Q. Can you explain what a submix is?

Sound Advice : Mixing
 

I’ve come across the term ‘submix’ a few times recently. I can guess at what it means, but would like to know for sure. Can you explain?

Tony Quayle via email

SOS Reviews Editor Matt Houghton replies: A submix is simply mixing tracks down to ‘stems’, or sending them to group buses. For example, you can route all your separate drum mics to a group bus so that you can process them together. You’d call that your drum bus, and if you bounced that down to a stereo file, that would be a drum submix. Using buses in this way is very common indeed, whether for drums, backing vocals, guitars or whatever, because it means that you can easily gain control over a large, unwieldy mix with only a few faders.

A submix is simply a way of sending several tracks to a group bus. This enables you to process the tracks all together. In the example shown here, a compressor is being used on a side-chain input, causing the whole submix to be ducked by the kick drum.

These days, there’s rather less call for submixes, particularly now that you have the full recall of a DAW project. However, they can still be useful in a few situations, such as providing material to remixers, or allowing you to perform ‘vocal up’ and ‘vocal down’ mixes if you’re asked to. Bear in mind, though, that if you’re using any processing on your master bus (for example, mix compression), you can’t simply bounce each group down on its own and expect to add them all back together to create your mix; the bus compressor will react according to the input signal. You’d have to bypass bus processing when bouncing the submix, and re-do any such processing when summing the submixes back together.  

Published in SOS July 2011