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• Higher values move the middle signal back toward the center of the stereo mix, but
this also has the effect of swapping the side signals of the recording. For example, at
values of 180° or −180°, the middle signal is dead center in the mix, but the left and
right sides of the side signal are swapped.
Getting to Know Stereo Miking Techniques
There are three commonly used stereo miking variants used in recording: AB, XY, and
MS. A stereo recording, put simply, is one that contains two channel signals.
AB and XY recordings both record left and right channel signals, but the middle signal is
the result of combining both channels.
MS recordings record a real middle signal, but the left and right channels need to be
decoded from the side signal, which is the sum of both left and right channel signals.
Understanding AB Miking
In an AB recording, two microphones—commonly omnidirectional, but any polarity can
be used—are equally spaced from the center and pointed directly at the sound source.
Spacing between microphones is extremely important for the overall stereo width and
perceived positioning of instruments within the stereo field.
The AB technique is commonly used for recording one section of an orchestra, such as
the string section, or perhaps a small group of vocalists. It is also useful for recording
piano or acoustic guitar.
AB is not well suited to recording a full orchestra or group as it tends to smear the stereo
imaging/positioning of off-center instruments. It is also unsuitable for mixing down to
mono, as you run the risk of phase cancellations between channels.
Understanding XY Miking
In an XY recording, two directional microphones are symmetrically angled, from the center
of the stereo field. The right-hand microphone is aimed at a point between the left side
and the center of the sound source. The left-hand microphone is aimed at a point between
the right side and the center of the sound source. This results in a 45° to 60° off-axis
recording on each channel (or 90° to 120° between channels).
XY recordings tend to be balanced in both channels, with good positional information
being encoded. It is commonly used for drum recording. XY recording is also suitable for
larger ensembles and many individual instruments.
Typically, XY recordings have a narrower sound field than AB recordings, so they can lack
a sense of perceived width when played back. XY recordings can be mixed down to mono.
129Chapter 7 Imaging Processors