Microphones: Stereo Miking Techniques

The use of stereo miking techniques utilizing matched pairs can make all the difference between mediocre and outstanding recordings. After all, we listen to the world around us in stereo via matched pairs of ears. Stereo miking can be used in applications ranging from individual instruments to small ensembles to full orchestras and other concert events. In the next several issues, we’ll cover some of the proven stereo miking techniques that have been used on countless professional recordings. These include X-Y, Blumlein, ORTF, mid-side, spaced omni and Decca Tree.

One of the critical factors in stereo miking is the use of matched pairs of microphones. M-Audio’s Solaris and Luna mics are perfectly suited for the job since every single mic has a manufacturing tolerance of +/-1dB across the entire frequency range and in comparison to our factory “golden microphone” standard. (Many manufacturers charge more for matched pairs—often including special ordering—and hold to a looser tolerance.)

Several factors must be considered in determining the best stereo miking technique. Although results vary with different polar patterns, one should use distance from the source to determine the amount of room reflection versus direct source signal desired. Restrictions in distance or position also come into play, such as the need to maintain clear lines of sight from audience to stage. It is also advisable to consider mono compatibility, especially if the resulting material will wind up on radio or television.

The stereo miking techniques we’ll explore fall into two basic categories—coincident and spaced. Coincident techniques rely on the microphones being placed in extremely close proximity to one another, while spaced techniques place them further apart. While the coincident methods are considered to be very accurate, some listeners find them to be too accurate. Common criticisms are that the stereo field is too narrow or confined to the speakers on playback. (You can sometimes compensate for this by moving the coincident mics slightly apart from each other in order to introduce a time delay between sides.)

Spaced techniques are considered less accurate, yet more spacious sounding. In effect, widening the space between mics widens the virtual placement of our ears. As with everything surrounding microphones and their techniques, these considerations are subject to interpretation and experimentation. In fact, it is not uncommon to find engineers employing techniques from both categories simultaneously. In such a case, the coincident pairs provide a well-defined primary signal, while the spaced pairs are placed to capture the reflected sound that provides extra control over ambience.

Stay tuned next month as we dive into the X-Y stereo miking technique.

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