- Posted: 14/03/26
Equalization...The Why and How.
Mission: Dissect The Equalizer. How do you use it, and How does it affect your sound?
After discussing acoustics in a small studio environment, and then touching on the questions to ask when selecting your D.A.W, where do we go from here? What’s next? Audio Processing! More specifically, EQ!
The major audio processing tools are EQ, Compression, and TDR (time-delay, reverb). In the third installment of the SPS we’ll tackle one of the most important tools in any engineer’s toolbox. I know that sometimes students and novice engineers use EQ’s (mostly EQ Plugins) and may not fully appreciate why equalization can be so important, and how to take advantage of what it offers. Let’s check out what it’s all about…
First off, let’s define the type of equalizers we’re likely to come across in our D.A.W, or in our gear while recording or mixing.
- Fixed frequencies and bandwidth (Q) with variable gain.
- Up to 30 Frequencies
- Example:Digital Graphic Plugins such as the iTunes EQ, P.A. EQ’s, Home Theater EQ’s or API’s 560
- Variable Frequency, Bandwidth (Q), and Gain
- These are the vast majority of EQ’s we use while mixing and recording.
- Examples: Neve’s 1081, Digital Parametric Equalizer's such as Logic’s stock EQ etc.
What’s in a typical Equalizer?
Typical parts would include resistors1, capacitors2, potentiometers3, op amps4, and the power supply. There are many types of each of these items, but they are the foundation for the electrical signal manipulation. At a basic level it’s helpful to understand what is being done to your signal, and a definition of these terms is included at the end of this article, just to make you a little more familiar with them.
The Parametric Equalizer
If you’ve looked through your EQ plugins in almost any D.A.W, you’ve noticed that parametric EQ’s’ vary from 1-band, to as many as 10-bands (if my memory is correct). In many ways EQ’s are like anything else in engineering, if you understand how to operate one band you will understand “basically” how to operate 10-bands. I think a great place to start if you are looking at your EQ in your D.A.W right now would be your frequency window and how it’s broken down into 10 audible octaves.
- 1st octave center freq of 31 Hz 6th octave center freq of 1 Khz
- 2nd octave center freq of 63 Hz 7th octave center freq of 2 Khz
- 3rd octave center freq of 125 Hz 8th octave center freq of 4 Khz
- 4th octave center freq of 250 Hz 9th octave center freq of 8 Khz
- 5th octave center freq of 500 Hz 10th octave center freq of 16 Khz
Knowing the octave range breakdown of the frequency window will really help you when you use the functions of an equalizer such as the bandwidth knob, (heretofore known as (Q) for the rest of the article). For instance, if you are adjusting the pluck on your bass guitar around 125, depending on how narrow your Q is set will determine which other aspects of the bass you may be adjusting as well. Here is an additional page that you will definitely want to check out that gives you a better understanding of what sounds typically lie in these octaves, that knowledge in addition to how they relate to the octaves above will solidify more informed EQ decisions. An example of corrective use of this knowledge would be to listen to a piano’s signal passing through your EQ and wanting to attenuate the piano player’s middle A. Knowing that based on the equal tempered scale that all western music uses, middle A is set at 440 Hz. You can then set a high Q ratio and reduce gain at 440 Hz. This would be more of a surgical use of EQ than you would use with most of your EQ applications, but it does represent using all of this knowledge in tandem to be better prepared to make educated EQ decisions.
Your Q adjusts out from the center frequency that you set. How wide your octave adjustments are are based on how high or low your Q settings are. Rough Q settings are listed below:
- .667 – 2 octaves
- 1.044 – 1.3 octaves
- 1.414 – 1 octave
- 2.8-2.9 – ½ octave
- *to jump just a bit* A Q of around 17 relates to adjusting 1 pitch (like the 440 Hz example above)5
Q values generally go as high as 17, and as I iterated earlier, the larger the Q the narrower the bandwidth that is being affected.
