That’s an interesting input. My distance to the rears is much more far away, around 3m (~ 10 feet) to my listening position. With 5.1 surround I can barely hear anything from my rears. Whatever I try, the sound seems to come from the front.

Hi ​@Zorro88 

It’s possible that the surrounds are not playing when they should - please reboot your Arc Ultra by removing power for a time.

It can also sometimes help to remove the surrounds, then add them on again.

However, as stated, it is important to test with content you know will produce clear surround sound effects. The best example that comes to mind is the first few seconds of the first Transformers movie - even before the movie starts, there’s great surround effects during the Paramount company logo animation - as the flying stars go behind the camera, you should clearly hear the “Transformer” noise come from the surrounds.

I hope this helps.

I just rebooted the Arc Ultra again with removing the power for a few minutes: nothing changed. Additional I have resetted my Sonos home cinema (Arc Ultra + Era 100 rears) already multiple times in the past and added it again to the app. Nothing changed.

And it seems here is some missunderstanding. Of course I can hear the rears very good with some soundtracks. Dolby Atmos or 7.1 soundtracks are perfect with sound all around. I would absolutely be happy with it. It is an isolated issue for 5.1 soundtracks. It has to be something wrong with the upscaling process from 5.1 to the 9.1 channels of the soundbar.

Sonos upscales 5.1 surround to this virtual 9.1 speaker arrangement (rear channel 4 + 5 in circles). In this case the channels 6,7,8 and 9 are nearly silent (in our case the rears):

To fix this issue Sonos should route during 5.1 surround the 4th and 5th channel to channel 8 and 9 on their virtualized 9.1 sound system. So we could still get real sound from behind, exactly like it is specified in the 5.1 speaker specifications.

This is all my own opinion, because of my deep investigation and testing. But the picture shows exactly what my sound system sounds like with 5.1 soundtracks. And it explains everything why soundtracks with more channels don‘t produce this issue.

Hi ​@Zorro88 

I concur, and mentioned this in my report to my engineer colleague.

To be clear, if the surrounds perform correctly in any way for a prolonged period (like the length of a movie), then troubleshooting as I suggested above need not be done. What you are reporting is variance in behaviour across different formats, which can and should be provided as feedback (which has been taken - thank you!), but does not require troubleshooting. Apologies if I just wasted your time there.

The problem with the 300’s is the outside drivers (looking face on at the 300’s the outermost left and right drivers) play only with side, or rear effects. The inner drivers simply never play.

This needs to be reconfigured so the side drivers play side and the rear drivers play rear.

happy for the Ultra to ‘assist’ the side drivers, but the rear sounds should play from the rear drivers of the 300s.

The front and rear (ultra and 300) height drivers need to be independent as well. All 4x play at once even if there are front or rear height channels.

This is very much an oversight from Sonos…

Yes, the scene from Transformers that you described works Fine, but:

I have an example from a music Blu-ray. Schiller - Atemlos live. In the title „Blind“, the synth sound that runs around you once (L-R-RR-RL) is reproduced completely washed out via the ARC Ultra. 
I've listened to this song a lot on the ARC and ERA 100 and the sound moved around you wonderfully. Since I've had the ARC Ultra, it sounds strange because the sound from the rears is also reproduced on the Ultra. This doesn't seem to have a negative effect on Transformers, but you can really hear the difference in this music video.

Hi ​@Downsideup 

Thank you for this example, and with the comparison to Arc. I have a meeting with some engineers on Monday to discuss feedback like this that we are receiving. I’ll add this as an example to be discussed.

Thank you! I appreciate your help and Support!

Hi Corry P,

Thank you for the update.

It would be great if the Sonos engineers can come up with a solution (asap) to this issue with the DTS 5.1 to the ERA 100 rear surround speakers via the Arc Ultra.

At least it would mean being able to enjoy the true benefits of this somewhat expensive recent Sonos upgrade in GBP !.

2 months after purchasing the Ultra.
I’m just thinking to myself, why did I risk buying something brand new knowing all the issues Sonos is having with newer hardware product releases. (IE the ACE).

I remember: its because I already have Sonos speakers and I can use them as Surrounds etc as a upgrade and cost savings.

Now I think to myself, had i just gotten another brands suround sound set…… dont care the fact that it doesnt pair with other speakers, I could be sitting down now watching movies without checking Sonos forums every day to see if the issue is resolvewd.

I just wanted Sonos really for the Home theater speaker flexibility……. but this decision I have come to regret severely.

Its really a shame, I waited so long for the ARC successor to come out and im better off using my older setup AMP + Symfonisks….