The Guitarist’s Introductory Guide to Graphic EQ

If you're used to the standard three-band EQ section found on many of today's guitar amps, a graphic EQ may seem a little intimidating. And for good reason - all those numbers and sliders are more akin to a mixing board than an amp. However, a graphic EQ system isn't all too different than your regular bass/mid/treble controls and can actually help you fill in many of the gaps that these controls alone can't cover.

What is Graphic EQ?

A graphic EQ consists of a set vertical sliders (level controls) from 5 up to 30 in a horizontal row. Each fader corresponds to a frequency band where the indicated frequency is the center or peak frequency of that band. The low frequencies usually start on left going right to higher frequencies. Each slider controls the amount of boost or cut for that frequency band. The center position of the slider is the zero position where that frequency is neither boosted nor cut. These frequencies are labeled in the standard unit of frequency Hz (Hertz) and kHz (Kilo Hertz or 1000Hz) as opposed to the more common bass/mid/treble format. It is important that you take the time to become familiar with each frequency and how it affects your sound.

Let’s take a look at the Carvin Audio X100B as an example.

Here we have the front control panel of Carvin Audio X100B guitar amp, showcasing the graphic EQ control along with the bass, mid, and treble active tone controls. There are five frequency ranges on this graphic EQ that you can cut or boost: 75Hz, 150Hz, 500Hz, 1.5kHz, and 3kHz. Here is a quick, simple breakdown of how each frequency affects your overall guitar tone. (For a bass-friendly rundown, check out this article).

75Hz: you can consider this a bass control. Affects the bottom end of your tone and can make it more boomy when boosted.

150Hz adds fullness and body. Consider it a low mid control. Turn it up for a fatter guitar sound and cut it to thin it out.

500Hz adjusts the “sizzle” of your guitar and serves a big role in shaping the overall presence of your midrange.

1.5kHz affects the attack of the guitar, making it more or less pronounced, much like a high midrange control.

3kHz affects the high-end harmonics and presence. Excessive boosting in this treble range can make the guitar a little harsh sounding.

Why Would You Want to Use a Graphic EQ?

Now that we’ve deconstructed these numbers, you may be wondering why the X100B has two sets of EQ controls that serve the same purpose. While the standard active tone control knobs go a long way in dialing in your ideal tone, engaging the graphic EQ can help in fine-tuning your overall sound after you have the EQ knobs where you like them. If you have your bass knob set in a good spot, for instance, but are playing in a really boomy room, you can cut back on the 75Hz range to reduce some of the bass response. On the X100B, the graphic EQ is assignable to either the lead or rhythm channel, which also helps with dialing in a good dirt tone. In addition, a graphic EQ system is useful in that it provides a clear visual representation of your guitar’s frequency response, which can be helpful in visualizing your tone and making adjustments on the fly.

A graphic EQ is an excellent tool to fine tune your tone complementing the normal three-band EQ system. Getting a good feel for the frequencies you like boosted or cut in your tone will ultimately improve your understanding and ability to quickly adjust your sound. How do you set your graphic EQ?

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