548 Chapter 16
left-center, center, right-center, and right images, are
also shown. Note the changes in the direction of the
stereo patterns and the size of their rear lobes.
Taking the directional properties of real microphones
into consideration, it becomes clear that the M/S tech-
nique provides a higher recording fidelity than the XY
technique. There are at least three reasons for this:
- The microphones in an XY system are operated
mainly at off-axis conditions, especially at larger
offset angles. The influence of directivity imperfec-
tions is more serious than with MS systems, where
the M microphone is aimed at the performance
center. This is illustrated by Fig. 16-125. - The maximum sound incidence angle for the
microphone is only half that of the X and Y micro-
phones, although the covered performance area is
the same for all microphones. This area is symmet-
rically picked up by the M microphone, but unsym-
metrically by the X and Y microphones. The M/S
system can supply the more accurate monophonic
(M) signal in comparison with the XY system.
3. The M/S system picks up the S signal with a bidi-
rectional microphone. The directivity performance
of this type of microphone can be designed with a
high degree of perfection, so errors in the S signal
can be kept particularly small for all directions of
sound incidence. The M/S system can supply a
highly accurate side (S) signal.
4. In the M/S technique, the mono directivity does not
depend on the amount of S signal applied to create
the stereophonic effect. If recordings are made in
the M/S format, a predictable mono signal is
always captured. On the other hand, the stereo-
phonic image can be simply influenced by modi-
fying the S level without changing the mono signal.
This can even be done during postproduction.
16.7.5 The Stereo Boom MicrophoneMicrophones for stereophonic television broadcasting
have their own special problems. The optimal distanceFigure 16-122. Stereo pickup pattern of the Shure VP88 in
the L position. Courtesy Shure Incorporated.
Mid
SideA. Relative levels of the mid and side microphones.B. Pickup pattern of the system.Mid
SideFigure 16-123. Stereo pickup pattern of the Shure VP88 in
the M position. Courtesy Shure Incorporated.MidSide
A. Relative levels of the mid and side microphones.B. Pickup pattern of the system.