So audio on the far left appears identically in both the M and S signals. Using our formulas from earlier, we can see that Mid = L + R = x + 0 = x. Well, the left channel would have some amplitude (let’s say x), and the right channel would have none (so 0), because we’re talking about audio panned hard-left. Failing to understand how this overlap can manifest in your mix can result in severe and odious effects.Ĭonsider this: encode stereo audio into an Mid/Side matrix, and any audio that exists in the far left corner of your mix will be found in both the M and the S signals.

Mid/Side does not give you perfect separation between the center and the sides. But highlighting what Mid/Side actually is helps us illuminate a common Mid/Side mixing mistake:

The “sides” are also a mono signal: it comprises all the information from the left side minus the information from the right side (left + phase-inverted right).įull disclosure: there’s more that goes into the routing of a Mid/Side matrix that I can describe here (you can read more about Mid/Side matrices in this article). Since similar material is emphasized on both the left and right channels, the resulting audio will be perceived as mono. This ends up emphasizing things which are the same on both sides, and de-emphasizing things which are different.

What we call the 'mid' is actually the sum of the left and right channels. The better term for “mid/side” is arguably “sum/difference,” and here’s what I mean: Drum overheads and double-tracked guitars? Sides.īut this is not exactly correct. We think of Mid/Side as “mid/sides”-a way to separate the apparent center of the audio signal from the apparent sides (i.e.

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