You have probably read at least a couple of articles and tutorials on recording acoustic guitar. I’m also pretty sure that you are already familiar with some microphone placement methods. The ones we are going to discuss however are not the kind you stumble upon in audio technique books, they don’t often come up on websites either. They are somewhat more “exotic”, but they can give you great sounding results. SDC, LDC or ribbon microphones are recommended. Unbalanced pairs can work great, too.
Unusual microphone techniques
EV style: I have learned this one from Eric Valentine. When it comes to stereo sound, our mind likes things that make sense on a horizontal plane. For example, when we listen to stereo drums, we like when the sound of the toms and cymbals have a certain order from left to right. Same goes for the notes of a nice, wide stereo piano. Arguably, the “problem” with most of the usual stereo techniques on acoustic guitar is, they don’t give you that sense. Unless you mike them the following way: put a pair of microphones around the neck of the guitar, so they are pointing at the neck at 90°. This way, you can pan the low strings to the left and the high ones to the right. Experiment with the placement of the pair. You get a deeper sound closer to the sound hole, and more high end sizzle if you move them towards the headstock. Somewhere between the 12th fret and the sound hole usually gives the best results.
Vertical XY: You have probably tried recording acoustic guitar with the XY stereo technique before. This coincident technique is a pretty safe one; not at all unusual. It usually gives a good, usable sound in most cases. At least if you like the bridge-to-neck sound in your stereo image. It’s very easy to modify the XY to get the sound of the low-strings-to-high-strings though. All you have to do is rotate the pair with 90°. It might not give you the same width as the EV style setup (which is sort of a special case of a spaced pair), but the center will be much cleaner and defined. Just like a usual, horizontal XY.
Glyn Johns influenced: Yup, that one. It’s originally a technique invented and used for drum overheads. You’ll be surprised how good it can sound when it comes to recording acoustic guitar. For drums, the center of attention is the snare drum. The loudest, most mischievous one of the bunch. That’s where the two mics are aimed at; one (almost) right from above, and one from the right – floor tom – side. For acoustic guitar, it’s the sound hole that’s going to be our target. Place one microphone above the guitar, and one at the guitar neck, horizontally. The key to the whole thing is to keep the same distance from the center of the sound hole with both mics. You can use a string or the mic cable to measure it. Play around with the distances! This technique can give you very nice rhythm guitar tracks with good room reverberation, if you record in a good sounding room and keep a good distance with the mics.