Multichannel PCM 5.1 dropping out since 14.10 update

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Y
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Hi @OmriP & @mjsound 

I personally really don’t know much about it - I just found the information and shared it with you.

A search will reveal that many people with these particular TVs and all kinds of (non-Sonos) audio equipment experience the same. Here are three examples:

https://www.avforums.com/threads/lg-c1-oled48c16-issues-with-5-1-lpcm-over-earc.2422032/

https://www.reddit.com/r/LGOLED/comments/v9ly92/lg_c1_after_new_update_033006_uncompressed_51_and/

https://discussions.apple.com/thread/254122268

The issues also coincided with an LG firmware update for these particular models, and LG are actively seeking videos and other evidence from their customers in an effort to troubleshoot.

None of these linked issues are even remotely similar. 

Lmao what a shitshow. Skimmed the links:

1st link - PCM 5.1 no sound but DD 5.1 has sound. Turning the TV off and on again fixes the issue

2nd link - BOTH PCM 5.1 and 7.1 does not work

3rd link - Multichannel issue with ATV4K. Sometimes sounds do not come out of correct channels

Most seem to be generic uncompressed audio (arc vs earc) issue. Could be hardware/software, or could just be misconfigurations. But definitely not the HIGHLY SPECIFIC issue we are experiencing here i.e. everything works with Beam Gen 2 except PCM 5.1 which has a dropout every minute. PCM 7.1 works. Sonos Arc works.

While the provided links do not include exhaustive testing and only discussed limited use cases, it is safe to say that “None of these linked issues are even remotely similar.” You can type anything on google and you’ll find confirmations for whatever it is you want to see. And that’s just what Sonos lazily did.

I think Sonos is just capitalizing on the recently discovered cable (and to a lesser extent, HDMI1) workaround. Sonos wants to get out of this mess while the users have quieted down, already content with the solution they mostly paid for.

 

Edit: Who knows? Maybe one day Sonos will sell an official fiber optic HDMI cable.

Y
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Seems like someone from The Verge is covering the popping sound issue. Sent them a PM and tagging them in case they’re intested to look into this as well @tomwarren 

Corry P
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Hi all,

I highly recommend that anyone looking for this issue to be resolved get in touch with our technical support team to have your case sorted out. While we of course forward any and all information from the community here, it will help us all if you ‘officially’ create a case with our support engineers.
Please don't expect an immediate resolution, but each case will add further information that could help us get a resolution in place.

"Common sense is the collection of prejudices acquired by age eighteen." - Albert Einstein
R
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The issue had been gone for a while without me having to do anything, so I thought perhaps some update had fixed it. However today the TV received a software update and the issue returned immediately afterwards. I’m thinking software updates (as well as power outages) somehow “reset” the state of the tv, including reintroducing this bug.

Anyways, nothing I’ve tried so far worked.

It isn’t clear from your post, so I’m just checking - did you read the last page of posts where a ‘workaround’ was discovered? 

If you mean the workaround with the cable then I’ve read it, unfortunately I don’t have such cable and Amazon doesn’t seem to have it available (or they’re not sending it here).

It may be possible to use a slither of insulation tape to cover pins 10 and/or 12 (TMDS clock) similar to others managing to block pin 13:

https://bonigopalan.medium.com/how-i-solved-hdmi-arc-problem-between-a-set-top-box-tv-and-sonos-arc-using-scissors-54e3d0f23ca6

Looks quite fiddly, but if the TMDS clock is blocked then the TV shouldn't respond to any video signal, which reduces the number of pins needing covering. It may actually be easier though to cover all the TMDS pins (1-12) as the extra width will be less fiddly.

I have a short HDMI extender (can't remember it it came with the Beam or not), which should save the TV/Beam sockets from ingesting insulation tape should it come loose, so may try this a bit later.

Not sure of the warranty situation of doing this sort of thing either...

 

 

R
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Keep this menu displayed when playing 5.1 audio and when an audio drop comes, ‘6CH’ drops to ‘2CH’ momentarily before coming back (I managed to get this on video). Hit the up button on the remote every minute to stop the menu timing out while you do this.

Good spot, this is new behaviour.  I’ve recently seen the TV flick between 6ch and 2ch on this menu when I’ve confused it by making too many changes, but it’s the first time I’ve noticed the TV show any reaction at the time of a drop out. In my case it has just flicked between 6ch → 4ch → 6ch during the drop. It didn’t do this when I started looking at this months ago (when I’m certain HDMI 1 was also buggy). Perhaps this indicates LG is looking into this bug after all (or that I just have a bad memory...)

