Yo Tojo! Choosing a "stereo" track does not create a stereo image. Using 2 mics doesn't necessarily, either, although it's a start. Some stereo recordings use three mics, such as a Decca Tree. Stereo recording is *not* an electronic decision. What it is, is using 2 or more mics to create an acoustic model (it's only a model) of what your 2 ears would have heard if you had been there when it was recorded. Sometimes, as in binaural recording, the mics are actually placed as they would be in a real human head, with a baffle between them to substitute for the actual head. Other techniques, such as spaced stereo recording, use mics much farther apart than your 2 ears could ever be.
Mid-side, or MS stereo recording uses a figure-of-8 mic and a unidirectional mic, usually cardioid or hypercardioid. The figure 8 track is doubled and the phase reversed on one of the doubled tracks. There are a bunch of ways. Note that stereo recording, with all of its subsets, is only one way to record an acoustic, and there are numerous techniques involving 2 or more mics that are *not* stereo recording. Stereo recording is one plan, not the only one, and not always the best one. First do a search on these stereo recording systems- coincedent stereo (that's the X-Y system detailed above), Blumline (this is another variant of the X-Y concept), spaced stereo recording (mics many feet apart, often used for recording large ensembles, choirs, etc.), Decca Tree (this uses 3 omnidirectional mics in a triangular array), Jecklin Disc.(similar to binaural, if your head was turned sideways). Note that all of these systems, except MS, tends to use identical mics and preamps, or as similar as possible. Hence the market for "matched" stereo pairs of mics.
So the big question is- how do you record an acoustic guitar? First, most engineers prefer condenser mics over dynamics for that application, although ribbon mics, a specialized subcategory of dynamics, are sometimes used. Both small diaphragm and large diaphragm mics are used, sometimes both of the above. The most common spots for mic placement are:
1. close mic'd (anywhere from 6" to about 24") somewhere around the 12th fret. As the mic gets closer to the soundhole, it becomes bassier. As it is moved up the neck, brighter.
2. distant mic'ing- (about 3-12') This picks up more room reflections, and is often called a "room" or "ambient" mic. Often a stereo pair is used, usually in combination with a close mic.
3. Across the top of the guitar- This can be placed almost anywhere, but a common use is over the right shoulder of the guitarist with the mic pointed down across the bridge. The idea here is to pick up what the guitarist hears. After all, he's not in front of the guitar.
4. Sometimes an internal mic, as in a Fishman prefix or triad system, or even a pickup, piezo or magnetic, is recorded direct, and may be blended with tracks from other mics, or occasionally is used instead if the mic tracks came out badly. This can happen when the room, or for that matter the guitar, sucks.
I have used all these techniques, and almost all of the possible combinations. The above is pretty much "just the facts, ma'am". What follows are simply my opinions:
1. If your room sucks, or you have a lot of ambient noise (your room sucks), *don't* use room mics. You are only recording something that sucks. Conversely, if you are in a good room, make sure you *do* use room mics.
2. The over-the-shoulder technique sucks if the guitarist is a heavy breather. If he can't breath quietly, don't waste your time.
3. For whatever reason, if it is an acoustic with nylon strings, I've had better luck with small diaphagm mics backed off a bit, say 2-4'. This is when that X-Y stuff really shines. I have not had good luck close mic'ing nylon strings, and this goes for harp, also.
4. An X-Y array, either coincedent or Blumlein, needs a certain amount of distance to create its stereo picture, say 2 to 6'.
In general, I've had my best luck recording steel string acoustic with one large diaphragm close mic on the 12th fret adjusted up or down to taste, often using bass cut on the mic, the preamp, or both, to decrease "boom" (low frequency overload) panned to middle, and a coincedent pair of small diaphragms, backed off 5-6', no bass cut, panned hard left and right. The best choices I own for this are an AKG C414B-ULS up close, and a pair of Neumann KM184's for the X-Y pair. There are lots less expensive options for this, and much better ones that I can't afford. For cheaper, an AT4033 and a pair of Studio Projects C-4's work pretty well. If I was a really rich mofo, I'd use an ifet7 and a pair of Schoeps CM-6's. Hope this helps.-Richie
