Studio One: Mid-Sides Processing

The top and bottom Mixtool modules are encoding and decoding between L‑R and Mid‑Sides stereo, respectively. The Splitter tool then lets you process the Mid and Sides components separately.

Mid‑Sides processing is your gateway to creative manipulation of stereo sources.

Mid‑Sides processing is an easy way to do interesting things to stereo signals. Engineers have been doing it since the 1930s but sometimes it still feels a bit like a dark art. Studio One has been able to process the Mid and Sides components of stereo signals independently for a very long time, and the process has been streamlined over the last few versions. It’s the sort of thing that should be in everyone’s mixing toolbox and I’m going to show you how to make best use of it in Studio One.

What Is Mid‑Sides (M‑S) Processing?

It’s a neat idea where a stereo (Left‑Right) signal is matrixed into an alternative two‑channel format where one channel contains all the information that’s common to both left and right, whilst the other channel describes how the two differ. The Mid is also known as the Sum, because it’s the sum of the left and right channels; and the Sides signal is sometimes called the Difference, because it’s derived by subtracting the right signal from the left. So the Mid signal will contain everything that’s the same in both the left and right channels, and the Sides will lose anything that’s the same on both sides. If the left and right channels are identical, as they would be if you upmixed a mono recording to stereo, the Sides component will be silent as there’s no difference to represent.

Once a stereo signal has been converted to Mid‑Sides, you can process, compress, EQ, effect and generally mess around with those two parts separately, before it all gets put back together as a stereo signal. Centre‑panned mono sources such as kick and snare drums, bass guitars and lead vocals tend to feature predominantly in the Mid channel, and so M‑S lets you process those elements of your mix independently of widely panned elements such as hi‑hats, guitars, brass and keys.

Applying EQ cuts to the Mid component of an instrument can help make room for the lead vocal in a mix.

Mixtool

The key to working in M‑S in Studio One is the Mixtool. It’s a useful little plug‑in that can do a number of things, but what’s interesting here is that it will do the M‑S Transform for you in both directions (encoding and decoding). You’d typically insert it before the plug‑ins you want to use for processing and again afterwards so that you get the stereo mix back.

So, start with your stereo track of whatever you want to play with. Drag Mixtool across from the plug‑in browser and hit the MS Transform button. You’ll now hear your mix split differently left and right, with your mono and central parts on the left channel and your wider parts on the right channel. Drop another Mixtool in after it, or copy‑drag the existing one, and normality will be restored to your mix. Now, anything that goes on...