So it is not the sound bar. It is either the source (although no issue on my other TVs) or the TV. I’m guessing TV as why would it work on HDMI 1 if it was the source?.

There’s no issue on my alternative eARC devices either (Marantz in my case or Sonos ARC according to this thread), so that logic doesn’t quite stack up. Whilst the Beam 2 may not turn out to be buggy it isn’t blameless in this issue.

Same issue here. I have the latest Apple TV 4K (3rd Gen), LG C2 and Sonos Beam Gen 2 (all on the I also tried an earlier Apple TV 4K box (2nd Gen) and this bizarrely sends 5.1 audio as 7.1 - so I couldn’t use it to test with.

This is confirmed by a few posts on this thread - could be a h/w revision change between gen 1&2 and 3, or just that some manufacturers have no interest I back porting s/w fixes. I’m guessing Beam 3 won’t trigger this issue, will be interesting to see how C3 behaves (if not solved one way or the other by then).

Contributing factors to the bug seem to be:

  • Beam 2 reboots
  • CX-C2 (and G family) TVs
  • HDMI 3 (and 4?)
  • TV cache of HDMI devices (disconnecting the Beam 2 and reconnecting doesn’t clear the bug but fiddling with some of the TV audio/CEC settings can do)
K
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Extremely disappointing answer for all the people that has been extensively troubleshooting and reproducing the issue and giving mountains of data and details in this thread... 

M
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So it is not the sound bar. It is either the source (although no issue on my other TVs) or the TV. I’m guessing TV as why would it work on HDMI 1 if it was the source?.

There’s no issue on my alternative eARC devices either (Marantz in my case or Sonos ARC according to this thread), so that logic doesn’t quite stack up. Whilst the Beam 2 may not turn out to be buggy it isn’t blameless in this issue.

Fair enough. My thinking was that the hidden details state HDMI 3 (or 4) drops to 4CH (correction from above, it drops to 4CH not 2CH, but not every time). The TV is set to pass through audio, so it shouldn’t change the number of channels, but I also guess there is some kind of handshake going on with the Beam that could feed back different source requirements, causing the TV to stumble……? Either way, it sounds like exchanging the TV won’t help and everything now seem to work with Apple TV on HDMI 1. The devices on HDMI 3 and 4 don’t seem to output ‘Multistream PCM 5.1’, so that isn’t an issue.

See video below of the audio drop out and the channel number dropping to 4.

 

O
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I purchased the Beam Gen 2 yesterday as my first Sonos product, specifically to use with PS5 and LG C1 48. This is absolutely a specific issue related to the Beam and not LG.

I have used numerous other audio equipment, in a multitude of formats both with PC and PS5. No such issues with any other products. The audio drop outs with LPCM 5.1 are extremely disappointing. It is not acceptable to suggest the purchasing of a non-CRC Hdmi cable, or to switch to a compressed audio format (e.g. Dolby) as workarounds. Further to this, passing the buck to another manufacturer (LG) is not acceptable when there are no reasonable or methodical grounds to suggest doing so. I do hope that this fault is resolved soon, or the Beam will be returned and shall be my last Sonos purchase. 

Don’t hold your breath for a fix. This has been going on for a year now. If this bothers you, return it.

R
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but I also guess there is some kind of handshake going on with the Beam that could feed back different source requirements, causing the TV to stumble……? 

That’s my guess too. eARC has it’s own handshake: the Beam presents the TV with a Capabilities Data Structure (CDS), independently but similar to how the TV presents the AppleTV (and Beam) with an EDID. The CDS received by the TV on HDMI2 would drive the logic in the TV on what audio sink to present to the Apple TV in the EDID on HDMI3.

Without knowing what the audio stream on HDMI3 looks like during the dropout it’s difficult to know if the AppleTV is involved (maybe an HDFury device can “sniff” this) in dropping the audio. Having read a little about the HDMI port implementations it’s also difficult to know which point the 11111 menu is picking to determine the audio format. Is it really what’s in the TMDS stream, or is it examining a transposed stream on an internal I2S link or ARM bus - in which case the Beam 2 may already have had chance to interfere indirectly via the HDMI3 control registers (via a CDS handshake every 59s) whilst the AppleTV keeps streaming Audio/Video happily to HDMI3 as if everything is stable. We do know that the video stream is not interrupted.

