EQ For An Acoustic Guitar

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I’m behind the mixer and the pastor starts strumming a familiar sound.  He starts singing and I KNOW I’ve heard the song before.  I can’t place it but I KNOW it’s not a church song.  Then it hits me, he’s re-written the words to “Come on Baby Light my Fire” by The Doors.  That, my friend, was the first time I mixed an acoustic guitar.

Properly EQ’ing an acoustic guitar follows a four-step process similar to mixing any instrument.  Today’s post takes this process in a slightly different direction; I’m focusing the details on getting you a good baseline mix as quick as possible.  I’m all for learning the nuances of proper mixing but let’s face it, some days you just want things to be simple.

The Four QUICK Steps to Acoustic Guitar EQ’ing

1. Trim the excess

Mixing consoles have a channel-level control labeled “HPF.”  This stands for high pass filter.  The HPF will allow only high frequencies to pass through the filter.  In analog mixers, the HPF has a set frequency point, such as 100 Hz or it has a knob for controlling the range.  If you see a label by a button that reads, “/100″ then that’s the HPF label indicating a 100 Hz set point.

Engage the HPF so that all frequencies below the set point are cut out.  These frequencies can muddy the sound of the guitar.  There are other instruments on the stage which are better suited for producing these low-end sounds, such as the bass and kick drum.

In the case of a HPF with a controllable frequency point, start it around 100Hz and increase it as you see fit.  I’ve run them as high as 230Hz because for that instance, for that guitar, a 230Hz HPF was needed to get the sound I wanted.

Before you read further…
There is a significant difference in the control you get with an analog mixer compared to a digital mixer.  Apply these recommendations accordingly.  You know how your mixer works and its limitations.  No use in telling you what you already know.

2. Control the guitar’s bottom-end

Now with the lowest of low’s out of the way (no tax-collector jokes, please), let’s look at the guitar channel’s EQ. You’ve already cleared out the unnecessary low-end frequencies but there is still more work to do down there.

Slowly cut the low frequency knob, for the guitar channel, until you get a better sound.  While the guitar does have a large octave range, it’s just not a bass-heavy instrument and decreasing the bass in the 250 Hz area can help.

If cutting the low’s doesn’t help and you feel the guitar is missing something, you can boost a little of the low end.  Because the 6th and 5th strings are bass-ier than the other strings, you can boost the low end EQ.  If you are running a digital mixer, look to the 150 Hz range for a little boost.  Test this yourself to find the sound you like.

3. Clean it up and make it good

The following breaks frequencies into EQ ranges.  Digital consoles can work within the different frequencies.  However, the basic analog channel EQ’ing with only 3-to-4 knobs will not give the same level of control.  Check out this article for exploring how to improve mixing on an analog mixer (it’s great of digital mixing, too). Therefore, apply these as they fit best to your situation.

  • 150 – 300 Hz range: Use to beef-up the tone of the guitar but as mentioned, it’s easy to get muddy again so only boost frequencies in this area if it CLEARLY improves the sound.
  • 300 – 600 Hz range: Can be boosted if you have a thin sounding guitar.
  • 600 – 800 Hz range: Your meaty mid-range sound.  Cut this to give better tone and better distinguish the guitar from other instruments (more on cross mixing in a moment.)
  • 1,000 – 3,500 Hz range: These frequencies can push the guitar to the front of the mix and affect note definition.  Boost these frequencies when looking at fingerpicking-style guitar and lead (not rhythm) guitar.
  • 3,500 – 12,000 Hz range: It’s all about the sparkle.  This range adds brilliance and can make the guitar jump out.  This range can be further broken down into 3.5-5 kHz, 5-8 kHz, and 8-12 kHz.  Start at the 3.5 to 5 kHz range for adding that sparkle to the acoustic guitar.  If you want more, jump to the next range and boost a little there.

4. Mixing the guitar with other instruments (cross mixing)

The guitar is an instrument that produces a wide range of frequencies.  Its tonal characteristics are dependent on properties such as brand of strings, brand of guitar, and type of wood used in the guitar.  You can create a great acoustic guitar mix for (most) any guitar but you have to remember that when you place that same instrument in a realm with other instruments such as the piano, bass, and violin, equalization is very important for blending and contrasting among the instruments.  Two excellently mixed instruments can sound terrible when merged together.

While cross-mixing is a bit more complicated that what I want to tackle here, there is a big tip that will help you a lot. You are likely mixing against other instruments that can have their foundational frequencies (the frequencies that define the instrument) in one of the above bullet-pointed frequency ranges.  You can either boost or cut one instrument’s range over the other’s range so the two instruments sound distinctly different instead of stepping on each other.  It’s best to cut the key frequencies of one instrument instead of boosting the one you want to stand out.  Less is more.

