If you’d like to go back and check, go ahead! If you think back to our breakdown of how level and polarity determine position in mid/side recording, you may have noticed that the only difference between left and right was a reversal of polarity in the side channel. Lastly, before we get on to the juicy bits, let’s talk about that phase thing a little. We’ll come back to the ramifications of this in a bit, but this is important, so try to internalize it. Yup, that’s right, hard-panned elements are split 50/50 between mid and side, and it’s only in the absolute dead center that sounds drop out of the side channel entirely.

Decode from mid/side back to left/rightīefore we get into the how and why of using this in mixing or mastering, there are some important details to be aware of.

Process mid and side channels independently.

In any event, this gives us a pretty good picture of how a mid/side-capable plug-in works. This can be done at the encode or decode stage, or even split between them. After all, if you just keep adding signals together they’ll just get louder and louder. Technically there’s also some gain compensation in there. To get from mid/side back to left/right-also know as a mid/side decode-is equally trivial: In this context, subtracting a signal really just means adding a polarity-inverted version (hint, hint, remember the polarity difference between the front and back of the figure-eight mic?). The simple version of what’s know as a mid/side encode is this: However, a little understanding of what’s going on under the hood here goes a long way, and it’s also not terribly complicated. So if you want to apply mid/side processing, how do you convert from left/right to mid/side, and back? Luckily, this isn’t something you really have to worry about since pretty much any plug-in that offers mid/side processing will include the conversion-also known as a mid/side matrix. I’m willing to bet that when you create or receive stereo tracks they’re in left/right format rather than mid/side. But how do you do this, and why would you want to? Glad you asked. To answer the titular question then, mid/side processing is the practice of applying processing-EQ, compression, saturation, etc.-to the mid and side channels individually. The polarity relationship between mid and side determines whether a sound is to the left or right, and the level balance determines how far in that direction it is. A little of this can sound exciting, but too much can quickly sound very weird, and has implications in mono.Īnother way to think of this is that the mid mic captures everything, and the side mic encodes the direction of each sound.

If level in the side channel becomes greater than in the mid channel, the stereo position can appear to move “outside the speakers”-left of hard left, or right of hard right.

As level drops in the side channel compared to the mid, the stereo position moves toward the center (polarity still determines left or right).

Signal in the side channel only = wonky (in practice this doesn’t happen).

Equal level but opposite polarity signal in the mid and side channels = hard-panned right.

Equal level and polarity signal in the mid and side channels = hard-panned left.

Signal in the mid channel only = center-panned.Here, a sound’s stereo positioning is determined by both the level and polarity relationship between mid and side. In mid/side recording, things are a little different. And of course different balances of left to right can give us positions anywhere in between.Signal in the right channel only = hard-panned right.Equal signal in the left and right channels = center-panned.Signal in the left channel only = hard-panned left.If you’ve ever used a pan knob this probably feels pretty intuitive, but to state the obvious: In left/right stereo recording, a sound’s position is determined by its level balance between the left and right channels. This is very important, as we’ll see later, but back to the matter at hand. It’s worth pointing out now that the two sides of a figure-eight mic have opposite polarity to one another.

But hopefully stereo