If the sound studio were a manufacturing unit, it would have been awarded an ISO 2001.

In essence, THX is an exclusive set of technical standards established by engineers at the world-renowned production company, Lucasfilm Ltd. THX grew from George Lucas' personal desire to make the playback of film soundtracks in both movie theaters and Home Theatre as faithful as technically possible to the original film itself. Before any Studio or Theater component can be THX certified, it must first pass a rigorous series of quality and performance tests. Only then can these products feature the THX logo.

How do DTS and THX work together?

DTS and THX often work together in the world's finest theaters to deliver the very best digital sound experience possible. Simply put, a theater's digital sound system is made up of two areas. The first (Area 1) consists mainly of projection equipment and actually "reads" the soundtrack of the film, decodes it, and processes it. The signal that results is fed to the second area (Area 2), the theater's amplification and loudspeaker system.

DTS technology is utilized in Area 1, where cinema sound processors convert the analog and digital sound information through CD-ROM into top-quality audio. THX is involved in Area 2, especially for loudspeaker placement and the acoustics of the theater auditorium. To obtain THX certification, a theater must comply with their standards and make use of equipment from THX-approved manufacturers. All DTS equipment is approved for usage in THX certified theaters.

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What are the technical criteria for THX certification?

•  Background Noise
One of the most important tests conducted is the measurement of all sources that relate to a studio's background noise. Potential noise sources include items such as HVAC units, projectors, exhaust fans, lobbies, concession stands, and transformers. An auditorium cannot exceed NC-30 in any octave band. THX mixing facilities must not exceed NC-25.

•  Isolation
The mixing room must be adequately isolated from external noise sources, including sound leakage from adjacent auditoriums.

•  Reverberation
The reverberation time must be within required limits calculated for each individual studio. Direct reflections such as "slap echoes" must not be audible during a film presentation.

•  Viewing Angle
The optimum audience-viewing angle for the Cinemascope image (2.39:1) from the screen to the farthest seat in the auditorium is 36 degrees with 26 degrees as the acceptable minimum.

•  Projection
Projectors must be placed on center with the image (± 3% optimal with a maximum of ± 5% allowed). All SMPTE projection standards must be met. In addition, screen illumination must also conform to SMPTE standards of 16-foot lamberts (± 2 foot lamberts).

•  Equipment
Equipment approved for use in THX theatres is listed on the THX Approved Equipment List. Components for each installation are individually selected from the list in consultation with the THX design office.

•  Installation
Layout and installation of equipment is individual to each mix stage, and must be in accordance with the specifications provided by the THX Design Office.

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