Last time we looked at the basics of buss compression – what it is, where to use it, and what compressor to use. This time we’ll be looking at master buss compression: a subject that flummoxes many budding engineers but that is essential for cohesive mixes.
What compressor should I use?
Compressors built for the master buss are subject to much adulation, mythology and devotion. Everybody has their own favourite so the answer really is to download as many demos as you can and try them out.
The same rules apply as for mix buss compressors (and really they’re generally the same models/plug-ins). There are the fast and ‘grabby’ models in the tradition of the SSL G series and the more gentle ‘vintage’ style.
Probably the most popular software master buss compressor at the moment is the Waves SSL G-Master Buss. But a cheaper alternative (just as credible, and preferred by many, including myself) is Cytomic’s The Glue.
Famous hardware compressors used for the master buss include API 2500, SSL G Series and Smart Research C2 in the fast and grabby vein, Manley Vari-Mu and Thermionic Culture Phoenix in the slow and gentle tradition of the infamous Fairchild 670.
Try out various software emulations and you’ll quickly get a feel for what style of compressor you prefer.
Why compress the master buss?
Master buss compression is most often cited as necessary for ‘glue’ i.e. a sense of cohesion. It’s often talked about as ‘what makes a record sound like a record’. Good use of master buss compression will give a mix definition, punch and depth.
When you first experiment, you’re listening mainly for all the parts gelling together, sounding like one piece of music rather than separate parts. As you get more confident you’ll learn to use slight pumping to introduce movement and punch – but be careful not to overdo it. As with all use of compression, too much can result in everything sounding flat and unexciting.
How do I set it up?
Needless to say, the two different styles react very differently and so require very different settings. This again is subject to much individual style. It’ll take a few mixes for you to zone in on your own personal favourites, but when you get them you can save it as a preset so it’s all set up when you start mixing. Always mix into your compressor rather than slap it on afterwards.
When mixing, I tend to set up The Glue with the following settings:
- Threshold -14dB
- Attack 30ms
- Release 200ms
- Ratio 2:1
- Sidechain HP filter at 100Hz
I then mix so that the needle is just about pushed by the kick. If I want a gentler compression I use Stillwell Audio’s Bombardier using the following:
- Threshold -20dB
- Attack 40ms
- Release 200ms
- Ratio 2:1
- Feedback/forward depending on the song
Again, there should be no more than 2-3dB of gain reduction – just enough to achieve depth and glue.
The advantage of having a set threshold to work to is that you end up with mixes that are roughly the same level, without having to turn it down to prevent clipping. It gives you a good starting point for your kick and vocal to act as reference levels for everything else.