Microphone Technique – Acoustic Guitar

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In part 3 of our series on microphone technique we look at the simple acoustic guitar. As discussed previously there is no standard way recording this instrument but we hope to give you some starting points with this instrument. The Acoustic guitar can produce percussive sounds as well as musical notes and how you blend these two factors together will determine how your overall mix of this instrument sounds. So whether your style is gentle finger picking or a full on strum this guide will show you how to get the best out of your acoustic guitar.

The key to capturing the sound of this complex instrument is experimentation. Depending on the style, room and type of guitar various microphone placements will have different results. It’s going to be down to you to find the best results that suit your style. Acoustic guitars can open a wide path for sound manipulation and even slight repositioning of a microphone can yield drastically different results. So with these factors in mind let’s try and make it a little easier with some starting points. Using two of the same microphone can result in some great textures, yet it’s not a stereo track we are after. Start by placing a microphone approximately 7-15 cm away from the guitar pointing directly at the sound hole. Then place your second microphone about 1.2 meters away. This basic setup will capture the direct sound of the guitar as well as the room it is in to create a little more ambience. As stated this is not a stereo track we are after, record each microphone dry to its own mono track and you will have two very different sounding acoustic guitars. By combining these two tracks we have achieved a direct sound source as well as a more open sounding noise. By adding different EQs and effects as appropriate we can create a full sound scape with just two microphones on one sound source.

Once you are comfortable with the idea of this dual technique you can start experimenting with different microphone placements. By moving the closer of the two microphones nearer the sound source you will pick up more percussive elements of the guitar. This can be particularly effective when strumming and you want to capture the sound of the pick hitting the strings as well as the actual sound of the guitar. You can increase the technique above to 3 microphones, one nearly “on” the instrument another at 15cm and the last at 1.5M. This will give you plenty of tracks to work with and over time you will develop an ear for where each instrument and playing style has its sweet spot.

In order to help you develop these techniques we have listed some common microphone placements when using an acoustic guitar and listed the type sound you can expect to get from them.

Microphone Position Acoustic Character Description
20CM from Sound Hole Low end heavy – semi percussive If excess room noise is a problem this is a good placement. Microphones with bass roll off can compensate for extra low end being so close to the instrument
7CM from Sound Hole Very low end heavy – very percussive This will capture the sound of the stings being hit very well. Bass roll off is highly recommended otherwise you can run the risk of sounding muddy.
10CM – 20CM from bridge Mellow mid/low can miss out on some top end sparkle. This is a good position to use in combination with the one above. It will capture the sound of the guitar as opposed to the strings and is good for reducing pick noise
15 CM above the side of the guitar – over the bridge Good all round tone – will be slightly bright Picks up most of the guitar and some of the room. Good for capturing the natural sound of the guitar
1M away pointing at sound hole Ambient and bright Will pick up the sound of the guitar as well as the sound of the room. Good for combining with any of the above but not hugely useful on its own.
Clipped Condenser microphone – Outside of sound hole. Warm and well balanced – will pick up string noise Arguably the purest interpretation of the acoustic guitar sound. Highly recommended for finger picking style. Dynamics may be an issue if used with a heavy strummer
Clipped Condenser microphone – inside of sound hole. Big low end and reduced pick sound Great if you want create a “big sounding” acoustic instrument. May be best combined with another microphone technique in order to capture some top end.
Microphone (miniature or piezo) in-between strings and bridge Very bright This will capture the top end of the instrument and reduce room ambience and feedback.

So what type of microphone should you be using? Given Acoustic guitars relatively low SPL it’s extremely safe to use a condenser microphone. This will pick up the natural sound as well detailing the little nuances that make up an acoustic guitar tone. As described in the chart above its also useful to have a bass roll off on the actual microphone particularly if you close micing the guitar.

The AKG C451B is the gold standard for recording acoustic guitars.
The AKG C451B is the gold standard for recording acoustic guitars.

AKG C451B – This really is the gold standard of acoustic guitar recording. It can pick up all the detail in the guitar sound and is great for recording close up or at a distance.

The AKG C1000SMKIV is an excellent budget alternative to the C451B
The AKG C1000SMKIV is an excellent budget alternative to the C451B

AKG C1000SMKIV – If the C451B is a little outside of your budget then this is a great alternative. It still provides fantastic audio as well as a bass roll off. Great if not quite as detailed as the C451B.

The AKG C414XLII is the latest evolution of AKG's classic studio condensor microphone.
The AKG C414XLII is the latest evolution of AKG's classic studio condensor microphone.

AKG C414XLII – The classic studio recording microphone is just as adapt at capturing acoustic guitar as it is pretty much everything else. The multi pattern can be particularly useful as setting a figure 8 for example can capture the direct sound as well as the room with one microphone. We’ve opted for XLEII version over the XLS version for the slightly brighter top end it provides. Using a larger diaphragm it will also capture more of the low end of your guitar than the C451B or the C1000.

The AKG C314 is based on the AKG C414.
The AKG C314 is based on the AKG C414.

AKG C314 – Based on the legendary C414 this is a great all round microphone that uses multi pattern technology to provide a versatile microphone to suit people on a more modest budget.