I haven’t yet thought of a way to prove/dismiss the above with any of the equipment I have to hand though. Introducing any kind of passthrough sniffer device may even alter the signalling enough to fix the problem enough so that it can’t be observed :(

R
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I only recently realised (when looking into how optical HDMI cables are wired) that my logic analyser can decode both the DDC and CEC HDMI signals, so I found a cheap HDMI breakout PCB on e-bay and now have it connected between the TV HDMI2 and Beam2 using the original Sonos cable (not the reversed optical).

When I restart the Beam2 I can now read “Sonos Beam” being spelt out in ASCII in the CEC SetOSDName command and the EDID being transferred over the DDC I2C channel during the initial boot up. However, when a drop out happens I see no obvious immediate activity on either channel, so I’m thinking the HDMI2 connection is not collapsing every 59s. I haven’t put much thought yet into how I could monitor the TMDS/eARC lines as I think my test equipment is too basic.

One thing I don’t understand though is why HDMI 1 is unaffected. While this may be an unpopular opinion, I think this fact suggests the problem may be the TV after all…..

Purely speculation, but maybe HDMI 1 and 2 share a bus on the board, and 3 and 4 share another. 3 and 4 are affected as they are on a different bus to the Beam Gen 2. So the signal from the Beam Gen 2 to the TV is normal, but the TV deals with it incorrectly on HDMI 3 and 4 or it has an issue passing it between busses. Again… this is purely speculation.

This has been speculated before but then the question is why isn’t the Arc affected if the TV is at fault?

The Beam2 could possibly be sending a valid (but slightly different to the Arc) format over TMDS that triggers a bug when eARC is routed from HDMI3 (maybe HDMI 2, 3 and 4 are sharing resources with HDMI1 having the better isolation). The bandwidths involved shouldn’t be maxing out the HDMI 2.1 circuits though if my A1 can handle the same configuration? So maybe not load related. I was reading about InfoFrames in the TMDS signal, so maybe something buried in there.

Alternatively though, the Beam2 could be sending an anomaly over TMDS and the TV is just handling it differently (but within spec) depending on which source the eARC stream is being sourced from.

But it could also be that both devices are operating reasonably, but so close to some tolerance that only when combined triggers an interrupt/underflow in the TV HDMI circuitry.

There are more things that I don’t understand:

  • Why is the issue only audible on 5.1 if 7.1 also show an anomaly on the 1111 menu every 59s?
  • Why did HDMI 1 become more robust?
  • why did the dropouts change from every 39s to every 59s
  • Why does cutting the CEC line stop eARC working, it shouldn’t need CEC to operate
  • What did Apple change between gen2 and gen3 to make AppleTV correctly use 5.1 instead of 7.1 - and why wasn’t it back ported to gen 1 or 2 in the same TVOS patch

My C1 wanted to download a new firmware today, but I haven’t installed it yet in case the behaviour changes yet again...

O
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Interesting, could you explain how the LPCM 7.1 is the same as 5.1 if you know why, please? If I were to guess, I would assume that either the 7.1 can be down mixed to 5.1 by the Beam, or the extra two channels are effectively "empty" placeholders within the audio formatting? 

As far as I understood from people who researched it, they’re just empty channels. The Sonos app will show you 7.1 when you select soundbar as source type, but it’s actually 5.1.

O
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I should add that this bug completely nullifies the possibility of playing Nintendo switch with surround sound sound together with the beam 2 and an LG tv because unlike the PS5 the switch has no option to change the surround sound output to anything that’s not 5.1 Multichannel PCM.

The fact that such a long time has passed without any update from Sonos with regards to whether they’re even looking into it is infuriating.

LG is one of the most popular TVs out there, and the first choice for many people who want OLED TV. Odds are high that people who use Sonos also use LG OLED since they’re both premium products.

How come the priority of this isn’t high?

O
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For me the problem has not returned since I solved it by turning off that LG feature I previously mentioned, even with multiple power cycles. But I’m not using an AVR.

Had several power outages for a few consecutive days and now the problem has returned after being gone for about a month.

This is so frustrating, and neither Sonos nor LG seem to care.

I’m on LG G2, so it’s definitely not limited to the C1.

