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No sound from rear speakers with ATV and simultaneous AirPlay

  • 30 November 2022
  • 3 replies
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Hi,

I have Sonos Beam gen. 2 with to Sonos One SL as rear speakers. As my wife is hard of hearing we use an apple airport express to connect her headphones to the Apple TV via AirPlay. 

The beam is connected to a LG Oled via eARC. LG ist set to “passthrough”.

When we’re watching Dolby Atmos movies and activate AirPlay additionally the Sonos app shows “stereo PCM” and I hear at least up mixed stereo from the rear speaker.

But when I watch non-Atmos movies (for e.g. 5.1) the Sonos app shows Multi-Channel PCM 7.1 and the rear speakers don’t receive any sound information and are  muted when we activate AirPlay additionally. 

Can anyone help me to understand this behaviour? What can I do to at least have stereo up mix output on the rear speakers when watching 5.1 movies.

 

 

 

 

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Best answer by Corry P 1 December 2022, 13:20

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Hi @ramshazar 

Welcome to the Sonos Community!

When the headphones are playing, does the Sonos app indicate it is also playing AirPlay? I’ll presume not.

I don’t have any Apple devices so I can only guess, but it is an educated guess - I presume that when you activate the headphones, the Apple TV determines that headphones are being connected and that they are stereo. Therefore, the soundtrack is converted into stereo prior to playing. I assume the Apple TV is incapable of outputting both a stereo stream and a surround sound one simultaneously (and there’s nothing unusual in this), therefore both output devices receive stereo. I also presume that when you see McLPCM 7.1, you are in fact only receiving 2.0 which is being padded-out to 7.1 with empty channels to match the requested output format specified the the ATV’s settings. And because there are now rear channels already (even though they are empty), Sonos cannot up-mix stereo to surround and thus you hear nothing from the surrounds.

An alternate option might be to connect the headphones to the TV via the optical link, if that’s possible? This should allow the headphones and Sonos to play all they can as the ATV would no longer be converting the audio type for the headphones, and as optical is one-directional, the TV has no idea that anything is connected so changes nothing. You may need to activate optical output in the TV’s settings, and you may need an extra device to convert the signal into something the headphones can accept (Bluetooth, maybe?). It really depends on the headphones and what they can do. Personally, I see this as a better solution than using AirPlay.

I hope this helps.

 

 

Hi @Corry P ,

Thank you for your quick answer. Well, this is what I was afraid of.

So the only solution for this problem could be to force the Apple TV to output stereo instead of multi channel PCM in order to receive the stereo up mix from the beam, right?

Unfortunately, my LG OLED isn’t capable of playing line-out or toslink optical out with HDMI simultaneously. A lot of TV manufacturers don’t do this. I think only Sony and Panasonic have a few TV models that can output audio through line out and TV speakers or HDMI simultaneously. We really have to look for this option when buying a new TV. But for now (and the next years)… too bad. :(

Userlevel 7
Badge +18

Hi @ramshazar 

So the only solution for this problem could be to force the Apple TV to output stereo instead of multi channel PCM in order to receive the stereo up mix from the beam, right?

I think that would be the only solution for your current headphone connection method, yes. However, I do not work for Apple and have never owned any of their devices - it’s possible I am missing something.

Unfortunately, my LG OLED isn’t capable of playing line-out or toslink optical out with HDMI simultaneously. A lot of TV manufacturers don’t do this. I think only Sony and Panasonic have a few TV models that can output audio through line out and TV speakers or HDMI simultaneously. We really have to look for this option when buying a new TV. But for now (and the next years)… too bad. :(

Well, if the TV won’t do it, a HDMI audio extractor with a 3.5mm stereo jack (if that’s what the headphones use) output should. This would only work with external sources (so not with the TV’s apps), but it sounds like you mostly use your ATV anyway. Such a device will not be expensive, though I recommend ensuring you have the option to return it if it doesn’t help. They range from about £$€15 to 50 - personally, I would aim somewhere in the middle, but try to ensure it will decode the audio formats you use, like Atmos. While I can’t recommend a particular unit, a search of “HDMI audio extractor 3.5mm atmos” should yield plenty of results. This device would sit on HDMI between the TV and the ATV (not between the TV and Sonos).

Please remember that such devices are unsupported by Sonos, and that it is a personal opinion of mine that this all should work - Sonos cannot take responsibility if it does not.

I hope this helps.

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