Some of us need to record  vocals and guitar performances to make good mixes. Here are a few things to consider.

The guitarist who sings or the singer who plays the guitar while sings – a very common occurrence. Your laptop, an USB mic or a mic + audio interface, a good pair of headphones (AKG K 271 MK II – worth the money) is all that you need to comfortably record yourself or someone else singing and playing the guitar at the same time.

Performance vs recording separately

You can record the guitar and  vocal separately to have complete mixing control without any overlapping bleeds in the vocal or guitar track. This is especially useful if guitar and vocals is just part of a bigger arrangement. Maybe more tracks and instruments will be recorded separately and added to the vocal guitar performance and mixed for the final result.

Will recording separately affect the feel of the performance? Is it necessary to record the guitar and vocals at the same time, so that the final result has the same kind of feel like in a real performance?

Basic variables

Here are a few things that will effect the recording:

  • the acoustic environment (the room, the position within the room)
  • the type of music
  • the playing method of the guitarist
  • the polar pattern of the instrument
  • the instrument used

The instrument and playing

The sound of the instrument is different at different distance and angle from the instrument. When miking, we need to be aware of this and make the best use of the 'polar pattern' of the instrument (similar to polar pattern of mics) .

Acoustic guitar basic behaviour:

  • base end, nearer to the sound hole: more low-frequency content
  • more towards the neck: more high-frequency harmonics and finger-board noises

The finger noise and harmonics generated can vary with the method of playing.

Some engineers listen to the sound through a headphone, as they move the mic around the instrument. Some experienced engineers suggest that sticking a finger into one ear while listening to the instrument from different angles, helps understand the instrument make a good judgement.

If there is too much boom of the bass frequencies, try the changing the place, especially avoiding the corners and placing mattresses to reduce reflected waves from reaching the mic.

Simplest solution

Try recording using a single mic, positioned appropriately to get the right balance between vocals and guitar.

Recording with a single mic produces a mono sound source. This can then be treated in a sequencer to tasteful room reverbs and output as a stereo track. The result can be very natural sounding. You could even try recording the natural room reverb using separate mics for a natural stereo reverb which can be added to the guitar voice main track – but this will work only if the room sounds good, and is proofed from external sounds.

You can try using mics with different polar patterns. The mic will have to be kept a few feet away from both the sources, in such a way that both the sounds are able to reach the mic sufficiently.

Since it is not close micing, the mic being directional or omni directional may not have a big effect. Usually what most of us will have are directional cardioid mics. Try using them.

Directional mics will have an advantage when the recordings are made in spaces which have external noises. Point the mic to the two sound sources, trying to keep the nulls towards the main external sounds. Later while mixing, we maybe able to do some basic eqing or band compression to further reduce the noises.

Using a condenser mic records the sounds more real. The high frequencies are recorded well by condenser mics, while dynamic mics will sound dull, needy of equalization.

Our aim Guitar sound quality + vocal sound quality + balance between the vocal and guitar in the recorded track

Adjust the left-right alignment to capture the guitar sound appropriately. More towards the sound box, bassier and warmer the guitar.

It is a good idea to point the mic at the vocals, giving it prominence, because most often the guitar is naturally louder and reverberating than the vocals.

More than one mic

Recording the vocal and guitar into separate tracks allows us to treat them separately during mixing.

  • Compression, reverb and any required equalizing for the vocals.
  • Separate equalizing, compression, panning, a different reverb for the guitars.

Two mics can be used on the guitar, placed to the left and right. The two tracks can be panned while mixing, to get a stereo guitar sound.

Spills

The guitar sound spills into the vocal track and vice versa.

Spills are not a big problem if it is mainly the direct signal from the other sound source, and not much of boom and mud from the reflected room sound. If there is too much room sound in the spilled sound, correcting it is not easy without affecting the quality of the main intended sound source in the track.

How to separate

If the performance can be recorded by recording the guitar and the voice separately, one after the other, there is no question of spills. But this maybe decided against, if the feel of the performance, the wholeness and conviction, is evidently present more when both the voice and guitar are recorded at the same time. After all, together is probably how the performer has practiced always, is used to and therefore comfortable.

Acoustic screens are used for physically discouraging sound sources from spilling into microphones meant for other sound sources. It may not be practical in our case, because physically placing an acoustic screen below the singer's head and above the guitar, is not easy or maybe outright uncomfortable for an undisturbed performance.

Mic placement for separation

Close micing Place the mic close enough to the sound source so that the sound from it is recorded at a much higher ratio than any other sound source or sound in the environment. When the ratio of needed signal to spilled signal is high enough, the recording can be used well to make good quality mixes.

Advantages of certain polar patterns Use directional mics. Point the mic at the sound source we intend to record with that mic. Place the mic so that the nulls of the microphone faces the other sound sources, which you don't want to spill into the track of this mic.

The best polar pattern to record with minimum spill


Limited Separation

Suppose we place a cardioid directional mic close to the guitar. This will record the guitar sound well. The voice now reaches the mic at 90 degrees to its axis. In the case of a cardioid polar pattern, the right angles are 3db less sensitive than the axis, but since the vocals is close enough, it will spill into the guitar mic. The same way, the guitar will spill into the vocal mic recording too, if a cardioid pattern mic is used.


Good separation

The figure-of-eight polar pattern mics record from the axis and completely rejects what comes at right angles to the axis. Using a figure of 8 mic for the guitars makes sure that the vocals is rejected well. Similarly, using it for the vocals will reduce the guitar spill. 

Care with figure of 8s

The sounds from the back side of a figure eight mic will also be captured as loud as the front, with the opposite polarity. Make sure that these two factors do not cause trouble in the recordings.

Figure of 8 mics have proximity effect. So better not keep the mic too close to sound hole of the guitar, bassy part of the instrument, since bass is boosted in close miking. Coles 4038 ribbon microphone is a dedicated figure of 8 mic (BBC fame). AKG C 414, the Neumann U87etc are studio condenser mics switchable to a figure of eight polar pattern.

If using figure of 8s for the vocals, make sure to take care of the plosive sounds (p, b, f etc) since this kind of mics are very sensitive to air blows. Also the distance between mouth and mic should be maintained the same throughout – recording with figure of 8 mics change with distance noticeably.

What differentiates a good recording from a great one can most often be things which the conscious mind cannot explain without suggesting about chance, serendipity, 'observed to be so' etc… When you know what you are doing, you don't need an array of expensive high end equipment to get good results. Feel free to experiment. Decide what you like based on what you need, your taste and your idea of art.