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If you’ve ever had the unfortunate experience of taking a mix you’ve done outside your studio only to find out it doesn’t sound nearly the same or nearly as good on other playback systems and devices, it’s time to take your stereo mixes into the mono realm.

If mixing in mono for better stereo results sounds counter-intuitive right now, watch as Ryan takes you through some of the benefits on a huge multi-track production by songwriter Matt Tinsley.

Transcript

What mono and stereo mean

What you’re about to hear is nothing short of a miracle. Let’s actually start today at the very beginning, so that we’re all on the same page. What do I mean when I say mono and stereo? Well, way back in the very beginning of the recording arts, musicians were often recorded with a single microphone, ending up on a single track of wax or vinyl, or broadcast over AM radio’s single channel, where it played back over a single speaker. From initial capture to final presentation, the sound was monophonic, coming from a single source. And because of that, engineers had a pretty easy time predicting how their studio recordings would translate to consumers.

Why stereo made mixing less predictable

However, reaching popular use in the 1960s, stereo recordings included a second channel of audio to simulate the directionality of real-world spaces. Stereo mixes were awesome… except for one thing. You see, some people had stereo playback ability, but some people still had mono systems. The predictability was gone.

Why mono compatibility still matters

And if you think the 50 years since has removed the uncertainty, well, guess again. That smartphone in your pocket, the tablet you couch surf on, that Amazon Echo in your living room? Yeah, they’re still mono speakers. So our job as mix engineers is no different in 2016 than it was in 1966: we need to check our mixes for mono compatibility.

But what if I told you that in the process, not only would your mixes be safe across listening environments, but even your stereo mixes would get better as a result? Let me show you what I mean. And this should go without saying, but if you’re not listening on headphones or, even better, studio monitors, everything we do here will be tough to follow.

Setting up a mono button with Selig Gain

First of all, there’s a couple ways we can get set up for mono mixing. There’s a Rack Extension by Selig Audio called Selig Gain. It has a whole host of great gain-related tools worth checking out on its front panel, but one of them is a mono button. In my own mixing template I drag a Selig Gain into the Master Section’s Insert FX, I enable Keyboard Control, and turn on Keyboard Control Edit Mode so I can double-click the Mono button and assign it to the “N” key on my computer keyboard. N as in Not-stereo, but you could choose any key you like that isn’t in use. Now once I exit Keyboard Control Edit Mode, I’ve got a quick shortcut to toggle my master output between mono and stereo.

A mono summing Combinator

Of course, if you’re the kind of person who likes to make the most of what you’ve already got, Reason comes standard with a mono summing Combinator. If I go to the All Effects Patches folder in the Factory Sounds and search for “mono”… there it is: Stereo Flip & Mono. And just like before, I can assign the Mono button on the Combinator to my keyboard shortcut.

The mix: a song by Matt Tinsley

Now that we’re set up, let’s take a look at a mix I’ve been working on to see how checking our mono output can catch problems in our stereo mix. This is a song by an artist named Matt Tinsley. It is an epic arrangement of instruments, with overdubs upon overdubs of charging percussion, drums recorded with multiple microphones, layers of guitars, pianos, and even a string ensemble, all totaling a massive 81 channels in my mixer that need to be balanced, EQ’d, panned, effected, and, well, mixed.

“Agoraphonia”: how stereo can fool you

But mixing in stereo can play tricks on you, and it can let problems go by unnoticed, resulting in a psychological condition that I’ll call “Agoraphonia”: the unshakeable feeling that your mixes don’t sound good when played outside your own studio.

Mixing is three things

Mixing is about three things: relative volume, relative frequencies, and stereo position. If we remove that last one from the equation, we get a better sense of how we’re doing with the first two. This is because our brains are really good at selectively hearing things as long as we can determine directionality. Allow me to demonstrate. But listen to these voices in mono. We instantly realize that in order to achieve clarity, we need to adjust our mix’s volume.

Finding the lost piano

That same decision making can be applied to Matt’s song. In the mix I’ve got going here, I love the interplay between Matt’s guitar in the beginning and these piano chords. When you add in his stellar vocal, our mix is off to a great start. But when we switch to mono… where’d our piano go? It’s lost, buried under the guitar, bass, and vocal. With stereo positioning out of the way to fool us, we’re left to consider the piano’s overall volume and its frequency content.

