The Mid Side (MS) microphone technique was developed early in the advent of stereo recording history. One if its major advantages is the ability for the stereo signal to collapse into a phase coherent mono signal. (That would be a good thing.) Microphones with specific pick up patterns are required in order to capture MS stereo. One microphone would be a forward facing uni- directional (cardioid) pattern element (MID.) This is positioned directly above a side facing bi-direction (figure 8) pattern element (SIDE.) The two signals can be recorded separately in the field to better facilitate processing later in the studio. Or it can be processed direct to "tape." In the recording studio (or in the field) the bi-directional signal is split into two equal signals. One signal is panned to the left. The other signal has the polarity reversed (phase rotated 180 degrees) and panned to the right. The middle signal is then blended into the mix while panned to the center. The width of the stereo image can be adjusted by varying the center signal. The result is a huge phase coherent stereo image that can collapse into proper sounding mono, without artifacts, when necessary. The final LEFT channel consists of MID and SIDE+. The final RIGHT channel consist of MID and SIDE-. The microphone pictured to the left has two 1" diameter gold sputtered diaphragms stacked one atop the other. The top element can pivot 270 degrees above the bottom element. Each element is a multi pattern microphone.