M/S Stereo

Also known as M-S, an abbreviation for Mid-Side, a method of stereo miking and recording. M/S recordings capture the relative intensity of different sounds across the stereo soundfield. In order to make an M-S recording one must deploy a cardioid pattern mic facing the sound source(s) and a figure 8 pattern positioned sideways to the source. The figure 8 mic is connected to two channels of the mixer, with one channel having its polarity reversed. Each of the two signals (one of which is polarity reversed) of the figure 8 mic, when combined with the signal from the cardioid mic produces either a left or right “image” that is roughly equivalent to two cardioid mics positioned with a 90-degree angle between them. The only advantage to the M-S method is the user can alter the width of the stereo image by varying the relative levels of the two microphones. There are several disadvantages, most of which are a function of having two dissimilar mics reproducing the same signal. Of course they can’t occupy the exact same space either, which produces other phase and frequency response anomalies.