^Good advice as always. Below was being typed as that was being posted..
I’m wondering if the X/Y position is worth it or just stick to the A/B setup?
I suggest you do neither!
X/Y is a
coincident microphone pair configuration. That means both microphones occupy (ideally) the same point in space, which in practical terms means placed as close together as possible, typically one positioned immediately above the other. Mid/side is another example of a coincident microphone pair configuration. Because both microphones occupy the same point in space, coincident arrangements rely solely on the microphone's directional pickup pattern in combination with the angle between micrphones to produce a form of stereo based entirely on
level-differences between the two channels. This type of stereo works on the same basis as the
pan control on a mixer or
balance control on a playback stereo unit in how it effects stereo image by way of level.
A-B generally implies a relatively wide-spaced configuration. Both microphones are spaced a significant distance apart rather than attempting to occupy the same point in space. Omnis are generally used for this (partly because due to their omnidirectional sensitivity pattern, an angle between them will not create significant level difference and thus would not generate significant stereo in X/Y). There is no default spacing distance implied by A-B, but typical spacings are from a couple feet apart up to 10's of feet apart (~50cm to meters). 3 feet or 1m apart is pretty common. This arrangement produces time-of arrival differences between channels. Sounds which arrive from direclty in front, above, behind, or below (more technically, the plane which is at a right angle to an imaginary line drawn between the two microphones) will arrive at both microphones at exactly the same time. However, sounds originating from off-center over toward one side or the other will reach the microphone on that side first, producing a
time-of-arrival difference between the two channels. This is a different type of stereo cue than level difference. A-B arrangements may also produce level differences, oviously so with angled directional microphone patterns, but even with omnis due to one source being closer to one microphone than the other. However the configuration is primarily used for generating time-of-arrival stereo.
These two methods are very different in the type of stereo information they produce, the result of which upon playback of the resulting stereo recording is a different type of sound, stereo image, and overall feel. Both can and are used to make good recordings.
Some advanced 4-channel microphone arrangements combine two pairs of microphones, one setup as a coincident-pair, the other as an A-B pair, in an effort to combine the best of both.
However, there is an easy way to combine some of the attributes of both approaches while using only a single pair of microphones. That's what a
near-spaced stereo microphone pair arrangement is intended to do. Directional pattern microphones with an angle between them are used in combination with a relatively small amount of spacing between them, but not as much as would typically be used for A-B. In this kind of arrangement the stereo microphone pair generates both level-differences and time-of-arrival differences. In this case it is the combination of
pickup pattern, angle and spacing that determines the particular balance of stereo cues. One can work the balance between more of one cue and less of the other while retaining approximately the same apparent stereo width on playback by trading angle against spacing. Cool huh?
This kind of near-spaced arrangement is probably what will work best for you. The near-spaced pair approach is the most common one used by tapers employing external microphones, and for good reason. When you hear or read about stereo microphone pair configurations by the name of
ORTF, NOS, DIN, DINa, etc, those are all near-spaced configurations which use slightly different combinations of pickup pattern, microphone angle, and spacing. Plenty of tapers settle on one near-spaced configuration that they use all the time, such as cardioids in DIN, supercards in DINa or whatever.
But to really take charge of things, you can adjust the angle and spacing between the two microphones to specifically fit each recording situation for best results. The easiest way to do that is to use the
Improved PAS Method in which you point whatever microphones you have directly at the PA stacks (or just outside them) and adjust the spacing between microphones to the value indicated on the table found here-
https://taperssection.com/index.php?topic=167549.msg2087409#msg2087409.
To really dive deep into how microphone pickup pattern, angle and spacing work together and can be played off each other to advantage, check out the
Stereo Zoom paper. You'll find it here-
https://microphone-data.com/media/filestore/articles/Stereo%20zoom-10.pdf. It may take a few readings for it to really sink in. The Improved PAS table is really just a made-easy way to apply the Stereo Zoom concept, oriented specifically toward concert taping. It was designed to keep things as simple as possible while optimizing a near-spaced PAS (Point At Stacks) microphone arrangement for best results.