Mastering in the mix…
Why do we need a separate mastering stage at all? Why not simply add your mastering plugin chain to the mix bus, and mix and render the final product in one step?
Well, many important aspects of mastering aren’t addressed with this method. You won’t be able to tell whether or not your final mix will fit with other songs on the same album. You won’t have the ability to set the spacing between songs. You’re also, of course, mastering your own mix, which – until you’re confident in your abilities, at least – may not be the best course of action.
If you can’t be a different pair of ears, you can at least be a fresh pair of ears, and save the mastering stage for another day. The longer the gap you can leave between mixing and mastering, the less chance your mastering decisions will be coloured by your memories of mixing. You can also take the time to listen to the mix in other rooms: checking it on your living room hi-fi or in the car will help to inform your subsequent mastering decisions.
So, processing the mix bus isn’t really ‘mastering’. But don’t let that stop you if it makes your mix sound better. Compression and saturation react very differently when applied to a full mix, and can give you a sound you would never get by processing individual channels, so don’t be afraid to throw these on your two-bus while mixing.
Also, aside from a quick ‘loudness test’, we definitely suggest leaving your final limiting to a separate mastering stage, so that it can be judged in context with other songs on an album or EP.