Trifield


The Trifield process is a form of audio rendering in which a
conventional two-channel signal is decoded to an additional number of loudspeakers, typically three in
the form of a Left-Centre-Right front stage. The technique provides
significant additional image stability, especially when the listener
is moving or off-axis.
It was developed by Dr Geoffrey Barton, a major figure in the "second
wave" of original Ambisonics development, and Michael Gerzon. It
should not to be confused with a Yamaha system with a similar name.
Trifield also has applications in conventional surround mixing. There are
several problems involved in mixing with an additional centre front channel
for many engineers. The channel itself was originally designed for dialogue
in matrix cinema surround systems and does not have a direct application in
music mixing, where a 2-speaker stereo stage is generally, and traditionally,
employed.
Many studio engineers with a background in conventional stereo music mixing
find that simple panning of a source to the centre-front channel makes
it fail to blend in with the stereo mix. However, if the CF channel is left
silent, consumers may believe there is a fault with the disc or with their
equipment. A way around this problem is offered by Trifield. The processor
typically takes a 2-channel L-R signal and renders it for L-C-R, and no
signals are sent to the CF except for those generated by the Trifield
processor. Not only does CF content now blend with the mix: in addition,
the resulting soundstage is more stable and listener-position independent,
while the listener can confirm that something is actually emerging from
their centre-front loudspeaker.
The Trifield process is included in some surround decoders and is generally
praised highly by reviewers, even though they generally don't know what it
is. The technique is patented and can be
licensed from Trifield Productions.