Mastering Tips Part 4 - Multiband Compression

As the name suggests, compression is the process of compressing audio material.

Colage of different multiband compressors

The dynamics of a song are changed (interplay between loud and soft tones within a recording).

For example, a loud explosion should be just as audible as a soft whisper, without having to turn the volume control.

 These parameters depend on the style of music, the quality of the audio material and musical taste.

Where are compressors used?

Most common in the Music production, as well as at Mixing or mixdown and with analog mastering Compressors with only one tape used which is the complete frequency spectrum cover. That means everyone Frequency ranges be lowered for the same length of time.

A Multiband compressor can be used more flexibly because it does audio signal divided into two or more frequency bands. Especially in the Mastering process this is often used. Filters are used for this. Then the individual filtered signals are transmitted to their own compressor and processed by it. The resulting individual signals will later become closed again a single compressed (stereo sum).

Advantages of the multiband compressor and multiband compression

A Advantage using the Multiband compressor is it that a loud event im low frequency Area no longer in the dynamics of the hi hats can intervene. Since each band is compressed individually, the individual bands do not affect each other. In addition, each frequency band can be compressed differently, whereby different values ​​for attack, release, threshold and ratio are possible. It is also possible to edit each band individually with regard to level and volume or loudness or dynamics.

And how do I adjust the compressor bands?

The question now arises as to where to separate the bands in multiband compression. Unfortunately, there is no fixed standard for this, the separation always depends on the respective audio signal to be processed.

Here is an example from a current production of mine:

For example, I chose a band that goes up to about 90 Hz, which helped me to compress the low frequencies without having to change the kick too much. I then worked with another band in the higher frequency range (around 10 KHz).

Please note the following with multiband compression:

It is important to ensure that the end result does not sound false if you use many different settings for the individual frequency bands in multiband compression. Of course, not all bands can always be compressed equally or slightly, so by using the Make-Up Gain you can change the level of the individual bands so that the song sounds natural again.

As a little tip - with a multiband compressor, I often make the following settings for the attack and release times:

  • First and lowest band: medium attack and release times
  • Middle bands: same setting as for a normal compressor
  • Highest band: fast attack and release times

Application examples for multiband compression

These will come in the next edition of our mastering tips. It starts with the bass range.