Knowing how to EQ an acoustic guitar comes from having a good understanding of equalization and frequency response for your instrument. To make your acoustic guitar sound better, cut the low-end at 80 Hz and low-mid muddiness around 100-250 Hz. You might as well consider cutting frequencies around 1-2 kHz to make your guitar sound natural. Boosting frequencies around 80-100 Hz will emphasize the low-end and high-shelf boost around 10 kHz will give you some additional clarity. More often than not, you should avoid any overlapping frequencies within your mix and always choose to boost the frequencies that will emphasize the character of your instrument and, at the same time, make it sit better in the mix.
Now low take it a little deeper.
EQing acoustic guitar
We should start with a rather disappointing thought, there is not an easy and applicable to every situation acoustic guitar EQing technique. Different mixing situations and creative visions require different acoustic guitar EQing, which almost always are not interchangeable. So instead of covering every possible mixing situation and figuring out which EQing technique to use in that particular situation, we will try to give you a few basic tips on the nature of acoustic guitar sound in general. This will give you an opportunity to implement equalization freely and creatively without any regard for the mixing situation that you are in at the moment. But there are things you might consider doing even before you apply the equalization.
Things to do before EQing
You might be very surprised to hear that there is not much to do in terms of EQing if the recording was done in the right way. In other words, there are quite a few mistakes that should be avoided, some of which could not necessarily be fixed with an equalizer.
Firstly, the actual guitar you are recording does matter. It is understandable that most of us work on a rather tight budget and therefore cannot afford a vast collection of acoustic guitars. If you indeed have a collection of acoustic guitars, consider yourself lucky.
But most of us have a couple of those at best. So you’d probably need to be sure that your guitars sound different. It would be rather unwise to have two different tools that serve the same purpose. And it is even more unwise to expect an entry-level instrument to sound like vintage Martin. That being said, it doesn’t mean those cheap acoustic guitars couldn’t sound great. In fact, modern entry-level instruments very rarely feel like a cheap knock-off and have a very decent and usable sound.
The type of guitar matters too. If you record a flamenco part, you can’t possibly expect it to sound great on a guitar with steel strings. No matter how intense the EQing would be afterward. Of course, it all depends on your personal artistic choices. But generally speaking, it is very hard to avoid cliches in a creative way.
That means that certain styles require a very particular guitar sound. And without that sound, your composition wouldn’t be very convincing. After all, your life would be much easier if you have the right tools for the right purpose.
Secondly, and even more importantly, your guitar should be properly maintained. Always change your strings before the recording because old strings tend to sound rather dull and uninspiring. If your budget does not cover frequent string changes, you can always boil them. It’s a very old trick that could be extremely useful in certain situations. If your guitar is exposed to humidity and temperature changes before you start recording, make sure that your neck is straight.
Proper mic placement
In terms of recording acoustic guitar, it is hard to imagine something more important than the right microphone placement. The type of microphone, of course, matters too, but we won’t cover this topic in this article. Chances are that if you are working on the budget, you don’t have the luxury of choosing a lot of different mics. And even if you do, for the sake of the conversation, let’s pretend that you only have one.
The most obvious place to put your mic is right in front of the soundboard of an acoustic guitar, but most of the time, you will end up with a rather muddy sound with an excessive amount of mid-range frequencies. Instead, you may consider placing a mic in front of the soundboard but turn it towards the end of the neck. Some recording engineers prefer to place the mic in front of the twelfth fret. In both situations, you will get the full sound spectrum of the guitar with balanced mids.
Another interesting technique is to place your microphone directly behind the bridge. You might consider the resulting sound to be rather thin, but it works if your arrangement is already too dense. This mic placement also works in the stereo configuration in case you have a second microphone and place it in front of the twelfth fret. And the distance your mic should be placed is something you should investigate yourself.
As a general rule, place your mics closer if you want detailed sound with a lot of nuances. If you prefer softer transients, place your mics farther.
Assuming that you already know your way around EQ, we won’t cover the different types but instead will try to summarize some areas of concern in acoustic guitar sound. When it comes to low-end, there is hardly any useful information below 80 Hz. So you should cut those frequencies in order to eliminate low rumble in a dense mix or clean up a solo acoustic recording.
In a range between 80-100 Hz, you can find frequencies that could add some weight to the sound of your guitar. But use them with caution. If you consider boosting those frequencies, they may overlap with drums or bass. Then again, in the case of a solo guitar recording, there is no reason not to boost those frequencies.
Muddiness and boominess of acoustic guitar sound could be found somewhere between 100-250 Hz. Typically, you might consider making a wide cut within that range. How deep the cut should be, depends on your recording, but as a rule, you don’t really want to cut too much because this will make the sound of your guitar too thin and lifeless.
You can add some additional low-mid weight by boosting frequencies between 200-350 Hz. Consider how it will affect the rest of the mix since it’s the area most of the instruments overlap in terms of frequency response. So if you decide to boost those frequencies in the acoustic guitar, it should be complemented by a cut in other instruments.
A cut somewhere between 400-800 Hz could fix a problem with old strings. But if your strings are new, you can easily leave this area untouched. Normally, any cut in low-mids will bring up the high-end upfront, so try to avoid too much cutting since it will make the sound of your guitar rather unbalanced and unpleasant. It very much depends on the situation, but most of the time, you will find that boost and cuts of 3-4 dB are a sweet spot in terms of EQing acoustic guitar. That being said, you should definitely rely more on your taste and hearing.
By boosting frequencies around 3-8 kHz, you might gain some additional presence but within that range lay most of the attack and various pick noises and scratches. So too high of a boost might bring up some rather unwanted nuances in the sound. If you feel that your guitar sounds somewhat robotic and unnatural, you might cut some frequencies around 1-2 kHz. But be careful because too much of a cut will bring up additional boominess. It is always rather important to make room for vocals, so a gentle cut somewhere between 1-5 kHz should do the trick.
Finally, to add clarity, you might consider making a high-shelf boost somewhere around 10 kHz. But consider that those frequencies might overlap with the same frequencies in drum overheads. It is relatively uncommon to cut high frequencies on acoustic guitar, but depending on your mic frequency response, you may consider making a low-pass somewhere around 16 kHz. This might make your acoustic guitar sound more contained.