Sonos Beam 2 Centre Channel over Airplay

That normal behavior like expected, because direktly using Airplay to Sonos Soundbar uses music mode and there these options are not available. 
The other way the soundbar is connected via cable and audio is coming in this way. So there you are in tv mode and seeing these options. 
 

But the most important question you perhaps can answer is: „If sending a 5.1 audio track via Airplay from one ATV to the other one, what audio format does Sonos app show for playing on the soundbar?

OK this one is slightly perplexing…

Projector - HDMI - ATV - AirPlay - ATV - TOSLink - Beam 2

In the above setup the vocals are “clearly” coming out of the centre channel yet the Sono App is still reporting PCM Stereo.

Projector - HDMI - ATV - AirPlay direct to Beam 2

The vocals are evenly spread over the Beam 2 - there is a clear difference - it’s obvious - but the Sonos app is reporting the same PCM Stereo (as you would expect in this scenario).

I can only conclude rather vaguely by careful auditioning that 5.1 is in fact reaching the Beam 2 just fine via the ATV TOSLink - but the Sonos app for some reason is still reporting PCM Stereo - perhaps the Sonos app just can’t keep up with the hopping about between the 2x ATV’s I don’t know.

So conclusively it would seem that 5.1 is getting through - but I cannot provide any evidence of this - just use your ears.

I will say though that for improved audio performance you must go via the ATV with optical out - so there is in fact a reason to have the 2nd ATV with TOSLink as a proxy.

There you go - make of that what you will. If anyone can prove anything more conclusively please feel free to chip in. People with projectors and want to use Sonos will really appreciate this thread.

Hi ​@supernova 

It is possible that one of the Apple TVs is calculating some binaural changes so that the stereo feed can sound a bit “more than stereo”, while still being encoded as stereo PCM. We do something slightly similar, so perhaps it is even a combination that is producing the difference between the two feeds that you hear. To be clear, this is a guess.

I’d stick with whatever sounds best. Unless you are concerned about electricity consumption, in which case I’d turn off one of the Apple TVs.

As mentioned above, the centre driver in Beam is the tweeter - if it is not only bass that is playing, then any sound on any channel will come from the middle of the unit (when there are no surrounds).

If the Sonos app is reporting Stereo PCM, that is what it is receiving.

I hope this helps.

Yes I know you mentioned earlier that the centre driver in the Beam is the tweeter - but male vocals (for example in the series Reacher) are clearly isolated in the middle of the Beam and Reacher’s voice (plus other deep male vocals) will require more than just the tweeter.

There is an audible and obvious difference when playing, for example Reacher, when using the 2nd ATV via TOSLink as the proxy. No doubt about it.

I know that 99% of you use your Beam 2 properly by hooking it up to a TV - I guess I am just having fun with a Projector and getting the best sound from a well known high quality brand such as Sonos which is why I am putting the effort in.

Now stupidly (you may say) I just purchased the Sonos Sub Mini in the sale - let’s see what happens now with my weird and wonderful setup !!! ???

There are more pressing electrical saving items that need considering other than just powering up a 2nd ATV. Also I am sure that sub mini is going to add to the bill :)

Hi ​@supernova 

Vocals will be on the centre channel in 5.1. This means that in stereo, voices are on both the Left and Right channels. When something is played through both channels, it will sound as if it is coming from the centre. Also, there are woofers on either side of the tweeter, so they are also somewhat central, even if they are not centre speakers.

Perhaps Apple can shed some light on why this might be?

The Beam will offload (some) Bass duties to the Sub Mini even when playing stereo sources.

Yes, I doubt an Apple TV uses much, but it will use some, and it all adds up. A Sub Mini will indeed add to the bill.

But yeah, if you have 2 refrigerators, for example, then you could likely save more energy by turning one of them off than by turning off all your Sonos and Apple devices.

I hope this helps.

OK just to carry this thread on here I have a few more tests to complete - I managed to wangle a long enough HDMI lead along with stretching power cables I have temporarily located the Beam 2 into the middle of the room for direct sound testing without wireless (it’s resting on the coffee table for now - obviously not ideal and will not stay like that).

With the older ATV I need to subscribe to Apple TV+ because no other subscription services like Netflix are included on this older model. Anyway - done - signed up for a trial to simply test this all out.

With direct optical connectivity and not running sound over Airplay the indicator on the Sonos App is now reading - for the first time - Dolby Digital 5.1 !

That of course is to be expected - but I like to have some sort of confirmation anyway.

I can also get Dolby Digital 5.1 running when I play video from my iPhone and send it to the ATV in this configuration.

Next test - does playing the Apple TV+ service from my 4k ATV and using the older ATV as a proxy over Airplay allow 5.1 pass through (simply because I am using an Apple TV+ subscription which is all nicely nested in the Apple TV infrastructure). Well I’m about to find out ...

​@supernova 

I agree with ​@Corry P that the Sonos app shows what audio format exactly comes into the system. 
So imho the ATV to ATV Airplay connection doesn’t stream multichannel audio but only stereo pcm. 
As said before I just found information about Airplay sending multichannel audio for Apple Homepod. 
What also was an update to Airplay was Atmos music spatial audio but other formats like DD5.1 were not mentioned. 
 

The reason why it sounds a bit different streaming Airplay directly to the Beam is use of music mode or tv mode. In tv mode the dsp works a bit different. 

Hi ​@Schlumpf 

Good thinking, Batman!

This is very likely to be the reason it sounds different.

OK well in TV mode the sound as a result of the DSP is far superior when using the 2nd ATV as a proxy.

Aside from that - Apple TV+ streaming app makes no difference using the ATV proxy / TOSLink. Thought I would give it a go anyway.

Disney+ The Avengers has always sounded bad with action sounds overwhelming dialogue significantly - so I will plumb in optical direct and see if this improves (no other streaming app is quite as bad in that manner - but we will see what happens with Airplay out of the picture).

OK I think I can conclude that ATV with proxy ATV is better sounding than ATV Airplay direct - but other than that I suspect that 5.1 will never work over Wi-Fi, it’s a shame in the world of Projectors when it comes to Sonos, but there you go.

If you are interested in sending 5.1 wirelessly to an alternative sound system, the package that fully adopts this is the Amazon Fire TV to an Amazon Echo Studio for you projector aficionados.

In fact, this system goes beyond that and sends the full Dolby Atmos over WiFi too.

I hope everyone had a good time following my “experiment” with Sonos. It probably doesn’t apply to 99% of you.