Unlocking Dolby Atmos for Home Studios

There’s a misconception that Dolby Atmos is only for studios with expensive setups or high-end home theaters. But many people don’t realize that Dolby Atmos is scalable, all the way down to a two-channel immersive format that’s well-suited to home studios. In fact, you may already have what you need to get started with Dolby Atmos.

Dolby Atmos & Immersive Audio with Two Channels?!? How Is That Possible?How to Become Dolby Atmos ReadyMixing in Dolby AtmosThe Dolby Atmos WorkflowRendering with Dolby AtmosWhat About Mastering?Into the FutureHow Can You Get Started in Dolby Atmos Right Now?

Dolby Atmos & Immersive Audio with Two Channels?!? How Is That Possible?

It’s not possible with speakers, but it is possible with headphones. Because so many people listen to music on headphones, and more home recording enthusiasts mix on headphones, this isn’t much of a limitation. Although it’s counterintuitive that headphones pressed against your ears can deliver immersive audio, binaural audio is the science behind it. If you’ve used Waves Nx plug-ins or the Steven Slate Audio VSX headphones, both of which emulate different studio control rooms, then you’ve experienced binaural audio. It’s uncanny how listening on headphones with those plug-ins lets you “sense” the space of being in a control room.

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Traditional binaural recording captures audio using a mannequin-like dummy head with lifelike ear canals and a mic in each ear. The sound that reaches the dummy-head mics (or human ears) has different levels, frequency responses, and delay times, depending on whether they arrive from the front, the sides, above, or behind. Because binaural recording captures the aural cues that provide sound localization, listening to a binaural recording through headphones is surprisingly like hearing sound in a real-world space.

Atmos simulates that real-world space. When you mix, you can place sounds not just in front of you like conventional stereo but also around you. Of course, listening on headphones doesn’t deliver an experience like sitting in a surround sound home theater’s sweet spot and having the sound from multiple speakers wash over you. But headphones can deliver a step that goes beyond stereo.

The genius of the Dolby Atmos system is scalability. Dolby Atmos renders material recorded for multiple-speaker setups (like 7.1.4, with seven ear-level surround speakers, one subwoofer, and four height speakers) to a variety of formats. These include 5.1 surround, binaural two-channel immersive sound, and even old-school stereo.

How to Become Dolby Atmos Ready

Current DAWs that incorporate a Native Dolby Atmos workflow include PreSonus Studio One Pro, Steinberg Nuendo, Pro Tools Ultimate, Apple Logic Pro, Merging Technologies Pyramix, and Blackmagic Design DaVinci Resolve Studio. This roster will likely expand in the future.

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Along with a suitable DAW, you’ll need high-quality headphones. Mixing on headphones lets you know what the music will sound like for your listeners. However, trying to find “perfect” headphones is difficult. Closed-back headphones tend to have a flatter response, but even wearing glasses may interfere with the seal and unbalance the response. Open-back headphones tolerate different head and ear shapes better and usually have good imaging. That’s important for mixing immersive audio, but the out-of-the-box frequency response is generally not as flat as closed-back types. Some headphones have a great frequency response but more distortion, and so on. There are many trade-offs involved with creating sound from those tiny drivers.

Rather than obsess about this, remember that people will play your music over systems that vary wildly. Any pair of headphones will let you mix with Dolby Atmos; however, some are better than others. For those on a budget, the Mackie MC-450 and Sennheiser HD 560S headphones are affordable and have a relatively flat response. For a bit more money, the AKG K612 Pros are a good choice. Step up to the next price range with models like the Sennheiser HD 650, Audio-Technica ATH-R70x, and, for a closed-back model, the Shure SRH1540 headphones. The Sony MDR-MV1s are particularly noteworthy because they prioritize imaging for mixing immersive audio. The low and high frequencies are hyped a bit, but that could be an advantage because you’ll be basing your mix on the profile of most consumer headphones. 

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Mixing in Dolby Atmos

Under the hood, mixing in Dolby Atmos is different compared to mixing in stereo or surround. Stereo directs audio files to two speakers, while surround directs audio to multiple speakers. Dolby Atmos embeds metadata within mono or stereo audio. The metadata provides instructions to playback systems on where and how to place those mono or stereo sounds in a virtual 3D world. This is what provides scalability: Dolby Atmos manipulates the metadata, not the sound itself, to render the audio for a specific playback format.

