Buss compression is one of the most effective techniques in mixing, but also one of the easiest to get wrong. This is a guide for those new to the discipline, wondering where to get started.
What is buss compression?
Simply put, buss compression is slapping a compressor over a stereo buss. Most commonly this is used on drums and on the master buss, but it can be used on anything.
The idea is to compress everything at once, making it sound more cohesive. This is why it’s particularly popular on drums where each part can sound oddly separate from the others.
What compressor should I use?
Any stereo compressor can be used although some work better than others. Buss compressors are the subject of much adulation as some impart a certain ‘magic’ that others don’t.
Try out everything you’ve got and see what works best for you. My favourite buss compressor for mix work is the Stillwell Audio Bombardier, but I’ll also often use the Fabfilter Pro-C for something a bit more transparent.
If you’re looking at analogue emulations, buss compressors usually fall into two camps: gentle and slow in the vein of classic tube compressors like the Fairchild 670 and the Manley Vari-Mu, or fast and punchy in the SSL tradition.
If you want to put buss compression over a group, send everything in that group to its own buss. So if you’re doing drums, route the kick, snare, hi-hat etc. to a stereo buss and stick your compressor over that.
Basic buss compression is all about using a gentle squeeze for a sense of cohesion:
- Use fairly slow attack and release times – 30-50ms attack, 200ms release
- Low to medium ratio – 1.5:1 to 2:1
- Set the threshold for no more than 2-3dB of gain reduction.
This works with anything you want to add a sense of ‘togetherness’ to – drums, double tracked guitars, backing vocals, strings. Good buss compression is that mythical ‘glue’ you hear so much about.
For a drum buss feel free to go anywhere up to 6-10dB of gain reduction to achieve ‘pumping’ – when the kick triggers compression in the higher frequencies to add more movement and a real smack to your kit.
Mix into or add after?
You may need to compress individual elements of the group as well as the stereo buss. This is fine, but the best advice here is to apply the buss compression first and then work backwards. Doing it this way makes you far less likely to over-compress.
Next time – master buss compression