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majelbstoat
Contributor I
November 14, 2020

PS4 Pro outputting PCM via LG CX shows Multichannel PCM 7.1 for Sonos Arc, but rear surrounds have no audio

I have the Arc, Sub, and Sonos 1 in a surround setup, connected to an LG CX via eArc. Previously I had the PS4 outputting Bitstream (Dolby), and Sonos reported Dolby Digital 5.1.

The fix that added LPCM to Sonos Arc recently went live, so I updated PS4 Pro to output PCM, and the HDMI input on the TV to PCM. (The output remained Passthrough). After doing this, the System Status page for Sonos shows Multichannel PCM 7.1.

However, I now get no rear surround audio in games like Assassin’s Creed Valhalla. (It’s not faint, there’s really none.) I get the full surround experience if I change it back to getting Dolby Digital 5.1. On the PS4 Home screen, I do get sound from the rears in PCM 7.1, albeit very faintly, compared to Dolby Digital 5.1.

Does Sonos not downmix the extra channels properly? It’s kinda bad that a higher fidelity signal sounds worse.

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    127 replies

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    ledzep1
    Headliner II
    April 7, 2022

    Perhaps its not an issue as such, and just how the lg and sonos arc report everything in LPCM as 7.1.

    I must admit when the sonos arc reports something as multichannel pcm 7.1 it sounds fine to me.

    i don’t have any rears though, just the ARC and Sub here.

     

    In any case It would be nice if someone from support could respond, as much as I love sonos, I think their communication could be a lot better.

     

    So this down mixing feature/fix do you have any update sonos support?

    I’m sure even the sonos ceo tweeted a long while ago that its in the works and in active testing. I can’t find the tweet now though. Please respond sonos, silence is not a good approach.

     

    Hey look at this, 3 months ago, posts since and no response from sonos support on anything in this thread for ages.

    I have resurrected a few threads on the subjects to keep the possible issue highlighted and to show how poor sonos support has been on giving updated feedback on any progress, they did say they were working/testing this a long while back.

    ste_ms
    Enthusiast I
    April 7, 2022

    I’ve raised this again in another thread and had a response from Sonos that this is not a bug apparently

    https://en.community.sonos.com/home-theater-228993/sonos-arc-and-7-1-downmix-to-5-1-6863804

    Naekyr
    Enthusiast II
    April 7, 2022

    That is correct it is not a bug. What is is poor design choices and poor quality assurance during testing on Sonos part, knowingly and or unknowingly releasing a feature that would inherently lead to push back from users - whether they had anticipated this or not is irrelevant, the fact is it happened. 
     

    The reason it's not a bug is because the feature claims to work with 5.1 lpcm and it does; the thing is Sonos never bother actually testing the feature using consumer products that users would have to use, they either used some in-house custom audio equipment or just did all work in virtual environments. If they had tested this feature using consumer audio visual equipment they would have seen that they had a big problem with the way lpcm is handled by audio equipment.

     

    Sonos has designed its LPCM support using a fairy tale lalaland idea of how its speakers would interact with other audio visual equipment and this is the outcome. It's still not bug though. I don't know how LPCM support is advertised for the Arc’s product page I haven't checked the main Sonos site in a while but they should possibly just remove all mention of LPCM and stop selling the ARC to people who expect flawless LPCM playback; it's reasonable for users who spend lots of money to expect something to just work without excuses so if they can't deliver that then stop advertising it that's my opinion 

    SONOS ARC | SONOS Sub | SONOS Play 1 x 2 | LG C9 OLED | PS5 | RTX3090 Gaming PC | Sennheiser GSP600 Headset | Audio Pro T8L Desktop Monitors
    106rallye
    106rallye
    April 8, 2022

    I have resurrected a few threads on the subjects to keep the possible issue highlighted and to show how poor sonos support has been on giving updated feedback on any progress, they did say they were working/testing this a long while back.

    I'm not sure intentionally cross posting on a forum is a very good idea.

      Corry P
      Corry P
      Sonos Staff
      April 11, 2022

       Hi Everyone,

      Well, this is embarrassing!

      After some investigation, I’ve found that downmixing of 7.1 channel LPCM to 5.1 channel LPCM was indeed implemented on the Arc as a feature last year, but our literature wasn’t properly updated to reflect the change.

      To be clear, the Arc does downmix 7.1 LPCM to 5.1, has done for some time, and we are working on updating our documentation to reflect the fact. Beam (Gen 2) has always supported LPCM and has always downmixed.

      Thank you all for pointing this out to me so we can now make sure that this information becomes public. I’m sorry for the unnecessary confusion. I’ll post this in multiple threads.

      This other issue with LG TVs is unrelated, but we’d very much like to get on top of it. We’ve requested the investigation of LPCM channels being played from the wrong speakers when an LG TV is involved, specifically when 7.1 channels are reported, and we will reach out to LG with details once we’ve gathered some solid evidence for them. Therefore, we’d very much appreciate it if anyone affected by this specific issue would visit this new thread I’ve made for gathering some details. Thank you.

       

      "Common sense is the collection of prejudices acquired by age eighteen." - Albert Einstein
      Aarown
      Lyricist I
      May 31, 2022

      Not Sonos related but PS4 Pro related- I’m having an issue with my receiver and PlayStation. I’m always seeing Multichannel pcm 7.1 regardless of source content and I don’t hear anything out of my center channel and/or surrounds at times. Seems like a PlayStation issue…

      emcleod
      Lyricist I
      June 2, 2022

      I had the wonderful bug where the audio channels were not sent to the center channel. A simple restart of the stream fixed it but something with the CX, Apple TV and Arc don’t work quite right. I hate when it happens as I don’t have a good fix other then try again  and hope it’s ok this time. 

      ste_ms
      Enthusiast I
      June 30, 2022

      So as a welcome update this appears to be fixed with the latest LG CX firmware update 04.40.10. I had to turn eARC on and off after the software had updated but I am now seeing Dolby Digital 5.1 rather than Multichannel PCM 7.1. Not had chance to check for any sound change/improvement but glad it’s now sorted.

      ledzep1
      Headliner II
      July 1, 2022

      So as a welcome update this appears to be fixed with the latest LG CX firmware update 04.40.10. I had to turn eARC on and off after the software had updated but I am now seeing Dolby Digital 5.1 rather than Multichannel PCM 7.1. Not had chance to check for any sound change/improvement but glad it’s now sorted.

       

      Yeah same on Xbox, set to uncompressed 5.1 outputs in Multichannel pcm 5.1 , used to say 7.1.

      Still doesn't display correctly for 5.1 audio on the apple tv 4k though, everything is still in multichannel pcm 7.1, but Im sure its outputting correctly still as it sounds ok to me.

       

      Just weird that some devices match up and others don’t.

      kikeminchas
      Lyricist III
      July 1, 2022

      Confirmed working as well with PS5, however selecting pcm 5.1 causes audio dropouts every 1-2 minutes.

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