How To Use Mid Side Mixing To Get Fatter, More Powerful Mixes

Mid side processing is one of those topics that isn't well understood by a lot of music producers despite being very common in modern plugins.

Or if you more or less understand it, you may not know the subtleties of it and what it's limitations are, so you're constantly guessing as to when to use it.

You also could have landed here because you got a deal on some sweet new plugins that has have mid side buttons everywhere and no idea when to push them.

But no worries, you're in good hands! By the end of this article you'll have a better idea of what it going on and when to use what technique to get your mixes sounding huge with mid side techniques.

What Exactly Is Mid-Side Processing?

The short answer is mid-side channels are an alternative way of representing the stereo information in audio. There is a middle channel and a side channel instead of left and right channels.

The middle is a mono signal and the side channel is only the material that is different. A more technically accurate way of describing this instead of Mid/Side would Sum/Difference.

Huh?

Left and right channels vs Mid and Side channels

You probably are comfortable with thinking about stereo recordings as left and right channels.

This makes intuitive sense. Half of what you hear comes out of the left speaker and and the other half comes out the right speaker. You can mute one side at a time to isolate what is happening in the right channel or left channel and get perfect separation.

An element like a snare drum that is panned dead center will live in your mid channel and have very little or no information in the sides, unless you've added stereo effects like reverb.

However, a wide stereo signal like a synth track or a full drum kit will have both mid information as well as a bunch of things only happening in the side channel.

Mid and Side Separation Is Not Perfect

You don't get perfect split between the middle and side channels. There will always be a bit of overlap and that is helpful to know when choosing to use a M/S tool or a more conventional one.

This is a simplified explanation of what is going on, but if you want the really nerdy details in all their glory, this article is a good source: https://www.soundonsound.com/sound-advice/q-how-does-mid-sides-recording-actually-work

Why Does Mid Side Matter?

The advantage to this way of dealing with stereo information is you can process the stereo image of the sound differently than the mono component which let's you fix otherwise unfixable problems, find ways of achieving bigger perceived width instead of using typical stereo widening plugins, or get totally crazy when you're doing sound design and looking for new creative territory.

If this sounds complicated to do, no worries! It's not.

To use mid side mixing, you can set it up easily with basic phase flip plugins built into your DAW. And plenty of modern plugins have built in mid side switches that do this part for you.

How Do You Use Mid-Side Processing During Mixing?

There are tons of possibilities here, but a common one is helping to resolve issues with conflicting frequencies that more conventional techniques don't solve for.

Say for example you have a bright lead synth playing over cymbals that are also pretty bright with a lot of energy in the high frequencies. They sound fine soloed, but together its too much.

What are your options to fix this? You might try just picking one element to be the the brighter thing, throw a high pass filter on the other, then call it a day. That's certainly one viable option.

But having mid and side signals gives you another dimension to experiment in.

You could try cutting some high end in the sides of your lead synth and cut some highs from the mid channel of your cymbals as a basic solution. Maybe you even automate the EQ to only happen during problem areas.

How to Use Mid-Side Processing When Mastering Music

A lot of mastering engineers don't actually do a lot of mid side work unless they have to!

Mid side processing can be a bit of a heavy handed technique at times and a mastering engineer's job is not to dramatically reshape a track. They are there to help it shine and be it's best.

With that said, sometimes a boosting high frequencies in the side channel with a high shelf filter can be pleasing. Or if there is a resonance somewhere in the frequency spectrum that is confined to either the mid channel or sides, it makes sense to use a mid side tool for that job.

When NOT To Use Mid Side Mixing

Before we talk about all the cool things mid side mixing can do to make a mix sound fuller and spice up your audio production, it's worth mentioned situations where this might not be the tool for the job.

Mix Bus Compression

It might seems like a cool idea to compress the sides of a full mix to get a wider stereo image. Make the stuff that adds width perceptibly louder and then instant presto way huge happy mixdown down time, right?

No.

Compressing the middle differently than the sides usually gets strange and not in a cool way because certain elements can start to be pushing in conflicting directions.

Try it for yourself of course, but a standard bus compressor usually sounds better in this scenario. Mid side compression is much more using for sound design purposes in music production.

If you want to use mid side mixing to create stereo width, a gentle mid side EQ is often a more natural sounding too.

Fixing Mix Problems

If you run into a problem that can be fixed in the mix, fix it in the mix. No reason to overcomplicate things.

Yes, sometimes more sophisticated techniques like M/S processing can get you out of trouble in a pinch when you don't have access to the original stems or something, but this is usually inferior to just getting to the root of the problem.

The biggest argument here to tread lightly is it is very easy to introduce phase cancellation problems with mid side processing that just wouldn't happen with conventional stereo gear.

When Things Are Already Overcooked

It's super easy when a mix sounds muddy due to over processing and try to carve out space in the mid frequencies or undo damaged from overuse of stereo width plugins, but this usually doesn't work.

You might be able to open things up a bit, but overall, overcooked is overcooked and adding more plugins and processing is usually not the way out of this problem.

Adding Stereo Width to Create a Fuller Sound

Let's start with stereo widening. There are dozens of stereo imaging plugins and stereo expansion tools that promise a wider stereo image.

Many of them work in a similar way: you have two signals for right and left, then the plugin delays one channel slightly to introduce some phase cancellation in the center and give a feeling of wideness.

