What is THX?

THX Limited (THX Ltd.) is a high-fidelity audio/visual reproduction standard for movie theaters, screening rooms, home theaters, computer speakers; gaming consoles, and car audio systems. The common guess is that THX is a movie sound format, but it’s not; it’s something entirely different.

Short history

THX was named after THX 1138 (George Lucas’ first feature film). It was developed at Lucasfilm in the early 1980s. His desire was to ensure a movie would look and sound exactly the same regardless of the theater.

Theater problems

Tomlinson Holman, former corporate technical director for Lucasfilm, and a team of THX engineers developed the baseline set of standards. This group identified the following theater problems that adversely impact audiences while viewing films:

  • External noise (from the lobby or other auditoriums)
  • Internal noise (from the projector or air conditioning)
  • Audio distortion
  • Obstructed or uncomfortable viewing angles
  • Uncontrolled reverberation in the theater
  • Insufficiently bright images on the screen
  • Non-equalized or poor audio

THX is a set of guidelines that resolve these problems.

Standards and certifications

For cinemas

To display the THX logo, a theater must adopt a baseline set of standards and then be certified by Lucasfilm’s THX division. The first movie to be shown in a THX-certified auditorium was Return of the Jedi in 1983. There are now thousands of auditoriums around the world that have this certification.

For home theaters

To help match the best speakers and receivers for your listening needs, THX has established certification categories to ensure your home theater system can deliver crisp, clear THX reference-level sound in the room
size you desire. Which THX Certification is right for you?

  • THX Ultra2: these certified products bring the cinematic experience to larger home theaters, 3,000 cubic feet in size with a viewing distance of 12 feet or greater from the screen.
  • THX Select2: the certified products are for medium-sized rooms, up to 2,000 cubic feet in size, with a 10-12-foot viewing distance from the screen.
  • THX I/S Plus Systems: Certified Systems (AV Receiver + Speaker Bundles) have the power to fill a small home theater or dorm room where the viewing distance from the screen is 6-8 feet.
  • THX Certified Multimedia Products: these products are designed and engineered for PC gaming and multimedia on the desktop.



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