Multichannel PCM 5.1 dropping out since 14.10 update

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@Corry P is at least aware of the issue (look at first page of this thread) but no idea if this is really actually being looked at by engineers.

I’m pretty sure this is not being looked at by Sonos given the chat conversation I’ve had with support

Quick update, support call did not help, told it was a WiFi issue despite the beam being hardwired and the only Sonos product on my network. Was also told to do a factory reset but I’m reluctant to do that as Sonos seem to generally discourage that. 

It seems that they won't check it out without factory resetting TV and Sonos. I cannot do that because I would lose trueplay and I don't have easy access to an iPhone. Others in the thread refused to factory reset for different reasons so I am afraid we are stuck, stupid really...

Factory reset of the TV was originally requested in the thread which is much more inconvenient than resetting the Sonos, but I eventually did it and there was no change to the drop outs. Now my drop outs have returned I’ve also factory reset the Beam (which seems to be the new request from support). Now on Sonos 14.19 (LG still on 03.33.11), but the factory reset of the Beam did not resolve the drop outs, so I’ve submitted diagnostics 403846833 to capture.

I don’t necessarily disagree with this sentiment. They really need to fix it.

I just noticed that there is a new firmware for LG C1 and a new Sonos update, I won’t be home for a while so I can’t test, did it solve the dropouts by any chance ?

Adjunto la información que me da la aplicación Sonos


Esto es correcto. Si no te haces problemas quedate con esto.

Pues tengo cortes, lamentablemente tengo corte de audio cada minuto es muy molesto así que tendré que pasar Dolby digital de momento..

Así es, aquí desde México y con el mismo problema. Lo que impide jugar Nintendo Switch de manera envolvente, ya que Nintendo es tan avara que no paga licencias de Dolby ni de DTS. Y la única manera seria LPCM 5.1 y desgraciadamente, sufrimos de estos cortes tan molestos. Llegaremos a 300 - 500 comentarios y Sonos no resolverá esto? Decepcionante.

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So after seeing the Verge story about the audio popping issue being fixed I wondered whether this ever got resolved. I can’t easily swap my cable out but may try it seeing as there have been a few firmware updates for the LG CX recently, as well as the Beam obviously.


Anybody still monitoring this?

Sounds like it’s an issue in the TV set somewhere. Sonos plays whatever it’s handed. 

Have you contacted the CS for the manufacturer of the TV set?

Another small bit of information from testing with 4k blu rays being played on PS5. (LG C3 and Sonos Beam 2 w/ 2 era 100s
-Dunkirk 4k UHD had audio dropouts (5.1 soundtrack with ps5 set to 7.1 on HDMI port 3)
     -I had hoped that the 7.1 sound setting would have covered this since it works fine for video games.
     -After switching to HDMI slot 1, the issue resolved.
-Mission Impossible: Fallout (Dolby Atmos HDMI port 3) worked flawlessly without any tweaks necessary.

I haven’t had any issues with dropouts when it comes to streaming from the TV directly. That includes 5.1, and dolby atmos. Hopefully at some point, Sony will push out dolby atmos support natively to PS5, maybe with the rumored console revision.

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Hi guys, same here the issue is back ☹️

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Why the hell are we trying to do Sonos’ work for them here?

This product is bugged. They should be the ones breaking their heads over it, not us. It’s obvious there’s nothing we can do to fix it, we’ve already done more than enough to identify and pinpoint the exact problem for them.

I’m not sure my recent ramblings on AppleTV HDMI signalling will help Sonos out at all, I just noted that both @yofalat611 and @ste_ms mention ATV4K Gen 3 can trigger the issue, whereas I’ve never seen it on my ATV4K Gen 1 because of a different bug. What they have done is re-assured me that behaviour that looks so obviously like a bug in the TV can be changed by the upstream/downstream vendor.

