A Deep Dive Into Stereo Width
Updated: Sep 8, 2022
Welcome to the fifth edition of my Pro Producer's Tips series! This time the topic is all about width, a fundamental parameter to understand correctly in order to give your productions and mixes the wings (as metaphorically the cover art of this blog post suggests) to fly and shine, like a metamorphosis and natural evolution from a premature and closed cocoon into a proud and beautiful butterfly.
I've done a pretty extensive research this time because I like to get deep and experiment to find out more unconventional and creative techniques, so it will be a very long post without the claim to be 'the ultimate guide to..' or 'everything you need to know about..' since, as always, knowledge is unlimited.
Because of that my humble goal is to inspire other people and artists with both my discoveries and common practices, so please feel free to comment down below your thoughts and anything that comes to your mind really.
Now it's time to start our journey, take a cup of tea or coffee, sit back and enjoy!
Understanding the principles
It's often said that a mix has three dimensions: height, depth and width.
Here we are focalising our attention on the latter one but keep in mind that these dimensions are correlated and not separate worlds: for example EQ, reverb and pan, while candidates to represent the aforementioned categories respectively, can influence more than one category at once as we will discover.
To put it in the simplest form, width in a stereo mix is achieved by creating differences between the left and right channel; in fact the mono channel represents what is shared and common between the two channels, while the side contains just the differential parts.
Now, how can you create differences between those two channels?
Actually, there are many many ways to do that, the only limit being your imagination once you have grasped the concept.
My attempt will be to provide you with a wealth of proved techniques to try for yourself so that you can go on and keep experimenting with a more clear vision of what you're doing and trying to achieve. Let's get started!
2. Width Techniques
- Autopanners & Rotary effects
One category of effects really useful to add stereo interest is autopanners.
Personally, I use them in every project I do because they are so effective and simple to use. The idea is to move some sounds in the stereo panorama in a rhythmic fashion, by syncing the movement to the tempo or applying free modulation.
As you may know panning in a DAW is achieved with volume differences between the left and right channel, so by moving a sound to the left you are getting less volume from the right channel and viceversa.
Later in this article I'll discuss how to create a psychoacoustic panner which sounds more natural and realistic, by constructing an Ableton rack which you can download for free ;)
In the following video tutorial you'll first hear a very centered DnB loop followed by a version of itself with some autopanners involved: to the hi-hats with a random LFO employed to create a more unpredictable movement, to the snare very slightly for a less repetitive stereo placement of each hit, to a pad with an automated slowing sync rate for a tremolo-like effect, to the bass with various sync rates for each part of the loop.
Keep in mind that when using autopan you are lowering the focus on the center of the stereo field so you may want to compensate for the loss in volume with an utility gain boost (usually from 1 to 3 dB based on how drastic you go).
In this example almost every element a part from the kick has been autopanned to show various scenarios and applications but in a typical situation you may want to be more subtle, because contrast in music is key as it is keeping the most important elements centered and focused.
Also be careful when using stereo effects to bass elements as they may loose mono-compatibility, a fundamental aspect I'll focus more deeply later, so a better idea would be to monoize the low to sub bass (like below 100 Hz) and apply some autopanning or other special effects to the frequencies above.
Be careful also with the stereo balance because for example a sine wave LFO in an autopanner creates an equal movement from left to right but other asymmetrical waveforms concentrate the effect more towards a channel than the other.
An other interesting technique to try with autopanners is using them with MIDI or audio triggers.
In reality this is great to try with any kind of effects like distortion, compression (the side-chain technique involves using an audio trigger indeed) and so on, because linking the movement and application of audio processing to a sound based on the timing event of an other makes for compelling sonic interactions.
In the video tutorial I used a MIDI trigger which clones the kick pattern to restart the cycle of the autopanner applied to a pad.
Some free autopanners I suggest to try, if your DAW doesn't have one, are PanCake by Cableguys and Panstation by Audio Damage.
- Width with Delay & Reverb
Delay and reverb are fantastic tools not only to achieve depth in a mix, but as we'll see width too.
You don't have to necessarily create an obvious delay or reverb effect to achieve width, you can be more subtle with short decay times.
With delays try slightly different settings between the left and right channel and hear how starting from a mono source you'll get a wider stereo image.
With reverbs, to achieve a similar effect, you just need the early reflections, which are short and give the sense of space, so shorten the decay times and late reflections if you just want the widening effect.
In the ValhallaRoom plugin, the Depth control sets the balance between early and late reflections so by turning it to 0% you are isolating just the early ones:
In more capable reverbs like this one you have a very deep control on early and late reflections separately, so you are able to customize the effect as you like.
