Introduction

Have you ever found yourself listening to a car or home stereo and didn't like what you were hearing and immediately reached for the Treble (high frequency) and Bass (low frequency) knobs to adjust the sound? If so...then you just stepped into the world of equalization. 

Now it's not my intent to try and cover every aspect of equalization in this article, because there could never be enough written. I'm also not going to focus on too much technical theory, because we're guitarists right - just give us the basics. So I'm going to try and write this article to be as simple to understand as possible.

What Is Sound Anyway?

In order to better understand the principles of equalization for tone manipulation, one needs to first understand the underlying nature of the audio spectrum. To put this all simply, sounds are made up of different frequencies. Different instruments sound the way they do because of the complex manner in which the frequencies they produce all add up. There are frequencies we can hear and those which we cannot hear. Why? Because the human ear is designed to only hear sounds that occur within a given frequency range.

So what frequency range can the human ear hear? A good, young, healthy, and undamaged ear can hear frequencies in the range of approximately 20Hz - 20kHz. Frequencies are often expressed in Hz (hertz) or kHz (kilohertz). For those who need to understand the math, 5000Hz = 5kHz, or 1.2kHz = 1200Hz, etc.

Take Note:

Things start to get a little more interesting when we start to look at how frequencies play their part in the guitar world. It helps to know that the lowest E-string on a standard 6-string guitar is tuned to 82.41Hz. It also helps to know that guitar amp speakers are not capable of producing too many frequencies above 4kHz. Guitar speakers are designed with a limited frequency response and cannot playback a full-range of frequencies such as recording monitors or a P.A. system. I know this is over-simplifying things, but Vettanarians should initially start off concerning themselves with the frequency range between 80Hz - 4kHz (and perhaps a little further on either side of this range if needed), when equalizing patches on their Vetta. 

Guitar String Frequencies 

Cutting Instead of Boosting

One of the biggest patterns of EQ behavior that people often make is that they tend to approach it by boosting the gain of frequencies rather than lowering them. It's not that there's anything actually wrong with boosting, but you can often achieve your tonal goal by negative equalization - by rolling off or reducing an area of frequencies rather than by boosting them.

Sometimes the tone (timbre) you are wanting to hear already exists within what you are hearing. The best analogy for this is to consider a stone sculpture. Think about how an artist can take a large piece of stone and then begin carving away the areas of the rock that are not needed to create the image they desire from within. This same approach can apply to creating guitar tones as well.

For example, if you find yourself boosting both the highs and lows, you can sometimes achieve the same (or better) results by scooping out the mids instead. Keep in mind that any time you can reduce, rather than boost frequencies, you are automatically helping to reduce noise as a beneficial side-effect. Second, if you can achieve the same results with one band of cut than two bands of boost, you have saved yourself an extra band for later use, and you are helping the original signal to sound more clear and clean.

Take Note:

When adjusting an EQ's gain up/down, reductions will generally be larger than boosts. Why? Because of the way in which our ears hear a change in sound. Please keep in mind that boosting a band of frequencies will tend to increase the overall signal level significantly, and if overdone, this can result in unfavorable effects upon your tone. On the opposite side of this, cutting a band of frequencies doesn't change the overall signal level much at all.

Graphic Equalizers

Graphic equalizers are certainly a great tonal tool for shaping sound spectrum, but they are not necessarily the best tool that could be used. As you can see from the image below, the center frequencies are set: 100Hz, 200Hz, 400Hz, 800Hz, 1.6kHz, 3.2kHz, and 6.4kHz. Please realize that with a graphic equalizer, you are not boosting/cutting just these specific frequencies alone, there are other frequencies on either side of these set frequencies which will be affected as well when you move the slider. In other words, these sliders have a fixed center frequency (which you see) and a fixed bandwidth (of which you don't really know - unless the manual tells you). 

