Equalization in audio production is basically the process of adjusting the volume of specific audio frequencies for obtaining a balanced frequency spectrum. Right use of eq can indeed make your songs sound significantly better. With it you can cut the unwanted frequencies or boost the ones that needs to be more presence.
Let’s take an example. You have two bass heavy sounds – bassline and big fat lead synth for example. Both may have quite a lot low end and and when you try to mix them together, they overlap each other causing the low end sound blurry or it can even lead to distortion. Equalization can help you here. Take one of those sounds (most likely that fat lead synth), add eq to it and decrease the volume of the low frequencies. Now that fat lead synth sounds a little bit thinner, but try to mix it with the bassline again. Most likely they work a lot better together now.
Internet is full of in-depth and very technical equalization tutorials so I won’t go there now. Instead, I’m just going to show you how the eq affects to the sound.
I’m going to use Fruity Parametric EQ 2 (it’s a parametric equalizer) to show you what the different filters does to a sound. It’s a very good eq and it’s my go to -tool for almost all of my equalization needs in my music production.
Alright, lets get down to business.
When you first open Fruity Parametric EQ 2, it opens with neutral settings – no boosting or cutting – and there’s already all the seven bands enabled. For each band you can independently choose a different type of filter. But look at the pic below and I’ll explain the controls first:
1. Band Type Selector. This is where you select the filter type.
2. Filter Slope Selector. Use this to select how steep or gentle you wan’t the filter slope to be.
3. Band Token. You can use Band Tokens for pretty much all the eq manipulation you need to do. By dragging the Band Token via mouse, you can control the center frequency (or cut-off point). You can also control the equalization level, select the Band Type and Filter Slope directly via Band Tokens by right clicking it.
4. Frequency Spectrum Analyzer. The Frequency Spectrum Analyzer monitors the signal and shows all the frequencies it detects in real time.
5. Shape of the equalization curve. The eq curve is based on the selected filter type, Filter Slope and Bandwidth.
6. Frequency Controller. This is another controller you can use to control the center frequency or cut-off point in addition to Band Tokens.
7. Bandwidth Controller. Controls the width of a band. In other words, the sharpness of the band of frequencies. You can also control bandwidth by using your mouse wheel when the cursors is on the Band Token.
8. Equalization Level Sliders. Use these to adjust the equalization level. You can also control the level via Band Tokens. Note that the slider is disabled for Low Pass, Band Pass and Notch filters because they don’t use this parameter.
Next, I’m going to introduce the filters and how they affect to the sound.
Firstly, here’s a drumloop which I’m going to use as a example on how the eq can be used to manipulate frequencies. This is how the drumloops sounds dry without eq:
Now there’s seven different types of filters in Fruity Parametric EQ 2 and they are:
Low Pass Filter. Passes low frequencies that are below (or before) a point that is called a cut-off point and attenuates (reduces the volume) frequencies that are above (or after) the cut-off point. Check the sound clip below the picture to hear how the Low Pass Filtering affects to the sound. I’m using the following settings: cut-off point frequency: 460Hz, Bandwidth: 61%, Filter Slope: Gentle 6.
High Pass Filter. Passes high frequencies that are above (or after) the cut-off point and attenuates frequencies that are below (or before) the cut-off point. It’s an exact opposite of Low Pass Filter. High Pass Filter is good for removing low frequencies from sounds. Check the example sound. Here’s the settings: cut-off point frequency: 460Hz, Bandwidth: 61%, Filter Slope: Gentle 6.
Band Pass Filter. Allows only a range of frequencies that are around the center frequency (in band pass filter the cut-off point is called center frequency) to pass through in a shape of a bell and attenuates the frequencies that are outside the center frequency on both sides. Listen the example sound below the pic. Here’s the settings: center frequency: 512Hz, Bandwidth: 61%, Filter Slope: Gentle 6.
Notch (Band Stop) Filter. Attenuates the frequencies that are around (on both sides) of the center frequency and passes through the others. This is the opposite to the Band Pass Filter. Listen the audio clip to hear it in action. Here’s the settings: center frequency: 512Hz, Bandwidth: 61%, Filter Slope: Gentle 6.
Peaking Filter. Either attenuates or accentuates (boosts the volume) a range of frequencies that are around the center frequency. It’s good for cutting or boosting specific frequency areas. Check out the example sound below. Settings: center frequency: 1721Hz, Bandwidth: 46%, Filter Slope: Gentle 6 and Band Level: 9.1dB. So basically I boosted the frequencies around 1721Hz about 9.1dB.
Low Shelf Filter. Attenuates or accentuates the frequencies that are below (or before) the cut-off point. Basically you can use it like a High Pass Filter – cut the low frequencies and let the highs pass through – if you use it for cutting. The end results are basically the same. But you can also boost with it. I like to use it for boosting low frequencies when needed. Listen the example sound. Here’s the settings: cut-off point frequency: 511Hz, Bandwidth: 49%, Filter Slope: Gentle 6 and Band Volume: -16.7dB. I cutted the frequencies starting from 511Hz and below about -16.7dB.
High Shelf Filter. This is the opposite of the Low Shelf Filter. It either cuts or boosts the frequencies that are above (or after) the cut-off point. If you use it for cutting you can achieve the same end results as with Low Pass Filter. I’m using High Shelf Filter for boosting the high frequencies to add brightness. Check the example sound and here’s the settings: cut-off point frequency: 511Hz, Bandwidth: 46%, Filter Slope: Gentle 6 and Band Volume: -16.7dB. I cutted the frequencies starting from 511Hz and above it about -16.7dB.
In Fruity Parametric EQ 2 you can use seven different bands simultaneously and each band can have a different type of filter. In the pic below you can see I’m using one Low Shelf Filter, five Peaking Filters and one High Shelf Filter. Check the sound example for how it sounds. (Sounds weird yeah, but it’s just an example).
The Bandwidth and Filter Slope affects to the equalization curve quite a lot. Test the different settings to see and hear what they do to the sound.
Okay, now you should have a rough idea what the different filters do to the sound.
The most used filters I use in my own productions are the High Pass Filter, Low Shelf Filter, High Shelf Filter and Peaking Filter. High Pass Filter is what I use when I wan’t to CUT low frequencies from instruments that doesn’t need to have them. Low Shelf Filter is what I use to BOOST low frequencies (like kick drum & bassline for example). High Shelf Filter I use to boost the high frequencies to give a brightness and clarity for some instruments. Peaking Filter is what I use to boost narrower frequencies of different instruments to make them more audible through the mix. I also use it to detect and cut problematic frequencies. I do it by setting a quite narrow Bandwidth, boosting few desibels and “sweeping” through the different frequency ranges and when I hear what the problematic frequency range is I cut it.
I recommend checking out these two articles. They include a equalization “chart” which you can use like a starting point for all your equalization needs:
For a pretty good equalization guide, check out this:
And finally, here’s the tutorial video.