Please read if you have encountered issues with 7.1 LPCM playback on Sonos via an LG TV

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RangerDog
Userlevel 3
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Solved with money spent!

So this issue has been annoying me for months since I added the Beam 2 to my system which includes a subwoofer and Play One rear speakers. My TV is an 75” LG 75QNED85AQA and an Apple TV Model A2169, e.g. 2nd generation.

 

As with many others, Dolby Atmos worked well when included in the media with all the proper check boxes. But reverting to non-Atmos media the Sonos app said Multichannel 7.1 PCM and many sounds, including speech, were muted. My solution was to go back to the Apple settings and change the sound output from “Atmos available” to “Dolby 5.1” which would then work fine but removed Atmos until I again changed the setting. As you can guess, going back and forth with the setting was annoying and sometimes forgotten, but at least it provided satisfactory results when done.

 

I read in this forum (Sorry to whomever’s idea this was originally but I don’t know the proper attribution.) that the issue was the Apple TV Gen 2 lacking HDMI 2.1 capability, something included in the Gen 3. It seemed to make sense to me.

 

First I made sure to acquire newer updated and certified HDMI 2.1 cables. Adding them to the Apple TV Gen 2 changed nothing. Then I bought an Apple TV Gen 3. VOILA! Now the Apple TV Gen 3 stays in the “Atmos available” mode and the app tells me (and my ears agree) when the media has 2 channels (Stereo PCM), 5 channels (Multichannel 5.1 PCM) or Atmos (Dolby Atmos).

With both the ATV Gen 2 and Gen 3 I played quite a bit with the settings. Whether I put the LG TV setting on “pass-through” audio or “auto” the results did not change for any media I played.

 

Essentially, the fix in my case was to get the newer Apple TV module. (And also being sure my HDMI cables were up to snuff.)

There does seem to be one bonus: The faster chip in the new ATV improves switching services with differing resolutions. It also seems to produce a better, brighter, clearer image on both lower and high resolution videos. I have no numbers for this but the first time I turned on the TV with everything hooked up, a little “Wow!” was set off in the back of my head. (You know, where the brain interprets the signal from the eyes.)

 

So I agree with those saying the problem is in the Apple TV and that Apple “fixed” it by offering (at a price) a newer model. Not only did that work for me, it seems pretty typical of how Apple does things. They make great stuff but you gotta pay for it. (Oh, Sonos does that too!)

R
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Mine does this as well. Multichannel PCM 7.1. Happens on my PS4 Pro when watching Blu-Ray's and my Nintendo Switch.

 

I notice the center channel sounds left oriented and the right side sounds very hollow. 

 

LG C1 55" Passthrough, eArc enabled. 

Devices connected: Sonos Arc, Nvidia Shield Pro, Nintendo Switch, PS4 Pro. 

Sonos Arc, Sub, two One's. 

Diagnostic: 368466851

Corry P
Userlevel 7
Badge +18

Hi @MJW75 

It’s a different issue, but not one that you should have to put up with.

The next time this happens, please submit a support diagnostic while it is happening and before trying to fix it. Once complete, record the number given then do what you need to do to resolve the issue. Then, when convenient, I recommend you get in touch with our technical support team who have tools at their disposal that will allow them to give you advice specific to your Sonos system and what it reports - give them the diagnostic number and they will be able to see what was happening at the time.

I hope this helps.

"Common sense is the collection of prejudices acquired by age eighteen." - Albert Einstein
Corry P
Userlevel 7
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Hi @exchgr 

Thanks! I don’t know if yours is quite the situation my colleague was looking for when he asked me to open this thread, but I will pass your report over to him nonetheless - it’s fairly close!

"Common sense is the collection of prejudices acquired by age eighteen." - Albert Einstein
Corry P
Userlevel 7
Badge +18

Hi @Professio7 

Thanks for the diagnostic - I will forward it on to my colleague.

It does seem to be a hardware issue, so I don't know if there will ever be a fix made available - it would be best to ask Apple.

 

Hi @hitmaker77 

Apologies - I have been off for a while.

The next time this happens, please submit a support diagnostic immediately afterwards and report the given number here when convenient. Thanks. Please note, however, that it is unlikely that we will be able to resolve this for you.

 

Hi ​​​@mac74 

Given the 7.1 to 5.1 down mix issue? Which is better, multichannel 7.1pcm or the just the standard dts 5.1 surround ?

Assuming the source media contains the DTS track, it’s better to just select that to be played to your Beam. It’s likely that the McLPCM track is being created from that anyway, so there shouldn’t be any quality difference.

 

"Common sense is the collection of prejudices acquired by age eighteen." - Albert Einstein
S
Userlevel 3
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No worries just wanted to make sure that you got some responses to this - hopefully some of the affected users from the other threads will pitch in here as it would be a shame to let this fizzle out, thanks.

Corry P
Userlevel 7
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Hi @JakeG 

Thanks for that report - I have passed the details to a colleague.

