Apple Impulse Response Utility - Manual (Page 30)

30
Microphone Suggestions for B-Format Recording
Perhaps the ultimate B-Format recording microphones are the SoundField single point
source microphone series. These microphones contain all the capsules you will need to
make a complete B-Format reference recording in one pass, and include hardware to
send the separate axis streams to individual Impulse Response Utility tracks. You will
only need to swivel the mic once towards each speaker position, and the mic and
processing hardware does the rest. For those who can’t afford SoundField mics, Impulse
Response Utility provides additional microphone options for B-Format recording.
Capturing the W (sound pressure) signal requires an omni-directional microphone.
Capturing the X and Y axis signals requires a microphone with a figure-eight pattern (to
capture signal from the front and back of the mic). Therefore, with two figure-eight
patterned microphones—one pointed directly at the speaker source (X), and another
positioned perpendicularly (Y)—and an omni-directional microphone for the sound
pressure (W), you can record each speaker position in one pass. Be sure to arrange the
microphones so that their capsules are as close as possible to each other—ideally, you
want to have a single, tight point of reference for each speaker position.
You will need to swivel each of the figure-eight pattern microphones to each speaker
position. The omni-directional microphone will not need to be swivelled, as it has a
360-degree capsule.
Even if your budget is too limited for three separate microphones, you can still create
B-Format impulse responses by recording each audio stream separately into Impulse
Response Utility. All you need is a microphone that allows you to switch between
omni-directional and figure-eight patterns. Many good microphones (at all budget
levels) have this capability. You will need to do a significant amount of pattern-
switching and microphone swivelling, but it can be done.