How do I learn the correct EQ technique

The great equalizer 1 × 1

Our Equalizer Tutorial covers the basics of EQs and helps you understand the effect and apply it correctly. Here you can find information about the use, the correct application and the different equalizers.

Here you can see the frequency spectrum of a trumpet shown graphically. |Image: cc-by-sa; Cantor JH.

By Carlos San Segundo

What is an equalizer?

The EQ is a signal processor and one of the most important effects in modern sound and music production. The purpose of a signal processor is to change, modify or improve an audio signal.

The most widespread is the equalization effect (often abbreviated to EQ. Every audio signal or the sound of an instrument consists of a large number of different frequencies, which are also referred to as the frequency spectrum of the sound or the frequency spectrum of the instrument. This frequency spectrum, which is specific to the instrument, gives it its own own timbre and timbre.

With the help of an equalizer you can change the entire sound of an instrument or a sound source by increasing and / or decreasing certain frequencies.

Reasons for using an EQ

There are a ton of different reasons for resorting to EQ. Common concerns can be:

  • To better mix different sounds or instruments in a mix.
  • Getting a certain sound, for example vocals, into the mix.
  • To highlight a particular track or instrument in the mix.
  • To improve the sound or timbre of a particular instrument.
  • To create a certain effect for creative reasons (e.g. telephone voice).

For the sake of simplicity, let's start with the various parameters of an equalizer, which you will usually find in one form or another on every EQ.

The parameters of an EQ

There are three basic parameters:

frequency
The frequency is measured in Hertz (Hz) and stands for the center frequency in the EQ. Not only does the set frequency change for itself, but also those around it. The extent to which the change takes effect is influenced by the slope or filter quality Q (see below). [1000 Hz is 1 kHz by the way]

Here you can see the frequency spectrum of a trumpet shown graphically. |Image: cc-by-sa; Cantor JH.

Gain
Gain is specified in decibels (dB) and denotes the increase or decrease in volume (change in amplitude) caused by processing with the EQ occurs at the set frequency.

Filter quality Q
The filter quality Q denotes the slope of the filter used. With Q you can set how large the area around the selected center frequency (frequency band) should be processed by the EQ.

Equalizer types

There are three different types of equalizers, which I will explain for you below.

Parametric EQ

Parametric equalizer shown in FabFilter.

Parametric EQs are widespread in recording studios and are also popularly built into channel strips and mixing consoles. They can also often be found in music software due to their flexibility and performance.

The parametric EQ offers setting options for gain, frequency and slope, which can be used for smooth transitions between frequency bands or for narrow processing with a high slope.

Depending on the adjustable slope, parametric equalizers can be used for almost "surgical" interventions in the audio material.

Shelving EQ

The shelving equalizer processes high and low frequencies.

The shelving EQ, which is used for global setting of high or low frequencies, is also widely used: From the selected frequency, either all frequencies above (high shelf) or all frequencies below (low shelf) are raised.

The bass and treble buttons on the stereo are often called Shelving EQ designed.

Graphic EQ

The graphic equalizer has sliders for all frequency bands.

With the graphic EQ, each frequency band is assigned its own (slider) controller. The center frequencies and the bandwidth of the individual frequency bands are usually fixed in this type of EQ. To edit the frequencies, there are usually vertically arranged sliders that allow the respective frequency to be boosted or cut.

Graphic EQs are often used to compensate for the room acoustics of the sound source and are often found on high-quality stereo systems or as outboard equipment for the recording studio.

In addition to the above-mentioned elementary parameters of an EQ, there are also controls for input and bypass on many hardware devices and software EQs. The input sensitivity can be adjusted on the device with the control for input, which is important to prevent unwanted distortion. The effect can be temporarily switched off for comparison purposes with the bypass button.

Equalizer Tutorial: Filter Types

There are five types of equalizer (EQ) or filters:

Peak EQ

Peak EQ

This type can boost or cut a certain frequency. The parameter "Q" indicates the slope of the filter and thus influences the width of the increase or decrease by the (characteristic) frequency. High values ​​for the edge steepness reduce the width, while low values ​​widen the affected frequency range.