"Common sense is the collection of prejudices acquired by age eighteen." - Albert Einstein
C

Thank GOD this is finally being properly looked into. I get this on ALL my devices plugged into HDMI port

 

LG CX 65 inch TV

Sonos Arc

 

Source(s): 

 

Apple TV 4K

PlayStation 5 (even if I select 5.1 lpcm it outputs as multichannel pcm 7.1)

Xbox Series X (same as above - if not using Atmos (the atmos delay on the series x is insane hence not using it)

LG UBX 90 4K UHD Blu Ray Player

 

Apple TV content: anything that is meant to be Dolby Digital 5.1 will output as Multichannel PCM 7.1 - regardless of App

 

diagnostic: 1122099704

 

(while playing Lost in Translation from iTunes Store)

 

happy to provide diagnostics from other content/sources/app if needed as I’m so desperate for this to be fixed! It’s been over 2 years now!

 

 


 

J
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Hello, I have the same problem …

I have an lg c1, sonos arc + 2 One + sub.
The sound comes out in 7.1 instead of 5.1 on Netflix, Disney + and Amazon prime. But also on ps5.

 

If I disable eArc i am in dd 5.1. With the eArc activity I am in multichannel pcm 7.1

E
Userlevel 1

hi i have the same problem, tv lg c1 sonos arc and 2 one sl.  Apple TV 4K 2021 I get LPCM 7.1 track although it should be 5.1 from any source connected to any HDMI on the tv.  I can say that it is a problem of lg because the same thing happens if I connect a Denon 2600h amplifier to the TV it receives 7.1 tracks instead of 5.1.

Corry P
Userlevel 7
Badge +18

Hi @efrem81 & @JefDc 

Please describe the way in which your 7.1 playback results in mis-mapped channels. Thanks.

"Common sense is the collection of prejudices acquired by age eighteen." - Albert Einstein
E
Userlevel 1

with playback in LPCM 7.1 you lose a noticeable power output on all channels, I have to turn up the volume a lot this happens if eARC and passtrough are enabled on the TV, no exchange of channels in my case .. while if on the TV you set audio output to auto, the Arc receives audio correctly in 5.1 with a much higher sound power, in line with the audio that can be obtained by passing directly from the apps installed natively on the TV.

S
Userlevel 3
Badge +2

with playback in LPCM 7.1 you lose a noticeable power output on all channels, I have to turn up the volume a lot this happens if eARC and passtrough are enabled on the TV, no exchange of channels in my case .. while if on the TV you set audio output to auto, the Arc receives audio correctly in 5.1 with a much higher sound power, in line with the audio that can be obtained by passing directly from the apps installed natively on the TV.

Interested in this, I have similarly not noticed channels being swapped but have felt that the volume needs to be turned up more than I would expect but I put that down to the difference between PCM and DD 5.1

E
Userlevel 1

with playback in LPCM 7.1 you lose a noticeable power output on all channels, I have to turn up the volume a lot this happens if eARC and passtrough are enabled on the TV, no exchange of channels in my case .. while if on the TV you set audio output to auto, the Arc receives audio correctly in 5.1 with a much higher sound power, in line with the audio that can be obtained by passing directly from the apps installed natively on the TV.

Interested in this, I have similarly not noticed channels being swapped but have felt that the volume needs to be turned up more than I would expect but I put that down to the difference between PCM and DD 5.1

there should be no difference between Dolby 5.1 and PCM, as PCM is nothing more than the track already decoded by the source

H
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@Corry P 

It happened again.

Diagnostic number: 1039983902

 

Corry P
Userlevel 7
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Hi @JakeG 

There seems to be a discrepancy between the format reported and the format actually being delivered.

We can see that it is because of this that the channels are getting downmixed to the incorrect outputs. That's why FC (Front Centre) and LFE (Sub/Low Frequency Effect) get rendered to RRC (Rear Right Channel) and RLC (Rear Left Channel) (which we downmix to LS/RS) resulting in the dialogue coming from the surrounds.

So if the Apple TV sends 7.1 MPCM, and the TV isn't passing it through correctly (some kind of mapping bug), it comes out of the LG signalled as 7.1 but it's only 6 channels instead of 8, and in the wrong order.

We believe using the following settings will fix things for you, as they have worked in our own (limited) testing:

I hope this helps.

"Common sense is the collection of prejudices acquired by age eighteen." - Albert Einstein
Corry P
Userlevel 7
Badge +18

Hi @hitmaker77 

Thanks! - I’ll pass that along to my colleague.

"Common sense is the collection of prejudices acquired by age eighteen." - Albert Einstein
L
Userlevel 5
Badge +11

Hi @efrem81 & @JefDc 

Please describe the way in which your 7.1 playback results in mis-mapped channels. Thanks.

 

Hi

Is there any particular content/ test pattern we could use to test this issue, as I presume its not easy to hear if there is an issue? 

I have an LG CX and all content over HDMI, be it oppo203, apple tv 4k, all the DD 5.1 audio is ouput as multichannel pcm 7.1, but as you say LG seems to up convert it.

