Arc Ultra/Sub 4/2-Era 300 not playing Dolby Atmos on video fadeout

Hi ​@choclatevw71 

Welcome to the Sonos Community!

Sorry to hear of this issue you are having with your new Arc Ultra setup.

Please reboot the TV by unplugging it from power for at least 1 minute. Please reboot the Arc Ultra in the same manner at the same time, but plug it in and wait for the flashing white light to stop flashing before plugging the TV back in. Then, test again.

If that does not solve the issue, we need to take a look at what the speakers are saying - while still playing content, and while hearing the fading issue, please submit a support diagnostic. At your convenience, please reply here letting me know you have done so, and I will see what I can find out for you. Please don’t share the diagnostic number given - I’ll find it without.

I hope this helps.

Unplugged and rebooted as per instructions.

The speakers are saying Dolby Atmos however the the issue of fading is still there. I have no problem playing this on PCM but that defeats the purpose.

Pass Through and Auto format while playing Dolby Atmos is my issue

Hi ​@choclatevw71 

Thanks for trying those steps, and thanks for the diagnositcs.

The diagnostics reveal that the audio feed coming from the TV is not constant - in the 7 minutes that the Arc Ultra has been on, about 1 minute of which would have been booting up, I basically see 6 minutes of the Arc Ultra complain repeatedly that the feed has stopped unexpectedly.

This issue is not entirely uncommon - if I understand your report correctly - but it can usually be fixed by unplugging the TV from power to restart its software - which is puzzling, as you have already done this.

Please ensure the HDMI cable is securely fitted at both ends - in fact, please try swapping the ends of the cable so that each end now plugs into the opposite device.

If there are any software updates available for your TV, please install them.

I have few questions for you:

• Has this only just started happening, or has it been an issue since you got the Arc Ultra?
• Do you happen to have a second TV in the home that you could test with to compare results?
• Just to confirm, you see this issue with TV apps as well as with the Apple TV?
• Do you see any change with the TV apps if you physically disconnect the Apple TV?

It does sound like the TV may be at fault here, but it could also be the Arc Ultra. Testing with another TV will be the quickest way to tell, but only if you have that option, of course.

I hope this helps.

I moved over to another tv and the arc ultra/sub 4/2- era 300 in dolby atmos mode works just fine.

It appears theres a setting on the 86" LG that needs to be adjusted

Hi ​@choclatevw71 

Thanks for performing that test! It really did narrow things down quite a lot! I appreciate that it would have been rather bothersome, so that’s great.

I am not overly familiar with the settings available on LG TV’s - please feel free to post some screenshots of the TV’s settings page(s) and I’ll be happy to highlight anything that pops out to me as a potential issue.

Hi ​@choclatevw71 

Fantastic - thanks for updating the thread!

Incidentally, audio is not difficult for even a basic HDMI cable to carry - 8K cables are only needed to connect an 8K source to an 8K display and even a 4K cable is not needed. eARC does require HDMI 1.9, however, due to it utilising an extra wire as compared to HDMI-ARC. Basically, what I am saying is that there is only a need to replace the supplied cable if you need one of a different length (or colour, I suppose). Having said that, your 8K cable should have worked - I can only assume it has a broken wire or connector.