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STEREO MICROPHONE PLACEMENT / CAPTURING A SPACE RATHER THAN A POINT


Microphone placement is crucial, as is the way that multiple mics will be placed together in order to create an overall sonic image.  Individual microphones may be placed where they will pick up the strongest sound of the instrument being captured, but multiple microphones (usually two for a stereo image) must be positioned while taking into consideration phase and contribution to the overall image.

X/Y Positioning involves placing two matched microphones across each other at 90 degree angles, with their capsules kept close to avoid “holes” in the sound. Stereo microphones actually consist of two mics that are already connected.

Using a combination of a cardioid and figure-8 pattern, it is possible to create a very nice stereo image using a technique called “MS” (middle, side).  You basically set up the mics in the same vertical axis (close together).  Aim the figure 8 so that it captures the sides, and the cardioid so it captures the front.  Then send the cardioid to both tracks, the figure-8 to the left track, and the figure-8 (out of phase) to the right track.  The stereo field will vary with the proportion between the two mics.  I suggest that after you check the sound you also record the cardioid and figure-8 mics to their own tracks rather than only combining them into the MS tracks. That way you can change your mind about the ratio later.

Left track = Cardioid & Figure-8 (in phase)  /  Right track = Cardioid & Figure-8 (flipped out of phase)

BINAURAL recording involves placing two sensitive omnidirectional condenser microphones into ear positions of a dummy head, so when the sound actually reaches the microphones it is more similar to sound reaching human ears.  This techniques results in remarkably realistic stereo images that are most impressive when heard in headphones.  When heard through speakers, the sound image is reduced because the sound travels over human facial features TWICE rather than only once.

DON'T FORGET TO EXPERIMENT

Ah, screw the rules!  Sure, set up something traditional and even TRACK it to be on the safe side (what the hey – we’re digital so tracks are not an issue) but be sure to PLAY AROUND AND EXPERIMENT with your stereo field.  Capture what you can and you can always decide what to use later.

REMEMBER you had better make sure that you are aware of the PHASE of any mics that are to be heard together, and especially aware of the phase of any mics you are combining.  ALWAYS be sure to double check mics you are combining by flipping phase on one of the mics and listening to see if there is better low end.