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March 2023
Vol. 22, No. 6
32nd Annual San Diego Music Awards

Ask Charlie...

Spin the Knobs, Take Your Chances

by Charlie LoachSeptember 2012

Hello Troubadourians! Last month we talked about different techniques you can use to make your guitar sound more “natural” when using a piezo pickup. This month I’d like to talk a little more specifically about equalization — what it all means and how to help you understand that it’s more than just weird numbers and tech-speak. Hopefully you’ll know more about what it all does and how it relates musically so that you can effectively use this powerful tool.

As I said last month, equalization (EQ) is intended to be used to compensate for environmental differences in performance venues so that everything sounds “normal” or natural. The biggest mistake that most musicians make with EQ is attempting to use it to alter or enhance the sounds they are making. Vocalists are especially prone to using the mixing console EQ to make them sound “better.” The opposite effect is the usual result. If you desire to make something — instrument, vocal, whatever — sound radically different, there are effects devices that will accomplish that task much more satisfactorily that futzing with the EQ. I think it’s easiest to think of EQ as volume controls tailored for specific frequencies or frequency ranges. Often “less is more” or “adding by subtracting” is the best approach where you can boost the perception of a frequency by cutting or reducing a different frequency. So, let’s get specific with what types of EQ you are likely to encounter and what they do best.

Shelving EQ is the most common implementation and is found on instrument amps, lower-end PA systems, and even in some instruments themselves. Shelving EQs are just as likely to be called tone controls and are like painting with a roller instead of a brush. Whether you have one knob labeled TONE or two labeled TREBLE and BASS (three if you are also have a midrange control — labeled MID), these controls affect a broad range of frequencies and are highly interactive, meaning that adjustments made to the frequencies of one control will also have some effect on the frequencies of the other controls. Cool for electric guitars, horrible for vocals and acoustic instruments. Adding to the confusion, there is no accepted standard as to what specific frequencies are considered TREBLE, MID, or BASS so a favored setting on one mixer will sound completely different on a mixer by a different manufacturer. Minimal adjustments are usually best when using
Shelving EQ.

Graphic EQ is so named because the sliders assigned to the specific frequency ranges are vertically positioned, and moving the sliders creates a graphic display of which frequencies are boosted, cut, or unchanged. This type of EQ is most commonly found in the “mains” section of a mixing console. The intended utilization is to correct for sound frequency problems in the room where you are performing. (Note: It’s not intended to make the lead singer sound “really bitchin’, dude.” Just sayin’…) Graphic EQs are able to perform more precise adjustments as they are configured with sliders that affect a relatively narrow frequency band that is centered on a specific frequency. For instance, if the slider has a center frequency of 1k Hz (1000 Hertz or cycles per second), boosting or cutting that slider will only affect the frequencies within 50 percent above or below the center frequency of the slider. Usually, most of the frequencies that are either feeding back or are too weak can be compensated for with a simple adjustment of the Graphic EQ. As an aside, if you really want to mess with the sonic character of a specific instrument or voice, a small narrow-band EQ might be what you’ll need to apply to that specific input for the desired effect without compromising the entire mix.

Parametric and Quasi-Parametric EQ can be considered something of a blend of the functionality of both shelving and graphic EQ. Sounds complicated. It kinda is but I’ll explain… While the other EQs have essentially a one knob/slider per function correlation, Parametric EQs require two (sometimes three) knobs to do their thing. One knob selects the center frequency that is to be EQ’d and the corresponding knob controls the amount of boost or cut at that frequency. (Note: In a two-knob Parametric EQ, the width of the frequency band is fixed at a certain percentage of the center frequency. Three-knob Parametric EQs allow you to expand or contract the width of the frequency band.) A full Parametric EQ will have control knobs that are dedicated to multiple and separate frequency ranges (usually three to five) and would most likely only be found in studio applications. Performing musicians are much more likely to encounter Quasi-Parametric EQs as they are becoming more popular in the EQ sections of pro and semi-pro mixing consoles. Most often, these consoles will have shelving EQ for the bass and treble controls and a two-knob parametric for the midrange control. This arrangement works really well for most input sources, especially vocals, and provides the ability to dial-in very natural tonalities without a lot of tweaking. Additionally, Quasi-Parametric EQs tend to be more uniform and less interactive between the separate frequency bands associated with the particular controls which allows them to be more repeatable when EQ-ing a sound source for different venues. Combine a Quasi-Parametric EQ in each channel of a mixer with a 7-10 band graphic EQ in the main section of a mixing console — and taking the time to learn how to use them properly — can afford excellent flexibility and sonic sculpting for almost any performer in almost any indoor performance venue.

It’s all about balance and making things sound normal. If you find yourself turning knobs or moving sliders to their extreme positions on a regular basis, you should probably stop and think about how you’re using your EQs. Listen, listen, listen, and read the manuals for your gear. Knowing how and why they work will help you deliver your best sound and best performance.

Need to know? Just ask… Charlie (

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