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Tips & Tricks

Understanding Dolby Atmos and Sonos Arc

Forum|Forum|6 years ago
June 18, 2020
41 replies
39823 views

One of the most exciting features of the new Sonos Arc is its ability to play Dolby Atmos sound. As with all relatively new technology, it’s understandable that you might feel a little confused when it comes to making sure you have a compatible setup for the feature.

Head’s up—we’ll be talking about things like “codecs,” and “audio formats” below, but don’t panic. We’re here to make sure you understand why those things are important in setting up Arc to play Dolby Atmos. Rest assured that no matter what you’re listening to with Arc, it’s going to sound great. But to get the most out of Arc, it’s worth ensuring that your system is set up to deliver Dolby Atmos. And, as always, we’re here to help. If you have questions, feel free to ask.

Dolby Atmos (as in “atmosphere”) is a format that allows sound to be heard three-dimensionally —including from above! (Arc achieves this by bouncing sound off of the ceiling). To facilitate this experience, Atmos information is contained within an audio wrapper (known as a codec), which has metadata instructing the audio drivers how to direct the sound within your space.

Arc-compatible codecs that contain Dolby Atmos include Dolby Digital Plus, Dolby TrueHD, and Dolby MAT. Most streaming services that have Atmos content use Dolby Digital Plus, while Blu-rays usually use Dolby TrueHD or Dolby MAT.

To get Dolby Atmos sound from Sonos Arc, you need to address the following:

Connections. Sonos Arc needs to be connected to your TV with an HDMI cord (one is provided with Arc) via an ARC or eARC port (eARC is required for Dolby TrueHD and Dolby MAT).
Compatibility. Every device that ‘touches’ the audio (e.g. Blu-ray player, Apple TV, Fire TV) needs to be able to pass Atmos on to the next in line—from the source of the content to Sonos Arc. For Blu-ray, the individual discs need to have Atmos content and the player needs to be capable of sending Atmos as well.
Apps. Your app (e.g. Netflix, Disney+) needs to be capable of playing Atmos content via your particular TV.
Content. Your content needs to have Atmos audio in an Arc-supported codec: Dolby Digital Plus, Dolby TrueHD, or Dolby MAT.

Some things to note:

Not every episode of every show may have Atmos, even if the streaming service supports Atmos.
A device (such as your TV or a streaming box like the Apple TV) may support Atmos, but not for all apps running on it.
Some devices may not pass Dolby Atmos by default without making some adjustments to audio settings.

We’re happy to help answer questions, but in some cases you may need to contact the manufacturer of certain devices to check compatibility.

When set up properly, your Now Playing screen in the Sonos app will display the Dolby Atmos logo.

If you have all of the above set up, but are still not getting Dolby Atmos sound, let us know what you’re experiencing in a new thread or join an existing one and we’ll try to help you address the problem.

This topic has been closed for further comments. You can use the search bar to find a similar topic, or create a new one by clicking Create Topic at the top of the page.

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ekwok

Prominent Collaborator I

Ryan S,

In the webpage https://www.sonos.com/support/en-us/sonos-user-guide/index.html#t=sonos-user-guide%2Farc%2Farc.htm , it states that:

Arc’s advanced processing creates five phased-array channels that deliver sound to your ears from all directions.

What are those five channels? Where do the height channels fit in there?

Thanks

ekwok,
The five channels mentioned will be the left, right, center, LFE (bass) and the upward facing ‘height‘ (reflective) channel for Dolby Atmos.

Where do the rear surround come in then?

I always thought that we have RF, center, LF, LR, RR, plus the 2 height channels. 7 in all.

Ken_Griffiths

ekwok,

It’s a 5.1.2 system when you add the rear surrounds and sub …the two height channels are the ‘pseudo’ downward firing channels. So I was mistaken, but this link may assist...

https://origin-www.dolby.com/in/en/guide/speaker-setup-guides/5.1.2-overhead-speaker-setup-guide.html

So the 5 Arc channels referred to are: FL, FR, Center and 2 x height channels.

E

ekwok

Prominent Collaborator I

ekwok,

It’s a 5.1.2 system when you add the rear surrounds and sub …the two height channels are the ‘pseudo’ downward firing channels. So I was mistaken, but this link may assist...

https://origin-www.dolby.com/in/en/guide/speaker-setup-guides/5.1.2-overhead-speaker-setup-guide.html

So the 5 Arc channels referred to are: FL, FR, Center and 2 x height channels.

Ken_Griffiths,

The Arc by itself without the sub and the surrounds is 5.0.2 already, right?

And if the 5 channels are FL, FR Center and 2 height channels, then what about RL and RR? Where do they come in? They are built into the Arc already. The two side firing woofers at the extreme ends of the soundbar.

