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Corry P
Corry P
Sonos Staff
April 11, 2022

Please read if you have encountered issues with 7.1 LPCM playback on Sonos via an LG TV

Hi,

We want to gather some details from people experiencing issues with playback of 7.1 LPCM audio streams on a Sonos Arc or Beam (Generation 2), via an LG television set. Specifically, when channels are playing from the wrong speakers - for example, but not limited to, if you hear dialogue only coming from the rear speakers, consistently.

If you have experienced this channel mis-mapping, please provide, in this thread, the following details:

Your LG TV model number

Your media source device name and model number or TV app that the issue was noticed on, and the name of the movie/show that was affected

Models of any other HDMI devices connected to the TV (if applicable)

The confirmation number of a Sonos system diagnostic submitted while the affected media was playing and 7.1 LPCM was reported in the Sonos app.

Thank you for your assistance.

 

 

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    75 replies

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    exchgr
    Trending Lyricist I
    November 29, 2023

    Just for information, I don't have problems of wrong audio channels, but with lg C1, arc, sub gen 3 and two one as surround the “source also consistently shows as “multichannel 7.1” problem is completely solved with Apple TV 4K 3rd generation (2022) in fact now always shows "multichannel 5.1" when the track is in that format

    Confirming that upgrading from a 2nd gen to a 3rd gen Apple TV 4K fixed all my multichannel PCM 7.1 mapping issues. Now the Sonos app shows multichannel PCM 5.1 for 5.1 content, and everything is mapped correctly. So this issue definitely lies with the 2nd gen Apple TV 4K. Since the two generations run the same tvOS, I’m assuming this is a hardware issue in the 2nd gen.

      Corry P
      Corry PAuthor
      Sonos Staff
      November 30, 2023

      Hi @exchgr 

      Thanks for the update - glad to hear you got things working properly.

      "Common sense is the collection of prejudices acquired by age eighteen." - Albert Einstein
      Professio7
      Avid Contributor I
      December 4, 2023

      I’m having some serious channel mismapping issues with my setup. I’ve got an LG C2 and a Sonos Beam Gen2 with 2 Era’s as Surrounds using eARC (Bitstream, Pass through). I recently purchased an Apple TV 4K (Gen 2) where everything is converted to LPCM 7.1, even 5.1 signals.

      Generally higher end Bluray Remuxes and Dolby Atmos stuff (over DD+) seems fine. However, I’ve watched an episode of Rick & Morty in Dolby Digital 5.1 which sounds very weird. Dialog coming from the the sides rather than front. If I set “Change Format” to “Dolby Digital 5.1” in the Apple TV settings, everything is fine. Unfortunately that severly degrades audio quality for other higher end sources.

      Is there a fix in the works for the 2nd gen Apple TV or do i need to upgrade to a 3rd gen?

      Diagnostics number: 1022034678

      exchgr
      Trending Lyricist I
      December 4, 2023

      I’m having some serious channel mismapping issues with my setup. I’ve got an LG C2 and a Sonos Beam Gen2 with 2 Era’s as Surrounds using eARC (Bitstream, Pass through). I recently purchased an Apple TV 4K (Gen 2) where everything is converted to LPCM 7.1, even 5.1 signals.

      Generally higher end Bluray Remuxes and Dolby Atmos stuff (over DD+) seems fine. However, I’ve watched an episode of Rick & Morty in Dolby Digital 5.1 which sounds very weird. Dialog coming from the the sides rather than front. If I set “Change Format” to “Dolby Digital 5.1” in the Apple TV settings, everything is fine. Unfortunately that severly degrades audio quality for other higher end sources.

      Is there a fix in the works for the 2nd gen Apple TV or do i need to upgrade to a 3rd gen?

      Diagnostics number: 1022034678

      I haven’t been able to get a response from Apple on this re: the Apple TV 4K gen 2, but I can confirm that the Apple TV 4K gen 3 fixes this particular issue. With Apple TV 4K gen 2, 5.1 surround sources were converted to Multichannel PCM 7.1 and the channels were incorrectly mapped, whereas with the Apple TV 4K gen 3, 5.1 surround sources are converted to Multichannel PCM 5.1, and everything is mapped correctly. I assume it’s a hardware issue that got fixed in the latest gen, but I can’t be sure.

      hitmaker77
      Lyricist III
      December 5, 2023

      I`ve made some little different experiences with LPCM and my Sonos system.

       

      I own a LG C2, Sonos Arc with 2 Era 300 and Sub & Apple TV 4K, newest Gen.

      I use the system for atmos, and most of the time it works flawlessly.

       

      But sometimes when I start a stream (e.g. Amazon Prime) all voices are missing and I can only hear the music and some effects. I have to restart the stream an everything works fine again.

       

      And sometimes I only get stereo PCM although I know, that it should be Multichannel PCM 5.1.

      A new start of the stream or sometimes closing und opening the app again helps.

       

      So for me it could be a problem of mapping the LPCM the right way. But who is guilty in the row? (Apple/LG/Sonos)

       

      Has anyone had similar experiences?

       

       

      hitmaker77
      Lyricist III
      December 11, 2023

      Noone?

       

      Yesterday in PrimeVideo again - 5.1 Multichanel was recognized as Stereo PCM = I cannot hear voices, only music.

       

      Even restarting the app did not help. Only after playing a stream with real Stereo PCM the 5.1 Multichanel on Amazon was recognized correctly.

       

      mac74
      Trending Lyricist I
      December 14, 2023

      I have same issue, LGCX, Beam 2, sub, 2x 1 sl’s. Blu ray 5.1 dts-hd discs play in multichannel 7.1pcm.

      I can get the standard dts 5.1 surround via a work around (optical out on the ub820 conv to hdmi), but it means swapping out the hdmi leads at the back of the soundbar each time i want to watch a dts film.

      My question is: 

      Given the 7.1 to 5.1 down mix issue? Which is better, multichannel 7.1pcm or the just the standard dts 5.1 surround ?

      Thanks M

      Corry P
      Corry PAuthor
      Sonos Staff
      December 14, 2023

      Hi @Professio7 

      Thanks for the diagnostic - I will forward it on to my colleague.

      It does seem to be a hardware issue, so I don't know if there will ever be a fix made available - it would be best to ask Apple.

       

      Hi @hitmaker77 

      Apologies - I have been off for a while.

      The next time this happens, please submit a support diagnostic immediately afterwards and report the given number here when convenient. Thanks. Please note, however, that it is unlikely that we will be able to resolve this for you.

       

      Hi ​​​@mac74 

      Given the 7.1 to 5.1 down mix issue? Which is better, multichannel 7.1pcm or the just the standard dts 5.1 surround ?

      Assuming the source media contains the DTS track, it’s better to just select that to be played to your Beam. It’s likely that the McLPCM track is being created from that anyway, so there shouldn’t be any quality difference.

       

      "Common sense is the collection of prejudices acquired by age eighteen." - Albert Einstein
        hitmaker77
        Lyricist III
        January 22, 2024

        @Corry P 

        It happened again.

        Diagnostic number: 1039983902

         

        Corry P
        Corry PAuthor
        Sonos Staff
        January 23, 2024

        Hi @hitmaker77 

        Thanks! - I’ll pass that along to my colleague.

        "Common sense is the collection of prejudices acquired by age eighteen." - Albert Einstein
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