Gain settings on an equalizer do what gain settings do everywhere else; they boost or cut wherever your center frequency and Q are set…Pretty easy, right?
Coarse controls- just so we don’t leave out some of the major parts of an equalizer that tend to have more of a broad effect, bandpass filters (high pass or low pass), center around a “corner” frequency. In a bandpass filter beyond the corner frequency the attenuation increases precipitously. These filters are extremely useful in cutting out any information beyond that corner frequency. In adjusting Q settings in these situations it determines how sharp or how smooth the attenuation curve will be from the point of the corner frequency. Another coarse control that many engineers use frequently are the Shelving EQ’s, either High Shelf or Low Shelf. Shelving EQ’s act very similar to the previously mentioned bandpass filters accept they don’t cut out all of the frequency information beyond the corner frequency. A High Shelf for instance, might be set at 14 Khz to attenuate all of the frequencies beyond 14 Khz but using a shelf here instead of a low pass filter doesn’t cut the frequencies out, it just attenuates them. If you are looking to add air on your overhead drum mics you might want to set a corner frequency around 10 Khz and add a High Shelf here to raise all of the information above 10 Khz up a dB. Shelving EQ’s are used in a variety of situations, but they are commonly used across the stereo buss to do more “overall sound” adjustments rather than something more targeted i.e. making things “brighter” or “darker”.
Now that we’ve discussed in detail about the parts of an EQ, and how each element affects your signal, on a broader scale let’s answer the larger question.
(Included for more precise use of setting your Q’s in the future)
Why Use EQ?
There are two reasons to use EQ in the mixing stage, Corrective and Creative, these are the only types of EQs that exist and it is important to make sure you approach each situation accordingly. The first step in Corrective EQ isn’t actually EQ at all; it’s correct mic choice, placement and pre-amp selection. I digress though, this article is about the mixing stage in the SPS, but it’s important to always remember the recording is at least 50% of the mix. So!...assuming our recording choices were correct, your Corrective EQ choices will pertain to fixing things that clash in your mix or don’t sit well etc. i.e. your bass and your kick need their own space, or in your melody instruments there’s too much midrange honk from your horns. A great example of Creative EQ would be a filter sweep for effect on a dance track, or a “telephone” effect on a delay vocal. One of my favorites from a top mix engineer that I distinctly remember is the one from Lady Gaga’s “Just Dance” track, in the bridge section she has a left signal and a right signal that are EQ’d creatively so that it sounds as if it’s just a time-delayed effect, but Robert Orton (the mix engineer) states in the Sound On Sound article that the tracks aren’t just delayed but creatively EQ’d opposite each other.
All mixes turn out better when the correct recording choices are made, as opposed to having to be heavy handed with corrective EQ, and I’ve always aired more on the side of cutting before boosting to get the right sound, this will help control the overall sound level as well, after all, if you boost everything, then everything just gets louder (right?) and may sound better, but that’s not often the case. The Western ear perceives louder sounds as generally sounding better…but that’s another topic for another day (ha ha!). I can’t forget to add that the use of compression and panning can also be important supplements to your EQ choices as well.
Learning the 2 reasons to use EQ, the octaves you are adjusting and how to use Q, center frequency, and gain in tandem to better understand one of the most powerful mix tools we have is at the least beneficial in better grasping your mix so that you are better equipped to achieve the sound you want.
See you next Article!!!
**If you have any comments on this or any other article, catch us in the forum and let’s discuss! **
- Resistors- passive two terminal component, that implements electrical resistance
- Potentiometers- three terminal resistor with a sliding or rotating contact forms a voltage divider. (commonly controls gain)
- Capacitor-passive two terminal component used to store energy in an electric field
- Op Amp- (operational amplifier) A DC (direct current) coupled high gain voltage amplifier with a different input and single ended output.
- Kauffman Chart figures.
Note: RecordingEQ.com, Dave Moulton’s Golden Ears Program and the Kauffman chart were referenced while composing this article.