Using two mics on an acoustic
guitar is a common recording technique
that provides a good stereo image, but
may also cause phase issues due to the
two mics interacting. Stereo miking also
doubles the amount of mic preamp noise,
and requires more setup time.
|The three audio tracks are to the left, with the original at the top. The EQ to the immediate right shows the 24dB/octave lowpass filter response, while the EQ to the far right shows the 24dB/octave highpass filter response (unused EQ sections are grayed out for clarity). The Gloss button is a Sonar X1 feature that adds a little extra sheen to the highs.
On the other hand, recording in mono
with a single, high-quality condenser or
ribbon mic eliminates phase problems and
reduces noise, but loses the stereo image.
However, equalization can create a stereo
image from a mono signal, resulting in
a spacious, big sound that is particularly
well suited to solo guitar. Furthermore,
you can dedicate your gear budget to a
single, high-quality mic, rather than two
mics of lesser quality.
To create this virtual-miking perspective,
first copy the original, monaural guitar
track to two additional tracks. One track
will be the “finger noises/high frequencies”
track. Solo it, and set its EQ for a highpass
filter response with a 24dB/octave
slope and frequency around 1kHz. Pan
this track right, because if you’re facing
a guitarist, the finger and neck noises will
be to the listener’s right.
The second copied track is the “guitar
body ” track. Solo it, and set its EQ
response to lowpass, with the slope to
24dB/octave, and frequency at about
400Hz. Pan this track left, as it provides
the guitar body’s “boom.”
While monitoring all three tracks, pan
the original track to center and bring up
its level. The result should be a big, rich
guitar sound with a great stereo image,
but we’re not done quite yet.
The balance of the three tracks is crucial,
as are the EQ frequencies. Experiment
with the EQ settings, and consider trimming
the ranges covered by the high and
low tracks in the original track. For example,
if the body track consists mostly of
frequencies below 400Hz, trim frequencies
below 400Hz from the original track,
as that will increase the separation. Similarly,
you might want to trim the highs
on the original track in the same range as
the finger-noises track. If the image is too
wide, simply pan the two copied tracks
more to center.
You may be taken aback to hear a stereo
guitar with no phase issues. The sound is
stronger, more consistent, and the stereo
image is rock-solid. Give it a try!
With condenser mics, a
gives the best transient
response—yielding a tight,
present sound—while a
large-diaphragm mic gives
a somewhat warmer vibe.
Given only one option for
recording acoustic guitars,
I’d go for the small-diaphragm