Equalizers or EQ are tools to alter the frequency response of an audio signal. This means that the main function is to adjust the amplitude of a specific range of tone. By these kind of filters, the use of equalizers can change the frequency response depending on the type of audio we are working on.

Equalizers are used in a lot of different audio work areas, as music production, radio broadcast and basically in any work that audio could be involved.

They are very useful because they give the option to modify the sound and create a very specific range of frequency information, at the same time that they allow us to refuse all those tones that don’t work for us.

Even they all do and work almost in the same way, there are a lot of types of equalizers. We can actually find them in analogue or digital format, so that improves the possibility to work with them.

In this post I’m going to show some kinds of them; simple EQ, Graphic EQ, parametric EQ and graphic EQ. As you will see, they can probably do the same kind of equalization but some of them are more specific with the frequencies and the gain or amplitude.

Watch the next video to discover what’s en EQ


Simple EQs

As we get into the concept of an equalizer we can start from the number of bands. The bands are the total number of points we can use to modify the frequencies. For example: if we have a 10 band equalizer, it means there are 10 points to add gain in the frequency spectrum. So, simple EQs are those which only can work with one specific number of frequency.

Some uses we can give to simple EQs are the high and the low pass filter. It means we can cut those frequencies we are not interested in. For example: if we are recording a voice for a radio broadcast we don’t really care about the low frequencies, because most of the information for voices in the spectrum range are most of the times in the high bands. If we cut those low frequencies we’ll get a clear and noiseless sound for the track.

Simple EQ by AVID 


Graphic EQs

These kind of equalizers give more options of equalization because they have much more filters and bands. This is a very functional tool, so we can work with predefined frequencies and get more variations with the sound. Each filter passes the portion of the signal for every band. Most of them have from 25 to 31 bands of EQ, so there are more options to modify the frequency we are working on.



Parametric EQs

Parametric EQs allow us to modify three different parameters: frequency, amplitude and bandwidth. Selecting the frequency we can increase or decrease the amplitude of it and also the bandwidth can be widened or narrowed.

The big deal with these EQ is the easy way to create a new frequency response with just three knobs.

Most of the boards used for broadcast, TV, radio or music have these kind of EQs, just because it keeps it simple and allows to the engineer to modify however we wants the track in the mix.


Paragraphic EQs

Summing the concept of graphic and parametric equalizers the result would be paragraphic EQs. With this tool we are able to create new frequency responses with graphic modulation. Also they allow us to work with very specific frequencies, amplitudes and bandwidth. Paragraphic EQs are also a good way to watch the sound and not just listening to it. Some times we are not able to listen some low or high frequencies, but they are actually there. A bad monitoring system could not play those high and low sounds, but moving to a big PA system or another monitoring system would give us problems and we could think there’s something wrong with it. To avoid this, it is important to watch and not just to listen to the sounds.

Another example of this would be in an interview or a recorded conversation; the wind gives some low frequencies that we can not listen in laptops speakers because the woofer is not big enough to do it.


It seems simple, but the equalizers are probably the most important tool in the audio production. EQs are the way to increase the parts of the audio information that we care the most. Specially in the music production and mixing, EQs are the best rated tool to create a sound. It’s not just a way to modify frequencies, it’s the art of making lots of sounds living together in the same audio space. Starting from the cheapest digital tool to the most expensive analogue equalizers, EQs can make a difference between an abstract sound to a clear track.


Watch this video to know about an useful way of EQs:



1. http://www.waves.com/

2. http://en.wikipedia.org/wiki/Equalization_(audio)

3. http://www.howtogeek.com/59467/htg-explains-what-is-an-equalizer-and-how-does-it-work/

4. http://electronics.howstuffworks.com/how-to-understand-sound-equalizer.htm

5. http://www.stereotechnicalinformation.com/education/equalizers/whatsaneq.htm





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