I just acquired an ATV4K gen 3 and guess what, it does negotiate LPCM 5.1 correctly when Gen 1 & 2 could only manage LPCM7.1. So if Apple can “fix” an “LG issue” between gen 2 and gen 3, then it’s quite plausible that Sonos are in a position to do the same for the dropouts (but most of us already knew that, right...). What did Apple change? No idea. All my ATVs are on 16.3.2 which leans towards a h/w difference, which goes back to @yofalat611’s conspiracy theory.

Also, I’ve observed that the A1 and C1 behave very differently at the HDMI eARC level (even for non-2.1 features), despite what appears to be otherwise identical system software on both. This may help other users diagnose similarly symptomatic issues but which have a different root cause.

Turns out I am still in warranty after all, but sounds like the retailer would send the Beam 2 for “repair” rather than swap out for a newer unit (the build date is stamped on the exterior of the packaging though).

5.1 PCM started to work fine with PS5 and LG CX 3 days ago. It worked perfectly for two days, 3-4 hours of gameplay each day and no cutouts at all, until I had to cut power from all three devices, and now the issue is back again. I wonder what did I do to make it work for 2 days?

EDIT: I just read this thread a bit more and realized that the same happened to a lot of people before, but then the issue came back again. Sigh...

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TL;DR for my post: what fixed it for me is turning off QuickStart+, enabling AV Amplifier 5.1ch in the PS5 menu and turning the PS5 and TV off. When wanting to use your PS5, allow it to fully turn on before turning on the TV.

A lot of people have seen that this fixes it temporarily but it does eventually return, seemingly whenever the beam is restarted. You could maybe test this and confirm? 

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A1 and C1 are set to passthrough. Beam 2 will accept “Dolby Multichannel LPCM 5.1” if set to auto, but I think this is the PCM in MAT (bridged by the TV) so not triggering the dropouts either.

This is because setting it to “Auto” in effect limits the TV. It becomes like the Optical/ARC TVs of old where it can only receive Stereo PCM and uses Dolby for multichannel. Stereo PCM is outputted as such however the TV unpacks AC3 and repacks it into Dolby PCM 5.1 before sending to the soundbar.

With “Auto”, I’m guessing the Apple recognizes that the TV cannot do multichannel PCM so the Apple already sends audio as DD/AC3 even if you had set “change audio format” to off. Tested this before with a PS5 where using DD output results to Dolby PCM 5.1 while all PCM formats (2.0, 5.1, 7.1) only result to PCM 2.0. So sadly this can’t be used as a workaround. Just set to / test for “Passthrough”.

Sure - I see the same on Auto, wasn’t suggesting it as a workaround (unadjusted audio sync is atrocious too) just wondering if MAT is being generated by the TV in this flow compared to the ATV in Atmos passthrough flow (I don’t get why it would make the effort creating a MAT stream instead of outputting the extracted plain LPCM on eARC), and whether I am interpreting the Sonos audio format labels correctly:


5.1 source → ATV4k.x→ “AC3 1Ch 48000Hz” → LG A1 → “Dolby Multichannel PCM 5.1” (PCM MAT?) → Beam2

5.1 source → ATV4k.x→ “AC3 9Ch 48000Hz” → LG C1 → “Dolby Multichannel PCM 5.1”→ Beam2


5.1 source → ATV4k.1 → “PCM 6Ch 48000Hz” → LG A1 → “Multichannel PCM 5.1” → Beam 2

5.1 source → ATV4k.1 → “PCM 8Ch 48000Hz” → LG C1 → “Multichannel PCM 7.1” → Beam 2

5.1 source → ATV4k.3 → “PCM 6Ch 48000Hz” → LG C1 → “Multichannel PCM 5.1” → Beam 2

Atmos source → ATV4k.x → “MAT 9Ch 192000Hz” → LG C1 → “Dolby Atmos” (PCM with Atmos MAT?) → Beam 2

Atmos source → ATV4k.x → “MAT_ATMOS 1ch 192000Hz” → LG A1 → “Dolby Atmos” → Beam2


This bug is an issue with PSVR2 as well when using home theatre audio on my Beam 2 / LG CX setup. PSVR2 ignores the fact that you have Dolby Digital 5.1 selected and outputs in PCM 5.1 (presumably due to the headset audio). You then get the sound drops. Fortunately you can fix it by selecting 7.1 in the PS5 settings with the PSVR2 headset connected.


