Capturing the nuances of an acoustic guitar can be difficult, so experimenting with different microphone techniques is a good way to find the perfect sound. Microphone techniques can help reveal the subtleties of recording an acoustic guitar.
The first step to finding a microphone technique is to listen. While the guitar is being played, listen for variations in resonance. Place your ear at points you might place the microphone. On an acoustic guitar, the most resonant spot is usually at or around the sound hole. Each guitar is slightly different, so it’s important to determine where the guitar’s “sweet spot(s)” are to decide where to place the microphone(s). A condenser microphone is the most common type of microphone to record acoustic guitars with, yielding the broadest dynamic range and clarity, but any type of microphone will work well.
Mono
If you’re using one microphone (Mono), its placement will be more crucial. Usually, the microphone will be placed three to five inches above the strumming hand, depending on the technique and directed straight into the sound hole. You can experiment with the angle of the microphone for variation in tone. It’s also a common technique to place the microphone above the fingerboard, near where the neck meets the body. Always make sure there is enough room for the guitar player to strum comfortably without bumping the microphone.
Stereo
When recording acoustic guitar, the most common microphone technique is to use two microphones (Stereo), one near the sound hole and one above the fretboard. The microphone near the sound hole will be more apt to capture the low bass frequencies, whereas the microphone above the fretboard will caputure the higher frequencies (especially if the mic is a condenser).
There are a number of mono or stereo microphone techniques that can be used when working with acoustic guitars, but first it is best to determine the context of the guitar within the mix of the other instruments. An acoustic guitar which was recorded with a mono microphone will be mixed differently than one recorded using a stereo technique. A mono microphone may be a good choice if there are other instruments in the same or similar frequency ranges, this can help each instrument fit in the mix. A stereo microphone technique may be preferable if the acoustic guitar will be the main instrument in a song, allowing it to fill up the sound-space. Experimenting with mono and stereo microphone techniques is best for making decision about the function and placement of an acoustic guitar within the context of the recording.