Hi chuck. Thanks. Interesting question. I've spent many hours over the years trying to work out how to get the best sound possible from my gear - as the process is a tad unconventional, I don't post much here about "this is THE way to record acoustic guitar" as I can't be bothered getting into philosophical arguments about it, but what I do works for me.
Firstly, any solution is source specific - what works for me might not work for you. I use a
Maton Messiah which is a serious high end Australian guitar which sounds exceptional live. That it does sound so good live is in fact what makes it difficult to record - it's loud, quite strong bottom end, cut through top end etc. So normally what I do is aimed at reducing the sound into something that sounds OK recorded, rather than enhancing a weak sound to the same end, if that makes sense.
I have two basic tenets that I always follow:
TENET 1. There is no single mic that I have that can record THIS acoustic guitar to my satisfaction. THERE'S ALWAYS SOMETHING MISSING. So I use multiple sources. I use an AKG451B SDC as the main mic. Always. Over the years, the secondary source has been a number of things, from a pickup line in, to another mic, to a DI signal into an electric guitar tube amp (set to clean, obviously) miked via a SM57 back in (weird, but it works...).
The most recent recordings (Welcome to the World & Ghosts of Cloudland from the video collection) use a second mic for the second source - that being a Neumann KMS105. Yep, it's a stage vocal condenser mic. But it works. Putting two sources together in roughly the same pan location (not always exactly) lets me feed in some of that missing frequency, which is usually in the mids somewhere. I put the AKG in via a Mindprint Envoice channel strip (without using either EQ or compressor sections) and the Neumann in via a Presonus MP20. Does this make a difference? Don't know, but I have them, so I use them.
Then, on the theory that the brain gets distracted from the essential awfulness of the noise if you have the same thing played twice, I record the piece again. Same guitar, same mics. One set panned left, one set panned right. All fairly standard stuff.
TENET #2 - there is no sweet spot, or at least I can't hear it. Anyone who can tell me that moving a mic an inch (in a general location) results in a "sweeter" sound, has better ears than me. This is not to say that I put them anywhere, I don't, but I don't think too long and hard about their exact positioning. I put the AKG 20 - 30 cm out from the 12th fret, or the body join at the 14th, angled slightly towards the sound hole. The distance depends mainly upon what's being played and how dynamic it is. The more dynamic, the further back I mic. The 12th / 14th thing depends upon how much I remember about where I had it last time, which I usually can't. Either works for me. The second mic is positioned higher (blasphemy!) up the fret board. None of this "down by the lower bout" stuff for me - too boomy, too woody ON MY GUITAR, which as I've explained is a loud beast made of high quality wood, so you get more boom from it. YMMV. So I'll put the second mic up about 7th - 9th fret or so, same distance out, angled a bit more towards the first mic so they're sort of pointing at the same spot on the fretboard.
And that's pretty much it. I'll EQ quite harshly at times, rolling off the top end and bottom end and a bit of a mid boost. Both the tunes I mentioned were capo'd up at least three frets, so that in itself takes care of lots of the boom (TIP - tuning down a half step and capoing at 1st fret, if you know what you're playing and don't find it disorienting, can reduce boom as well, if that's a problem for you). I'll generally add some standard "large hall" reverb, more on the secondary mic rather than the first, depending upon levels, and if I have the volume fader for the main mic set to 0, then the fader for the second mic will be anywhere from 0 to -20, depending...
Hope that proves useful!
Cheers