High-pass filter

The high-pass filter.

This filter lets through all frequencies above the set characteristic frequency and cuts off frequencies below.

Low-pass filter

Low-pass filter

This guy is the exact opposite. It lets the low frequencies pass while the high frequencies are cut off.

High-shelf filter

High-shelf filter

With this EQ, frequencies can be raised or lowered from the set characteristic frequency.

Low-shelf filter

Low-shelf filter

With this type of EQ, frequencies below the set frequency are boosted or cut.

High-pass, low-pass and the two shelving filters are ideal for giving tracks more transparency and clarity of sound.

More details: EQ filter types FAQ »

General tips about the equalizer

When mixing a song, there are basically two ways to edit a track with the EQ effect:

  1. You edit the track in solo mode
  2. You edit the track in the context of the overall mix

When in doubt, you should always opt for the second method, because otherwise it quickly happens that you invest a lot of time in a "perfect sounding" track, only to later notice that it seems impossible to mix the remaining instruments sensibly. Either the track stands out too much or it just gets lost in the mix. Too bad about the time, because now you have to start all over with the equalizer.

The solo mode, on the other hand, is ideal for finding the characteristic frequencies or undesired frequencies of a track by means of so-called "sweeping". Sweeping means nothing else than sweeping through all frequencies with a peak EQ with a lot of gain and paying attention to which frequencies stand out.

Whole books could be written on the use of equalizers in music production and home recording, so I only want to refer to the following two articles on the subject of EQ for further reading at this point:

EQ: Three basic rules of equalizing
EQ: When to raise and when to lower

Application of the EQ

Like everything else in music production and (home) recording, applying EQ is an art in which you have to rely on your own ears and first make all mistakes in order to learn from them.

A healthy human ear can hear frequencies between 20 Hz and 20 kHz, which are divided into different frequency ranges.

Overview: Equalizer frequency ranges »

It is advisable to internalize this subdivision in order to be able to create any desired effect on a track later. With a little practice you will quickly learn to differentiate between certain frequencies in the mix and to use them correctly.

Here is a brief overview of some instruments and their relative frequencies that you can use as a starting point to find your own EQ settings:

  • Snare drum: fullness, smack at 250 Hz / crisp, hi-fi at 5 kHz
  • Cymbals and hi-hats: fullness at 240 Hz / clarity at 8-12kHz
  • Bass: body and base at 60-80 Hz / clarity at 2.5 kHz
  • Electric guitar: angularity at 2.5kHz / body at 200 Hz
  • Acoustic guitar: body at 80-120 Hz / fullness at 240Hz / clarity at 2.5kHz
  • Piano: body at 80-120Hz / presence at 3-5 kHz / sharpness at 10 kHz
  • Female vocals: fullness and warmth at 200 Hz / presence at 5 kHz
  • Male vocals: fullness and warmth at 120 Hz / presence at 5 kHz

As usual, these are not generally always valid settings, the ear is the last resort!

Does the EQ influence the volume?

There is a lot of discussion about the use of EQ when mixing and sometimes losing sight of the essentials: the influence on the volume.

Whether you should use the EQ before or after adjusting the volume ratios of the instruments to one another, you can be divided. Some sound engineers swear that the first step is to edit a track with the EQ and only then adjust the volume. Others do it the other way around - I myself could almost no longer separate these two work steps from each other.

An example from the series of EQ plugins: The FabFilter Pro-Q 2.

No matter how you approach this task: you should always be aware that a reduction or a boost in the EQ also means a change in the volume of the instrument.

What does that mean in practice? If I have roughly found the volume of the vocals and raise it by a few dB at 3-4kHz, the relative (and also the absolute) volume of the vocals increases. So it makes sense to lower the volume of the vocals a little in order to restore the old relationship. And vice versa, of course.

When it comes to volume ratios, it is also true that contrast has the greatest influence on the listener's perception and that it is not just about absolute values.

Tutorial: Make the mix louder in 10 steps »

Incidentally, I can only advise against using effects in general to increase the volume of an instrument. Sometimes it's better to take a step back to recording.

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