Ok so twice more I have been able to make it go away. I don’t know how but it definitely involves turning QuickStart+ on then turn off the tv, wait a few minutes, turn on tv wait a while, turn off QuickStart+ then start playing randomly with every setting related to sound (simplink, passthrough to pcm or auto, bitstream to pcm, turn on and off eARC repeatedly etc). Then turn off tv, wait a while, turn it back on and leave it on some screen playing music (for example Home Screen of ps5). Then this error just goes away after a while and doesn’t return unless there’s another power outage. I know it sounds like total voodoo and hand waving but it already worked 3 times for me. I’m even wondering if my actions actually have any effect or it’s simply time passing that fixes it but anyway that’s all I have for you so take it for what it is and I hope it helps. The method is a bit random but the results are consistent and stay fixed.

Y
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I should add that this bug completely nullifies the possibility of playing Nintendo switch with surround sound

Sharing borked scenarios that I am aware of as well as possible workarounds if any. If any prospective buyer comes across this and has a similar use case, just turn around and run:

Switch - You’re stuck with Stereo as PCM 5.1 surround is borked

PS5 - You are forced to set it to PCM 7.1

Bluray - For DTS, you’re stuck with Stereo if your player only converts DTS to PCM 5.1 (are there even bluray players who can convert DTS to Dolby?)

Apple TV - The ATV doesn’t do DD/DD+ passthrough and outputs them as PCM 5.1. So non-atmos and non-stereo contents are borked. Workaround is either force the ATV to output as DD (DD only, not DD+) which is a downgrade or use the LG webOS app

PC - Using Dolby Atmos for Home Theatre is sometimes bugged esp for non-Atmos content (I think it’s an nVidia/Microsoft issue) so in those cases you’re forced to set it to PCM 7.1

With the popularity of LG OLEDs, there is something for everyone lol.

 

I finally returned my Beam and One SL and got a refund.

What’s funny about this issue is Sonos completely screws over customers who actually spent on building a 5.0/5.1 system. If I had used all this money for an actual surround system, I sure as hell would want to set my devices exactly to PCM 5.1 and avoid downmixing from 7.1.

M
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That would give the illusion to a Beam2 owner that it somehow was triggering the problem yet in reality it was still functioning 100% to spec, particularly as eARC devices are still relatively rare and the Beam2 was likely the first eARC device connected up. Testing a different eARC device (for the fewer users who have access) would work fine and look like only the Beam2 was bugged.

Apple TV 4K 2nd Gen and later support eARC so could be used for testing. I may give this a go if I get a chance later today (my HDMI ports are a real pain to access though).

https://support.apple.com/en-gb/HT207117

O
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It almost seems to infer that the LG Technical Team are aware of a hardware issue with that TV model. I would have the repair and just see what happens after that.

No don’t try to pawn off the issue to LG lol. It’s a Sonos issue as well, clearly.

To be fair, I did think of a scenario where the Beam 2 is blameless: Maybe the TV has a bug that means the first device eARC device it registers (and it does seem to cache the details of eARC devices) is bugged, but subsequent devices are not (it’s not uncommon for first items in software containers to trigger additional logic or follow modified algorithms that subsequent items added do not).

That would give the illusion to a Beam2 owner that it somehow was triggering the problem yet in reality it was still functioning 100% to spec, particularly as eARC devices are still relatively rare and the Beam2 was likely the first eARC device connected up. Testing a different eARC device (for the fewer users who have access) would work fine and look like only the Beam2 was bugged.

However, if this was the case here, I’d expect to see reports on internet about other devices having dropouts, because they’re the first plugged in, but I couldn’t find any. I could (probably) test this by factory reseting the TV and connecting my AVR as the first eARC, but the lack of evidence on my searches suggests this would not be worth the effort.

Also, that doesn’t prevent Sonos support actively help isolate the issue, and/or even giving some sensible technical engagement (I do appreciate @Corry P’s recent update indicating related activity by the community team).

If this were the case you’d see loads of posts here about people with Sonos Arc, or any other soundbar. The fact that it’s so specific to the beam 2 suggests it isn’t blameless.

O
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I have contacted LG UK (since I just assumed the local LG Israel here will be completely useless in addressing the matter) and after a good 4 days they responded to my email. I will update if I come up with anything useful.

P
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Looks like no fix in 15.2, disappointing as I hoped this would be the one. 

That is disappointing. At least my workaround is still working (see my previous posts if you haven’t already), so I’m happy enough that it will no longer cause me issues. I’ll still follow this for a proper fix though.

