Hi @Forstal,

Welcome to the Sonos community and thanks for reaching out to us. Let me share some information to help you out. 

The Sonos Arc can play Dolby Atmos audio. ARC and eARC are protocols responsible for sending audio over an HDMI cable to home theater sound systems like Sonos Arc. Sonos Arc must be connected to HDMI ARC or HDMI eARC to play any Dolby Atmos content. Not all TVs have HDMI ARC or HDMI eARC, so check your TV’s user manual to see which HDMI connections you have. Your TV must be Dolby Atmos compatible.

Getting Dolby Atmos audio can also depend on the physical source device playing the content and the format or output must be set to one of our supported home theater audio formats. Some TV and movie streaming services now support Dolby Atmos. Please note that even if a service supports Dolby Atmos, some shows and movies may not have Dolby Atmos audio. Check with your streaming service provider to see if they support Dolby Atmos.

Hope this helps. We can wait for suggestions and feedback from our Sonos community members, they might provide their inputs about this. If you need help with any other information, please be sure to let us know.

On your Apple TV 4K, go to Settings > Video and Audio and select Audio Format. Under Immersive Audio, check that Dolby Atmos is ON.

You might also try a different HDMI cable for your Apple TV.

There is also a very good possibility that your TV cannot pass through Dolby Atmos audio.

Before you purchase a new TV, have you considered the HDFury Arcana? It allows your Apple TV to bypass your TV’s HDMI ARC port and send audio directly to the Sonos Arc. https://hdfury.com/product/4k-arcana-18gbps/

I addressed most of that, except for your statement about tv Atmos compatibility.

As far as I understand, any TV that is HDMI 1.4 compliant can pass a DolbyDigital 7.1 stream (aka DD+), without regard to the package its carrying, and Atmos object data is treated the same as anything else in the stream by the 1.4 compliant circuit. The only thing I’m aware of affected by transfer via 1.4 is closed-captioning, which is a function of the CC decoder looking for a substream that doesn’t exist in a standard 1.4 compliant stream.

Since this is the internet I’m sure someone will correct me if this is wrong...

If this TV were not 1.4 compliant, I’d agree with you about the pass-through. As far as the cable, its a MonoP 15428 - 18GB/s, which is HDMI 2.0 spec. I know that with that in place my aTV 4K reports all HDMI tests passed, and my aTV works at its top capability.

There is no setting in my Apple TV 4k for Immersive Audio. Other people have reported this missing as well, and Apple’s only advice is “If you don't see Immersive Audio and Dolby Atmos as an option, you might need to change how your home entertainment system is set up.” and there’s no further explanation. I have an aTV 4K hooked to my LG display via standard HDMI, and the Arc is attached to an HDMI ARC port, which is exactly what Sonos tells me to do.

I looked at the Arcana, but frankly if I have to spend $200 plus shipping on a box that is back-ordered with no guarantee on shipping, it seems I should just get a new TV. There’s a 70”  Vizio available thats fully buzzword compliant, and it has 3 HDMI ports including eARC, which ends the whole problem.

I switched the HDMI cable out to a brand new 18GB cable and re-ran the HDMI test in the Apple TV 4k. After three minutes it reported “Your HDMI connection has improved”.

I figured that was it, so I started an Atmos movie on Disney + and checked my Sonos app - still showing Dolby Digital 5.1, and after the movie was over the title card no longer showed Atmos.

I considered the Arcana, again, but I’ve decided against it. It has a single input, so what do I do when I switch to a Blu-ray? Switch cables? Add an HDMI switch?

This is getting too complicated for something that should be easy.

If you purchased the Arcana and wanted to connect multiple devices to it, you would need to purchase an HDMI switch. This is my setup:

Your aTV is two generations older than mine - so is your tv. The newest thing you have there is the Arcana and the Sonos…. how are you getting Atmos now?

I get Dolby Digital Plus/Dolby Atmos from Disney+, VUDU, and Apple TV+ from my Roku Ultra.

I get Dolby TrueHD/Dolby Atmos and multichannel PCM from Blu-rays and UHD discs on my Panasonic UB820 Blu-ray player. I also can get Dolby Digital Plus/Dolby Atmos from the built-in Netflix app from the UB820 too.

Because my TV is from 2013, I wouldn’t be able to get any of this without the Arcana.

Sorry I was just focusing on the Apple TV. I know nothing about Roku.

Doing it your way would end up costing an extra $300 and add a few more connections to the rats nest under my TV.

There is no reason why my TV would be causing the problem so I think there is something wrong here, either with the aTV or the Sonos. I wish Sonos had put a pass-thru HDMI port on the Arc instead of us having to go through contortions to make things work.

I’ve been searching the web for info on “Apple TV 4k immersive audio doesn’t work” and similar terms, and I just get people who quote the single Apple support doc or link to it. One guy said that only the newest TVs would work because “Apple used a high bandwidth form of Atmos”, so I guess he never read the technical specs on it  - its spelled out pretty clearly that the Atmos is carried by DD+, not TrueHD, so its the compressed Atmos. Again, it shouldn’t be a problem on an HDMI 1.4 connection.

The Apple TV 4K outputs Dolby Atmos using Dolby MAT 2.0 not Dolby Digital Plus.

“Certain content devices, such as Xbox One X/S and Apple TV 4K, come with a Dolby Atmos MAT encoder, which is designed to encode, decode and incorporate Dolby Atmos metadata into lossless pulse-code modulation (PCM) audio, allowing listeners to experience Dolby Atmos even in PCM audio.”

Quote from Apple website:

“Apple TV 4K uses a high bandwidth form of Dolby Atmos that doesn’t work over ARC connections.”

