Are you using Netflix from the TV's built-in Netflix app or an external source?

Hi John, 

I’ve always used the Netflix LG app which has supplied Atmos in the past. The only thing that’s changed here is that I switched soundbar to an Arc. 

Have you checked your TV settings?

My guesses 

1. the c7 isn't doing pass through cause of tv settings
2. the c7 isn't capable of passing Atmos and the Seinheisser soundbar was doing virtual Atmos upscaling 

edit: yep confirmed this in the Ambeo specs - the Ambeo up samples 5.1 into Atmos. So option 2 is what's happening - your C7 was actually never doing Atmos pass through to the Ambeo, the Ambeo was itself trying to create a virtual  Atmos output from the Dolby 5.1 input 

Thanks - but not convinced. Compressed Atmos is possible via ARC, and the input source codec display from the Sennheiser app showed Atmos.

1. One guess is that the Sonos App is in fact playing Atmos via DD+, but doesn’t label it as such explicitly.

2. Or it could be that the Arc handshakes with the TV apps differently, such that Netflix etc. thinks it isn’t capable of Atmos, so drops back to its 5.1 audio marker.

Someone may know more about this than I!

Regards, Greg.

I think the TV would need eARC for Atmos audio - see this link:

https://hdguru.com/understanding-dolby-atmos-from-an-supporting-lg-tv/

The HDMI-ARC v1.4 port on your TV would likely struggle by all accounts - its time to perhaps buy the C9 or CX

Thanks, no you can happily pass Atmos over ARC - just in DD+ compressed format. 

Just as an update, the problem seems to relates to the LG Netflix app, I am able to receive Atmos (DD+) now from Amazon Prime Video (Jack Ryan) and Disney+.

Cheers for your help.

Are you on a Netflix plan that supports streaming in Ultra HD as that is required too.

Thanks yes. A bit of Googling indicates a peculiarity with the Netflix app.