Sonos Arc Ultra Sound Dip

Are you using an Apple TV as a streaming device?

Does this happen only when you are watching movies or shows with Dolby Atmos audio?

I have the same problem but with a Samsung TV. 

Does the led light up briefly when these dips occur?

If you have a voice assistant installed the dips in sound may be due to false awakenings.

No.

it happens with everything but more often on Dolby atmos, currently watching Liverpool vs Forest on tnt ultimate and every time the sound dips the Dolby atmos logo appears in the top right corner when the sound returns. 

No, I don’t have the voice assistant activated 

Does the logo appear on the TV screen or within the Sonos app? If its on the TV screen, it would appear its not the same issue that I have and may not be a Sonos issue at all.

When the Arc is receiving and producing Dolby Atmos contend, it is displayed about mid-screen for that room in the sonos app.

On the tv screen.

running out of ideas, don’t know what else to try 

Try these settings on the TV:

Sound Out: HDMI ARC

HDMI Input Audio Format: Bitstream

Digital Sound Out: Pass Through

eARC: On

Auto Device Detection: On

Simplink (HDMI-cec): On

Auto Power Sync: Off

I think these are all set to your recommendations.

can not find auto device detection or auto power sync.

appreciate your help 

I have the exact same issue with my LG g4. I get the Dolby vision/ Dolby atmos notification each time the audio drops out when watching Dolby atmos content (every few seconds).

Only fix I’ve found so far is unplugging and plugging in both tv and soundbar, but then the issue is back after a half hour or so. I’m past my return period otherwise would have returned it but I’m now worried the bar is faulty which Sonos don’t seem open to admitting.
 

I have spent hours on the line with support but they’ve bucketed it into ‘interference’ issues which doesn’t make sense as it’s only my fire stick nearby and I never had these issues when running my playbar with the five and subwoofer surrounds over the past 7 years. I’ve tried hardwiring the arc ultra as part of troubleshooting but no luck so far.

You feel my pain and how frustrating it is.

like you mentioned, I’ve spent hours researching to the point it’s really getting boring now, I haven’t bothered ringing Sonos as like every company they will tell you to do all the same things we’ve already tried but I agree there is definitely an issue.

As I previously mentioned I had the same issue with the previous Arc, didn’t expect to have the same issue again, I genuinely love there products and have spent a fortune but maybe it’s time for a change.