by Laura Ackley
THX are a design and quality control system for the playback enviroment in a theatre
First the aspiring theatre must meet certain acoustic criteria:
Most of the sound one hears in the movies comes from behind the screen, from 3 channels usually. (Occasionally 5, but that's a different lecture!) Because of this, the theatre must also have a good length/width ratio. (i.e., No bowling alleys.) From the visual standpoint, this is of course desirable, and from the audio standpoint, it means having a good "stereo image" between the left and right channels, so that the patron is actually hearing in stereo -- in every seat in the house!
High-quality hardware in THX theatres
Incidentally, the only Cinema Processors which THX were accepted until quite recently were made by Dolby, so any THX theatre was by default a "Dolby" theatre.
THX are not in competition with Dolby, THX are a complementary technology to Dolby Processing. Recently, Ultra-Stereo also had a processor approved for use in THX Theatres.
THX not in the business of selling any equipment, just assuring high quality hardware in THX theatres. The only piece of hardware that is specifically "THX" is an electronic crossover network, which is leased, not purchased by the theatre.
The surround speaker array is designed to provide optimum sound pressure and audience coverage. (and to integrate with the interior design whenever possible).
THX coordinate all this with the architects, owners, and equipment installers. Once the theatre has been completed or successfully retrofitted, THX field technicians visit the theatre to align and "tune" the sound system, then they measure the acoustical characteristics to make sure that they meet THX requirements. This test data is then evaluated, and if the theatre passes on all counts, it becomes a "certified" THX site.
This, entitles the theatre to use the THX name and show the THX trailer. (You know, "The Audience is Listening.") The theatre is re-tested every 6 months to ensure that the quality of sound remains high.
THX are not a method of recording, encoding, or processing movie soundtracks! THX are a design and quality control system for the Playback enviroment .
This means that every film will sound better in a THX theatre, not just a select few. The premium quality of a THX theatre is often well-demonstrated by "special-effects-extravaganza" films, because they are mixed with a very wide dynamic range and a lot of "loud" or "low" sounds that might distort when played back through a lesser system.
THX theatres are especially well-equipped to handle the demands of the new digital theatre soundtracks (like "Cinema Digital" and "SR-D") because of their high performance and headroom.
Home THX system
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