Some people are still under the impression that an acoustic guitar is just for folkies and old fogies. But just because it doesn't have any wires sticking out of it doesn't mean you can't lend your wooden instrument an powerful presence. The acoustic guitar has certainly proven its worth for "padding" rhythm tracks and for adding a percussive feel with that great sound of the pick attacking six strings. However, making it the featured instrument--especially on a rhythm rocker--is a different story altogether. Led Zep's "Hey Hey What Can I Do," Pearl Jam's "Daughter," and Shawn Colvin's "Get Out Of This House" are prime examples; sure, there are plenty of electric colorations going on, but it's that up-front, commanding acoustic rhythm that supports the song throughout. Bringing out the best in your own acoustic doesn't necessarily require lots of rack-mountable gizmos or other expensive gear. Years before effects-processing patches became standard equipment inside a home studio, players sought remarkably different acoustic guitar tones simply by trying every conceivable method of recording. Very often this involves manipulating the instrument itself, or your recording of it, rather than attempting technical embellishments. Let's take a quick look at some approaches that might work for you.
There are plenty of ways to get great acoustic tracks at home. First, though, make sure you're getting a good, strong signal from your source. Most players prefer to record their acoustics with condensor mikes, which are sensitive enough to pick up a guitar's nuances. Try aiming a condensor mic at the 12th fret, angled slightly downward to avoid your extraneous breathing noises and away from the soundhole to prevent bass boom (especially prevalent in certain rosewood dreadnoughts). For a stereo recording, suspend a second mic near the bottom of the guitar's face and point it across the soundhole in order to pick up the sound as it goes by. You'll probably need to try the mikes in a number of positions before you hear the right sound going to tape.
Once you're ready to record, there are limitless options. You could go with the lone-guitar approach, since it isn't always necessary to pile on the tracks in order to achieve a big sound. A dollop of effects processing like delay or reverb may work on occasion, but for a real tried-and-true sound, try squashing the guitar through a compressor/limiter--even a decent pedal will do the trick. For mono guitar, pan the track not-quite hard left, with a "companion" electric rhythm filling up the space on the opposite channel.
Of course there's no better method of making a big sound than making it twice, and the sound of two distinct and loud acoustic-guitar parts coming through opposite channels is quite unbeatable. Naturally, any garden-variety digital multitracker will let you cut-and-paste your original part onto a separate track, but for the real deal, do it manually. Those small variations in your performance will help make the combined tracks sound fat and full.
For even broader sonic variation in your acoustic tracks, try recording the two parts with different chord voicings. Then map out two guitar parts, each with different voices for every chord, and record both parts. You'll be amazed at the sound--you'll hear more voices than a piano player could handle. A similar approach involves the use of a capo (capoed voices are available on the Chord Generator, too). If one track starts on a G chord in first position, for instance, you could try a second pass with the capo on the 5th fret, fingering a D shape. See Figure 1. Again, you'll probably want to map out the chord shapes in advance so you don't end up laying down two guitar tracks in two different keys! Try the capo in different positions to achieve effects with open strings, dropped tunings, and higher notes. You'll learn a host of new chord fingerings in the process.
If you're lucky enough to have more than one acoustic, you can achieve contrast by doubling parts on different guitars. Three-quarter size guitars, 12-strings, and even some beat-up old box can add depth to your tracks.
Another way to add color and density is to vary the rhythm of the second track. If you've played the first part as a straight 4/4, balance it out with a busier strum, maybe leaving a few holes. Try some fingerpicking to distinguish a verse from a chorus, or to make a hook more pronounced. Any differentiation will produce a nice stereo contrast. (Check out the Beatles' Let It Be opener "Two Of Us" for an aural demonstration.)
Other tricks? Open-tuned acoustic guitar, when properly miked, is one of the most captivating sounds under the sun. Using your imagination, you can come up with limitless combinations. For instance, consider offsetting a capo-5 chord pattern in D with a second guitar tuned to open G, heavily compressed to achieve maximum ring. For a less complicated variation on that theme, tune all six strings down one whole step from standard. If your song is in the key of D, you would now transpose all of your changes up a step, as if you were in the key of E, to know what shapes to play; the D chord becomes an E chord, an E minor becomes an F# minor, and so on. Now when you finger an E chord it actually sounds a D, but you've got lower notes than you could've played in standard tuning, and you're still playing in the key originally intended. Get it? Many dreadnought acoustics are responsive to lower tunings, as Neil Young made evident with his Martin on a whole slew recordings (including "Don't Let It Bring You Down" and "Tell Me Why").
You might also find success with such tricks as varying tape speed, offsetting the time on digital doubles, using different mikes, placing mikes in odd places, recording in different rooms, and using stompboxes. If you were to find the session notes for some of your favorite acoustic tracks, you'd probably see different recording methods used for each one. The possibilities are only limited by your imagination.