One last note on EQ’ing acoustic guitars

The information in this post is meant to get you a good acoustic guitar mix in a short period of time.  That being said, getting a great mix takes a bit more work.

If you want to take the quality of your mixes up a few notches, check out my detailed guide, Audio Essentials for Church Sound.  It covers EQ’ing all your standard instruments and vocals.  You’ll learn how to create a great song mix by properly mixing all of your channels together.  The best part?  It’s a step-by-step guide so you know WHAT you need to do, WHY you need to do it, and WHEN you need to do it. Check it out!

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Comments

  1. Thomas says

    Hello, great blog!

    I agree with most of what you describe, but I wouldn’t automatically put the HPF in for an acoustic guitar. The bottom E string played open is 82Hz, on a desk with a 100Hz HPF this will be down considerably more than 3dB at 80. Assuming you have a low shelf fixed EQ at 60Hz, you may be able to fatten up the bottom end again, compensating for the upper edge of the HPF whilst still filtering out the sub content. Experimentation (it takes only seconds) during a sound check is all that’s needed.

    I also think it’s worth mentioning that the fundamental frequencies of a 6 string guitar are between 80Hz and 1KHz (that’s from bottom E, open, to a high b (b6) on the top E string), anything above this is harmonics. So though you may be able to get a guitar sounding audible by boosting outside of this range the ‘musicality’ of the instrument can only be manipulated in the sub-1kHz range.

    I also think it really depends on context and what purpose in the mix the guitar is serving. If it’s playing mainly rhythm parts and is accompanied by a full band with bass guitar, drums, keys etc then it’d be perfectly acceptable and probably beneficial to take out some bottom-end from the guitar and boost in the high-mid area and seat it in the mix volume-wise so that it’s just audible, it’s there primarily to add texture to the sound. If however the line-up is lead acoustic guitar and a single female vocal you’ll want to milk the guitar for everything it’s got, probably boost the bass (without HPF) and boost the very top to ‘sparkle’ it up nicely, may add some reverb to it or maybe even a sub-harmonic processor. But you’d want the vocal to occupy the high-mid space and almost certainly wouldn’t boost in that region (unless it was a very deficient pick-up).

    Sorry that ended up being a bit long!

    cheers :)

    Thomas

  2. Chris says

    Excellent information especially regarding sonic space.  JB said it like this once; make a small band sound big (greater sonic space).  With a larger band, the sonic range per instrument will probably need to be tighter so it doesn’t blend so much with other instruments that it sounds like they just all bled together.

  3. Cajundaddy says

    Yes. We almost always use the HPF cut to prevent a boomy acoustic guitar. My personal preference is to cut problem frequencies rather than boost preferred ones. I often will pull down the 300-2k which tends to clean up rhythm guitar and give it some gentle character. A notch filter is also very useful on acoustic. Every soundboard tonewood has a resonant frequency (mine is Ab) that will tend to resonate or feedback easily. With a notch filter you can pull down a very specific note or group of notes to eliminate this resonance when everyone is playing at volume.

  4. Barry says

    thanks for sharing..
    I have 30 yrs experience as guitarist, performer, worship leader, and sound engineer. I can tell you that a huge percentage of the time you will find that acoustic guitars with transducers as pickups will sound nasty if you boost the hi-mids (3.5k to 6k)…. in fact I find that on almost every acoustic I have used or recorded or done live sound for, adding the ‘sparkle’ in about 10k to 12k range and cutting the hi mids and a very slight boost at about 800 cleans it up and makes it smooth and yet clear. It is almost always true that using HPF is best. Even if the low E string is 3db down, it is very likely that the pre-amp in the guitar has a boost or a built in slope in the preamp that brings the lows up by about 2 db anyway. It is important that the HPF cuts the lows BEFORE the signal passes through the mixer channel, so that it can run cleaner and not risk distortion in th elow end. If you do that and need to add a little lows back in this is better way to get it thicker, and claner for the preanmplification in the mixer…
    I can also suggest a careful use of compressor/limiter on acoustic guitar. Some of the acoustic amps like the Fender Acoustisonic that I use have this built in. It means the guitar can be fairly strong and defined for fingerpicking and softer bits, but protected and controlled in the more dramatic adn aggressive strumming. Set compresser to create 5db of gain reduction at the hardest hits, and a release time of about 250ms. You may find as I have that this also prevents blowing tweeters and horns so often. take carre and God bless — Barry

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