Focusing the piano with filters and EQ

On its own, our piano is a nice full-range sound, but what my ear tuned into and loved while listening in stereo was the haunting quality of its midrange attack. The lower-end frequencies aren’t critical to achieving that, and in mono we can hear them occupying the same range as the bass guitar. The result, even in a simple two-instrument mix, is a muddy sound. So let’s use low-pass and high-pass filters to focus our piano into the mid-range, and we’ll use our Channel EQ to enhance that mid attack even more. Even with just the bass and piano, you can hear separation and definition. Bring in the guitars, and our piano still holds its own space in the mix.

Back to the full mix

Back to the full mix. Okay, we can hear our piano, but now we can make uncompromised decisions about the overall volume, and to my taste I want to hear more of it. To me, this sounds nice. If I now switch between stereo and mono, you’ll notice that our mix doesn’t sound different… just wider.

Balancing the lead vocal

Those types of decisions will play out all through your mixing. In fact, one of the trickiest balances to find in your mix is where to sit your vocal. There’s a lot of techniques that go into getting a good-sounding vocal, some of which I’ve covered in another tutorial, but once you’ve got your vocal sounding nice on its own, you’ll ultimately want to balance it against your overall mix, and mono referencing is great for that.

Matt’s lead vocal is really nice, and I want to feature it, but I don’t want it to sound like he’s singing karaoke over an instrumental. Listen to the second verse: lots of percussion and strings have entered the arrangement, and in stereo mixing I’ve pushed Matt’s vocal up to sit above all that. Switch over to mono… he is undeniably too loud. In mono, I can pull his vocal down to a point where it is understandable but cohesive with my instrumental, but in doing so, I also notice that one of the reasons I must have pushed it so much while mixing in stereo is that the strings are also too loud. After adjusting, my mono and stereo comparison once again feels similar, despite the stereo mix’s obviously wider sound.

Mono reveals real problems

But mono doesn’t just help us decide matters of taste. It can reveal real problems in your mix too. Matt’s acoustic guitar was recorded using two microphones for stereo imaging, and to an untrained ear, this probably does sound nice and wide, but listen in mono… where’d the low end go? Mono referencing has revealed a classic phase problem in our guitar recording.

What is phase, and why is it a problem?

So what is phase, why is it a problem, and how do we fix it? All good questions. The recording process is nothing more than the conversion of sound vibrations, in this case a guitar string, into electrical signals which are stored digitally. When you combine those electrical signals during mixing, if they contain conflicting information, they can work against each other. Zoom into our waveform and you can even see the problem with your own eyes.

Here are the electrical waveforms captured by our two microphones on the guitar. You can see the electrical signal oscillating up and down in what’s called the signal’s “phase.” The signal captured by the first microphone goes up while the other one goes down. They’re traveling in nearly opposite phases. And this can happen from simple things like the distance between each microphone while recording, the angle they were pointing, or even the electronics inside the microphone.

But out-of-phase signals cancel each other out when summed, the same way in math that 4 plus -4 equals 0. Our guitar signals aren’t perfectly out of phase, so you could say our sonic equation is more like 4 plus -3 equals 1: some of our sound is audible, but it’s thinner and quieter.

Fixing it with phase invert

What would be great is if we could flip one of our signals around so that they aren’t working against each other. Well, we can, and we do that up at the top of the mix channel using the phase invert button, which does exactly what its name implies: it inverts, or in other words flips, the phase of our signal. Listen to our guitars in mono when I invert the phase of either microphone. Of course, I only want to invert one of them. If I invert both, we’re back where we started. In stereo, our acoustic still sounds good, but in mono we no longer have phase cancellation messing up our mono mix.

When to check your mix in mono

So this raises the question: when should you be checking your mix in mono? When you’ve got the perfect stereo mix ready to go and want a safety check? No. I’d recommend that you’re jumping back and forth all along through the mixing process, to catch problems and make decisions as they come up. Other engineers might even say you should spend most of your time in mono, because if you can get a good-sounding mono mix, you won’t have a hard time with your stereo mix, and the same can’t be said the other way around.

Wrap-up

In short, the best remedy for your agoraphonia affliction is to get mono… no, not that mono… yeah, that mono. So good luck mixing, and I’ll see you soon with another pick for quick mix fix tricks.