Your acoustic guitar sounds boomy when recording? This is a common problem and thankfully one that’s easily fixed. In the article below we’ll cover the different reasons for a boomy acoustic guitar recording and show you how to prevent it in the future.
If your acoustic guitar sounds too ‘boomy’ when recorded try moving the microphone further away from the guitar (at least 8 – 12 inches) to reduce the ‘proximity effect’ and make sure the microphone is not pointing directly at the sound hole. In most cases, aiming at the 12th fret of the guitar will produce the best results. You should also get as far away from your walls as possible, consider acoustic treatment if the room naturally sounds boomy, and record with a cardioid microphone, as these are less prone to the proximity effect
Hopefully, the information above makes a huge difference to your recordings, but there’s actually a lot more you can do to understand and ultimately prevent boominess from creeping into your recordings. Below we’ll discuss in more detail and provide some additional options you can try to improve the sound of your recordings even further.
What causes a boomy sounding acoustic guitar recording
The acoustic guitar is an instrument that, although seemingly simple enough to record, can be quite difficult to take from sounding just OK to that rich, clear, and warm acoustic sound we all know and love. Consider the sound of the acoustic guitar on just about anything by Tommy Emmanuel and you’ll know what I mean.
What is Boominess?
You might not find the word in the Oxford dictionary (trust me, I’ve checked) but boominess is a real concern when recording. It’s essentially an abundance of low-end frequencies (around the 100 – 250hz range) that sustain for longer and drown out other frequencies. If you’ve ever watched an action movie (with plenty of explosions) in a small, reflective room you may have noticed the ‘boom’ of the bass frequencies, this is a good example of ‘boominess’.
|Boominess||100 – (150 – 250) Hz|
|Muddiness||200 – 300 Hz|
It differs from ‘muddy’, although the two are often used interchangeably. Muddy is the term used to describe a lack of clarity in general, as the source of the sound is slightly dampened.
Boominess, unlike muddiness, is often uneven e.g. it accentuates some frequencies causing spikes, whereas a muddy-sounding mix, for the most part, affects the entire track.
Boominess can also sometimes be useful e.g. if recording instruments such as acoustic drums or bass a boomy sound may not necessarily be such a bad thing, if controlled, in fact, it might be just the ticket to add fullness to your recordings.
So now we have identified the problem, what can be done to address it?
Before doing anything else try experimenting with your mic position, taking into account proximity to the guitar, positioning of the microphone with regard to where it is pointing on the guitar, and lastly the angle the microphone is placed upon.
Avoid the soundhole
For one, if you are aiming the mic at the sound hole this is almost always going to be where the problem lies. Sound ‘whooshes’ out of the soundhole due to the internal resonance contained within the body that is ultimately released via the soundhole.
Positioning the microphone further up the neck (aiming at the 12th fret is a great starting point) will reduce boominess 99% of the time.
Secondly, your mic may be too close.
If anything less than 8 inches from the guitar this is also a likely culprit. Try moving the mic to at least 8 – 12 inches out from the guitar and then try a test recording to see if this helps.
Lastly rotate the mic (off-axis) so it is on an angle approx. 45 degrees. Changing the angle of the mic in this way can alter the frequency response and have a noticeable effect on the overall clarity of your recordings.
If recording acoustic guitar the best microphone to start with is a cardioid condenser microphone. There are really no hard and fast rules when it comes to microphone selection, but a condenser microphone offers greater sensitivity than a dynamic microphone making it the ideal choice for recording acoustic guitar.
The term ‘cardioid’ refers to the polar pattern of the microphone e.g. the sensitivity of the microphone with regard to where the sound is being detected from.
Cardioid microphones detect sound from the front of the microphone and largely ignore the sound from the rear of the mic. As a result, they are less prone to the proximity effect than other polar patterns, with the exception of omnidirectional microphones which aren’t prone to the proximity effect at all.
What is The Proximity Effect?
We’ve talked about the proximity effect but what is that really? It’s a phenomenon caused when the source of sound being recorded e.g. the acoustic guitar, in this case, is too close to the microphone. When this occurs low-end frequency response is increased and will continue to increase the closer the instrument is to the microphone. It’s a pretty big factor if recording low-end frequencies e.g. around or below 200mHz and can affect acoustic guitar (your low E string is around 80Hz) and male vocals especially.
How your room can make your recordings sound boomy
Another fairly big factor that can contribute to a boomy-sounding recording is the sound of the room itself.
Most people who record at home don’t give this enough consideration. But the acoustic guitar is an ‘acoustic’ instrument and the natural acoustics of the room have a big impact on the quality of the sound recorded. This affects all instruments to some extent unless using direct input but is especially an issue for acoustic guitars.
If you have the option, try a number of different rooms in your house using your ears to guide you. Look for rooms that are not perfectly square and offer enough distance from the walls if you were playing in the center of the room to prevent reflections.
Avoid low ceilings also and don’t worry if the room already contains things like bookshelves or wardrobes. These can actually be used to your advantage to absorb soundwaves that would otherwise be reflected from the walls and be captured at full strength by your microphone.
Remember when recording, try getting away from your walls as much as possible to reduce the amount of reflected sound being captured by the microphone.
You can also experiment with acoustic treatment, including using sound panels and bass traps in the corners of your room to further reduce reflected sound and cut down on excessive low-end frequencies. You can read everything you need to know about acoustic treatment here in my in-depth guide.
Mixing and EQ Settings to reduce boominess
What if you have tried everything suggested above and still find your acoustic guitar recordings sound boomy?
The last thing to try is removing some of the offending frequencies using EQ.
If you have recorded several tracks of acoustic guitar, combine them by bussing the tracks together – e.g. combine the tracks and control eq as a group, and then use a high pass filter to cut down on unwanted low-end frequencies.
Move the filter up until it becomes noticeably poorer sounding and then step things back a notch.
You should also identify additional frequencies by sweeping around in your EQ plugin. They will most commonly be in the 100 – 250hz range, but don’t limit yourself to this frequency range alone.
Sweeping essentially means hunting out rogue frequencies by accentuating their effect within your mix and then reducing them to improve the overall sound.
‘Boominess’ on acoustic guitar recordings can, thankfully, under most circumstances be easily addressed using the tips above. Remember, before you make wholesale changes e.g. buy a new microphone, move your entire home studio to another room, or even buy a new guitar (although, that’s never a bad thing 🙂 try simply pointing the microphone at the 12th fret of your guitar, on a 45% angle at least 8-12 inches away from the body of the guitar. In 99% of cases, this will reduce the boominess being picked up on your recordings considerably and greatly improve the clarity of your track.