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RECORDING TECHNIQUES |
February, 2002 "RECORDING" ISSUE |
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MICING
THE
ACOUSTIC
GUITAR |
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BY BOB DENNIS
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| The
Acoustic Guitar |
| The acoustic
guitar is shown in figure 1. Understanding how it works to
generate its sound allows you to properly place close microphones on
this instrument. |
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FIGURE 1 -
THE ACOUSTIC GUITAR |
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| The acoustic guitar has 6 strings, each tuned to a
different pit. There is a fretboard on the neck
of the instrument that allows the player to sound different pitches with
any string. For our purposes, we need to understand that the
vibrating strings begin the sound wave. |
| The bridge of the instrument is at
the tail of the strings. Since the bridge is in contact with both
the strings and the top plate of the guitar, the front plate will
vibrate, driven by the strings. The area of the bridge of
the instrument becomes a sweet spot for the guitar. Placing a
microphone 1-3 inches directly over the bridge area will accent the
instrument's brilliance and clarity, making the sound heard though many
other instruments playing along with it in a mix. When there
a lot of instruments in the production, especially when there are
electric guitars playing along with the acoustic, this microphone
placement is preferred. |
| Maximum Body |
| The hollow body of the acoustic
guitar is a resonator that amplifies one octave of vibrations centered
around 150 Hz. This effectively amplifies the lowest frequency
pitches generated by the acoustic guitar. There is a "hot" spot of
this low-end guitar energy over the hole in the body. Placing a
microphone over this area of the guitar tends to reduce brilliance and
clarity but increases the body in the sound. This microphone
placement may be used when the acoustic guitar is played by itself of
with only a vocal. |
| Stereo Micing
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FIGURE 1 -
STEREO MICING THE ACOUSTIC GUITAR |
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| You can pick
up both of the hot spots by placing X-Y stereo microphones as shown in
figure 2. The blue microphone picks up the bridge of the
acoustic while partially rejecting the sound hole. The red
microphone picks up the sound hole while partially rejecting the bridge
sound. When these mics are panned stereo in a mix, you will have
both body and clarity in the acoustic guitar sound. |
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Acoustic Guitar Hot Spot Demo |
| The two hot
spots on the acoustic guitar are the bridge and the sound hole of the
instrument. In the following demo, an acoustic guitar sounding an
open A (a fundamental frequency of 110 Hz) is heard miced over the
bridge and then over the sound hole. The sounds are then repeated
several times with a small beep at the point of switching the sound.
Go here for the demo. |
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