Even the Vetta's Graphic EQ center frequencies are set: 

LOW = 80Hz

LOW MID = 200HZ

HIGH MID = 800HZ

HIGH = 3kHz

Take Note:

Graphic EQs limit your choices to specific center frequencies and pre-determined bandwidths to boost or cut. But because of the fixed nature of these guitar graphic-eq stomp boxes, they can teach you a thing or two about which frequency areas you should be paying attention to. When you look at most every eq stomp box like this, the frequencies are typically the exact same (or very close) for a specific reason. Why? Because many years of experience has taught design engineers that these are the frequency areas that are most often needing to be adjusted by guitarists.

Parametric Equalizers

When you want to get down to some serious frequency tweaking, the Vetta's 4 Band EQ is the tone tool of choice. Why? Because in addition to the Low & High Shelving EQs, there are two bands of fully parametric EQ. A parametric EQ is very powerful because it gives you complete control over the center frequency, the width = Q, and the amount of cut/boost. With a parametric EQ there are no longer limitations. You are no longer limited to the pre-determined center frequencies used in a Graphic EQ. So you can move them up and down the frequency range to dial into the specific frequencies (or area) that you want to. 

Still confused - don't worry, parametric equalizers always seem to confuse and intimidate users, but they're really not that difficult to use or understand. Probably the most confusing aspect of a parametric EQ is the "Q" parameter, which just happens to be the real power parameter behind this type of EQ.

What is "Q"

The "Q" parameter is what sets the width of the band of frequencies that will be boosted or reduced. In other words, it determines the amount of frequencies on either side of the center frequency. The basic idea behind the "Q" parameter is this: why boost/cut frequencies that don't need to be. By being able to control the actual width of the band being boosted or cut, you have more flexibility to shape the EQ to fit your needs.

Understanding Q Bandwidth

The "Q" parameter is what sets the actual width of the band of frequencies you can work upon, anywhere from a very broad bandwidth, to a very narrow bandwidth. You can see this for yourself from the images below. 

Finding The Sweet/Sour Spots

One of the biggest frustrations with applying EQ is that we don't often know where to begin. Where exactly are the sweet spots that bring out the life in the tone? Where are those annoying sour spots that make us cringe? Should I boost or should I cut? Good questions - but very difficult to answer. Learning to use EQ can be an art all unto itself, and a very subjective one at that. But there is a fundamental method to help you get into the ballpark.

Effective EQ involves finding those areas of the tone that may need to be increased or decreased in strength. When you think a tone sounds too muddy or too bright, those are typically areas of the tone which contain more energy than surrounding areas.

Suggested Q Setting

In general, start with a "Q" setting of 0.7 - 1.0

The simplest method to find sweet/sour spots is to turn up the gain (about +10dB on the section of the equalizer you are using) then slowly sweep the frequency control up and down. Try not to focus on the overall sound itself, learn to listen for how the equalizer is affecting just the frequency area you are sweeping across. Remember, you are trying to dial into an area of frequencies (similar to a radio station). When you hit that area of resonance - which is that naturally occurring peak in the sound that already stands out as good or bad to your ears, this area might benefit from being boosted or cut. After you think you've got the right tonal color, then re-adjust the Q parameter to try and trim the bandwidth to just the right width that you need.

Take Note:

If you use the Vetta's 4 Band EQ, you can increase your accuracy in pinpointing the area of frequencies to be controlled by adjusting the "Q" control for a very narrow bandwidth.

Vetta Cab Models As EQ

Patch programming habits may be hard to break. Many of us are probably guilty of taking the easy (lazy) way out by just using the default amp/cab settings which come up every time, but that doesn't necessarily mean they're the best combination of amp, cab, and parameter settings. With all the tonal versatility that exists within the Vetta, experimentation will be the key to tonal success. And possibly one of the most overlooked applications of EQ are the cab models themselves.

Experiment with different cab models before reaching for the EQ

How many of the Vetta's cab models do we scroll right past and overlook because our narrow thinking has pre-conditioned us to NOT even consider using them? Don't think of the Vetta's cab models in terms of their speaker size and configuration, instead, think of them as 28 (different) preset EQ templates which must be tried out with whichever amp model you are working with. You may come to find out that the "magical" tone you're striving for suddenly appears from using a particular cab model you would have never considered using previously.

General Guitar Equalization Tips

Frequency Areas

Equalization Is A Fundamental Practice That Must Be Mastered