Dolby Atmos was developed for movies, so it deals with two different audio elements. The first is a surround mix, which Dolby Atmos refers to as the Bed. It’s like a big stem based on a conventional, channel-oriented mix with defined channel specs — like 2.0 (stereo), 5.1 (five channels with a subwoofer), or 7.1 surround (seven channels with a sub). The second element is Objects. These are discrete pieces of mono or stereo audio you can place anywhere in the 3D Dolby Atmos space. Objects aren’t tied to particular channels (or speakers) but can float and move in space.

For example, consider a movie where the visual is you standing on a landing strip. The Bed could consist of the environmental sounds in the background, airplanes in other sections of the airport starting their engines, cars and trucks driving across the airfield, and the like. An Object would be like an airplane flying overhead from close behind you, which then makes a banked turn and lands in front of you at a distance.

Another way to think of Beds and Objects is by visualizing a band onstage. The rhythm section and keyboard player are stationary. They form the Bed. The lead singer who runs around the stage and the wireless-enabled lead guitarist who goes into the crowd are Objects.

Panning

Atmos panning comes in two flavors: Surround panning and Object panning. Surround panning (fig. 1) places sound around you by augmenting the stereo channels with more speakers: center channel for dialogue, left rear, right rear, and a subwoofer for a movie’s bass requirements (explosions, earthquakes, and so on). There can be additional side and height speakers. For mixing to two-channel binaural, you can choose any virtual space you want — even a setup like seven virtual speakers and a couple of virtual height speakers — because it ends up being rendered to binaural anyway. Note that the subwoofer and center channels (used for sound effects and movie dialog, respectively) are often not used with music-only projects. Decent playback systems have sufficient bass response to reproduce low musical notes, and it’s easy enough to create a phantom center by placing the same audio in the left and right channels.

Panning for surround is like panning for stereo, except that surround panners replace standard panpots, and you have more choices of how to manipulate the audio. In addition to panning from left to right, you can pan from front to back, vary a track’s stereo image width, change its position in the surround soundfield, and choose whether the sound is close to the listener or farther away. Even better, these parameters are automatable.

The Object panner’s interface moves Objects around in a 3D space (fig. 2).

Figure 1: Each surround panner has two views: one from above and one from behind. The top panner is panning stereo audio. The bottom panner is panning multichannel surround audio. The pink dots represent placement for height.

Figure 2: The upper section shows the left/right and front/back settings. The lower section shows the height. In this case, the audio is behind the listener, high up, and more toward the right rear than the left. Automating these changes gives motion.

Dolby Atmos defines up to 128 tracks, including Objects, to create the spatial field. Movies typically mix 10 tracks for a 9.1 surround Bed and up to 118 Objects. However, you can distribute the 128 tracks any way you want. The metadata specifies location and panning data, including how fast an object moves, the level of the audio, etc. Basically, metadata is the audio’s traffic director that routes audio in the 3D soundfield based on your mix.

The Dolby Atmos Workflow

Different people and DAWs have different workflows. The following is how I create Dolby Atmos projects in Studio One.

Because my recordings involve mono and stereo tracks, tracking begins in a conventional stereo project, not Dolby Atmos. It takes time for drivers to deal with the Dolby Atmos stream, so round-trip latency (typically around 60ms) is unavoidable. This isn’t an issue when mixing, but it’s problematic for real-time monitoring when tracking virtual instruments or recording guitar parts that use amp sims. (However, if you’re recording multichannel surround parts, then you need to track in a Dolby Atmos or surround environment.) After tracking, a first pass at mixing involves tweaking the balance, EQ, levels, arrangement, etc.

When there’s a rough stereo mix, it’s time to start the Dolby Atmos remix process. Although it might seem Dolby Atmos’s ability to place sounds all over a 3D field would complicate mixing, in reality, it means that you have more options.

With Studio One, switching to a Dolby Atmos environment simply means going into the Song Setup menu and choosing Dolby Atmos as the Spatial Audio Mode. The stereo panners turn into Surround panners, and the Dolby Renderer module appears. The mix will sound somewhat like the rough stereo mix, so you’re not starting from scratch.

Mixing the surround Bed comes next. This is analogous to conventional mixing, where engineers often mix the rhythm section before adding the lead parts. With panning no longer limited to moving sounds solely from left to right, you can do mix moves like bringing the lead vocal closer to the listener for intimate parts while simultaneously moving the background singers literally to the background. There are also new dynamics options, like emphasizing particular parts by simultaneously increasing an instrument’s spread and moving it closer to the listener. Surround processing tools (fig. 3) increase your creative options further.

Figure 3: Several Studio One effects have been retooled for surround, like this Surround Delay. Different delay taps can appear in different areas of the 3D space.

