Quintaphonic Stereo was a "one hit wonder" technology, with its sole motion picture release, Ken Russell's rock opera Tommy (1975). Quintaphonic Stereo, as the name implies, is a five-channel stereo presentation that offers full bandwidth stereo surrounds. The speaker placement is frontLeft, Center, frontRight, rearLeft, rearRight (fL,C,fR,rR,rL) (see illustration). After Tommy's release, it would be another fifteen plus years before motion picture sound achieved the same result with a variety of 5.1 channel surround stereo systems (SR-D, DTS, SDDS).
The underlying technology for Quintaphonic stereo is Quadrophonic four-channel stereo that was used in the record and broadcast industries in the 1970s. By employing the Sansui QS-4 encoding matrix to reproduce the frontLeft, frontRight, rearLeft,rearRight (fL,fR,rL,rR), the film could be exhibited on specially striped 35mm magnetic prints using the CinemaScope™ four-channel sound track layout (see illustration). A discrete center channel is the fifth channel of the mix and carries predominantly the vocal and limited instrument or sound effects.
Because Qunitaphonic Stereo relies upon expensive mag-striped prints and the few remaining theaters that could play this format often had poorly maintained equipment, Quintaphonic Stereo was not adopted for any other film. However, Quintaphonic Stereo is an important technological milestone because of its use of a matrixed stereo signal to present the sound track. Matrixed stereo sound became wide spread with the introduction of Dolby® Stereo on optical sound tracks in the in the later half of the 1970s.
Tommy was shown at Cannes in 1975, out of competition. It premiered in 1975 at the Fox-Wilshire Theater in Los Angeles.
One final component of the Quintaphonic Stereo story is the development of an optical method to play back the five-channel stereo sound track. The Colortek Optical Stereophonic Sound Film System employed a video camera to read the five-channel sound on an optical soundtrack. The system never progressed beyond a demonstration version. The underlying scanning technology was adopted by Rick Chace in 1985 to read optical sound track negatives with a device he called the Chace Optical Sound Processor (COSP™).
By employing the Sansui QS-4 encoding matrix to reproduce the frontLeft, frontRight, rearLeft,rearRight (fL,fR,rL,rR), the film could be exhibited on specially striped 35mm magnetic prints using the CinemaScope™ 4-channel sound track layout.
The Quintaphonic Stereo speaker placement is frontLeft, Center, frontRight, rearLeft, rearRight (fL,C,fR,rR,rL)
The Sansui four-channel synthesizer decoder QS-1: four-channel stereo from two-channel sources.