Multichannel PCM 5.1 dropping out since 14.10 update

Hi @throwawaybeam2 

Welcome to the Sonos Community!

As you have experimented and found this to be repeatable, I recommend you get in touch with our technical support team directly so they can take some diagnostics and gather information regarding this occurrence. Thank you. 

Hey @Corry P 

I checked the link and unfortunately my country is not listed on the dropdown so I can’t call and chat indicates that there are no representatives available.

For anyone with a PS5 who would like to test the issue out, you could do the following. No need for a bluray film / game as you could test it simply with the audio that’s playing on the background of the settings screen:

• Go to Settings→ Sound→ Audio Output→ HDMI Device Type→ Set to “AV Amplifier”
• Go to AV amplifier→ Number of Channels → Select among 2 ch, 5.1 ch, and 7.1 ch
• If you select 7.1 ch or 2 ch from the dropdown on the PS5, Multichannel PCM 7.1 / Stereo PCM will be reflected on the Sonos S2 App. Listen to the background audio and there should be no issue.
• If you select 5.1 ch from the dropdown on the PS5, Multichannel PCM 5.1 will be reflected on the Sonos S2 App. Listen to the background audio and there should be consistent audio dropouts once every 1-2 minutes.

I guess you could also test with a PC or any device where you could force toggle between Multichannel PCM 5.1 and 7.1.

Hi @throwawaybeam2 

Please recreate the issue and submit a support diagnostic, replying here with the number given. Thanks.

Diagnostics: 1458431194

As I have no idea how Sonos gathers the data, I had my setup run for 5+ minutes where the issue appeared multiple times. I hope it’s enough.

It’s a really weird issue as I’ve tried out various Dolby and LPCM formats since updating to 14.10 and it only appears on Multichannel PCM 5.1. The only format I’ve been unable to test is Dolby MAT Multichannel.

Hi @throwawaybeam2 

Thanks for the diagnostic. The Beam is reporting underflow errors, meaning that the audio is being interrupted before it reaches the Beam. As this happens with two source devices, the source of the interruption is likely the TV itself, or the physical connection between the TV and the Beam.

If you haven’t done so already, please unplug the TV from power for at least 2 minutes. In the majority of cases, this simple step usually fixes such issues. I didn’t mention it before as you mentioned installing a TV software update - this would include the TV rebooting it’s software. Perhaps it’s the hardware that needs to restart instead.

If this doesn’t help, please swap the ends of the HDMI cable linking your Beam to the TV - put the end that’s currently in the TV into the Beam, and vice versa. Also, are you using the cable that was supplied with the Beam? If not, please do so. If so, please try another (HDMI 1.4 or better).

I hope this helps.

Hi @Corry P 

I’ve already tried unplugging both the TV and the Beam on my previous tests. As per your suggestion, I unplugged both again to no avail.

As for the HDMI cable, I am using the one that was supplied with the Beam. I just tried your suggestion of switching the ends but alas the issue still persists.

It’s really weird though that Multichannel PCM 5.1 would fail when Multichannel PCM 7.1 works. Would be easier to understand if it was the other way around. And Multichannel PCM 5.1 is something that worked flawlessly prior to the Sonos 14.10 update.

As I have made no changes to my setup except for updating my Sonos to 14.10, I am inclined to believe that it may have introduced this weird bug. I also haven’t moved any device / HDMI cable physically. As mentioned, I have already discovered the issue before I updated my LG C1 so it should have no bearing. So Sonos 14.10 really is the only change on my end.

Edit: Is it possible to downgrade back to 14.8 so that we can conclusively tell if the issue is with my setup or with 14.10?

I don’t have an Xbox, but 5.1 multichannel LPCM audio is working okay for me albeit from an Apple TV 4HD connected to a slightly older LG C9 TV with Arc, surrounds & sub. No audio interruptions/dropouts. TV digital audio-out is set to ‘pass-through’, rather than ‘auto’ in the LG sound settings.

Maybe try toggling the TV audio-out settings and perhaps consider removing anything else connected to the other TV HDMI inputs (leaving just the Xbox & Arc connected) to see if that might make any difference. 

Hey @Ken_Griffiths 

Thanks for responding. I’m on PS5 and Beam 2, but yeah. My LG C1 is already set to Bistream / Passthrough / Earc On. It’s really weird that LPCM 5.1 would get bugged when LPCM 7.1 works just fine. And I was able to use LPCM 5.1 just fine right before updating to Sonos 14.10. 

Sorry as I don’t have an Apple TV device, just wanna confirm if your Apple TV outputs as the normal LPCM Mutichannel 5.1 and not Dolby MAT Multichannel 5.1. Also, are you already on 14.10?

Hi @throwawaybeam2 

I confess I misread your initial post and thought two sources devices were involved, but I see it was just the PS5 and either games or movies on it. We would ideally like to check another source capable of 5.1 PCM, but if you don’t have one that can’t be helped. There was a PS5 update on the 12th of May, so we can’t rule out either that update or our own until we can reproduce the problem, or not, with another source.

I take it you have no issues with built-in TV sources like channels or apps? I don’t believe they would provide 5.1 PCM, so it seems likely, but please check if you haven’t already.

Given that other formats work without issue, including 7.1 PCM, I think we can safely rule out the cable - something that should have occurred to me already. My assumption at this point is that it is a software problem - I’m just not sure who’s, as it could be Sony, LG, Sonos or a weird combo of all three. I’m going to flag this with a colleague to see if we can reproduce this ourselves.

Hi @throwawaybeam2 

OK, that did not take as long as I thought it would - my colleague spotted some issues happening on the CEC network and suggests you factory reset your TV. A HDMI CEC-less adaptor between the TV and PS5 should prevent it happening again long-term.

I hope this helps.