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Mid Side Mastering:
'E x p a n d i n g'  The Possibilities!

Mid Side Mastering:
' Expanding '
The Possibilities!

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What’s the attraction about Mid Side Mastering?

One of its potentials is to avoid the time, cost, and frustration of a remix.

Ultimately its use is to directly control the stereo image. It may simply be a need to preserve the original integrity of the stereo image after intense processing.

This topic is so charged, so potent, that it needs its own unique section on it.

But before I get in to it…

What is “Mid Side” itself first?

Mid side mastering (mid side anything!) applies to stereo signals only.

Mid Side separates and allows control of those stereo signals into the phantom center (Mid) and everything else (Side).

Here's a little "Stereo Audio - 101":

Stereo consists of audio signals for the left and right channel. When you're positioned between those two channels - or speakers - you can of course hear sound from the left and the right, and everything in between (and sometimes beyond). When both channels contain identical signals, and play back at exactly the same time, that signal appears to emerge from between the two speakers.

That is the phantom center.

This Part is Rather Important too...

To experience the effects of anything mid side, It’s important that you’re seated properly between the two speakers. You should form an equilateral triangle with your head and the two speakers.

So, one more time:

Music, in stereo, has different types and levels of left and right audio information. The more similar the information, the closer it appears in the center - the phantom center. Any information that appears in both channels at the same time and at identical levels comes from that phantom center.  

This phantom center is the MID portion of Mid Side Mastering.

It follows logically then that the SIDE portion is everything but the phantom center. You should also understand that there is an ongoing interaction between the mid and side portions of a stereo track: The mid and side signals heard alone by themselves - in isolation - become an entirely different thing as I'll point out later.

So mid side mastering refers to either working on the phantom center exclusively - the MID portion; or everything but the phantom center - the SIDE portion; or some combination of the two.

So What Can Be Done With This?

One of the most simplest things is to raise the level of the MID - the phantom center. This also has the result of narrowing the stereo image, or the level of the SIDE (everything but the phantom center). You can also look at this scenario as lowering the level of the SIDE. (This will have the effect at the same time of raising the MID - or phantom center). Your choice.

Or, we can increase the level of the SIDE. This opens up and widens (expands) the stereo image while lowering the MID portion (phantom center). Again you can also look at this as lowering the MID - phantom center.

Here's another important point to know:

If we continue to lower the MID portion til we don’t hear it anymore, we will of course have nothing but the SIDE portion. However - and this is critical - while the SIDE is defined as everything else but the phantom center, we are not left with a signal that has a distinct, pure left-only and right-only signal: we have an out-of-phase ‘wash’. This means there is no pinpointing or discrete location of instruments in this SIDE portion. And any processing on the SIDE only - like EQ for instance - is on this ‘wash’.

As I said before there is an ongoing interaction between the mid and side portions of a stereo track. It’s when MID and SIDE are combined that we hear the results we want. To understand this better and why this is happening, read the section on Mid Side Processing.

What's Covered In This Section?:

In addition to the overview on this page, I discuss this:

Mid Side Processing
Why Some Engineers Won't Do It
Mid Side Vinyl
Mid Side EQ
Mid Side Compression
Mid Side Limiting
Mid Side Software
Beyond Mid Side: Stereo Imaging
Advanced Stereo Imaging
Mid Sid Monitoring

The last item is - I feel - one of the most important and crucial aspects of the whole (stereo) audio production process. The term looks and sounds complicated, but in reality is really simple. Once you use it you’ll wonder why you’d ever mix without it. You’ll be way ahead of the curve with a foundation for a solid mix and have an immediate edge over anyone that chooses to ignore or misunderstand it.

So Is There A Secret To Mid Side Mastering?

Well if there is one, it’s knowing - not - how to use it, but when to use it.

That comes from experience.

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