Errata - Exotic Positions
3 out of 4 ways of recording in stereo...
Let me start with (the old master) Alan Dower Blumlein. While it is certainly correct that "he did most of the theoretical analysis necessary for the development of stereo recording" he was also very much into exploring the practical aspects of recording. And while "he developed a stereo miking system [the Blumlein setup] that solves many of the problems inherent in XY and ORTF techniques" it is important to note that not only ORTF came 30 years later, but that Mr. Blumlein invented all three coincident setups, including XY and M/S. The latter is listed under the "true exotica" section although it is the de facto standard of stereo in moving picture sound.
Back to the start of the post. XY creates a stereo image strictly by differences in sound pressure level. The term "volume differences" is not accurate. And while often arranged at an angle of +-45, resulting in a huge recording angle of 196°, any angle can be used. It is important to note that the size of the inter-capsule-angle is inversely proportional to the size of the recording angle. Point the capsules father apart for a smaller soundstage!
Visit Eberhard Sengpiel's stereophonic playground for some experimentation.
Rather than saying that "typically, XY recording produces a narrow soundstage" I'd explain that using an XY pair with an inter-capsule-angle of 90° results in a semicircular pickup range. I use this configuration when I have to mike very close to an ensemble and don't want to go for AB, perhaps because I want to reduce the influence of the room or attenuate audience noise.
"Getting fancy: ORTF"
I'd personally place the near-coincident pair stereo technique after XY, Blumlein and M/S. Or, if I were to sort the approaches by their practical relevance to me it would be at the top.
The very nice stereo image that ORTF (and other near-concident techniques: NOS, DIN, EBS, ...) can produce relies on a combination of differences in sound pressure level volume and time of arrival cues. The reason that "sources are rendered in correct spatial perspective rather than in the narrow soundstage endemic to XY recording" is due to the fact that the recording angle is 98°, a little more than half that of XY (at +-45°).
"The old master: Blumlein"
I consider Blumlein to be a special case of XY, using bidirectional capsules / ribbon transducers angled at +-45°. While it is true that "Figure-8s tend to maintain their pattern at all frequencies" the statement that "at least some of them have excellent bass response" is doubtful. Look at the frequency charts of all bidirectional capsules for a pronounced proximity effect / LF-attenuation. As an example please compare the charts on the cardioid Schoeps MK 4 with that of the fig-8 Schoeps MK 8. David Royer has argued that this does not hold for ribbons (see the Royerlabs SF-1) and I have done a few one-point Blumlein recordings that seem to justify the assessment, but I am as yet uncertain on this point.
I don't agree with the statement that "because the pickup pattern is bidirectional the microphones will pick up lots of room sound, leading to a very wet recording." AB gives me much more spaciousness, but since AB (with two parallel omnis spaced at a distance of 51.5 cm) results in a recording angle of 180° I place it much closer to the ensemble than a Blumlen setup with it's recording angle of 76°. Therefore it is definitely true that the sonics of the recording space matter a lot when using a Blumlein setup.
Read all about Tony Faulkner's Phased Array here: Part-1, Part-2, Part-3.
The Jecklin disk uses "a pair of omnidirectional mics spaced a foot or so apart with a large plastic disc between them." That much I can follow. The statement that "this creates the equivalent of a pair of cardioids pointed outward at 180˚" sounds wrong as (in the case of coincident capsules) this would result in a recording angle of 102°.
Regarding M/S the post states that "what’s most useful about this is a high degree of mono compatibility". In fact M/S is completely mono compatible: Use only the central channel...
Interesting to me: the "Swedien technique"--although in theory coincident yet angled true omnidirectional microphones can not generate differences in sound pressure level. Paul Stamler does say the setup pertains to the use of large diaphragm condensers though. I'll give it a try when I get the chance.
"Step up to the bar"
The sturdy yet inexpensive K&M 23550 stereo bar does a good job for XY & ORTF. Don't forget one or two K&M 218 thread adapters to be able position one mic above the other without undue vertical angling.
"What, when, and where"
Much of this is a matter of taste, but I'd usually not recommend using "a pair of good condensers overhead in ORTF formation (panned hard left and right) [...]" for recording drums. True, a stereo overhead and two mics, one for the snare (or a central position) and one for the kick is all you'll need, but if you don't use a coincident overhead you can not reduce the spread of the image in post without introducing comb filtering!
"Try a few true-stereo single pair recordings just to hear what the technique can do. And if you have the tracks, try using stereo miking techniques on multitracked projects. You won’t be sorry." I am happy to say that I wholeheartedly agree with that final statement. "Happy pairing" to you as well :-)
[Please check out Eberhard Sengpiel's website for detailed insights into various stereophonic configurations, recording angles etc.]