There’s a case to be made for ‘sweetening’ your mix bus. Many mixes can benefit from some subtle processing to bring out the best qualities of the tone of the mix and to use dynamics to give the mix a more compact, controlled sound.
To bring out the best qualities of the tone of the mix, an EQ is the most appropriate tool. For this task, however, don’t reach for your highly-flexible ten band fully parametric equaliser. Instead, go for something with character and vibe – not just in sound, but in workflow. The idea here is to use something with fewer controls, but where each control does something interesting. The recent Pultec-modelled EQ plugins are a good choice. The reason for this is that this tonal adjustment isn’t a corrective task where surgical precision is requied. It’s artistic, impressionistic. You’re trying to be creative, to add colour, to make it interesting.
To use dynamics to give the mix a more compact, controlled sound, compression is the most appropriate tools. Unlike individual track compression, the best results here are achieved by being subtle. You don’t want to completely change the dynamic behaviour of the mix. Instead, focus on less than 3dB gain reduction, and configure the compressor to simply ride the gain. Use high ratios when you want a pronounced effect, particularly on mixes with very little dynamics (such as rock music or dance music that is almost always at the same level). Use very low ratios for more dynamic music (coupled with a lower threshold to catch the lower-level audio). Faster attack and release times will produce a more pronounced effect, whereas slower times will be more more gentle and transparent.
The real tip here, however, is to do all this at the mix stage – not mastering. The mix is where you’re focussing on creative sound adjustments, on making the song sound special. Mix bus processing clearly fits here. Mastering, by contrast, should be as transparent as possible – focussing on preserving the creative decisions that were made during mixing and translating that sound to the target playback format.
The best time during mixing to apply this sweetening is at the very last stage – after reverb and panning, just before rendering or recording the stereo mixdown. This is when you’ll have the best perspective to apply processing to the overall sound. Otherwise you may end up chasing your tail in circles as further track-level changes necessitate mix bus changes.