2 . ORTF . The stereo mic technique developed by the Office de Radiodiffusion Télévision Française ( ORTF ) provides a realistic stereo image that ’ s slightly wider than the standard X-Y configuration . This technique produces excellent results when using two high-quality cardioid condenser microphones . The mics should be aimed 90 – 110 degrees apart , separated by 17 centimeters ( 6.7 inches ). Whether using the ORTF or X-Y techniques , special mounting brackets help facilitate accurate and repeatable positioning of the mics .
3 . Spaced pair . Place two omnidirectional mics in front of the source , spaced between three and ten feet apart . This technique produces a very good stereo image , especially in a room with excellent acoustics . A spaced omni pair is best when used for recording but in a live sound
application the omnidirectional mics would cause problematic feedback . When recording a small group , such as a vocal quartet , keep the mics about three feet apart , for larger groups , increase the distance between the microphones . A variation of the spaced omni pair uses a baffle between the two mics , which increases the stereo separation and widens the image .
4 . Blumlein . The Blumlein technique is a coincident technique because the mic capsules are very close together and on the same plane . This technique uses two bidirectional mics in an X-Y configuration , so when summed to mono , the sound isn ’ t significantly degraded . The sound produced by this technique is similar in separation to the X-Y configuration , but with a little more acoustical life .
5 . Mid-side . The mid-side ( MS ) technique uses a
bidirectional mic positioned with its side aimed at the source along with a cardioid mic aimed at the source . The bidirectional ( sides ) mic signal is split and sent to two separate channels , then the polarity of one of those channels is reversed for a wide stereo image . The mid ( cardioid ) mic is blended with the side channels for a naturalsounding stereo recording . When summed to mono the two side channels completely cancel because they are opposite in polarity so the sound is pure and clean from the mid cardioid mic .
Bill Gibson Teacher at Berklee College of Music Online , content creator for LinkedIn Learning , and author of more than forty books and videos about live sound and studio recording . Most recent book releases : The Ultimate Live Sound Operator ’ s Handbook , 3rd Edition , and The First 50 Recording Techniques You Should Know to Track Music . He also recently self-published an eBook / Audiobook combo called Stream Great-Sounding Audio : Guide for Streaming Church Services and Other Events .
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