Trending Lyricist I

Multichannel PCM 5.1 dropping out since 14.10 update

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Anyone else experiencing the same issue? Multichannel PCM 5.1 blanks out for a second every 1-2 minutes. I don’t think it’s a bandwidth issue as it works flawlessly with Multichannel PCM 7.1 (thorough test) and Dolby TrueHD Atmos (quick test). And it may have been caused by the Sonos 14.10 update. Setup is PS5→ LG C1→ Beam 2 (via earc).

2 weeks ago before the 14.10 update, I watched a bluray film wherein I had my PS5 transcode the DTS-HD MA 5.1 audio to Multichannel PCM 5.1 (as the C1 does not support DTS) and had no issues. Earlier today, I played a bluray film for the first time in 2 weeks and I encountered consistent audio dropouts every 1-2 minutes. It had the same setup where DTS-HD MA 5.1 → Multichannel PCM 5.1. I tested other bluray discs including the one I watched 2 weeks ago and they all now have the same issue.

Curiously, I’ve been gaming heavily on my PS5 the past two 2 weeks and haven’t had any audio issues. Then I realized that I’ve been using Multichannel PCM 7.1 when gaming on my PS5. So I made some changes under the PS5 sound settings to make it output Multichannel PCM 5.1 instead. Lo and behold, I am now getting the same consistent dropouts in games and even on the PS5 main menu.

I think it’s due to the Sonos 14.10 update as that’s the only firmware update I’ve done in the last 2 weeks. No PS5 update, no LG C1 update. Well actually while I was composing this post, I received and applied the latest LG C1 firmware update and I still have the same issue.

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Pinned Reply By Corry P

Hi @throwawaybeam2 et al

We now recommend you reach out to the TV manufacturer (LG) as this behaviour is also occurring with different soundbar manufacturers (so it’s not a Sonos-specific issue).

Alternatively, please utilize different audio formats from McLPCM 5.1 (e.g., McLPCM 7.1, DD+, etc).

I hope this helps.

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M

mser

Lyricist II

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.

Thank you very much for your testing and also thanks to @RANDUSR23296 for the extensive debugging work!

I’ve gone ahead and ordered said cable as well (from Amazon Germany) and will report back once I was able to test it.

To follow up on this, like others who’ve bought this cable, I can also confirm the issue is gone.

O

OmriP

Lyricist III

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.

M

MJW75

Enthusiast I

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?

R

RANDUSR23296

Enthusiast I

My oscilloscope only has a bandwidth of 30MHz which is inadequate for displaying even the TMDS clock signal (74.250MHz from the Beam2), however it does show some smoothed waveforms so is enough to detect gaps in the signal.

Whist I didn’t see any disruption on the TMDS clock, I finally managed to trap some physical layer evidence - on HEAC+ (pin 14). Unsurprisingly, the TV’s eARC output is showing disruption during the dropouts. Sadly this doesn’t really help narrowing down the cause more than any of the observations that have already been made on this thread.

HEAC+ is the upper waveform (red) and apparently is some S/PDIF-like format, the analogue audio is lower (yellow). Audio waveform was actually captured from a Sonos port line output in multi-room mode as this seemed easier than trying to hook up a microphone to the scope, so it won’t line up exactly:

I was wondering whether I could feed a test video signal in from the Raspberry Pi on the TMDS pins, but spliced with the eARC pins routed to the Beam2. This might isolate whether there's some problem in the Beam2 video stream or whether any video on HDMI2 will activate some buggy logic inside the TV (the Beam2 is still doing something different to the Arc, so maybe on the eARC control line).

O

OmriP

Lyricist III

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).

R

RANDUSR23296

Enthusiast I

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...

X

Xassefras

Lyricist II

It might be semi off-topic, but just a heads-up for anyone considering upgrading an Apple TV 4K Gen 3 to fix the LPCM 7.1 issue: the new model does output in LPCM 5.1 according to the Sonos app, but audio quality is noticeably worse compared to forcing Dolby Digital 5.1 on it. Especially voices sound more echoey somehow.

R

RANDUSR23296

Enthusiast I

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:

Masking pins 10/12 with a *sliver of tape does seem to have the same outcome, TV no longer recognises the video on HDMI2 (as per 11111 menu) and the dropouts are gone:

S

ste_ms

Enthusiast I

Just seen update 15.3 released - I can’t update until later however I have now changed to the fibre HDMI cable so won’t be able to tell if it’s fixed anyway. Anybody else able to check?

I think if this isn’t it then it’s never getting fixed.

P

pcfarrar

Lyricist III

Just updating mine, will test shortly.

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