At some point you’ll probably want to know how to record acoustic guitar. Sadly, unless you have prior recording experience, chances are that the results will be underwhelming. In this post I’ll give you some tips on recording and signal processing that hopefully will get you results you’ll be happy with.
Let’s get the obvious facts out of the way first: you’ll need a good-sounding acoustic guitar, properly tuned, with fresh strings. Furthermore, you’ll have to have practiced the piece, and hopefully have an idea about what you hope to achieve.
How To Record Acoustic Guitar – the video:
Reality vs The Microphone
An acoustic steel-string guitar has a complex sound emission pattern (PDF), the details of which are beyond the scope of this post. Suffice to say that there’s a huge build-up of booming bass and low-mid frequencies right in front of the sound hole; a lot of the midrange radiates from the top itself, and most of the high frequencies come directly from the contact between the strings and fingertips/pick. When you listen to an acoustic played in a room, all of the tonal components blend into what we hear as a well-balanced guitar sound.
The problems start when you set up a microphone, as they don’t “hear” the way we do. You can’t just place it where your head would be if you were listening to a friend playing. Microphones are no more documenting the real world (whatever that means) than a camera is capturing a true image of reality. As a consequence, if you just position a microphone where your head would be, you’ll end up with a dull, flat sound that probably is excessively noisy. It’s also likely that you’ll get far too much of the sound of the room itself – reverberation, reflections, and a less than satisfying frequency response. Microphones, it seems, are inherently flawed devices.
A good starting point is to place a large-diaphragm condenser microphone where the neck meets the body of the guitar. Leave 10-30 cm distance, and maybe point the microphone a hair away from the sound hole area. I’ve experimented with using several microphones in stereo setups, but because of acoustic limitations in the room I’ve been using I’ve given up on this method. Given a nice sounding room with the right amount and quality of reflections, stereo miking would be preferable. Alas, we home studio rats have to make do with less than ideal recording environments (probably why it’s called “home studio”). Consequently, I’m sticking to mono recordings, adding the necessary ambience later.
Once you’ve gotten a good performance on tape (no mean feat in itself) you’ll need to process the raw tracks. This is essential for getting a recorded sound that’s close to how we’re used to hearing acoustic guitars on records or CDs. There are three key components: compression, equalisation, and reverb.
Compression is essential for getting professional results, no matter the source. Drums, bass guitar, keyboards, vocals and guitars (acoustic and electric) are compressed to a varying degree in all the recordings you’ve ever heard.
What a compressor does is basically to reduce the volume difference between the softest and the loudest signals. It does this by turning the volume down for signals louder than a preset threshold, and increasing the volume for signals under the threshold. The net effect is that the guitar will sound more present and to the front of the soundstage. It’ll also sound fatter and more robust. Be careful of overdoing it though, as overly compressed sounds can cause listener fatigue.
Because of the microphone’s weaknesses when it comes to getting a true representation of the sound in the room, you’ll need to do some tonal and timbral corrections. A little goes a long way, and I would argue that if you feel the need to be heavy-handed with equalisation (EQ), there’s probably something wrong with the type of microphone you’ve used, its position, or both. As EQ can cause as many problems as it solves, it’s best to aim for gentle adjustments.
In my recording I had to shave off som low-end, and I gave it a gentle high-end lift to give it some air. EQs are a lot more forgiving when cutting frequency bands, so I try to be extra careful in situations where I need to boost. Also, keep an eye on the meters to check that you’re not overloading any part of the signal chain.
As I explained earlier, I chose to close-mike the acoustic because I didn’t have a nice-sounding room. This doesn’t mean that the guitar doesn’t need ambience, but a more pragmatic approach in a home studio is to add reverb after the fact. I do this to place the guitar in an acoustic environment that’s familiar to the listener. Remember, most people aren’t used to listening to acoustic guitars with one ear placed 20 centimetres from the guitar, and artificial reverb helps me to avoid it sounding like it was recorded the way it was.
As with compression and EQ, it’s important to not overdo it. I always try to keep the reverb level moderate. Too much will push the guitar away from the listener. I’m always focussed on making a little bit of room around the guitar, not hide it away at the far end of a large hall. In addition to setting the level of the reverb, there’s another adjustment I like to do. Most reverb processors have a parameter called predelay, and what this does is that it delays the onset of the reverb “tail”. If you set this at around 40 milliseconds or more, you’ll keep the direct signal somewhat distinct from the reverberation, and this will help you avoid the “disappearing guitar” effect when you turn up the reverb level.
Too much is, well, just too much when it comes to processing, so try to avoid doing huge adjustments in the mix – a sure sign of bigger problems with the basic tracks. And don’t neglect the preparation stage: you’ll need to be well-rehearsed as it’s difficult to make edits – at least with solo guitar pieces. If you try to combine two takes, you’ll often find that the tonalities are different because of changes in the position of the mic.
Hopefully you’ll now have a clearer idea about how to get a good recording of your steel-string acoustic. Have fun playing and recording – and thanks for reading.