Greater Mix Width With The Upside-Down Triangle Concept

Stereo width is a staple in modern, professional mixes. However, there's a fine line when it comes to width in the mix.

• Too little, and we lose out on the potential for dimensionality.
• Too much, and the entire integrity of the mix falls apart.

It's certainly not the only strategy, and may not even be the best strategy for you. However, I think it's worth examining, and in this article, we'll do just that.

If you prefer video format, I have an accompanying video for this article that you can check out below:

---

The Upside-Down Triangle Philosophy For Mix Width

Imagine an upside-down triangle representing your track's frequency spectrum.

The low end, at the triangle's base, should remain narrow (mono) for solidity. As you move up to the higher frequencies, you can gradually increase the stereo width, giving the mix an open and airy feel.

Here's a simple diagram to show you visually:

This general philosophy is based on our natural hearing and can act as a guiding principle for achieving width in the mix. It's far from perfect, and may not yield the best results, yet its underlying idea is worth adhering to.

Let's start with the low end. Humans have difficulty locating the source of low-frequency sounds because of the long wavelength of bass frequencies. As the wavelengths become longer than the distance between our ears, we lose the ability to properly detect their direction.

Since we can't easily discern where bass sounds are coming from, having them in stereo doesn't provide the same spatial benefits as it does for higher frequencies.

Furthermore, to have stereo information, we need phase differences between the left and right channels. These phase differences will cause the channels to interfere with each other by way of destructive and constructive interference.

Excessive stereo separation in the low-end frequencies typically doesn't result in a perceptible stereo effect. Instead, the phase differences between the left and right channels can lead to inconsistent bass levels. As a result, it's advisable to maintain the bass frequencies in mono to ensure a stable and consistent low-end in the mix.

Things change, naturally, as the wavelengths of sound waves become shorter than the distance between our ears. At this point, our complex auditory system can indeed begin to identify the directionality of sound.

Translating this to our mixes, it means that the midrange and upper frequencies can be pushed wider, as we naturally hear them with a greater sense of directionality in the real world.

In general, our ability to localize sounds increases at frequencies above about 1 kHz. The ear nearest the sound receives a stronger signal than the opposite ear. Additionally, the ear on the far side of the head hears the sound slightly later than the near ear. With shorter wavelengths, we can naturally process the differences in phase and identify the direction of sounds.

At very high frequencies, the wavelengths become so short that the differences in phase between our ears change at incredibly fast rates. Detecting the direction of such sounds, then, becomes more about the differences in level between the ears.

With that, we can push the top end of our mixes wider to achieve an open brilliance range without having them necessarily fall apart (the phase differences between the left and right channels will be difficult to manage, anyway).

With that information, we can imagine the utility of visualizing the upside-down triangle for mix width, with the low-end frequencies at the bottom and the high-end frequency at the top.

---

Stereo Width And Mono Compatibility

A seemingly well-crafted stereo mix in a studio might not translate well on mono systems, leading to a degraded listening experience. Mono compatibility is always an important consideration, and we must mix in a way that will translate to a variety of playback environments and systems, notably mono systems.

The long wavelengths of low-end frequencies are perhaps the most susceptible to phase interference (constructive and destructive) because of the time it takes for a complete cycle to pass. If you have a lot of stereo information in the low end (differences between the left and right channels), then summing the stereo mix to mono will likely lead to a thinning of the mix as the low-end frequencies experience phase cancellation.

That's another big reason why bass frequencies tend to work best in mono. Note that I state “bass frequencies” and not necessarily “bass elements”, which will have midrange content as well — I love a great stereo-chorused bass guitar.

Moving onto the midrange elements, any tracks that are hard-panned or have a lot of stereo information will sound quieter when the stereo mix is summed to mono. However, when mixed correctly, they should cause the entire mix to fall apart — it's just part of the game, making great stereo mixes that also translate to mono.

So the upside-down triangle, once again, can be used as a simple visualization for stereo width, this time in the context of mono compatibility.

---

Practical Application Of The Upside-Down Triangle For Mix Width

Beyond the philosophical and theoretical, we need to be able to do something with the concept of the upside-down triangle. Let's talk about practicalities here.

Maintain Phase Coherence

Use correlation meters to check phase alignment. This ensures your mix remains intact when played in mono.

A phase correlation meter is a tool used in audio engineering to measure the phase relationship between two audio signals on a scale from -1 to +1.

We'll use phase correlation meters to measure the phase differences between the left and right channels of a stereo mix and, by extension, the “width”.

A reading of -1 means the left and right channels are completely out of phase (they'll cancel each other out when summed to mono) and a reading of +1 means the left and right are completely in phase (they'll act as if they're a mono signal).

Generally speaking, we want to maintain a correlation between 0 and +1. A reading of 0 is a sign of “maximum stereo width” but can still lead to issues during stereo and mono playback due to phase cancellation.

So I suggest using a phase correlation meter, but ultimately relying on your ears.

Your DAW should have a stock correlation meter. However, if you want a third-party option, the Voxengo SPAN is a great free plugin that offers a correlation meter along with a frequency analyzer, level metering and more.

Control Width

Adjust the stereo width judiciously. Over-widening can cause even more issues than keeping the stereo image narrower.

Use panning to your advantage, and try not to over-rely on stereo imaging plugins, if at all.

Automate For Impact

Automate width on certain mix elements or sections to create dynamic changes.

Music is technically sound changing over time, and automating width can give our records that much more dynamic interest.

I've even opted to use stereo widening plugins to reduce the stereo image in certain sections, and then when I wanted to open up the width of the mix, I simply automated the stereo widening plugin off. My go-to stereo widening plugin is the Waves S1 Imager, though there are plenty of options on the market.

Secure The Low End

Keep the low-end frequencies in mono unless you're entirely sure you want stereo information down there.

I recommend doing this at the mix level using panning, mono effects, and high-pass filters to remove low-end from stereo channels.

If you do decide on using a stereo widening plugin, try features like ‘Safe Bass' to keep low frequencies centred, ensuring better translation on various systems.

---

---

Related Questions

What is the Haas effect? The precedence effect (aka Haas effect) is a psychoacoustic effect having to do with sound localization. It states that slightly delayed sounds (early reflections, echoes, etc., less than 40 ms) are perceived as a single sound, with the directionality being that of the first-heard sound.

Why does stereo sound so much better than mono? While highly subjective, many people find stereo playback to sound better than mono because it is closer to our natural listening experience (we have two ears). Furthermore, stereo allows for width, greater separation, and more creative opportunity.