 

S
Userlevel 3
Badge +2

Whether channels are being mapped to the wrong speakers or not is almost irrelevant. Fundamentally the audio that we are playing from the source e.g. 5.1 is being messed with in the chain somehow and that is the problem - I upgraded to a Beam Gen 2 from a Gen 1 precisely because of the promise of eARC being able to handle full bandwidth audio transferred bit-perfect from the source and that is not happening. It’s possible that the end result is the same (e.g. the TV is adding 2 empty channels which Sonos then drops) but until we get some clarity from Sonos on exactly what is happening and why these questions will continue to be reported here and presumably through your support channels taking up valuable time and effort. Other audio systems e.g. AVRs connected to LG TVs don’t seem to do this as far as I’m aware.

I would assume it would be trivially easy to check some diagnostics and confirm what is happening? Maybe the Sonos end is somehow advertising itself as wanting a 7.1 signal, maybe it is too ambiguous and the TV assumes it’s 7.1 capable? Maybe the app is buggy and reporting 7.1 when in fact 5.1 is being played? Who knows, not the users on this forum certainly.

M

Hi, fairly new to the Sonos experience here. I have an issue similar to what you mention. Channels occasionally swap, often center channel swaps to rear. Sometimes no sound at all. This usually occurs when a new signal is “introduced” - if I change TV channel, change Netflix or Hulu programs or even sometimes when a commercial pops on. It’s resolvable by backing out of whatever I’m watching, switching to something else, then going back. I’d say this happens 20-25% of the time, which doesn’t sound like a lot, but it’s pretty annoying. 
Anyway, here’s my setup:

LG G2 65”

AppleTV 4K

Sonos Arc, Sub, 2 surrounds. 
 

thanks,

Dave

Airgetlam

Unfortunately, that data you’ve provided doesn’t really help track the issue. What you should do is submit a system diagnostic within 10 minutes of experiencing this problem, and call Sonos Support to discuss it.

There may be information included in the diagnostic that will help Sonos pinpoint the issue and help you find a solution.

When you speak directly to the phone folks, they have tools at their disposal that will allow them to give you advice specific to your Sonos system and network.

 

Bruce
P
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I’m having some serious channel mismapping issues with my setup. I’ve got an LG C2 and a Sonos Beam Gen2 with 2 Era’s as Surrounds using eARC (Bitstream, Pass through). I recently purchased an Apple TV 4K (Gen 2) where everything is converted to LPCM 7.1, even 5.1 signals.

Generally higher end Bluray Remuxes and Dolby Atmos stuff (over DD+) seems fine. However, I’ve watched an episode of Rick & Morty in Dolby Digital 5.1 which sounds very weird. Dialog coming from the the sides rather than front. If I set “Change Format” to “Dolby Digital 5.1” in the Apple TV settings, everything is fine. Unfortunately that severly degrades audio quality for other higher end sources.

Is there a fix in the works for the 2nd gen Apple TV or do i need to upgrade to a 3rd gen?

Diagnostics number: 1022034678

Corry P
Userlevel 7
Badge +18

Hi @exchgr 

Thanks for the update - glad to hear you got things working properly.

"Common sense is the collection of prejudices acquired by age eighteen." - Albert Einstein
E
Userlevel 1
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I’m having some serious channel mismapping issues with my setup. I’ve got an LG C2 and a Sonos Beam Gen2 with 2 Era’s as Surrounds using eARC (Bitstream, Pass through). I recently purchased an Apple TV 4K (Gen 2) where everything is converted to LPCM 7.1, even 5.1 signals.

Generally higher end Bluray Remuxes and Dolby Atmos stuff (over DD+) seems fine. However, I’ve watched an episode of Rick & Morty in Dolby Digital 5.1 which sounds very weird. Dialog coming from the the sides rather than front. If I set “Change Format” to “Dolby Digital 5.1” in the Apple TV settings, everything is fine. Unfortunately that severly degrades audio quality for other higher end sources.

Is there a fix in the works for the 2nd gen Apple TV or do i need to upgrade to a 3rd gen?

Diagnostics number: 1022034678

I haven’t been able to get a response from Apple on this re: the Apple TV 4K gen 2, but I can confirm that the Apple TV 4K gen 3 fixes this particular issue. With Apple TV 4K gen 2, 5.1 surround sources were converted to Multichannel PCM 7.1 and the channels were incorrectly mapped, whereas with the Apple TV 4K gen 3, 5.1 surround sources are converted to Multichannel PCM 5.1, and everything is mapped correctly. I assume it’s a hardware issue that got fixed in the latest gen, but I can’t be sure.

H
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I`ve made some little different experiences with LPCM and my Sonos system.

 

I own a LG C2, Sonos Arc with 2 Era 300 and Sub & Apple TV 4K, newest Gen.

I use the system for atmos, and most of the time it works flawlessly.

 

But sometimes when I start a stream (e.g. Amazon Prime) all voices are missing and I can only hear the music and some effects. I have to restart the stream an everything works fine again.

 

And sometimes I only get stereo PCM although I know, that it should be Multichannel PCM 5.1.

A new start of the stream or sometimes closing und opening the app again helps.

 

So for me it could be a problem of mapping the LPCM the right way. But who is guilty in the row? (Apple/LG/Sonos)

 

Has anyone had similar experiences?

 

 

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