BT TV Box Pro- Ultimate sound issues.

[Colesy7]

So what’s your current setup? 

and do you know if Atmos will still work on Ultimate on normal ARC.?

[NigelB72]

I've a Samsung QLED and Sony Soundbar that supports Atmos. PS5, Pro Box and a Roku are all HDMI to the TV. Audio goes out via 2.1 HDMI eARC on pass-through mode so there is no digital trickery from the TV. 

I bought a 4K compatible HDMI cable for eARC and as soon as I watched Ultimate, Disney+ or AppleTV with Atmos, the audio kept cutting out.

After much reading through geeky forums on the internet, it was whittled down to the cable not having enough bandwidth on a 2.0 HDMI cable. Atmos worked fine on 2.0 via Netflix because they compress their Atmos but Apple etc push through lossless Atmos, as do BT Sport. This is why I think you're having the same issue I had.

[Colesy7]

Okay thanks for providing this info.

which specific hdmi cable did you get?

[NigelB72]

I got mine from Mark's Electrical as they're local to us, it was £12.99. Curry's want £45 for them but just get one that's HDMI 2.1. you should be able to get one Amazon or eBay 

I've just checked eBay and there's plenty of choice and they're generally labeled as HDMI 2.1 8K 120hz