When most people think of stereo recording, the first thing that comes to mind is a matched pair of microphones, arranged in a coincident (XY) pattern. It makes sense, of course, since that’s the closest way to replicate a real pair of human ears.
But while XY microphone recording is the most obvious method, it’s not the only game in town. The Mid-Side (MS) microphone technique sounds a bit more complex, but it offers some dramatic advantages over standard coincident miking.
If you’ve never heard of MS recording, or you’ve been afraid to try it, you’re missing a powerful secret weapon in your recording arsenal.
More Than Meets The Ears
Traditional XY recording mimics our own ears. Like human hearing, XY miking relies on the time delay of a sound arriving at one input milliseconds sooner than the other to localize a sound within a stereo field.
It’s a fairly simple concept, and one that works well as long as both mics are closely matched and evenly spaced to obtain an accurate sonic image.
One of the weaknesses of the XY microphone technique is the fact that you’re stuck with whatever you’ve recorded. There’s little flexibility for changing the stereo image once it’s been committed to disk or tape. In some cases, collapsing the tracks into mono can result in some phase cancellation.
The MS technique gives you more control over the width of the stereo spread than other microphone recording techniques, and allows you to make adjustments at any time after the recording is finished.
Mid-Side microphone recording is hardly a new concept. It was devised by EMI engineer Alan Blumlein, an early pioneer of stereophonic and surround sound. Blumlein patented the technique in 1933 and used it on some of the earliest stereophonic recordings.
The MS microphone recording technique is used extensively in broadcast, largely because properly recorded MS tracks are always mono-compatible. MS is also a popular technique for studio and concert recording, and its convenience and flexibility make it a good choice for live recording as well.
What You Need
While XY recording requires a matched pair of microphones to create a consistent image, MS recording often uses two completely different mics, or uses similar microphones set to different pickup patterns.
The “Mid” microphone is set up facing the center of the sound source. Typically, this mic would be a cardioid or hypercardioid pattern (although some variations of the technique use an omni or figure-8 pattern).
The “Side” mic requirement is more stringent, in that it must be a figure-8 pattern. This mic is aimed 90 degrees off-axis from the sound source. Both mic capsules should be placed as closely as possible, typically one above the other.
