Recording - July 2012 - 57

As you will soon see, the mics don’t always end up pointed directly at the instruments, so we usually use smalldiaphragm condensers because they have a smoother frequency response for sounds that are off to the side. Your large-diaphragm (1" diameter) mics sound fat and warm when you sing right into them, but are not the best choice here. We will also try to use single-diaphragm mics rather than multipattern dual-diaphragm mics, because the dual-diaphragm mics tend to sound muddy when they are more than a foot or two away from the sound source. (For more information on this, google “Unique Directional Properties of Dual Diaphragm Microphones” by Guy Torio and Jeff Segota.) Stereo mic configurations are separated into three categories: coincident, near coincident, and spaced. Here we go.

Figure 2

Coincident (also called XY)
In setups called coincident or XY, a pair of microphones are placed so that their capsules are as close as possible to each other. Here are three examples of XY setups. ~ XY cardioids: Two cardioid mics are placed with their capsules as close as possible, angled left and right at 90 degrees from each other. Try a pair of RØDE NT5s, Neumann KM184s, or Oktava 012s (the real Russian ones). Record them to a single stereo track so that they are panned hard left and right. See Figure 2. Because we are using cardioid mics, sounds that come from the left are picked up a bit louder by the mic that is pointed left, and sounds from the right are picked up a bit louder by the mic that is pointed right. Sounds from the center are picked up at an equal, slightly quieter amplitude by both mics. If you set this pair up in front of a small group of instruments, singers, or maybe even a drum set, you will hear a nice stereo image with instruments distributed left to right between the speakers just as they are positioned in the room. Cardioid is a pretty wide polar pattern, so both mics pick up a healthy signal from sounds in the center of your ensemble. This results in a stereo image that is somewhat narrow, or squished in towards the center a bit. This can be a good thing or a bad thing, depending on what you are trying to accomplish. ~ XY Figure-8s (Blumlein): Named after Alan Blumlein, an English pioneer of stereo recording and radar, this setup is exactly the same as XY cardioids but you use figure-8 mics instead. You will hear a wider stereo image because the figure-8 mics attenuate sounds from the center of

the pair more than the cardioids do. You will also pick up sound from behind the pair because of the figure-8 pattern. This works great for instruments in a nice-sounding room because you will hear reflections from the walls as well as the direct sound. Try this with a pair of Royer ribbon mics pointing at the soundboard of a piano. ~ Mid/Side (MS): Mid/Side recording uses a forward-facing cardioid, a sideways-facing figure-8, and a mysterious process called matrixing. I just wrote an article on M/S that appeared in the November 2011 issue of this magazine, so I’ll not explain it here. But you can see a really cool video that also explains M/S at www.recordingmag.com/videos/videoDetail/18.html Because coincident techniques rely on the differences in amplitude or intensity between the mics, we sometimes refer to this as intensity stereo.

Near Coincident Techniques
Here, mics are placed close to each other, but not as close as possible. ~ ORTF: Developed by the Office de Radiodiffusion Télévision Française. Two cardioids with their capsules 17 cm apart are angled 110 degrees from each other. This setup mimics the spacing and directional sensitivity of a pair of human ears. See Figure 3. Figure 3

RECORDING JULY 2012

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Recording - July 2012

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