After getting a rough Bed mix, the next step is deciding which tracks need an Object’s mobility. I don’t go overboard on moving objects around. Nonetheless, sometimes, ear candy tracks in a conventional mix can be super-fun ear candy with Dolby Atmos. You can also make subtle changes. For example, when the background singers fade out, they could go more behind you and float up higher (although, I feel obliged to point out that elevation is the least headphone-friendly aspect of Dolby Atmos).

Rendering with Dolby Atmos

The Renderer is the last link in the immersive mixing chain. The Dolby Atmos Renderer that’s part of the Native Dolby Atmos workflow complements, not replaces, your usual workflow. One of its functions is giving a project overview (fig. 4).

Figure 4: The Renderer lets you see information at a glance, like what Objects are in use, the selected binaural modes, metering, and more.

More importantly, the Renderer can render your mix into several formats, including binaural, different surround options, or conventional stereo. Choose the Bed format you used as the Source and Binaural as the Output (fig. 5).

Figure 5: You can render to several different formats. Here, a 7.0.2 Bed format will be rendered to binaural.

For my latest song, I released a Dolby Atmos version and a conventional stereo version via my YouTube channel. Because Dolby Atmos can render as conventional stereo, two separate mixes aren’t needed. The rendering is excellent — an immersive mix rendered to stereo can sometimes sound better than a separate stereo mix because Dolby Atmos attempts to re-create the immersive nuances.

I was curious which version would get more clicks. The Dolby Atmos and stereo versions started with about equal clicks, but after a couple of weeks, the Dolby Atmos version pulled ahead by a 4:3 ratio. One plausible explanation may be that when people went back for another listen, they preferred the Dolby Atmos version.

What About Mastering?

You can master a Dolby Atmos binaural file like a standard stereo file. For example, I use the Waves L3-16 Multimaximizer so that the LUFS reading matches other songs in a collection. Because the L3-16 is a multiband maximizer, changing the gain of individual bands provides broad EQ changes. For more detailed EQ, the FabFilter Pro-Q in linear-phase mode gets the nod.

Note that you can still use headphone calibration software, like the Sonarworks SoundID Reference, for monitoring. When rendering to binaural, the output will go to a two-channel main output. Insert your plug-in there, and don’t forget to bypass the plug-in when exporting the final file for distribution.

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If possible, check your immersive mix on speakers. You don’t need an elaborate, calibrated setup. I use the IK Multimedia iLoud Micro Monitors to provide right-rear and left-rear sounds. That’s enough to confirm that what I hear in the headphones will at least be okay over speakers. 

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Into the Future

Some people are disappointed when comparing conventional stereo with binaural Dolby Atmos for the first time because the difference isn’t as dramatic as they expected. This may be because the music doesn’t change. You still have drums, bass, vocals, whatever. So, if you listen to a Dolby Atmos and conventional stereo mix back-to-back, then it might seem like this is much ado about nothing.

However, what does change is the sound. There’s an analogy with pitch correction. At first, you don’t notice it because you’re listening to the vocal. But then your ears start to hear pitch-correction artifacts. Eventually, you can’t “unhear” pitch correction. With Dolby Atmos, if you listen to Dolby Atmos mixes for a while, then your ears get used to it. Returning to stereo playback sounds oddly “flat,” and it is missing a certain vitality.

Although Dolby Atmos hasn’t conquered consumer audio yet, remember that stereo and mono vinyl records coexisted for a decade before the transition to stereo was complete. The transition from vinyl to CD took about as long. Currently, few streaming services let typical users upload immersive multichannel file formats. Although I can’t upload a 5.1 multichannel file to YouTube, it can play back Dolby Atmos files that have been rendered as binaural stereo. As long as people listen on headphones or earbuds, the music will have an immersive quality. So, it makes sense to create Dolby Atmos mixes and render to both binaural and stereo. Let your listeners choose which they prefer. As a bonus, if streaming multichannel immersive files becomes common, then your mix will be ready to render in that format.

Meanwhile, you can find out why Dolby Atmos is getting so many people excited. Best of all, you can start with nothing more than a Dolby Atmos–capable DAW and headphones. Just don’t blame me if you get hooked and start lusting after a full-blown Dolby Atmos system.

How Can You Get Started in Dolby Atmos Right Now?

If you’re ready to start today, whether in headphones or a full-blown 9.1.4 surround system, or if you just need more info to make up your mind, then call your Sweetwater Sales Engineer at (800) 222-4700, and they can provide you with all the gear and the expertise that you need to get going.
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