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I’m hearing a lot of people talking about updating the TV firmware to the newest version from the Korean website. Is that safe for a European model? And how is it done?

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I’m curious about whether I need the cable or need to just permanently switch the inputs. Also if anyone know what might be special about ports 1 & 2 on an LGC2 TV that would be useful (considering all 4 ports are labelled as 4k 120Hz HDMI 2.1 ports).

My 2 cents (and this is what I’m doing): If using HDMI1 is good enough for you, then hold off on buying the cable for as long as you can. In case the cable workaround has its own bug or IF Sonos decides to address to issue lol.

And then when you finally find the HDMI1 workaround insufficient/intolerable, then buy the cable.

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Ah, I see. I didn’t realise multichannel LPCM required eARC.

That hadn’t occurred to me either until I tried it, or that the Amp was just ARC. 


I’m a little confused as to how the fault could be with the TV though if it’s set to just passthrough the bitstream?

Presumably the TV shreds the HDMI data stream from the console/bluray and only copies the audio stream to the eARC HDMI port. There’s enough software there for a memory leak or an exception to disrupt the process inside the TV, we know the Beam 2 is reporting the stream drying up. From reading other threads and forums it seems LG have had a difficult time stabilising multichannel LPCM, especially on the 9/X models. Having said that, it doesn’t rule out the Beam provoking the TV into quitting sending data. Would be interesting to know if the diagnostics had shown any kind of handshake during the recovery of the audio drop outs.

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@Eruvatar, who just got a refund, only bought their unit Jan 2023 so unlikely that there are already revisions that address the issue. “Repair” could potentially be better if they secretly know how to address the issue but are keeping mum due to costs involved.

The unit on display in the store had “2107” stamped on it, like mine. I agree, if there’s a faulty unit with a very recent manufacture date then there doesn’t seem much point exchanging the h/w.

I'm also having this issue with the Sonos Beam Gen 2 and the LG C1. I had already disabled QuickStart+ and turn off the TV has not helped.


Is it the consensus that this is an LG bug? Is there any point contacting their support?

So after 3-4 days the issue returned after turning off QuckiStart+ LG recently started the roll out of a new update it is available on a few countries but no in the US 

I will download it manually through the LG Korea website and install it manually via USB and see if it is finally fixed 



Let us know if that works.


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Hi @kikeminchas, @ste_ms et al

If a factory reset of your LG TV does not help, I can only recommend you get in touch with our technical support team who can, at least, create a case and get things documented - if nothing is documented, there isn’t any evidence that there is a problem and it will therefore not be investigated.

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5.1 PCM started to work fine with PS5 and LG CX 3 days ago. It worked perfectly for two days, 3-4 hours of gameplay each day and no cutouts at all, until I had to cut power from all three devices, and now the issue is back again. I wonder what did I do to make it work for 2 days?

EDIT: I just read this thread a bit more and realized that the same happened to a lot of people before, but then the issue came back again. Sigh...

Thanks for taking the time to post the new data point. It seems that LG C3 chipset isn't drastically different to C1/C2.

Indeed, power cycling the Beam2 should re-instate the dropouts immediately.

Has anyone else tried the new firmware to resolve this issue?

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I think the fact that the mods are not engaging with this thread anymore is telling. I think Sonos have reproduced the issue and so don’t need any more diagnostics or support calls coming in.

At this point they either don’t know how long a fix will take, or how it can be done and hence don’t want to set expectations, or they know it’s unfixable and are hoping this just dies away in time.


Beam 3?


15.4 is out now, I’ve installed it on my system but not tested it yet. Prepared to be disappointed though. 😁