11. How does Ambisonics differ from quadraphonics?
Description
This article is from the Ambisonic Surround Sound FAQ, by Martin Leese with numerous contributions by others.
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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