For anyone interested, this is a the cable I’m using which fixed the problem for me. 
https://www.amazon.co.uk/dp/B09YPR5SD4

I ordered the cable. Should be delivered tomorrow. I will test it and report it here, if the dropouts are gone, too.

F
Userlevel 1

@Airgetlam I will contact the support this week. We will see ! 

Y
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A number of users have already filed tickets within the last 8 months. And as we can see from this thread and numerous other similar threads here and in other forums (e.g. reddit, apple), this is a real problem worldwide and not an isolated issue. And the issue has been well documented by the users they have practically handed everything to Sonos on a silver platter.

Any decent company would have at least officially acknowledged the issue by now. But I suppose within Sonos Time™ 8 months is not immediate enough.

 

While we of course forward any and all information from the community here

Ok, so can you explicitly confirm that you or your team have officially forwarded this particular concern/thread to the approriate engineers/support department? Of course no one expects you to solve the issue but this is the bare minimum that we expect from the forum mods.

Corry P
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Hi @yofalat611 

Thank you for your concern. Yes, I can officially confirm that we, the community team, are making our engineering teams aware of these kinds of topics. Just yesterday I updated the document in which we track all the relevant information from this topic, and made sure the engineering team is aware of it. During the update, I also noted that while there is quite a few users in this topic, there are not nearly as many registered cases, or, their community account is not the same as the account they use for their Sonos system. So again, I can only reiterate that if you’re experiencing this issue, please get in contact with our support team if you haven’t done so already.

"Common sense is the collection of prejudices acquired by age eighteen." - Albert Einstein
S
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I’ve so far failed to reproduce the dropouts with my ATV 4k as the source (gen 1 and gen 2), but I only use ATV+, Disney+, Youtube, Prime and Netflix apps there, nothing like Plex.

When I first set up our ATV4K gen 3, PCM 5.1 worked fine on it despite PCM 5.1 being bugged on my other devices (I only learned that ATV outputs DD/DD+ as PCM 5.1 when order was already on the way). Tested with Netflix and Disney+ and we were even able to watch a full movie uninterrupted. Couple of days later we played another non-Atmos movie and the bug was on and has been bugged since. I don’t think the gen matters. It’s probably more of the bug just hasn’t triggered for you yet. But inevitably will…

There’s definitely a difference with the Gen 3, I had no issue with the Gen 2 but that always showed 7.1 in the Sonos app. It’s also intermittent for me on the Gen 3, I can’t pin it down but a restart of the beam or software update always seems to trigger it

M
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Looks like no fix in 15.2, disappointing as I hoped this would be the one. 

That is disappointing. At least my workaround is still working (see my previous posts if you haven’t already), so I’m happy enough that it will no longer cause me issues. I’ll still follow this for a proper fix though.

For anyone interested, this is a the cable I’m using which fixed the problem for me. 
https://www.amazon.co.uk/dp/B09YPR5SD4

I ordered the cable. Should be delivered tomorrow. I will test it and report it here, if the dropouts are gone, too.

Make sure you run the cable with the TV at the source end. Fingers crossed this works for you too. I’ve been watching loads lately with 5.1 PCM and I’ve not had an issue. 

R
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Regardless it feels that we’re homing in on the issue here 

Also encouraging that recently more unique posters are finding this thread and describing similar experiences

Ken_Griffiths

I think there is a good chance that there is a hardware problem somewhere - there are just far too many reports of dropouts and other issues associated with eArc and it happens across the CX, C1, AND C2 which all run different processors, firmware versions, and WebOS versions.

At this point I don’t think it can be fixed and am now in the process of trying to arrange a refund even though I’m out of warranty period as under the UK sale of goods act a speaker that cannot play audio reliably in the manner that it was marketed to do is not fit for purpose.  

Shouldn’t you be returning the TV in this instance? As an example, I have the LG C9 OLED and not seeing this issue. It’s not like this applies to other TV models, or brands, outside of those you mention.

It could well be that Sonos are aware where the issue lies and if that is with LG, you cannot expect Sonos to publicly announce that. All they can do is fire off an internal ticket to LG to highlight the issue and ‘hope’ that LG go onto fix the matter for their customer.

My thoughts are if you’re going to return anything, then take into consideration where the evidence points and in my humble opinion, that seems to lean a little more towards certain LG TV models, rather than Sonos. Presumably LG support have been contacted by folk here and are currently looking into the matter from their end too on behalf of their own customers?

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