Try for example a small size room mode with a high early reflections density setting.
Other parameters worth exploring are the pre-delay, which creates a separation between the dry signal and its wet version (responsible to give a clue of the size of the room too) and the stereo dial if present (in the Ableton's stock reverb it sets how much the reverberation is independent between the two channel, hence a much wider result).
For a greater control on the widening effect try to isolate and monitor the side from the mono with a Mid/Side encoder plugin like the free MSED from Voxengo and just listen to the added stereo information you have added, then you'll have a better understanding of what you are achieving.
In the following audio example listen to how the mono bells open up when using this widening technique with a reverb having a short decay time:
To achieve a similar effect using mono delays or mono reverbs you have to create two copies of the same mono source, hard-pan them left and right and apply the mono effect of your choice to one or both copies with different settings on each.
- Width with Modulation Effects
You can also create width using modulation effects like choruses, doublers, phasers, flangers, frequency shifters and so on.. the idea is always to create differences between the two channels without having to drown the sound into an obvious wet result.
Choruses and doublers can create a detuned effect similar to the microshifting technique that we'll explore later.
In Ableton try moving the 'Spread' dial in the Frequency Shifter by a small amount like +5 Hz with the 'Wide' button engaged: in this way the right channel is phase flipped to the left one, achieving a wide stereo effect.
The problem with this is that when summed to mono you can experience some weird results due to cancellations between the two channels.
Always check in mono after doing such tricks to fine-tune the effect, if you care about mono compatibility.
- The infamous 'Haas' effect
A well known technique you may have heard about to achieve a sense of width is the so called Haas effect.
This involves using a short delay time of less than 30 ms (an amount higher than this is perceived as a distinct repetition) to the left or right channel.
Also known as the precedence effect it relies upon the way we hear in real life: the time differences between the left and right ears are sonic clues that tell our brain the direction a sound is coming from. So if we apply a delay of, say 20 ms to the right channel only, we perceive the sound coming more to the left.
While this can be really effective to create a dramatic stereo widening effect, it must be noted that in mono you'll experience comb filtering and so a thinner, altered timbre because you are basically summing a sound with a delayed copy of itself.
The way you can counterinteract that is by doing this: create three copies of a mono source, hard pan one left, one right and the third one leave it centered.
Lower the volumes of the three copies and apply a delay with an effect or with a function like the Track Delay present in Ableton to one of the two hard panned copies with a maximum of 30 ms or so.
In this way, the centered copy, which is mono like the original, preserves the mid presence and so gives the haas effect more mono compatibility.
In the following audio example you'll hear the previous 'Agogo Bells' loop first mono, then with the Haas effect applied, and finally with the addition of the third centered layer:
I will stress more throughout this article the importance of mono compatibility and some techniques that can preserve that more.
The idea is always to apply slightly different processing to the left and right channels, but to have full control on the effect we can work on the side channel only as a layer to the mono (mid) source as we will see later.
- Stereo Enhancer Plugins
Now that we have a better understanding on how to achieve stereo width let's explore specialized plugins that do just that, or claim to increase it.
How do they work? They most probably will employ one or more of the techniques explored throughout this blog post, but I suggest you to investigate more deeply by reading the manual or the plugin's internal hint boxes.
If they sound generic, make some tests for yourself by comparing various stereo enhancers, listening carefully on how the sound changes when you crank up that 'width' control and take a closer look at vectorscopes and correlometers to also see what's going on and if something starts to go out of phase.
This will help you decide what's best for you.
Comparing plugins realized for a similar purpose is a great ear training exercise indeed, and you can do that with EQs too, for example using softwares like the Plugindoctor by DDMF or the free EQ Curve Analyzer by Bertom to help you visualize similarities or differences when using the same curves.
Some great free tools I suggest when doing the width enhancement test are Voxengo Correlometer, Izotope Imager 2, which has a dedicated visualizer and stereo spread feature too, and Flux Stereo Tool v3.
Talking about free stereo enhancers there are aplenty, like Wider by Polyverse (which I tested in the video and even at extreme settings remains mono-compatible!), Dimension Expander by Xfer Records (which works with micro-delays like the old FX from the gold Massive synthesizer) and Stereo Touch by Voxengo, but there are many many more.
One of my favourites is SideWidener by Boz Digital Labs and Joey Sturgis Tones and it's part of the CM Plugin Collection, which means you get it for free by purchaising any number of the Computer Music Magazine (yes, I've been a subscriber and reader for like seven years now, but I don't get any percentage by telling you this, it's my honest opinion since here it's my blog and the place for my own thoughts :P).
