5 Popular Microphone Techniques for Acoustic Guitar

Depending on the sound you’re going for, your mic placement plays a huge role in what sound you’ll get, especially with an instrument with such delicacy and ambience as an acoustic guitar, the capture of the sound plays a huge role in the overall listening experience of a piece of music; and you’ll find that whenever you listen to a lot of different acoustic pieces, the sound of the guitar almost always differ. These 5 microphone techniques will showcase who to achieve different sounds and what to expect from each one.

1. Blumlein Configuration

The Blumlein Configuration requires the use of two Bi-Directional Microphones placed at a 90º angle. Bi-Directional microphones capture the signal in front of them and behind so the room ambience plays a big factor in the sound. Most microphones have a setting that looks like a figure “8” and can be switched easily into this mode. As you can in the image, it takes a bit of setup to get the ends of the microphones as close to one another as possible without having them touch. The next step is getting the 90º angle to face the sound source.

The outcome of this technique is usually a wide and clear sound that can accommodate most general acoustic guitar recordings, maybe where the acoustic guitar is the sole instrument as it focuses on the ambience as well as the overall capture of the sound and the clarity of what you’re getting through.

2. One Large Diaphragm

Condenser Microphone

This placement used a single Large Diaphragm Condenser facing the area between the sound-hole and the top of the fretboard. The microphone was switched into the Cardioid polar pattern setting to reduce any room ambience from behind the microphone. Cardioid focus the microphone to only retain signals from mostly in front of the microphone. This setting is much more narrow in comparison to a stereo configuration and would be perfect for double-tracking purposes where the player would strum two different performances of the same chord progression and pan them hard left and hard right.

By nature the microphone is very sensitive and picks up much of the low end of the acoustic giving it a very thick and chunky sound. This feature makes it the perfect candidate for acoustic guitar driven music where the acoustic guitar upholds much of the harmony for track.

3. Spaced Pair

This configuration uses two Small Condenser Microphones set about 2.5ft away from one another. One is pointed towards the 8th fret of the acoustic guitar and the other is pointed directly at the 12th fret just past where most of the strumming is happening. Setting these closer to the player means the microphones retain fewer lower frequencies than the large diaphragm microphones. They also tend to register the high end of the frequency spectrum with more detail.

The tricky part of this technique is making sure the microphones are placed at the right distance from the player, because if they’re too close, the sound is choked and you get no clarity, whereas if they’re too far away, the sound is thin and it lacks any layering of sounds.

In terms of the sound you’ll receive from this set up, you’ll of course capture the low and high end very well, meaning there is no need for any mids at all, and also the right mic is especially good at picking up things such as slides, hammer on’s, pull offs, tremolo, so if your track contains a lot of this, spaced pair is the set up for you.

4. Vertical Spaced Pair

For this set up use two small diaphragm condenser microphones, in a vertical spaced pairing about seven inches apart. The bottom microphone’s capsule is pointed directly at the lower three strings of the acoustic and the top microphone is pointed at the top three strings. Angling them inward balances both the high and low end so that there aren’t very many holes in the capture of the signal.

When panning these signals extreme left and right the stereo image is very interesting. Depending on strum direction you can almost feel the attack of the guitar pick on the high and low strings moving from left to right and right to left. This may not be every engineers ideal microphone placement but it does lend itself to some interesting mix options. I would experiment with this placement specifically on a singer/songwriter act that had only acoustic guitar and vocal. The quality of the recording is very intimate

and would be fitting for that style. Most of those types of acts rely heavily on the acoustic guitar for a controlled low end, present mid range, clear shimmering high end, without taking away from the vocal.

5. XY Configuration

The XY configuration is a stereo option for many different applications. For this you must have the two microphones placed at 90º angle with the capsules as close to one another as possible without having them touch. The angle is then pointed towards the sound source. For this placement I pointed the angle towards the sound hole of the guitar.

The idea is to capture a stereo sound, but this can sometimes be narrowed out by either phasing or having the microphones too close together, making this one a risky one to try; especially if you haven’t got a lot of time to record.