Sonos Arc LPCM downmix bug – would I be affected?

  • 29 March 2021
  • 2 replies
  • 361 views
O

I have a question regarding the current situation regarding multi-channel LPCM with the Sonos Arc and the broken down-mixing from 4 to 2 surround channels. I know there's supposed to be a fix coming, but I've seen it again and again that such promises have been broken (not talking about Sonos, but tech companies in general). Also, a fix has been promised for four months now, and the longer it takes, the more likely it is that it will never be fixed – it’s apparently not so easy to fix.

So I want to know what I'm getting into before buying the Arc + 2 One SLs as surrounds.

I use an Apple TV, an Xbox Series X and soon a PS5 with an LG GX (eARC-capable). With consoles, I'd like to use 5.1 LPCM. With the Apple TV, everything should be output as what it is (Atmos as Atmos, 7.1 as 7.1, 5.1 as 5.1, 2.0 as 2.0), but I don't care if as bitstream or as LPCM.

The question is: will the broken mix-down affect me with my setup?

  • Can I set the consoles to output 5.1 LPCM and the Sonos Arc will play the signal back correctly?
  • What about the Apple TV set to "Auto"? Atmos will be passed on as Dolby MAT (7.1 LPCM + embedded Atmos metadata) and "normal" 5.1 and 7.1 as LPCM, is that correct? So videos with Atmos and 7.1 tracks would be missing the surround back channels, but 2.0 and 5.1 tracks would play back correctly? Unless I change the output on the TV from “Passthrough” to “Auto”, which would lead to more lag?
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2 replies

G
Userlevel 7

Any 5.1 content should play correctly through the Arc. It is only 7.1 PCM content that seems to be missing a couple of channels, specifically the rear left and rear right surround channels. Rather than properly down mixing 7.1 to 5.1 by combining the side and rear channels together, the Arc will only play the left and right side surround channels.

"Receive with simplicity everything that happens to you." - Rashi
O

Hi GuitarSuperstar,

thank you for replying to me.

Yes, I’ve read how the bug manifests. What I’d like to know is how it would affect me with my particular setup. Do you know if the Arc will work as I described with XSX, PS5 and Apple TV?

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