Multiband compressors are one of the most misunderstood and misused mixing tools.
To many, the multiband compressor can seem quite complex and difficult to use in the mixing process. By understanding the basic functions and applications of a multiband compressor, you will be able to use this powerful tool in an impactful way.
In this article, I am going to go over what a multiband compressor is, why you would use it over a normal compressor, and when you would use it in your productions.
What is a Multiband Compressor?
A multiband compressor is essentially multiple compressors in one. These various compressors are divided up among the frequency spectrum, so each compressor operates on a specific part of the frequency spectrum.
Each of the compressors in the multiband compressor function independently of each other. A normal compressor covers the entire 20 Hz to 20 kHz range and is operated by one set of controls.
Why use a multiband compressor over a normal compressor?
When mixing your track, you will continually run into situations that require specific audio processing. There is no one size fits all solution when it comes to mixing.
As mentioned, a normal compressor compresses the entire frequency spectrum. But what if there is only a specific frequency range that needs to be compressed? A normal compressor would compress the entire signal and not just the frequencies that you wanted. This is where you would use a multiband compressor.
When specific frequency ranges need to be compressed, you will be better off using a multiband compressor. Compressing a frequency range that does not need to be compressed will cause a dynamic imbalance in your mix which is exactly the issue we are trying to fix with compression.
Basic Controls of a Multiband Compressor
The basic controls of a multiband compressor are similar to that of a normal compressor. Remember, a multiband compressor is a compressor composed of many different compressors.
A multiband compressor will have a ratio, threshold, attack, and release, just like a regular compressor. If you are struggling to understand the basic compressor controls mentioned above, take a look at the How To Use A Compressor article.
The only basic control that will not be similar on a normal compressor is the crossover points. Most multiband compressors will allow you to set what frequency range each individual compressor or band will affect.
This control is very useful for honing in on the specific frequencies that you want compressed.
When To Use Multiband Compression
There are three common situations in which we would use a multiband compressor.
The first is to fix frequency imbalances in the individual elements in your track. The full frequency sounds in your mix will be the most likely target for the multiband compressor. Full frequency sounds will most likely be needing only a specific part of their sound to be compressed. Go through the different elements in your track and listen for any imbalances. Chances are, one or two of the sounds in your mix will need multiband compression.
As far as setting the controls of the multiband compressor, you will set them just like you would with a normal compressor, except it will only be for the specific frequency range of the sound that is causing the issue.
For more information on how to apply a basic compressor to your individual sounds, check out the How To Use A Compressor article.
The second situation in which we would use multiband compression is to fix the frequency imbalances in groups of sounds. Often times, when you add more and more instruments to your track, the output of these sounds will create imbalances in the frequency spectrum. Even if you apply multiband compression to your individual sounds, you will often still run into imbalances in the groups of your sounds.
To fix these imbalances, you can group all the sounds in your mix that have similar frequency content. Grouping all the high frequency elements, mid frequency elements, and low frequency elements will help you to hear what needs to be multiband compressed. Put a multiband compressor on the groups of these elements, find the imbalanced frequencies and compress them.
The final main use of multiband compression is to bring out elements in your mix.
The elements in your mix can lose their clarity and power when you begin to build your track and multiband compressors can help bring your elements back to life in your mix. We are going to use a sneaky little trick in the multiband compressor to create more presence to your elements.
First, you will need to find the sounds that need more of a lift in the mix. Then you will add a multiband compressor to them. Before you begin compressing, you will need to find the frequency range in each element that gives the sound its weight and power. By soloing the sound and paying close attention, you can hear approximately what frequency range gives this sound its power. You will then set this frequency range for one of the bands on the multiband compressor.
Next, you will add 2 to 3 dB of gain on this particular frequency band. This will boost up the volume of the frequency range.
Next, adjust the attack to around 35 milliseconds and the release to around 40 milliseconds. From here, you will adjust the threshold and ratio, to compress the same volume that you boosted. By doing an equal amount of boosting and compression, the initial prominent frequencies in your sound will be more present in the mix, but not be imbalanced because the multiband compressor will tame them soon after.
The 35 millisecond attack allows this dB boost that you provided to be present for only a short period of time. This simple technique is a very powerful way to add presence to your sounds.
By understanding that a multiband compressor is a mixing tool composed of many different compressors spanning the entire frequency spectrum, you can start to understand just how efficient and effective this tool is. After reading through this article, you will be armed with the knowledge to tackle the toughest mixing problems that arise in the production process.
Daniel is a caffeine-dependent entrepreneur, music producer, sound design junkie, and world traveler crazy about teaching modern electronic music production through his site SoundShock.