When making a wide mix, phase cancellation will need to be used in one way or another to push the signal into the 180-degree stereo field. Mid-side processing is a great way to widen a mix if your stereo track has varying left and right channel signals.
Before we look into the techniques you can use to get a wide mix, let’s first cover a couple of essentials.
The stereo field is comprised of 3 primary sections. Let’s consider 0 degrees, which is everything that is mono and completely centered, 90 degrees which is everything to the far left and right and everything in between, and 90 - 180 degrees, which is what we perceive to be mix width.
Panning can only place a signal within the 90-degree field, and phase cancellation is required to access the 180-degree field. The exception to this is when panning 2 similar signals - phase cancellation between the 2 will cause some signal to move into the 180-degree field.
Let’s listen to panning that places the image between -45 and 45 degrees, or within the 90-degree field, and then delay processing that accesses the -90 to 90 degrees, or the 180-degree field.
The mid image is everything that is identical between the left and right channels in a stereo signal, this is sometimes referred to as phantom mono. The side image is everything between the left and right channels that are different - a processor isolates the side image by L + R∅.
By combining the left channel with a phase inverted right channel, we use phase cancellation to nullify or completely attenuate any information that’s identical between the 2, resulting in what’s different, or, the side image.
Let’s quickly isolate the mid and side images to get a better understanding of the signals that they contain.
With a better understanding of the important concepts from chapters 1 and 2, let’s insert a mid-side EQ on an instrument - I’ll use Logic Pro’s stock EQ and switch the processing to the side image. If I amplify any frequency on the side image, I’ll make that range wider.
So if I want my drums to have a wider high range, I’ll create a high shelf and amplify the highs. Apply this concept to other instruments and you have a quick way to widen a mix.
Let’s take a listen.
In chapter 1 I stated that panning can access the 180-degree field if you pan 2 very similar signals. If we don’t have this set up in our mix we can emulate this by duplicating a signal, panning both hard left and right, and then varying the processing on each.
For example, if I want a guitar to be wider, I’ll duplicate, and pan each, and then I could EQ one and not the other, or maybe EQ different frequencies.
Let’s take a listen and notice how the image goes from being phantom center, since the signal is identical, to a mix of different stereo placements.
Getting a wide vocal may seem impossible if it’s mono, but it’s really not too difficult to accomplish. If we use a stereo temporal effect like delay or reverb, the reflections on the left and right channels will vary, causing differences between the 2 channels.
With the differences, we now have a side image on our vocal, that we can amplify, while the majority of the vocal stays centered and focused.
So let’s use reverb on a vocal to create a side image, and then amplify the side image more with mid-side EQ.
Although you can use mid-side compression on any stereo signal with varying left and right channels, it works especially well on drums. Mid-side compression measures the mid and side signals separately, which often results in the mid image being compressed more than the side.
Whenever the mid image is attenuated but the side is not, there will be more side image signals respective to the mid, resulting in a wider image.
Let’s take a listen and notice how the effect both controls dynamics and widens the image.
When I’m mixing this is my favorite way to find a unique placement for something in the 180-degree field. All I need to do is insert a sample delay on a stereo channel, and increase the delay of one of the channels by a few milliseconds.
If we run a sine wave through the delay, we’ll notice that more delay doesn’t mean a wider image, just a different placement. So if you listen carefully when applying it you can find just the right spot for the signal.
Let’s take a listen.
When mixing or mastering, I sometimes like to separate the mid image and side on different tracks or on a parallel signal, so that I can process it individually. One way to do this is to send a stereo signal to an aux track, and use the free plugin MSED.
With the plugin, I’ll mute the mid image, and then add processing. I like to add some form of upward processing like maximization or upward compression to really get the details for the side, before blending in the signal with the Aux track’s channel fader.
Let’s take a listen.
Let’s use the same setup as the last chapter, but this time instead of an upward processor, let’s use transient expansion. Since the side image usually has a fair amount of reverb and other temporal effects, transients are almost always lacking on it, making this a really cool effect.
Let’s take a listen to this effect on drums and notice how it really augments and widens the instrument.
Some mastering and mixing plugins and hardware like to make stereo imaging more mystical or convoluted than it needs to be. For example, on the Neve master bus processor, you’ll notice a dial called Depth - this is really just a shelf or bell filter on the mid image.
Or on the Acustica Celestial plugin, the Dimension dial simply amplifies or attenuates a low-shelf filter on the side image.
Don’t get me wrong it’s a great plugin, but it’s something that could be replicated with a mid-side EQ once you know what the effect is doing.
Let’s see if we can get the same stereo imaging as Celestial’s processing by using a mid-side EQ.
