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Version: 2.8
Last-modified: 21 January 1998

Ambisonic Surround Sound FAQ

Section 11

Copyright: © 1994, 1995, 1996, 1998 by Martin J Leese
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11. How does Ambisonics differ from quadraphonics?

Quadraphonics was a collection of incompatible systems introduced in the 1970s. The collection included SQ, QS, UMX and CD-4. As the name suggests they assumed four channels feeding four speakers, and usually assumed that the speakers would be 90 degrees apart. (Compare this with the 60 degrees between speakers in stereo.) The systems strived for channel separation and were characterised by the ping-pung-pang-pong effects they reproduced. While these effects were extremely impressive, they were also the antithesis of fatigue-free realistic sound reproduction.

In contrast, Ambisonics attempts to recreate for the listener the complete sound field of the original performance. A particular number of speakers is not assumed and the technology can use various numbers and speaker layouts. With the Ambisonic Surround Sound system all of the speakers cooperate to localise a sound in its correct position.

A problem with the quadraphonic systems was that they did not work, and could never have been made to work because they were based on false premisses. As explained in the Sommerwerck 1984 reference, Part I, the major problem was that quadraphonics used the pair-wise mixing style. In contrast, Ambisonics does work.

It is possible to use Ambisonic technology to decode many of the quadraphonic systems. A decoder to do this was manufactured by Integrex Limited and most of the design published in the Gerzon 1977 reference.

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