The topic of mix bus compression can be a mystery and confusing for new mixers. Top engineers swear by it, claiming that it gives a mix more depth, punch, and glue.
Nonetheless, if you are new to mixing, it might seem like a dark art.
A well-tuned compressor on the mix bus can make a big difference in your mix! But a poorly tuned compressor can wreak havoc.
What is mix bus compression?
A mix bus compressor is an essential piece of equipment in any modern recording studio.
When you first start in the world of audio production, the term "mix bus compressor" is one that you're likely to hear a lot.
Though the specific features and functions of plugins or hardware bus compressors vary, they all serve one common purpose: to make all the elements of a mix sound louder and more cohesive.
This makes it easier to achieve a more polished sound.
By evening out the dynamics, a compressor can help a track sit well in a mix and ultimately sound better to the listener.
Used properly, it can help to glue a mix together, make it more consistent, and add punch and clarity.
Put simply, a mix bus compressor is an audio processor that's used to make individual tracks sound more cohesive as they are combined into a master stereo track.
In this article, we'll discuss how mix bus compression can be used to improve your mixes.
When to Use a Mix Bus Compressor
The most common mistake regarding mix compression is the order in which it is applied.
That is, novice engineers will often instantiate a compressor after they achieve a balanced mix with fader positions and inserts.
The problem is that the compressor changes the balance and transient response of the original mix; thus, any prior work done by the mix engineer loses its integrity and intention.
Instead, the better order would be to add the compressor to the mix bus before using any processing tools.
Doing so will allow the engineer to mix through the compressor with intent. Hearing the result of pushing faders into the compressor in real-time is the key.
You’ll get better results if you mix into it rather than adding later when you’re done with all the processing.
How to choose the right compressor
Compressors are an important tool for getting your mix to sound its best.
But with so many different types of compressors out there, it can be tough to know which one is right for your music.
Different compressors will yield different sonic results, so it's important to choose the right type for your mix.
Some may work better for certain genres than others, so be sure to do your research before making a purchase.
VCA compressors are known for adding punch to a mix. The famous SSL G-series, API 2500, and Neve 33609 use this solid-state design.
VCAs are known for gluing the mid-range and causing the music to breathe. These are a great choice for more aggressive styles of music like rock, hip-hop, and EDM.
They are also known for their ability to add glue to the mid-range frequencies and make the music sound more dynamic.
Another popular choice is the Variable-Mu compressor, which uses tubes to create subtle harmonic distortion.
This can give the audio a warm, smooth sound, as heard on famous models like the Fairchild 670 and Manley Vari-Mu. The variable-mu is particularly well suited to traditional acoustic genres such as jazz, blues, and folk music.
Different mixing engineers have different opinions on optical compressors. Some think that they react too slowly to be used on the mix bus, while others find them to produce a very clean and transparent sonic character.
In recent years, several new models have been introduced, like the Pendulum OCL-2, Tube-Tech CL2A, and Avalon AD2044, which are designed to address some of the previous concerns.
Ultimately, it comes down to the engineer's preference and what works best for the particular project.
These compressors are much faster and can be used on the mix bus without compromising sound quality.
FET compressors are a popular choice for many mixing engineers. They are known for their fast response time, which can be helpful when you need to tame quick transients.
But they can also be used for more than just peak limiting - some models, like the Daking FET 3 and Universal Audio 1176, work great on the mix bus.
So if you're looking for a versatile compressor that can handle a variety of tasks, then a FET compressor may be the right choice for you.
Be sure to consider these options when choosing the right compressor style for your mix. To be on the safe side, go for VCA on aggressive styles of music and use Tube compressors for acoustic genres.
The Risks of Compressing the Bus
If you're looking to add a sense of polish and smoothness to your mix, mix bus compression can be a great option.
However, it's important to keep in mind that using one can somewhat decrease the level of control you have over the mix.
The compressor will primarily affect the loudest parts of the mix.
