In general, if the spaced pair is too close together and too close to the source, you may experience swimmy-sounding phase issues in stereo, and cancellation and comb-filtering issues in mono. The 3:1 “rule-of-thumb” (which suggests that for every unit of distance you are away from the source, your mics should be three units of distance away from each other) is one decent, although imperfect reference point for this. Another common recommendation is that spaced pairs be placed 3-10 feet apart, and yet another is that the mics should be far enough apart that the time delay between mics is at least 1.5 ms (this could require as little as 2 feet, depending on distance from the source.) One more decent guideline is that low frequency instruments are usually at their best when centered at a point equidistant between the two mics.
Beyond the Basics: A Survey of Stereo Microphone Techniques | SonicScoop - Creative, Technical & Business Connections For NYC’s Music & Sound Community
