Soundfield History - Soundfield SPS200 User Manual

SoundField SPS200 User Guide

SOUNDFIELD HISTORY

In 1933, British scientist Alan Blumlein was issued a patent that stands today as a
landmark in the development of stereophonic recording and reproduction. Among its
numerous declarations, it defined the basis for all coincident microphone techniques,
including the Mid/Side and crossed bidirectional configurations. (The latter, in fact, is
commonly referred to as a "Blumlein Stereo" pair.) In the 1970s, British mathematicians
Michael Gerzon, Peter Craven and colleagues expanded upon the stereo concepts
pioneered by Blumlein to develop the concept of a microphone system that could
reproduce fully three-dimensional audio. Both Blumlein and Gerzon realised that only
when a soundwave is captured at a single point in space can it be reproduced faithfully
and without the phase distortion anomalies inherent in spaced microphone techniques.
Early SoundField prototype models were developed using Gerzon's theory in
conjunction with the National Research Development Corporation of Great Britain and
Calrec Audio. Chief Designer at Calrec, Ken Farrar, and colleagues played a leading role
in turning Gerzon's theory into a real product and Ken Farrar's contribution was later
recognised by his appointment as a Fellow of the Institution of Electrical Engineers
(F.I.E.E.). In 1993, the company SoundField Ltd. was formed specifically to manufacture
and further develop the range of products and their application in both stereo and multi-
channel audio environments. SoundField Ltd. is the owner of all patent and intellectual
property rights relating to SoundField Technology.
Today, the SoundField range enjoys a reputation as the ultimate microphones for
recording both stereo and the new developing multi-channel surround formats. These
unique microphones employ a proprietary four capsule array of closely spaced capsules
to capture an acoustic event in three-dimensions at a single point in space. This single
point source pick-up principle avoids all of the time - or phase-related anomalies
generated by spaced microphone arrays. Thus, surround recordings made with
SoundField microphones can be collapsed to stereo - or stereo recordings to mono -
without the phase problems that result in "comb-filtering" (phase cancellation)
distortions. Furthermore, a single point source system is the only one that allows a truly
phase coherent sub-channel to be derived. Spaced microphone arrays are unable to be
reduced without introducing significant phase errors unless some of the microphone
signals are discarded, which consequently results in loss of essential audio information.
SoundField History Page 5