How to record acoustic guitar

It’s quite easy to record acoustic guitar. However, there are a number of things you need to take into account, depending on what kind of sound you want to achieve.

It’s important to remember that acoustic guitars produce sound from the entirety of the instrument, not just through the sound-hole. This sound varies from place to place on the acoustic’s body too. You can record a nice, warm sound by putting a mic right in front of the body of the instrument, or a slightly thinner sound from the neck, with more finger sound being picked up. So, again, it’s up to you to experiment, think about the sounds your guitar can make, and what is appropriate for the song you are recording.

You may have an electro-acoustic guitar, and have noticed the handy output jack that you could just plug straight into your computer, via an audio interface. That’s not a good plan! The sound produced by the guitar’s pick-ups will not be very good compared to the sound you can achieve using a microphone. Your output jack is best off being left for live performance.

In terms of microphones, go for a condenser. It will be much better for picking up all the nuances and detail of the sound produced by an acoustic guitar. Large-diaphragm and small-diaphragm mics both have their uses for recording acoustic instruments, including guitars, and can both yield an excellent recorded sound. Let’s have a look at some examples…

One microphone

Using a single microphone in front of the sound hole

This is dead easy. Get a decent, large-diaphragm condenser mic and stick it in front of the sound hole. Don’t put it to close, or you’ll experience what’s known as ‘proximity effect’, and get some fairly nasty low-frequency noises as a result of the mic being to close to the source of the sound.

Here’s what it sounds like:

The mic being used is a Neumann U87, and is actually quite fancy and very expensive - in fact, if you just want to record your acoustic guitar, you probably don’t want to spend the thick end of two grand just on a mic to do it. Don’t worry though, as you should be able to get a similar sound with a cheaper large-diaphragm condenser such as an M-Audio Nova (£62.99). Note that there is no processing (EQ, compression etc) on this recording at all. The sound is quite warm and bassy – probably a result of the mic being right in front of the sound-hole, and the fact that I’m finger-picking rather than playing with a pick.

Two microphones

Here I’ve opted for a couple of small-diaphragm condensers. This should give us a slightly crisper sound, as opposed to the thuddier sound produced by the large diaphragm. I placed one of the mics pointing towards the finder board. This picks up a bit more finger noise and a slightly thinner sound. Here’s what it looks like:

Recording the acoustic with two microphones

And the results:

These are Neumann km184s, which again are fairly pricey. Companies like Rode and SE Electronics have loads of cheaper versions of Neumann’s legendary designs though, so similar results can be achieved on a budget. As you can hear, it’s a bit clearer than the single large-diaphragm mic. There’s still a bit of that boomy quality though. This can easily be fixed by rolling off the bass, as discussed in my posts on EQ. Again, this is the raw recording with no effects added.

Dynamic microphones

Just to show you why you should choose condensers over dynamics, I’ve done the same 2-mic setup but with dynamic microphones. It looks like this:

Attempting to record with two dynamic mics

And sounds like this (without any effects):

These mics are a Sennheiser MD421 on the left, and Shure SM57 on the right. They’re great for guitar amps, snares, toms and the like, but as you can hear, they’re not so hot for acoustic guitars - the sound is pretty dead, and the mics aren’t picking up the full tonal range.

Three microphones

Why not give it a go with three? Here we’ve got the U87 back on the sound hole, a km184 on the neck and another km184 a bit further away pointing at the centre of the guitar, like this:

three mics on acoustic guitar

Without any processing it sounds like this:

It has that nice warm sound from the soundhole as well as the crisper sound from the neck, and a general sound of the entire instrument and the room from the distanced mic. If anything, this technique just gives you more options when it comes to mixing.

Mixing

So you’ve recorded your acoustic guitar. How you mix the resulting raw tracks depends enormously on the context of the song. If it was a cheery pop song with chords blasting away throughout it would probably be a good idea to compress it a fair bit, knock off a lot of the bass and give it a bit more high end so it’s nice and bright and loud. However, if it’s a brooding, serious solo singer-songwriter type of affair, or maybe even classical acoustic, then it would be a good idea to retain as much of the dynamic and frequency range as possible.

Here’s what our last 3-mic recording sounds like with a bit of processing:

This is compressed a little bit, just to knock down any big peaks in the volume without making it an obvious effect. The EQ has rolled off the bass, but not too much. This gets rid of obvious boomy bits whilst retaining the warm sound of the instrument. There is also a slight boost at around 15kHz just to give it a bit more of a sparkle. I’ve also added a fair bit of reverb with quite a long decay time. This sort of processing is nicely suited to songs with only a few parts going on. If there were drums, bass and anything else going then the acoustic guitar you put so much effort into recording might start to get a bit lost!

Price-wise, as you can see from some of the kit I’m discussing here, the sky is the limit. However, if you’re using Garageband (Mac-only; £69.99 as part of the iLife suite) or Cubase Studio 5 (PC or Mac; £299), an M-Audio Nova (£62.99) and an entry level USB audio interface (£50-100) you can create a nice little home recording setup for just a few hundred quid - one which will also be able to record vocals and be easily expandable to deal with MIDI instruments and more mics.

If anyone has any questions on how to record an acoustic guitar, just post them in the comments - I’ll be glad to help.

Graeme Allen is the MD of Amati Studios, a company that works with some of the best mid-sized recording studios in the country.

In addition to his technical skills, Graeme is a first class musician in his own right, playing rock, blues and jazz guitar and classical violin. Visit his website at www.amatistudios.co.uk.

Tagged as: acoustic guitar, home recording, microphones