This is the third blog in a four part series looking at how to create a professional mix. The first covered Volume Balance and the second Stereo Image.
An crucial component of achieving a professional mix is the ability to control and shape the frequency content of individual tracks so that they work together as a whole.
Every sound you hear is a mechanical wave that results from particles vibrating back and forth through the air. Frequency is the measurement of these vibrations that a person subjectively interprets as its sound or pitch. Another way to look at frequency within the context of mixing is; a numerical system created to calculate and better understand the characteristics of sound.
The audible frequency range of humans is often described as 20 Hz - 20,000 kHz and human hearing isn’t linear meaning we hear frequencies at different levels which is an important factor to consider when thinking about mixing and can be further explained by Fletcher Munson curve (for those interested/geeky enough like me).
Right, now that the sciency bit is out of the way we can look at how this relates to creating a professional mix. Every instrument that you have within your song will occupy a frequency range based on its fundamental frequencies and resulting overtones. These frequencies will primarily depend on the type of instrument and register it’s played in. For example a bass guitar will roughly occupy frequencies between 60 Hz -1,000 kHz, a electric guitar approximately 80 Hz - 4,200 kHz and a female singer could range from 350 Hz to 17,000 kHz.
Logic Pro X's Equalizer
So how do you get all these potentially overlapping frequencies to work together within a mix?
Good question and I am glad you asked: To control and shape the frequency range of your individual tracks so that they work together an audio Equalizer (EQ) is used, like one pictured above. There are different types of hardware and software EQ’s but they all fundamentally do the same thing - alter the frequency range of sounds used within your mix by either cutting or boosting different user selected ranges. Some even come with frequency spectrum analyser built within them to help you visualize and identify the frequency range of sounds to be altered.
One way in which an EQ is often used is to help create frequency separation between two sounds, for example, the recording of an electric guitar might contain unwanted lower frequencies that are clashing with a recorded bass guitar, to give the bass guitar better audio definition within the mix an EQ could be placed on the electric guitar track and used to remove the unwanted lower frequencies so that the two instruments aren’t fighting over the same frequency space within a mix.
Although there is no right or wrong way to use EQ’s I personally tend to use them to remove frequencies from sounds rather than boost.
I often cut out the lower frequencies from most sounds except the drums and bass. The reason being this part of song is that I think people tend to fundamentally groove to, so I aim to to have a clear kick and bass shining through in a mix. It’s often the case that beginners to the world of mixing aren't aware of the benefits of subtractively using an EQ which can result in songs that have muddy, undefined low ends, with all the instruments fighting for frequency space and not being heard in their own right.
Another way to approach frequency separation between two instruments in a song is to; decide not to use two instruments that occupy a similar frequency range in the first place, play one of the instruments at a higher or lower register compared to the other instrument or even pan the instruments to create separation. These scenarios aren’t always possible and that's where your trusty audio tool the EQ can come into play.
You should now have a better understanding of Frequency content, how an EQ can be used to shape it and some typical ways in which you might like to use an EQ to create a professional sounding mix.
The next blog will look at how to create a sense of audio depth and what tools can be used create this.
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