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Question

Issue with center channel on Arc Ultra - even after replacement

  • May 18, 2026
  • 5 replies
  • 45 views
S

Dear Sonos community. 

I am currently in the situation of having issues with the center channel of my home theater setup. The dialogue in different media is sounding very muffled.

Here’s what I have done to troubleshoot

  • Got help from Sonos support. After an hour of troubleshooting with them on the phone, they decided to send me a new Arc Ultra. Issue still remains after the receiving the new speaker unit, so ...
  • I have used a specific youtube video to use as benchmarking the issue
    • I tested the video from my Computer (It’s hooked up to the TV), youtube app from my Nvidia Shield, and also the Youtube app on LG TV. Same issue.
    • However! The issue is not present when running the sound via Airplay.
  • Dolby Atmos content is not affected by this issue.
  • The media that I have without Dolby Atmos has this issue.

 

This issue appeared recently (last two weeks), so can it be that an update for the Arc Ultra is causing this to happen?

 

Thanks for the attention!

5 replies

Stanley_4
  • Stanley_4
  • Grand Maestro
  • May 18, 2026

YouTube has often mislabeled the audio format on their content.

Try a more reliable source and see if the sound is better.

    Airgetlam
    • Airgetlam
    • May 18, 2026

    I’d agree. The vast majority of content on YouTube is stereo, even when it is suggested that it is higher. Likely due to bandwidth reasons. Any ‘stereo’ signal is going to be ‘interpreted’, and the center channel will likely sound odd. 

    You may need to adjust the audio settings on your TV, too. It’s rare, but some TVs ‘change’ the format that it receives, and then passes on to Sonos. Since we have no idea what the TV is in your case, we’re not sure. 

    Honestly, a computer test is variable, too. We have no idea what type of audio is being passed to your TV. It certainly could be stereo, or higher. And if the issue is your TV changing what it is passing to Sonos, you’re still stuck. And the fact that Atmos content plays without issue certainly suggests an issue pre-Sonos. 

    Bruce
    S
    • sanbje29
    • Author
    • Contributor I
    • May 20, 2026

    YouTube has often mislabeled the audio format on their content.

    Try a more reliable source and see if the sound is better.

    Thank you for the reply. As mentioned it’s not only Youtube. I have also after a new test discovered that the issue is also present in Atmos content.

    I’d agree. The vast majority of content on YouTube is stereo, even when it is suggested that it is higher. Likely due to bandwidth reasons. Any ‘stereo’ signal is going to be ‘interpreted’, and the center channel will likely sound odd. 

    You may need to adjust the audio settings on your TV, too. It’s rare, but some TVs ‘change’ the format that it receives, and then passes on to Sonos. Since we have no idea what the TV is in your case, we’re not sure. 

    Honestly, a computer test is variable, too. We have no idea what type of audio is being passed to your TV. It certainly could be stereo, or higher. And if the issue is your TV changing what it is passing to Sonos, you’re still stuck. And the fact that Atmos content plays without issue certainly suggests an issue pre-Sonos. 

    I did some additional testing, at it seems that the issue is also present on Atmos content. 

    The TV is a LG C4. The thing is that this is a issue that suddenly appeared. No settings has been changed.

    N
    Forum|alt.badge.img+19
    • nik9669a
    • Senior Virtuoso
    • May 20, 2026

    Have you spoken to the tv manufacturer? The issue may lie there, rather than with Sonos. 

      M
      Forum|alt.badge.img
      • merry70327
      • Contributor II
      • May 20, 2026

      Thanks for sharing the detailed troubleshooting steps — that really helps narrow things down.

      Since the issue persists across multiple sources (TV apps, Shield, and PC) but does not occur via AirPlay or Dolby Atmos content, it does seem more like a processing or firmware-related behavior rather than a hardware fault (especially since even a replacement Arc Ultra shows the same symptom).

      It’s interesting that only non-Atmos dialogue is affected and sounds muffled. That could point toward a recent change in how the Arc Ultra is handling upmixing or center channel processing for stereo / non-Atmos content.

      Given that this started within the last couple of weeks, it’s definitely worth checking:

      • Recent Arc Ultra firmware updates
      • TV audio output settings (PCM vs bitstream / passthroughAny changes in Trueplay or
      • speech enhancement settings

      If others are seeing the same behavior after recent updates, it could indicate a software regression. Hopefully Sonos can confirm this or provide a fix soon.

       

      Moderator edit: This post may be AI-generated.

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