Acoustic Guitar EQ: Nylon vs Steel String Recording Tips
Guitarists today have to be versatile. Most players end up owning more than one instrument: a classical or flamenco guitar, a folk steel-string, maybe a jazz box. Each one has its own voice, and each one needs a different approach when you record it.
Ramzi El Rumbero records all of them through a single FlashTrack USB microphone. Below are the EQ settings he reaches for on nylon and on steel strings, plus a few less obvious ways to use the microphone’s line input.
In this article
The EQ bands you are working with
The microphone’s onboard EQ gives you six bands, each adjustable from -6 dB to +6 dB. Knowing what sits in each band is most of the work.
- Low-shelf, 100 Hz
- Bass, 250 to 500 Hz (centred at 375 Hz)
- Low-mid, 600 to 900 Hz (centred at 750 Hz)
- High-mid, 1 kHz to 2.5 kHz (centred at 1750 Hz)
- Treble, 3 kHz to 5 kHz (centred at 4 kHz)
- High-shelf, 8 kHz
One thing worth noticing before you start: almost everything below is a cut, not a boost. Taking problem frequencies out leaves more headroom than pushing the good ones up, and the result sounds the same. For more on where an acoustic guitar’s energy actually sits, and how much of this is really a mic placement question, see why acoustic guitar is so hard to mic.
EQ for nylon strings
Nylon-string guitars are almost entirely a subtractive job. Ramzi’s starting point is a cut on nearly every band.
Clearing the low end
A low-shelf cut of -6 dB takes out the rumble. This matters most when a reverb plugin is in the chain, since reverb will amplify whatever low-frequency mush is already there.
A bass cut of -6 dB follows, aimed at room resonances and the boominess that builds up when you record in a small space.
Removing boxiness and harshness
The low-mid band is where the worst artifacts live. Honkiness and boxiness both sit here, and a -6 dB cut clears most of it.
A high-mid cut of -6 dB handles whistling frequencies and general harshness.
Taming finger noise
Finally, a high-shelf cut of -3 dB reduces finger squeak. Note that this one is gentler than the rest. Cut too much here and the guitar loses its air along with the squeaks.
EQ for steel strings
Steel strings start the same way but end differently. The low end still gets cleaned up, but the top gets pushed rather than pulled.
Cutting the low end and the pick attack
A low-shelf cut of -6 dB removes unwanted low frequencies, whether they come from the room or from the instrument itself.
A bass cut of -6 dB deals with something specific to steel strings: the percussive thump of the right hand hitting the strings. This becomes far more noticeable with a pick.
Opening up both ends
A low-mid cut of -6 dB scoops the middle, which has the effect of highlighting both the low end and the high end of the guitar.
A high-shelf boost of +6 dB is the one place where Ramzi adds rather than removes. It brings out clarity and helps the guitar cut through when other instruments are present. If you are recording the guitar on its own, you will probably want less than that.
Guitars with an offset sound hole
Modern guitars with an offset sound hole need a different approach, and the reason is structural rather than electronic.
Sound hole placement works as a kind of built-in EQ. Moving the hole off centre leaves the soundboard longest on the bass side and shortest on the treble side. It also leaves the middle section of the soundboard uninterrupted, which gives a stronger midrange response.
The standard mic position for acoustic guitar is roughly at the junction where the neck meets the body. That spot usually balances the body resonance against the liveliness of the strings. On an offset sound hole guitar, the same position can capture an over-prominent air resonance, heard as a boom.
Two fixes work. Angle the microphone off-axis, or move it toward the bridge. Both reduce how much of that resonance reaches the capsule. Off-axis positioning also changes the frequency response of the microphone itself, which is worth understanding before you start moving things around, see microphone polar patterns and proximity effect.
Once the microphone is in the right spot, use the EQ settings above as a starting point and your ears as the guide.
Recording the pickup alongside the mic
The FlashTrack has a line input on the back, which lets a guitar with electronics plug straight into the microphone as a second sound source. A passive system with a healthy output works, and an active system with a volume control works better.
Having two sources in one device opens up three situations that are otherwise awkward to solve.
Separating vocals from guitar
Singer-songwriters recording with a single device usually have to accept whatever balance the room gives them. Plugging the guitar in changes that.
Position the microphone to favour the voice and use its cardioid pattern to reject the guitar. The instrument then comes mostly through the electronics, and you can set the two levels independently. For the version of this problem where you only have a microphone, see recording guitar and vocals with just one mic.
Recording in a noisy room
When the environment is noisy, turn the capsule level all the way down and take the guitar entirely through the line input. Nothing in the room reaches the recording.
Thickening a single guitar
The third use is blending. With the capsule and the electronics both feeding the same recording, the guitar gets more body and sits more solidly in a mix.
Balance is set with the capsule volume dial on one side and the guitar’s own preamp volume on the other. You can bring in a touch of piezo, run a 50-50 blend, or anything between. This is the same trade-off pickups and microphones always present, covered in more detail in the pickup and microphone guide.
The cable you need
A guitar has a mono output jack and the line input on the microphone is stereo. The cable below duplicates the mono signal across the left and right channels of the FlashTrack’s audio interface.
Common questions
Should I cut or boost when EQing an acoustic guitar?
Cut first. Almost every setting described above is a cut, and there is a practical reason for that. Boosting a band raises the signal level and eats into your headroom. That can push the recording into clipping further down the chain. Cutting the frequencies around the ones you want has the same perceived effect and costs you nothing. The one exception here is the high-shelf boost on steel strings, used to help the guitar cut through a mix.
Why do nylon and steel strings need different EQ?
They produce different problems. Nylon strings generate finger squeak and a muddy low-mid buildup, so nearly every band gets cut, including the top. Steel strings generate a percussive attack from the right hand, especially with a pick, and they benefit from added high-end clarity rather than reduced. The low-end treatment is similar on both; the top end is where they diverge.
Where should I place a microphone for acoustic guitar?
The usual starting point is where the neck joins the body, which balances body resonance against string detail. Pointing the microphone directly at the sound hole gives too much low-frequency boom. On guitars with an offset sound hole, even the standard position can pick up an over-prominent air resonance, in which case angling off-axis or moving toward the bridge works better. Move the microphone before you reach for EQ.
About Ramzi El Rumbero
Born in Beirut, Ramzi started guitar at 16 and continued his studies until graduating from the American University of Beirut. He came from a classical background and took on flamenco and Arabic pop along the way.
After years of concerts and recitals around Lebanon, he moved to the United States, where he plays and teaches in New York City. He was the first person in the world to create a flamenco guitar course in Arabic with online video lessons, and the first in the Middle East and North Africa region to cover Arabic pop songs with guitar tutorials.
EQ is one stage out of several. For everything on either side of it, from mic choice through to recording a cover, see Phone Recording for Musicians: The Complete Guide.
