Spectral balance and spectral mixing

March 8, 2021 | Know-how

Whenever someone praises a track or a mix by saying “that’s smooth,” it’s probably quite intangible what exactly they mean by “smooth”. Chances are high though, that “smoothness” has a lot do to with spectral balance. In this article we tell you more about spectral balance and spectral mixing.

In an ideal world, where instruments are played and recorded perfectly and the arrangement factors in masking effects, we would only have to turn up the volume of each track to the same level to achieve a balanced mix – spectral balance from the get-go, no EQing and no compression required. But that’s not how it works in reality – and, besides, what would be the fun in that?

What is spectral balance?

Spectral balance concerns both single audio tracks and mixes but let’s focus on single audio tracks first.

Generally, spectral balance is a well-balanced distribution of energy throughout the frequency spectrum. Due to the uniqueness of every track, there is no fixed parameter set or preset and this leads to the elusive nature of spectral balance.

Spectral balance is closely connected to naturalness – something that sounds pleasant and meets our listening expectations. Any notches and dips in the frequency spectrum of a track that cause it to sound unnatural as a result of its recording, unfortunate microphone placements, comb filtering, etc. need to be amended in order to achieve spectral balance.

Balance it out

Cleaning up a track with an EQ as one of the first steps in the process of creating a song and is also a crucial step in establishing spectral balance. The required amount of manual tweaking can be subtle or extensive depending on the quality of the track.

Without a defined parameter set from which to create spectral balance, it may appear impossible to automatically establish it using a technical tool like our equalizer smart:EQ 2. It is possible though. With the help of A.I., a huge amount of data and psychoacoustic principles, we can create an expectation. After analyzing a signal, smart:EQ 2 can create a filter that then tries to meet this expectation whilst taking the tonal characteristics of your track into account.

What is spectral mixing about?

So far we have talked about spectral balance within single tracks but achieving a spectral balance in mixes is also very important. Instead of notches and dips, the culprits that cause spectral imbalances in mixes are masking effects. When it comes to mixes, a spectral balance is accomplished when each instrument has its own space and can fulfill its function.

Each instrument/vocal must have its own spectral window to do its job. Take a bass for example: It usually lays the foundation of an arrangement on which every other instrument or vocals builds. If something relentlessly pokes and squeezes itself into this basis, everything else starts to wobble.

Tread carefully towards spectral balance

The concept of spectral mixing has one aim: Spectral balance in mixes. The first thing to do is to make decisions about the role of each instrument (including vocals) within an arrangement. When starting to tackle spectral mixing you should therefore always ask yourself the following questions:

  • Where do my instruments have their strong suits in the frequency spectrum?
  • Which instruments should be in the limelight and which ones act as support?

Then, it’s all about freeing up cluttered regions of competing frequencies. By editing the corresponding frequency regions of each single track in such a way that none of them masks another, spectral balance is established. Make sure that you are not overdoing the unmasking, especially in the transition sections while an instrument is being introduced, otherwise your mix may sound inconsonant. Therefore, if you are new to spectral mixing, start with small steps since a lot of your efforts will be trial and error at first – and that’s fine!

And, last but not least, keep in mind that your tracks will probably sound a bit off on their own after aligning them with other tracks, which can be irritating. The smoothness of the final result is worth it though – just remember to tread carefully and think holistically when it comes to spectral mixing.