Hello and welcome to this week's article! Today we're celebrating 10'000 visits to my blog, so I've made you a small gift, by updating many articles (such as the ones for Bass, Acoustic Guitar, Vocals...) with more precise settings in terms of Compression, Equalization, Reverb and so on, in order to make them even more helpful than ever :)
Today we're going to add another chapter in the Compression-themed articles, and talk about the Buss Compression. What is it? It's a Compressor loaded on the Stereo Mix buss, with very low settings, that if used since the beginning of the mixing phase, it will help us by giving the mix a more "glued" feeling, and will also make us use lower settings on the single instruments Compressors.
We must keep in mind that sometimes an instruments, e.g. the Bass, will need to pass through many compressors: the single instrument Compressor, or maybe a Compressor and a Limiter, the Buss Compressor, the Mastering Compressor, and the Mastering Limiter, so the various compression stages will stack up and in the end it will be VERY easy to have an oversquashed final sound. On the other hand, having more compressors stacked with lower settings, will lead if set carefully to a more pleasant result, at the same final level of compression.
It's wise to dial the single instrument compressors keeping already in mind (and in our monitors) the mixing Buss compressor, so we will have an immediate feedback on their interaction, thus we will not overdo with the single compressor settings: a slighly lower dynamic range on our mix will lead to less aggressive single compression settings, thus to a more effective and balanced Mastering phase. If the sound arrives already too squashed to the Mastering phase, we need to revert to the mixing phase and fix the problem :)
So, after this important introduction, let's talk about Business: the Buss Compression takes place right at the beginning of the Mixing Phase, and immediately after the Project Preparation Phase, when we have just the levels roughly balanced and the Panning set. Now take your Mixing Stereo Buss (sometimes called Master Fader, is the fader of your DAW that sets the output level of the entire mix), set it to around -10 to -6dbs to avoid any kind of clipping and to have a not too loud final mixed track, and put on the insert a Compressor, so that every single track will pass though it having its dynamic range slighly reduced.
Set the Compressor with low settings, for example an Attack of 30ms, a Release of 100 to 300ms (or, if possible, Automatic), a 2:1 Ratio, and lower the threshold enough to make it activate but without compressing everything.
The more aggressive is the music genre you are mixing, the lower you can go with the gain reduction, for example from 2,5 to 8db of gain reduction, (4db is the perfect "work with anything setting") but bear in mind that this needs to be compensated by using less aggressive settings on the single instruments, in order to avoid ruining everything :)
It is anyway still possible to mix without Buss Compression: we can just compress the single instruments we need and leave the others (like for example the cymbals) alone and then add the final Compression in the Mastering phase: the sound will be more dynamic, but less cohesive, and it will take a hard work of fine tuning to match the result of a project that uses Buss Compression. Often you'll find that if you want to leave some dynamics on your mix it's even better not to sum up mix buss compression with the Mastering one, therefore if the sound it's too squashed, once you have mixed with a mix buss compression, just turn it off and let the mastering compression to take its place.
Any Compressor can be used on the Mixing Buss (Multiband Compressors too, altough they are not suggested), but there are many dedicated Buss Compression plugins around nowadays, and the best ones (which are not free), such as the Waves SSL, recreates the sound of historical analog units, but there are also many Free ones, and among them, here are the best:
DC1A, effortless character compressor (nice sound, and only 2 controls!)