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n1c0
Trending Lyricist I
December 26, 2021

Sonos Arc and 7.1 Downmix to 5.1

  • December 26, 2021
  • 53 replies
  • 6785 views

Hi,

 

I recall that after we got the LPCM update for the Arc, it was noticed by the community that 7.1 LPCM tracks were not being properly downmixed to 5.1 and the end result were missing channels. Is that still an issue today? If I have the Sonos app reporting LPCM 7.1 does that mean I will be missing 2 channels  when outputing it to Arc, 2x Ones and a Sub?

Thanks

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53 replies

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GuitarSuperstar
Lead Maestro
February 16, 2022

Is this a problem for the LG G1?  Are we supposed to keep the TV audio set to auto still?  If my source file is a TrueHD 7.1 Atmos remux, do I still want my Sonos App to show Multichannel PCM 5.1?

The Sonos app should show the Dolby Atmos logo if you are playing a Dolby TrueHD/Atmos source. Be sure the HDMI Input Format setting on the TV is set to Bitstream and eARC is enabled. If it is a Blu-ray disc, set the player’s settings to Bitstream too and turn off Secondary Audio.

"Receive with simplicity everything that happens to you." - Rashi
bicyclemonkey
Lyricist II
February 16, 2022

 The Sonos app should show the Dolby Atmos logo if you are playing a Dolby TrueHD/Atmos source. Be sure the HDMI Input Format setting on the TV is set to Bitstream and eARC is enabled. If it is a Blu-ray disc, set the player’s settings to Bitstream too and turn off Secondary Audio.

This is on a 2021 Apple TV 4k with Plex.  I’ve tried the Plex app and with Infuse 7.  The TV is set to Bitstream and eARC is enabled.  I’ve tried with the TV set to both passthrough and auto.  Auto show’s multipath PCM 5.1 on the Sonos app and passthrough shows multipath 7.1.  It’s the same with any other source file I try irregardless of the sound format (unless it’s a stereo 2.0 source).

GuitarSuperstar
Lead Maestro
February 16, 2022

This is on a 2021 Apple TV 4k with Plex.  I’ve tried the Plex app and with Infuse 7.  The TV is set to Bitstream and eARC is enabled.  I’ve tried with the TV set to both passthrough and auto.  Auto show’s multipath PCM 5.1 on the Sonos app and passthrough shows multipath 7.1.  It’s the same with any other source file I try regardless of the sound format (unless it’s a stereo 2.0 source).

The Apple TV 4K doesn’t support Dolby TrueHD audio. You need an Nvidia Shield.

"Receive with simplicity everything that happens to you." - Rashi
bicyclemonkey
Lyricist II
February 16, 2022

The Apple TV 4K doesn’t support Dolby TrueHD audio. You need an Nvidia Shield.

So since the Apple TV converts the TrueHD audio, do I want it to be Multichannel 7.1 or 5.1 on the Sonos app?  Is the 7.1 problematic on the LG G1 or was that problem just with the LG CX TV’s?

GuitarSuperstar
Lead Maestro
February 16, 2022

The Apple TV 4K doesn’t support Dolby TrueHD audio. You need an Nvidia Shield.

So since the Apple TV converts the TrueHD audio, do I want it to be Multichannel 7.1 or 5.1 on the Sonos app?  Is the 7.1 problematic on the LG G1 or was that problem just with the LG CX TV’s?

From what I’ve read, I think the G1 has the same issue as the CX.

When you listen to the Multichannel PCM audio in 5.1 or 7.1, do you hear a difference? Is there any audio missing from the surround channels?

"Receive with simplicity everything that happens to you." - Rashi
bicyclemonkey
Lyricist II
February 17, 2022

From what I’ve read, I think the G1 has the same issue as the CX.

When you listen to the Multichannel PCM audio in 5.1 or 7.1, do you hear a difference? Is there any audio missing from the surround channels?

I don’t think there’s any audio missing, In the rear One SL’s, I still hear music and sound effects from the movie files I’ve played.  Correct me if I’m wrong but from what I’ve read, the full Sonos setup (Arc, Sub, 2xOne SL) is hardware limited to 5.1 anyway?

GuitarSuperstar
Lead Maestro
February 17, 2022

From what I’ve read, I think the G1 has the same issue as the CX.

When you listen to the Multichannel PCM audio in 5.1 or 7.1, do you hear a difference? Is there any audio missing from the surround channels?

I don’t think there’s any audio missing, In the rear One SL’s, I still hear music and sound effects from the movie files I’ve played.  Correct me if I’m wrong but from what I’ve read, the full Sonos setup (Arc, Sub, 2xOne SL) is hardware limited to 5.1 anyway?

Yes, the Arc, Sub, One SLs setup is a 5.1.2 setup.

If no channels seem to be missing from Multichannel PCM 5.1 or 7.1 audio playback and it sounds good to your ears, then that’s all that really matters.

"Receive with simplicity everything that happens to you." - Rashi
bicyclemonkey
Lyricist II
February 18, 2022

Yes, the Arc, Sub, One SLs setup is a 5.1.2 setup.

If no channels seem to be missing from Multichannel PCM 5.1 or 7.1 audio playback and it sounds good to your ears, then that’s all that really matters.

After tinkering with settings tonight, I found that if I turn off Atmos on the Apple TV and set it to DD5.1, and set the LG G1 to passthrough, I get the Dolby Digital 5.1 text on the Sonos app instead of Multichannel PCM 5.1 and the sound was much better with way. But if I play an Atmos title, I’ll have to change the settings again.

ste_ms
Enthusiast I
February 23, 2022

Any chance of an update from Sonos on this? Even if to just confirm that it isn’t a problem? 

pcfarrar
Lyricist III
February 23, 2022

It’s still a problem especially with an Apple TV and Sony PS5. I just set mine to output in Dolby Digital 5.1 now, it sounds really bad on PCM 7.1 in comparison. The only device that works well is the Xbox series x as it outputs all game audio in atmos so has no problems. 
 

 

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