Miking Acoustic Guitars and Similar Instruments
At the risk of offending acoustic guitar, banjo, dobro, harp, or ukulele players, all strummed or picked string instruments are grouped together for this discussion. While they all sound and play differently, the microphone-placement techniques for all these instruments are similar.
Because all these instruments have a resonating chamber, you can pretty much use the same mic placement for any of them but you use different types of mics for different instruments.
Making the most of the room
Because these are acoustic instruments, the room plays a role in the sound that you end up recording. Unless you have a great-sounding room, you want to minimize its impact on your instrument’s sound.
You can do this by recording with spot mics or by placing absorber/reflectors in strategic places around your room. Put the absorber side out if the room is too live or the reflector side out if the room is too dead.
For example, if your home studio resides in a spare bedroom with carpeting and that awful popcorn stuff on the ceiling, you can put a couple of the reflector panels around your guitar player and the mic. This adds some reverberation to your guitar. Any unwanted reflections from the ceiling or walls are shielded from the mics, because the absorber sides of the panels are facing the rest of the room.
Using your mics
Condenser mics are often preferred when recording acoustic instruments. The type of condenser mic you use depends on the overall tonal quality that you want to capture or accentuate.
For example, if a guitar has a nice woody sound that you want to bring out in the recording, a large-diaphragm condenser mic is a good choice. On the other hand, if you’re trying to capture the brightness of a banjo, a small-diaphragm mic is a better choice.
You can position your microphone in a variety of ways, and each accents certain aspects of the instrument’s sound. Even a slight adjustment to the mic can have a significant impact on the sound. You may have to experiment quite a bit to figure out exactly where to put a mic.
Here are some suggestions to get you started:
Put the mic 6 to 18 inches away from and 3 to 4 inches below the point where the neck meets the body of the instrument. Then make minor adjustments to the direction in which the mic points. Pointing it toward the sound hole(s) often gives you a richer, deeper tone.
Turning the mic more toward the neck brings out the instrument’s brighter qualities. The left image of the following illustration demonstrates this technique.
Place the mic about 3 feet away from the instrument and point it directly at the sound hole. At this distance, you capture the rich sound from the sound hole and the attack of the strings. See the center image in the following illustration.
Put the mic about 6 inches out from the bridge of the instrument. Try pointing the mic in different directions (slight movements of an inch or less can make a huge difference) until you find the spot that sounds best to you. See the image on the right in the following illustration.
Set up the mic at about the same distance and angle from the instrument as the player’s ears. Point the mic down toward the instrument so that the mic is a couple of inches away from either side of the musician’s head.
This is an unorthodox approach that is suggested because the player adjusts his playing style and intonation to correspond to what she is hearing when she plays. With this technique, you’re trying to capture exactly what the musician hears.Positioning the mic in these ways can produce a good acoustic-instrument sound.