Ken_Griffiths

ekwok,

It’s a 5.1.2 system when you add the rear surrounds and sub …the two height channels are the ‘pseudo’ downward firing channels. So I was mistaken, but this link may assist...

https://origin-www.dolby.com/in/en/guide/speaker-setup-guides/5.1.2-overhead-speaker-setup-guide.html

So the 5 Arc channels referred to are: FL, FR, Center and 2 x height channels.

Ken_Griffiths,

The Arc by itself without the sub and the surrounds is 5.0.2 already, right?

And if the 5 channels are FL, FR Center and 2 height channels, then what about RL and RR? Where do they come in? They are built into the Arc already. The two side firing woofers at the extreme ends of the soundbar.

Standalone, I assume it’s a 3.0.2 system (FL, FR, Cent + 2 height channels) ...although there maybe some sort of algorithm to merge sound from the rear channels to the front when the surrounds are absent?

The side facing speakers I’m sure are geared to simply also play the FL/FR channels and help broaden the sound stage.

To get the full atmos sound surround though, you ideally need the rear surrounds and sub.

S

SonosJames

Contributor I

So after a busy weekend I finally got the test files downloaded to a USB stick and played through the C9 USB slot - the Sonos app reporting Dolby Atmos (DD+). After toggling trueplay on and off a lot of times and listening to both leaf and amaze I could hear a slightly more pronounced height to the birds chirping with trueplay off. However I was impressed I was hearing the height as the chirping birds sounded like they where above! Maybe iTunes Atmos is not the best to really hear this level of detail.

E

ekwok

Prominent Collaborator I

ekwok,

It’s a 5.1.2 system when you add the rear surrounds and sub …the two height channels are the ‘pseudo’ downward firing channels. So I was mistaken, but this link may assist...

https://origin-www.dolby.com/in/en/guide/speaker-setup-guides/5.1.2-overhead-speaker-setup-guide.html

So the 5 Arc channels referred to are: FL, FR, Center and 2 x height channels.

Ken_Griffiths,

The Arc by itself without the sub and the surrounds is 5.0.2 already, right?

And if the 5 channels are FL, FR Center and 2 height channels, then what about RL and RR? Where do they come in? They are built into the Arc already. The two side firing woofers at the extreme ends of the soundbar.

Standalone, I assume it’s a 3.0.2 system (FL, FR, Cent + 2 height channels) ...although there maybe some sort of algorithm to merge sound from the rear channels to the front when the surrounds are absent?

The side facing speakers I’m sure are geared to simply also play the FL/FR channels and help broaden the sound stage.

To get the full atmos sound surround though, you ideally need the rear surrounds and sub.

Not so. Stand alone the Arc is 5.0.2. The side firing woofers tries to give reflected LR and RR.

when the physical surrounds are bonded, then the side firing woofers will be used to help with the left and right channels.

Ken_Griffiths

Standalone, I assume it’s a 3.0.2 system (FL, FR, Cent + 2 height channels) ...although there maybe some sort of algorithm to merge sound from the rear channels to the front when the surrounds are absent?

The side facing speakers I’m sure are geared to simply also play the FL/FR channels and help broaden the sound stage.

To get the full atmos sound surround though, you ideally need the rear surrounds and sub.

Not so. Stand alone the Arc is 5.0.2. The side firing woofers tries to give reflected LR and RR.

when the physical surrounds are bonded, then the side firing woofers will be used to help with the left and right channels.

ah right, then I must be mistaken again. I thought you had to ‘expand‘ the system and add two rears and sub to get the full 5.1 surround sound as mentioned in the Arc’s online manual. I have attached and highlighted the section I saw. (Edit: I did previously mention though about the two rear channels possibly being merged to the Arc when it’s setup without surrounds).

jgatie

ah right, then I must be mistaken again. I thought you had to ‘expand‘ the system and add two rears and sub to get the full 5.1 surround sound as mentioned in the Arc’s online manual. I have attached and highlighted the section I saw.

“Full” is a relative term. Front speakers using audio tricks to simulate surrounds is always going to be inferior to physical surrounds positioned behind the viewer. I myself would not call simulated surrounds as “Full” 5.1. OMMV.

Ken_Griffiths

jgatie,

I didn’t think the two Arc’s side facing speakers only were designed to operate as the pseudo rear channels .. I thought those speakers were to ‘mainly’ help expand the front L/R sound stage, but as mentioned I did think that the rear channels were merged into the Arc speakers that were playing the front left and right channels when surrounds were not being used.

If it’s just the two side facing speakers only, then I didn’t realise that the rear audio was confined just to those, I thought it included other FL and FR speakers too.

So if that is the case, then I accept I was mistaken.

jgatie

I’m not sure what the dynamics are, just going by what has been said in the forum by Sonos guys.

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