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Project #1 - Ambisonic Microphone - Exp2 DOCUMENTATION - Part 2 |
One change from my original microphone that helps
reduce the size of the box is the elimination of
the a- to b-format resistor matrix and output
amplifiers in the microphone enclosure. This
conversion is easily done in software and this
method has been adapted by several manufacturers
of the new lower-cost ambisonic microphones. A-format
is simply one output for each of the 4 capsules.
(See
Soundscapes
for further information on ambisonics and b-format.)
Below is a third-octave frequency response result on the test circuit with the microphone about 18 inches from a 3-way monitor speaker. By no means intended as an accurate frequency response test, my interest was to confirm that the system was responsive at 20Hz on the low end and at least 20kHz for highs. |
Frequency response test confirms presence of 20Hz and
20kHz tones. The high noise floor is from 2 computers
in the room.
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First recording with the new microphone circuitry.
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Test recording next to IH35 at Capital Plaza (no windscreen).
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Test recording along IH35. Camera case is being used
as a wind shield for microphone capsule taped to the luggage bar.
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