What I find cool about SideWidener is that it has three modes of widening with a diverse effect, it's quite mono-compatible and it also has an handy 'Tone' knob to concentrate the widened signal more towards the mid frequencies or leave it more open to the highs (like a filter applied to the side).
In the following video walkthrough I go over some of these plugins starting from the same source first turned completely mono, and you'll hopefully hear how many different width effects you can achieve, so that you'll eventually be curious about exploring more the ones that you already have in your toolbox, but also be more careful to not rely on them blindly, without knowing exactly what they are doing to your audio.
That's why sometimes they can be quick and effective when used consciously, other times it's better to do things 'manually' for yourself.
Among the paid-for softwares there are some pretty cool plugins I suggest investigating more like:
Cableguys WidthShaper, which has a lot of nice features for creating stereo effects;
United Plugins Expanse 3D, which tries to fill the three dimensions of width, height and depth in a mix;
Waves Brauer Motion, a 'circular stereo auto-panner' with four different panning modes;
Klevgrand Haaze, a simple to use yet clever tool for adjusting for instance panning and haas effect on specific frequency bands only;
Sound Particles Energy Panner which was given for free recently and looks pretty cool;
Goodhertz Panpot, a more advanced panner with psychoacoustics in mind (we will build our own at the end of the article!)
- The Microshift Technique
This technique involves using pitch as our variable for getting variations between the left and right channels.
So far we've explored time (for the Haas effect for example), level (for autopanners), space (using short reverbs, delays or modulation effects) as variables to employ in order to achieve width, but there are many many more as we'll see across this article.
If we consider timbre for a second, imagine how many different parameters you have at your disposal to modify it: the only limit really is your imagination.
For instance combining hard panned sounds in opposite directions with a contrasting and complementary tone is an other great way to achieve width, technique usually employed by guitarists for a wide guitar's wall of sound.
But turning our attention back to the microshift technique, as you can tell by the name, it involves creating very small pitch variations between the two channels.
If you want to do that manually try to shift the hard panned copies of a mono source by a few cents (1 semitone equals to 100 cents ) in opposite directions and listen to how the sound opens up without resulting in an obvious detuned effect.
Some plugins really good for that are MicroShift by SoundToys and Ultrachannel by Eventide, which has a dedicated 'Micro Pitch Shift' feature built inside it.
An other way to achieve a similar effect is by modifying formants, for example when time-stretching a sample you have at your disposal some controls to modify that (in Ableton, the Complex Pro time-stretching algorhythm has it got).
- Width with Phase
Let's look at an other fundamental parameter in audio: phase.
Understanding that is crucial also for grasping the concept of mid side encoding.
In the following walkthrough demonstrational video I've done some tests by duplicating a stereo audio track and working with panning and phase alone to achieve different results.
Ableton didn't have a proper dual mono pan since version 10 I believe, but now it has the handy 'Stereo Split Pan' feature that splits the single pan dial into two sliders to control separately the pan of the left and right channels of a stereo track.
What I've done first in the duplicate is turning the left slider to the right and the right slider to the left to invert the channels (I could use the Swap function inside the Utility's menu but I wanted to make it more visually clear in the video).
In this way when summing the duplicate with the original, by applying basic math, we are doing the following: L + R and R+ L , and since we've put the left channel to the right channel in the duplicate (and the other way around) we've monoize the result, because now the two channels share the same audio information.
(Remember that mono is also called mid).
Next I've flipped the phase of both channels in the duplicate so when summing with the original we are doing the following: L - R and R - L, so we are basically subtracting the two channels from each other, increasing the side.
This is an other effective technique for achieving width and if all of this sounds convoluted for you, a simpler option is to increase the side with a dedicated plugin which does the mid/side encoding internally like the free MSED from Voxengo, and decrease the Mid at the same time.
The final thing I've tried in the video is to sum the original with a phase-inverted copy.
You guessed it, that's the effect of phase cancellation: L - L and R - R.
An other technique you may want to try is flipping the phase of one send mono effect panned to the opposite way of the non-flipped send mono effect copy (in this way you are getting just side information from the send channel).
By doing so you are getting a wide effect when listening in stereo that cancels out in mono (remember that when summing to mono you are basically removing the side):
you get a dry and polished version in mono, where you have less space in the mix due to the channels collapsing into one, and a wetter, more compelling version in stereo: the best of both worlds.