding theaters. Theaters that
upgraded their sound systems were rewarded with larger audiences. Over
the next decade, Dolby Stereo became an established standard for film
sound recording — but theater sound systems, although improved, varied
in their ultimate accuracy.
In the 1980’s a new movie theater sound system was created under the name
THX. This system addressed, for the first time, the design of a theater
speaker system which could faithfully reproduce the film director’s inten-
tions. The THX Sound System complemented and enhanced the playback
of Dolby Stereo, and encompassed standards for power amplifiers, speak-
ers, and the acoustics of theaters themselves, to assure the best possible
reproduction of movie soundtracks. By 1998, this system was available in
over 1600 theaters across the country. The increased availability of film on
video tape, laser disc, DVD and broadcast, has led to a demand for home
audio/video systems which equal the best theater sound. The Home THX
Cinema system was designed to address this need.
Film Surround
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