More than likely, your TV cannot pass through the multichannel PCM audio containing the Dolby Atmos data the Apple TV 4K is sending because your TV is only equipped with HDMI ARC, not HDMI eARC. That’s probably the reason why you don’t see the “Immersive Audio” option on your Apple TV 4K settings.

So you either have to purchase a new TV with HDMI eARC or get the HDFury Arcana.

AppleTV uses high bandwidth for ATMOS and you need HDMI eARC for this. HDMI ARC will only support up to Dolby Digital Plus.

Dolby Digital Plus can support compressed ATMOS, but AppleTV will only pass Dolby Digital 5.1 via HDMI ARC.

I only have HDMI ARC and I have never seen the immersive sound option on my AppleTV 4K, this is because the TV and AppleTV are negotiating the connection and AppleTV sends 5.1 as it does not detect HDMI eARC.

options are the Arcana or a new TV that supports HDMI eARC

Sorry but that goes against everything I’ve read on the subject including Apple’s product pages. Apple TV 4K uses Dolby Digital Plus (compressed Atmos), not TrueHD (capable of carrying uncompressed Atmos). If Apple had uncompressed Atmos, that would mean they now have TrueHD on the aTV4k.

If you have any supporting docs that show Apple now has Dolby TrueHD on the aTV 4k please post the link so we can clear this up.

@forstal Read my message above.

Wow, I read that doc about 20 times and didn’t notice that line in the page. I really don’t understand why they’d offer a sub-service of Dolby that uses high bandwidth but not offer the standard carrier for that, which would be TrueHD.

FWIW, Apple has never updated their product specs to indicate that they had “Dolby MAT 2.0”, which I’ve never heard of until just now. I really wish Sonos had put some kind of disclaimer up that shows this won’t work with ARC and AppleTV. They’re probably hoping most people will just accept it and move on.

I guess this is going back. I’m not about to replace my TV over this, and I’m not going to spend almost as much as a TV to resolve it.

This is from the FAQ on the Sonos Arc product page:

Do I need a TV that supports HDMI eARC?

Sonos Arc can connect to TVs with eARC, ARC, or optical outputs. For greatest compatibility, eARC is recommended.

If you connect to a TV with eARC, the Dolby audio formats supported include Dolby Atmos, TrueHD, MAT, Dolby Digital Plus, and Dolby Digital.

If you connect to a TV using ARC, the Dolby audio formats supported are dependent on your TV model and manufacturer. The TV may be capable of sending Dolby Atmos, Dolby Digital Plus, and Dolby Digital. An ARC connection cannot support TrueHD or MAT.

If you connect to a TV using the optical adapter, the Dolby audio formats supported are dependent on your TV model and manufacturer. The TV may be capable of sending Dolby Digital. An optical connection cannot support Dolby Atmos, TrueHD, MAT, or Dolby Digital Plus.

Thats nice, thanks. Where does it say that it won’t work with Apple TV over ARC?

You bolded two lines in there to call my attention to them. The first one says nothing about Apple TV. I’m still trying to find where Apple says the aTV4k has “Dolby MAT”, never mind the Sonos docs.

The second line you bolded has nothing to do with what we’re talking about. I never once said I was using optical.

I guess it would be far too difficult to accommodate and test all combinations of set top devices, TV’s, streaming services, firmware settings app versions etc and to keep it all up to date to categorically say what does and does not work.

Frustrating, I know…. but I can see the problem 

Right… but this is the 2nd most popular device after the Roku. Distant third is some Android thing I can’t remember the name of. Regardless, there’s maybe 5 different top sellers, and I would think that they used those devices when they were testing Arc prior to launch. They should at least publish their aggregated results from the testing phase, if they don’t want to do us the tremendous favor of actually trying the Arc out with current equipment.

And it just occurs to me - in order for them to do tech support for the Arc, they should at least have basic experience with the devices, otherwise those would be pretty short support calls:

“So you have the Arc hooked up, the light is on, it shows up in the app, but there’s no sound?”

“Yep.”

“Thats a device issue. You’ll have to contact the manufacturer of your set top box.”

>click<

No need to get angry. We are just trying to help and inform you. It’s probably best for you to return the Arc and go with a different solution. A sound bar isn’t worth getting angry about. Hopefully you now have enough information that you can find a sound bar that will better work for your setup and meet your expectations. Good luck.

If I goto the Apple TV sound-out in its settings, the ‘uncompressed’ multichannel LPCM codec is shown on the screen display too (see attached). I guess that too shows/infers that an HDMI eARC port is going to be needed by the connected TV. 
 

Arcana is (currently) the cheapest way to get around the issue if the TV only has HDMI-ARC, but I also don’t understand why Apple TV doesn’t support DD+ (Atmos), as many of the major streaming services appear to have chosen to go down that route.

How did you get “angry” out of what I said?

I am getting frustrated, however. The first response to my thread was a bot from Sonos that essentially repeated the manual and then told me to wait for community members who would do Sonos’ job for them. The second response was yours, and you did fine. You gave me a few things to look at. About the only thing I could say anything negative about was your focus on the thing about the TV not passing Atmos.

BMF clarified the stuff that I just plain couldn’t see, maybe it was the gray type. (I’d still like to know where he found that the aTV had that “Dolby MAT” circuit, because I haven’t seen anything about that anywhere I’ve looked.)

What really burned my steak, so to speak, was when I jumped on the support chat right after that, and after fighting with the chat bot (don’t get me started on that thing), I got a human on the line who responded to my complaint about the aTV and Atmos with “I do apologize for that, yes, there's a known issue with that Apple TV 4K, it required eArc for Atmos audio format.”

That right there did it for me.