Recording Acoustic Guitar

Guitar

Obviously, the player needs to be good and know their material.
Have you chosen the right guitar for the job? The best results come from having the right sound at source.
The string gauge and quality make a huge difference to the tone. In general, thicker strings produce a deeper, more involving tone with more harmonics. Real telephone cables sound quite dull, though. Lighter strings are much easier to play.
The plectrum gauge is also important, if the player uses one. Lighter gauges are good for more percussive work, thicker gauges for more defined tones.
Nashville tuning (using the high strings from a 12-string set of strings on a 6-string guitar) works very well when doubling guitar parts.

Room

It can be quite hard to find a good sounding room for acoustic instruments.
You will need to audition various rooms and spaces; this is done without mics.
Reflective surfaces (such as a piece of MDF) can be placed on the floor or on a wall to alter the acoustics of the space.

Mic Choice

Many engineers feel that a small-diaphragm condenser is the ideal choice, thanks to accurate HF pickup.
Dynamics are not the best choice due to poor HF response.
Omnidirectional mics sound more transparent, but they are more reliant on the room’s acoustic.
Watch headphone spill, as it will be an issue when using sensitive mics.

Mic Placement

The soundhole is too influenced by the body’s resonances to produce an even tone. It sounds ‘boomy’, with few HF’s.
A good starting point is a cardioid condenser firing at the join of the neck and body from around 40 cm away.
- Move the mic toward the neck for more HF’s.
- Move the mic toward the body for more warmth and depth.
- Move the mic away from the guitar for more room sound.
- Move the mic closer to the guitar for more direct sound.
If you like a close-miked sound, but want more room sound, switch the cardioid for an omni.
Remember to use a pair of closed-back headphones and listen to the mic’s output as you move it.

Or …

Record using a binaural pair on the guitar player.
Fire the mic at a reflective surface instead of at the guitar.
Try miking elsewhere on the guitar, i.e. the underside.
Again, it’s important to listen to the mic as you move it; there are good and interesting tones all around the instrument.

Two Mics

Recording two complementary tones from the same instrument allows you to create a tonal balance; this is like a ‘natural EQ’.
Phase issues start to occur when using multiple mics. Some engineers place all mics the same distance from the soundhole, although this ignores the fact that sound radiates from all parts of the body. The other solution is to record the mics and then phase-align them in your DAW.
Piezo pickups are normally worth avoiding; they pick up the vibration of the strings, albeit influenced by the body.
Pseudo-stereo effects can be created by hard panning neck and body mics.
One standard technique is one mic behind the bridge with the other on the neck.
Try one mic over the player’s shoulder, and one 20 to 30 cm from the middle of the neck.

Mixdown Hints

Compression

Ratio of 2:1 to 4:1
Auto attack and release or attack at 10 ms, release at 300 ms
Threshold set for no more than 6 dB gain reduction

EQ

Bass roll-off: shelving filter @ 80 to 100 Hz
Boom: 100 to 250 Hz
Air: 12 to 16 kHz

Reverb

Using a stereo reverb to process a mono track adds width.
Ambience settings (those with high levels of early reflections) add ‘life’.
Plate or room settings create ‘space’ around the instrument.
Reverb should be used in context to help the guitar sit in the mix.

Gating

A gate or expander can be used to let the attack of the guitar through unaffected, but to ‘duck’ the sustain portion. This makes the attack seem much more prominent, and makes the guitar sound ‘punchy’ in the mix.

Links

Updated 29/09/06

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