Arc Ultra - not a good start

Update!

Arc Ultra is here. Setup was a breeze. First impressions. Regular TV audio which on Playbar was rather quiet, on Arc Ultra sounds better, clearer and louder. However, unlike with the Playbar, I do not have 5.1 sound on all my media. The reason is, I think, the difference in optical/HDMI connection. I use nvidia shield with Plex installed. Plex has the option for optical passthrough “AC3 encoding” which I used for my Playbar.. All of media, DTS, dolby digital and other played as dolby digital 5.1. Now I switched to HDMI passthrough on Plex and the option “AC3 encoding” is missing. Still have to figure it out on my new Arc Ultra. Any ideas would be greatly appreciated.

Neven

Unfortunately I don't know about nvidia shield and Plex, we don't have it here in Denmark i think :)

If your streaming service supports Atmos or 5.1 then you should also get the sound, (However, you have to pay extra for the most part to get Atmos and 4K) so it's your settings that we need to look at.

As for nvidia shield and Plex, others must help.

The first thing you need to make sure of is that your HDMI cable is connected to eARC on your TV.

In the settings on the TV, you also need to make sure that the settings are correct. I have Samsung, here are the settings:

HDMI-eARC mode: AUTO

Format for digital output: Pass-Through

For settings on Arc Ultra, Peter Pee has a pretty good handle on SONOS.

Make your Sonos Arc ULTRA sound better with these best settings!

Without eARC you will never get Atmos, it is only possible to achieve 5.1.
It is a shame because this is a much better soundstage.

First you need to make sure your TV is updated with Firmware update version 4.612 which is from 18/9-2024

When connecting a "BRAVIA" Sync compatible digital sound system and Audio Return Channel (ARC) technology, the connection must be made to HDMI IN 1 with an HDMI cable.

Press the HOME button after making the connection, then select [Settings] using the / buttons.
Select [Sound] using the / buttons, then press the button.
Select [Speaker] using the / buttons, then press the button.
Select [Audio System] using the / buttons, then press the button.
The connected sound system will turn on automatically. The volume can be adjusted using the TV remote control.
Press the HOME button twice to return to the source that was last viewed.

Once this is done, the settings in Nivida/Plex you need to play with, I think you can google your way to the answer :)

Your first sentence is, to the best of my knowledge, not true. A (compressed) DD+ stream can contain Atmos. That’s the way Netflix c.s. send Atmos info. The only stream that really needs eARC is an uncompressed stream, like from a BD-player or Apple TV.

Thank you. It all works. Don't ask me how I setup the Shield and Plex player on it but i get dolby digital 5.1 on all my surround content. I will post detailed settings so I can help out someone with similar problem.

Thank you

Neven

Hi ​@Neven 

Glad to hear that you got your Arc Ultra at last!

I also have an nVidia Shield and use Plex. In addition to having HDMI Passthrough enabled on the Plex player settings (not the server’s - I think it is set to supply original audio), I have the Shield’s audio format options set to Auto and my TV’s audio format also set to Auto (some TVs benefit from the Passthrough/Bitstream setting, but I get tiny interruptions when using this).

I can play all the formats I have so far come across without issue, including TrueHD, Dolby Digital + (reported in Plex as E-AC3, but there is no Atmos denoted - not all E-AC3 is Atmos, but all lossy Atmos is E-AC3), DTS, Dolby Digital, Dolby Multichannel PCM, DTS-HD/MA (Plex strips the DTS core from it and passes only that core to Arc Ultra, resulting in DTS being reported in the Sonos app and played - DTS-HD/MA is not actually played, but there is also no conversion/transcoding).

I do have Dolby Digital conversion enabled in Shield settings, so anything that Arc Ultra does not support is converted (like AAC, for example) and I also have the option to set PCM volume to Dolby levels enabled.

I hope this helps.

Hi ​@Corry P 

Since I plugged my Arc Ultra in HDMI arc (not earc) my Sony TV can output 5.1 linear PCM or Dolby Digital. On my TV the setting Digital audio out is set to Auto (not sure how this has anything to do with HDMI. For HDMI Arc I can not find any settings. On my nvidia shield Audio output is on auto, available formats also on auto (only dolby digital check is then on, I suppose because the Arc supports it.

The crucial setting is found on Plex app on Shield. For some reason i had to set passthrough to "optical"

(even the choices were also "HDMI" and "disabled". And I set optical encodings to ac3. Now my Sonos app shows dolby digital 5.1 Does that mean the shield is transcoding something? Should I turn on dolby digital conversion for some (all) the formats the Arc Ultra does not support?

Thank you for your help

Neven

Hi ​@Neven 

Bingo! Honestly, this setting had me convinced that the Shield actually had an optical port for quite some time - I only recently found out this is not the case!

If the source contains anything other than Dolby Digital 5.1, then yes.

Please also note that when looking at a movie in the Plex player, you can go to the three-dot menu, then Player Settings (if memory serves) and select an alternate sound track (assuming the content has multiple tracks in the first place, of course). If you ever get no audio, this may help (or if the movie refuses to start playing - I think this may be more common).

Yes, though it is the HDMI-ARC (as opposed to eARC) that will be the restriction, rather than what is supported by Arc Ultra (in the majority of cases). I only recommend changing settings once you come across something that does not play, however - “Auto” should take care of it.

You are most welcome!

I hope this helps.