What Exactly Is Mix Bus Compression?
Mix bus compression is one of the most used processing techniques for mixers and engineers looking to get better sounding productions. The tool itself is no different than any other compressor you might find on a track, and you can easily use stock plugins or compressors designed specifically for mix bus compression.
Even as common a tool as mix bus compression is, there are still plenty of questions and misconceptions about what it is and what it’s designed to do. Some newer producers may be avoiding it for fear of screwing things up for the mastering engineer while others are using it wrong – killing the dynamics that need to be preserved in a great mix.
So, what exactly is mix bus compression and how are you expected to use it in your sessions?
Let’s find out…
What Mix Bus Compression Is Not
Mix bus compression can do a lot of great things to enhance the sound of your mixes, but it certainly shouldn’t be used as a crutch or excuse for mixing a song.
Some mixers think that this is the case. They use mix compression as a shortcut to get from Point A to Point B, but they miss a lot of key elements of a good mix along the way. Yes – a mix bus compressor will catch stray dynamics across the entire mix. And yes – mix bus compression will glue things together. But trying to do all of that with a single plugin or piece of outboard gear is a recipe for disaster.
Instead of relying on the mix bus compressor to do the job for you, you should be taking an active role in mixing every song.
Panning, gain, EQ, instrument-specific compression, and other processing should be addressed on a track-by-track basis where you have the level of control that you really need to mix a song right. If it were as easy as putting a single compressor on the master fader, everyone would be mixing their own work!
The Purpose of Mix Bus Compression
The real goal of mix bus compression is to glue everything together after all other mix concerns have been addressed. By compressing your entire session at the master fader, you can bring up the softest parts and catch any stray peaks that only pop out when everything is summed together.
The net result is a smoother, more consistent mix - but even this requires a bit of moderation.
Unlike other stages of compression, mix bus compression should almost never be something that crushes your dynamics with a low threshold and aggressive ratios. Instead, we’re just looking to add some control and maybe a bit of color at the end stages of our mix like in this example from James Licata:
As you can see and hear, James uses BG-Mix to catch a few peaks and create a more consistent sound. He wasn’t crushing anything – just tightening the mix up.
This is going to be especially important if you intend to send your mix off to mastering. Mastering engineers won’t be able to do much with an overly compressed mix and may end up rejecting the work outright if the track is too compressed coming out of the mixing stage.
When To Add Mix Bus Compression
This has been and will continue to be an open debate, but there are essentially two trains of thought: you either add the compression right at the start of your mix session or you save it for the end. 
The crowd that supports adding mix bus compression at the start makes the argument that you’re able to mix more effectively into the compressor as part of your session’s signal chain. Any EQ adjustment, delay, reverb, or any number of other things you add are always building into the compressor – saving you any surprises at the end.
The other group of mixers think that having the mix bus compressor on from the start influences your workflow too much to be of much benefit. When you’ve got everything being compressed to some extent, you might miss certain things that you might otherwise hear. By adding it to the master fader at the end of the mix session, it’s just a final detail that enhances the work you’ve already done.
Personally, I lean toward the second group – especially for newer mixers who may not be familiar with their plugins yet. If you find that you’re constantly using the same compressor on the mix bus with similar settings for all your sessions, that’s when you might want to consider loading it up at launch. Until then, don’t assume you’ve got the experience to dial in that compressor perfectly at the start; mix without the compression and use it as a stamp of approval at the end of the session!
Using the Right Tools
If you work across multiple genres, it’s a bit of a challenge to find compressors that work well for mix bus compression. They’ll all get the job done, but if you’re looking for something that can add a bit of color, many mix bus compressors just don’t have that flexibility. They’re designed to have a specific sound and that’s it.
Knowing that many mixers today are working with rosters of artists that vary widely, we’ve built BG-Mix with multiple compression algorithms to make sure it has something to offer multiple styles. Whether you’re after a careful, transparent compression or a fearless and bold compression, it’s all available in this plugin.
