SoundField ST350 User Guide
Introduction Page 5
INTRODUCTION
The ST350 Portable Microphone System has been specifically developed for location recording and
in the design process both the microphone and control unit have been considerably ‘downsized’ in
comparison to all other previously available SoundField models. The ST350 simultaneously
provides both surround and stereo soundscapes and its big advantage over alternative methods is
that the multi-channel audio it generates from a ‘single point’ source is completely phase coherent.
This enables the recordist to collapse the surround to stereo or mono without loss of information,
frequency imbalance or any of the other phase problems associated with spaced microphones or
multi capsule ‘dummy head’ arrangements.
The ST350 can be powered by either battery (see page 19) or mains electricity and the microphone
can be used at close quarters on a hand held boom or alternatively situated up to 200 metres from
the control unit on the relevant SoundField mic extension cables (see accessories on page 25). The
ability to adjust all microphone parameters remotely from such a long distance is invaluable in
situations where the microphone is placed in an area which is difficult to access.
The ST350 is connected to the control unit by a single lightweight multiway cable which delivers
the four individual capsule signals to the control unit and carries the necessary power back to the
microphone. A small heating element is located in the microphone head to keep the capsules
condensation-free under normal operating conditions. The ST350 control unit outputs stereo
Left/Right, M/S and four channels of SoundField B-Format called W, X, Y and Z which is the
surround information. All outputs are at balanced line level.
The ST350 is designed to function as either a variable pattern single (mono) microphone, a variable
pattern, variable width, coincident stereo microphone array or to generate full surround from the
four B-Format outputs which will then be decoded into 5.1 by the SP451 Surround Processor or
Surround Zone software. This is achieved using four sub-cardioid capsules set in a regular
tetrahedron, and by adding or subtracting the outputs from these four capsules in different
proportions, it is possible to derive all possible polar patterns from omni, through cardioids to
figure-of-eights.
For surround sound recording the recordist should use the four B-Format output signals. These
contain the three dimensional information (Height, Width, Depth and Sub Bass LFE) required for
all current and future surround sound formats. The B-Format signals can be de-coded into surround
by either the Surround Zone software or the hardware SP451 Surround Processor, both of which
output six discrete channels (Left, Centre, Right, Surround Left, Surround Right and Sub Bass).
The Surround Zone software also provides full stereo re-mixing enabling adjustment of polar
patterns, stereo width and all other microphone parameters.
Please note: To maintain a high quality audio performance the ST350 microphone employs studio
grade condensor capsules - in environments of high moisture and humidity (or other extreme
weather conditions) their performance may be affected.
