The Complete Guide To Graphic Equalization/EQ

Graphic EQ is one of the common equalization types in audio technology and deserves a full article dedicated to its explanation.

In this article, we'll discuss graphic EQ in great detail, focusing on how it works to apply equalization and the situations/applications it is best suited to serve.

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A Primer On EQ

Before we get to dynamic EQ in more detail (skip ahead by clicking here), let’s quickly go over the definition of EQ.

As an audio process, equalization alters the relative balance/amplitude between frequencies in an audio signal. EQ uses filters to either increase or decrease the amplitude of some frequency bands compared to other frequency bands. It is used extensively in mixing, tone shaping, crossovers, feedback control and more.

Boosting and cutting refer to the increasing and decreasing of the relative amplitude of defined frequency bands, respectively.

Electronic filters are often described as processes that eliminate frequency content below, above or between two set frequency points. In the context of EQ, a filter (such as a “bell” or “peak” filter) can also be used to produce the previously mentioned boosting/cutting without affecting all frequencies beyond a certain point.

The range in which an EQ filter will act up is typically referred to as a band. Graphic EQs, as we'll find out, have fixed bands (and often plenty of them)!

Whether graphic or otherwise, EQ is one of the most important tools for working with audio.

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What Is Graphic Equalization?

Now that we know what EQ is, let's talk more specifically about graphic EQ.

As the name would suggest, graphic EQ gives users a pretty descriptive visual representation of how it affects the audio.

Graphic EQ does so with a set number of fixed frequency bands across the audible frequency spectrum. The number of bands, of course, depends on the EQ in question.

Each band has a defined centre frequency and Q value with controllable gain via a fader. The graphic EQ, as a whole, is made up of a bank of faders.

These bell/peak-type filters can be boosted or cut. Generally speaking, the bandwidth of each band is set so that there is minimal interference and phase complications with adjacent bands, though there will always be some amount of interaction.

Increasing the number of bands in a graphic EQ will mean narrowing each band's bandwidth and offering greater control and resolution over the equalization of the signal.

Typically the 0 dB gain spot will be midway between the fader's maximum and minimum positions. Pushing the fader upward will increase the band's gain (relative amplitude), while pushing the fader downward will decrease the gain (relative amplitude) of the band.

This is a lot easier to describe visually, so let's have a look at a screenshot of the Waves GEQ Graphic Equalizer: a graphic EQ plugin.

The following image shows a single channel of graphic EQ with 30 bands and gain variation between ±6 dB:

The way this graphic EQ is laid out has 3 bands per octave. An octave is defined as a doubling in frequency (since frequency values are logarithmic).

Each band's gain control fader has 0 dB (no gain) as the midway point of the fader. By adjusting the faders and affecting the relative gain, we can easily see how the graphic EQ is affecting the signal's equalization across the bank of faders. Hence the name “graphic EQ”.

As an example, let's consider the Waves GEQ once again. As we can see, graphically, in the picture below, I've left most frequency bands alone but set up a fairly abrupt 6 dB low shelf cut below 50 Hz and a more gentle 3 dB high shelf boost above 4 kHz:

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How Are Graphic Equalizers Used?

In audio mixing, graphic EQs are often passed over for the more flexible parametric varieties. However, that's not to say that graphic EQs are necessarily inferior. They can be used to achieve very similar results.

That being said, there are some instances where graphic EQs are commonplace:

Eliminating Problem Frequencies With Graphic EQ

Noise, resonances and other nasty frequencies can be found and removed by first boosting bands to find the problem frequency and subsequently cutting those bands.

Personally, I prefer using a sweepable band in a parametric EQ for this job, though graphic EQ works fine, too!

Feedback Elimination With Graphic EQ

Similar to problem frequencies. Can be used effectively in live sound situations to “tune the room”. This is common in live sound situations.

Tone Shaping With Graphic EQ

As with all EQ, graphic EQ can be used to Shape the tone/character of an audio signal/track by sculpting its frequency content in a specific way.

Tuning Monitors/Speakers With Graphic EQ

Monitors and speakers are imperfect electro-acoustic transducers that may benefit from a graphic EQ. Some stereo system amps/receivers have built-in graphic EQ (though shelving EQ is more popular in these devices)

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Examples Of Graphic Equalizers

Before we wrap things up, it’s always a great idea to consider some examples. Let’s look at 5 different graphic equalizers to help solidify our understanding of this EQ type.

In this section, we’ll discuss:

• 500 series graphic EQ unit: BAE G10
• 19″ rack mount graphic EQ unit: dbx 231s
• Graphic EQ effect pedal: MXR M108S Ten Band EQ
• Graphic EQ Eurorack module: Music Thing Modular Graphic EQ
• Graphic EQ plugin: Waves GEQ

BAE Audio G10

The BAE G10 is a 10-band graphic EQ designed in the 500 series form factor.

This simple graphic EQ has centre frequencies at 31, 62, 125, 250, 500, 1k, 2k, 4k, 8k and 16k Hertz that can each be a boost or cut of ±12 dB. In addition to the 10 bands described, the G10 also has selectable high-pass and low-pass filters, tuned at 80 Hz (10 dB/octave) and 12 kHz (6 dB/octave), respectively.

dbx 231S

The dbx 231s is a rack-mounted stereo graphic equalizer with 31 bands (3 per octave) per channel.

Both stereo channels include an input gain control with ±12 dB of gain along with a selectable low-cut (high-pass) filter at 50 Hz 12 dB/octave and a switch to increase the boost/cut range between ±6 and ±12 dB.

MXR M108S

The MXR M108S Ten Band EQ is an excellent 10-band graphic EQ effect pedal.

In addition to the 10 bands (each with its own ±12 dB cut/boost fader), the M108S EQ pedal has a volume control (±12 dB) and a boost/gain (±12 dB).

Music Thing Modular Graphic EQ

The Music Thing Modular Graphic EQ is a Eurorack graphic EQ with 7 bands.

This simple graphic EQ unit is based on the revered Boss GE-7 pedal and has centre frequencies at 63, 160, 410, 1k, 2.5k, 7.7k and 16k Hertz. Each band is adjustable by ±15 dB.

Waves GEQ

The Waves GEQ Graphic Equalizer is a stereo 30-band graphic EQ plugin.

This EQ plugin offers three graphic bands per octave for a total of 30 bands per channel. Each band can be boost/cut by up to ±18 dB (with ±6, ±12 and ±18 settings).

The left and right channels each have an independent high-pass and low-pass filter along with a single parametric bell-curve filter and gain control.

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Related Questions

What are the different types of EQ? When it comes to audio equalization, there are several types of EQ to be aware of. They are as follows:

• Graphic EQ
• Parametric EQ
• Semi-Parametric EQ
• Dynamic EQ
• Linear Phase EQ
• Passive EQ
• Shelving EQ
• Stereo EQ
• Mid-Side EQ

Should every track be EQed in an audio mix? As a general rule, equalization should be used with intent and, therefore, only be used on every track in the case that every track would require it. More often than not, there will be certain tracks in a mix that sound perfectly fine without EQ.

Though not always necessary, EQ can be used to achieve the following (and more):

• Correct The Response Of A Microphone
• Adjust Perceived Depth
• Cut Problem Frequencies
• Filter Out Low-End Rumble
• Accentuate Characteristic Frequencies
• De-Essing (Dynamic EQ)