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Connected Arc Ultra/ Sub 4/ 2-Era 300 to LG 86" TV and Dolby Atmos fades in and out hard to watch a movie..happens on regular TV, Netflix and AppleTV

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


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