In other words, if you want to make the kick drum louder in the mix, then you have to bump the kick fader up. Consequently, the compressor will apply more gain reduction to the kick.
This is why many producers prefer to control dynamic range on individual tracks rather than rely on the mix bus compressor.
However, that doesn't mean that you shouldn't use a mix bus compressor at all.
What I’m saying is don't use it as a crutch, rather use it for character and gluing the mix together as compared to fixing mixing issues.
Finding the Perfect Settings
If you're looking for foolproof mix bus compression settings that will work every time, try this simple approach.
You can use it on every song, or establish a default setting that you can tweak as necessary.
Perfect Mix Bus Compression Settings in 3 Steps
After doing this enough times with any compressor, you may not need to go through the steps at all.
1. Setting The Ratio
The first thing to do when setting a compressor on the mix bus is to choose the ratio and threshold.
Setting these two parameters is quick and straightforward for mix bus purposes. For the ratio, you want to go for anything between 1.5:1 and 4:1.
If you're looking for a more transparent and dynamic sound, go lower on the ratio (1.5:1 to 2:1).
If the track is more aggressive or needs more control, go higher (2:1 to 4:1).
Simply straightforward, don't try to complicate it because anything above 4:1 will squash the mix too heavily.
2. Getting the Amount of Gain Reduction
To get the best sound out of your mix, try applying a gain reduction of 1-4 dB during the loudest sections.
This will help even out the levels and make it sound more cohesive.
When you're first setting up your compressor, you may want to over-compress your mix temporarily so you can get a feel for how it works.
Whether you're starting to learn the ropes of bus compression or are a seasoned pro, don't be afraid to crank the gain reduction up to -10dB or more while you're dialing in your settings.
Listening with a lot of gain reduction can be a helpful way to learn what sounds best.
3. Attack & Release Settings
A good starting point would be using a slow attack (around 30-80ms) and a fast release (around 0.2-1.0ms). Then play around with the settings till you find what works best for your mix.
As you decrease the speed of your attack, you will notice a loss in the power and articulation of your strongest transient instruments (This is usually most notable in the kick and snare).
A slower attack will create a more aggressive sound, while a faster attack will result in a smoother, more controlled sound. Experiment until you find the balance between speed and quality to produce the best sound.
Release times can have a big impact on the sound of your music. Make sure to experiment with different settings to find what works best for you.
A good rule of thumb is to start with a slow-release time and then gradually make it faster until the gain reduction meter just barely recovers to zero between dominant beats (kick and snare).
If you're looking for a more aggressive, exciting sound, try setting the release time a bit faster. For a smoother, more controlled sound set it a bit slower.
The "auto" release feature on some compressors can also be very nice, and you shouldn't be ashamed of it if it sounds good.
Remember, it is always a better choice to mix into the compressor (start your session with the bus compressor engaged) as compared to adding it when you’re done with mixing.
Occasionally take note of how much it’s affecting the loudest parts of the song.
You can tell when it's too much if you hear "pumping", "breathing", "graininess" or if the mix just sounds kinda small, flat, and irritating, regardless of how you mix it.
If you're unsure, it's best not to compress by more than 2-4dB on the loudest sections of a song.
For more acoustic or dynamic genres, 2dB of compression is usually plenty. Sometimes all you need is 1dB for a little bit of extra glue.
What Are Some of the Best Mix Bus Compressor Plugins?
Choosing the right compressor for the mix bus is another challenging task because there are tons of them available in the market.
But lucky for you, I have compiled a list that you can use to get that punch, clarity, and glue in your mixes.
Check out the list in my previous blog post titled Best Mix Bus Compressor Plugin.
If anything mentioned in this post is confusing then I would recommend you to stay away from applying using a mix bus compressor.
Rather leave it for the mastering engineer. That way you’ll get much better results as compared to ruining a great mix.
However, it is always important to test so that you can improve your mixing skills.
If you need me to clarify anything then leave a comment below to ask your questions and feel free to let us know what you’ve learned today.