This can work, but mid side opens up some new techniques to get us there. You can then choose which one makes the most sense.

A great way to get started is to use your mid side EQ to shape the mid band frequencies a little differently. For example a lot of the mid range fatness in drum sounds, guitars, synths, or background vocals lives in the sides of the low midrange.

Is Delay-Based Stereo Imaging Mid-Side Processing?

They're similar. Try both. A gentle EQ boost in this area can be smoother and less colored than a stereo widener plugin in many cases. A/B them both and roll with the one that feels better for a given mix.

Where To EQ For Width In A Mix?

When you hear a mix as being big, wide, fat, spread, or whatever you want to call it, it's important to remember that information is getting to you from some parts of the frequency spectrum, but not others.

The highest of highs and the sub bass regions are not it! The bass is very important to make a track sound full and have weight, but the mid range frequencies are the dominant frequencies where wideness really lives.

Stereo Track Mid range Frequencies

Most of the qualities we hear in a mix live in the middle frequency range, simply because the midrange is the majority of what we can hear.

So when you're working the stereo field with mid side processing to make a mix feel bigger and better, focus your efforts here before you treat more specific issues in the extreme ends of the frequency range.

Want To Improve Your Bass With Mid Side Processing? Ignore the influencers!

The Bad Advice

We find that the social media influencer crowd loves explain techniques that sound good in a video and made for enticing clickbait, but in practice don't work very well.

One example of this is the numerous YouTube videos where people use a low end filter to scoop out all the low frequencies in the subwoofer range in only the side channel to "clean" the low end frequency range.

Please stop doing this unless you have a clear reason for it.

Why This Is Silly

The rationale here is that you want the bass to be a more or less mono signal to avoid phase problems in the low frequencies, especially when printing to formats like vinyl. So use the mid side EQ to scoop out all the stereo stuff, right?

We would said no because this is usually fixing a "non problem". Listen to commercial recordings with the side channel soloed if you don't believe us.

Many big records have all kinds of stuff going on in the 80Hz range and below, in the side channel. Usually at a significantly lower level than the mono signal so it isn't stepping on anything important.

Sometimes not though. Everyone says this is a party foul, but if it was that bad, why does so much successful music production (that we legitimately love!) just let this fly?

Clearly these engineers thought it was better to just leave it alone otherwise they would take it out like the YouTubers are suggesting.

Proof In The Pudding

If you were having significant problems with side channel information in this range, you should absolutely go back and fix this in the mix if at all possible.

The other reasons this technique is silly—you may be creating low midrange problems that need to be fixed with other plugins.

The knee of any filter is always going to have some resonance due to the phase shift inherent to how a filter works.

We're all for using unorthodox techniques as long as they work, but we've tried this a zillion times and it usually doesn't help. Or if it does it sounds cleaner to just fix whatever elements are adding extra sound in the sides.

What You Should Do Instead

Try lightly attenuating low frequencies with a mid side EQ instead a little higher up, closer to the low mids. 100-500Hz is probably a good range to start.

Use a bell filter and experiment with EQ moves +/- 3dB to see how that opens things up. Some EQs allow you to flip between stereo and mid side mode so use that feature!

Work The Low Mids

When a mix feel crowded and stuffy in the low mids, often a cut in sides will be more transparent that a cut of everything. You get to unclog some of that stuffiness and you don't lose punch in the mix. (Remember that a lot of fundamentals for elements like drums live in this range)

This can give clarity to your low sounds and sometimes remedy a master bus compressor that is getting too pumpy from the energy down there.

Homebrewed Mid Side Processing: How To Make The Encoder Yourself

You can make any plugin you want. You just might need to separated the mid and side channels yourself.

Thankfully, most modern DAWs have a built in stereo phase tool of some kind we can use.

It's highly recommended you try this at least once. It will show you what is actually happening when you engage a mid side plugin and give you a better sense of when this is the tool for the job and when it is not.

This can be done in basically all DAWs, but we like Ableton Live here so that is what we will be using because the racks and Utility plugin make it very simple to do.

To Make The Mid Encode.

This is easy. Take a Utility plugin and set it to Mono. Done.

Make the Side Encode/Decode

Take a Utility plugin, set it to Mono and invert the polarity of one side, but not both. Put another Utility plugin immediately after it, leave it in Stereo, and invert the same side on this instance as well. It's very important that both instances are inverted on the same side, so either both Left or both Right, doesn't matter as long as it is the same.

Combine the Two

In Ableton, the easiest way is to make an effects rack with a two chains labeled mid and side, respectively. Other DAWs may need you to route differently or have two tracks that feed into a bus or group.

If you want to apply an effect only the mid field, put it on the respective chain (or track) after your mono channel plugin. If you want to affect the side field only, you must put your effect plugin between the two Utility plugins on your side channel. For example if you wanted to apply Reverb to the side, the signal chain would be Utility #1 > Reverb > Utility #2.

Here is an example:

Thanks for reading!

Hopefully this has given you a better understanding of when mid side makes sense to use and when it doesn't.

Before you go, don't forget to check out out sample packs and playable instruments and use them to experiment with mid side mixing when you use them!

If you check out the sign up box at the bottom of the page you can get some free sounds from us to get you going.