Arc, Sub Gen 3 and Era 300

Corporate interests?  The Sonos corporation wasn’t even in existence when Dolby designed “Dolby Digital 5.1” to be 5 channels directional sound (Left-Center-Right Front and Left-Right Rear Surround) + 1 Effects channel (Subwoofer).  The definition is literally in the name - 5.1!

So what you are saying is that 1 era 300 is 100% capable of playing Atmos music with full surround by itself similar to an arc but no way It could work behind you as part of a group solo what am I missing?I understand speaker separation the wider the better but ..beating a dead horse here, Sonos sounds great just miffed Sonos released Atmos rears a month after I bought 2 sl ones for my arc sub 3 combo and 2 surrounds cost almost as much as an arc or a sub 3. maybe I can use the sl ones as expensive computer speakers for music production.

If you don't know what you are missing, I really don't know how to explain it.  So yeah, "corporate interests".  🙄

Years ago Dolby Pro Logic was a four channel analog surround system — Left, Center, Right, and surround. Even though two speakers were usually attached in the rear, it was a mono, reduced bandwidth channel.

In the modern digital era, broadcasts and movies use stereo in the rear. Certainly, the playback equipment could combine the stereo rear channel information and present it to a single speaker, but this is not the expected behavior for the wider audience and this behavior would involve extra work for equipment manufacturers. (Design, testing, maintenance)

In controlled listening, test environments you only needed two speakers or a headset for reproduction of full 3D sound. Soundbars attempt to accomplish this at home, but there are too many setup variations to make this wildly successful.

So... in all honesty, I have been generally underwhelmed by Dolby Atmos from my Arc. Not necessarily blaming the Arc (which i love, regardless) as I think perhaps Dolby Atmos in general is just the "Emporer's New Clothes" - a marketing scam embraced by the industry to sell more speakers. Maybe it's my living space but I have never really been able to differentiate the vertical sound (without a bit of imagination on my part). I also accept that maybe sound designers haven't really put it to good use, but I've watched all the supposedly best Atmos 4k blu rays. The sound generally better and brighter, but the supposed 3D soundscape just doesn't come through. (And yes, before you ask, I do have all the decoding tech required)

But I am a sucker, and I am wondering if I would have a better experience if I add 2 Era 300s to my home theatre?

What I want to know is- since the Era 300s would serve as rear speakers would the up-firing speakers even receive 3D information, or does Atmos put all the verticular sound in the front speakers?

The rear Era 300s would be receiving height sound cues along with the height speakers in the Arc.  You would essentially have a 5.x.4 system, with the ‘.4’ being front and rear upfiring height speakers.  As to Atmos performance, with upfiring speakers, it is highly dependent on your room.  Flat, even ceilings from 8-10’ high, and sitting the proper distance from the front Arc for the sound waves to bounce off the ceiling and hit the viewing area is optimum for sensing the Atmos effects.  I happen to have an optimum room (9’ ceilings, 13 ft away from the screen) and the effect, even without Era 300s, is dramatic.  

Hi, I have a pair of exa 300, my use is solely for music, what sub would enhance my listening enjoyment please?

Thanks. My ceiling height is fine, The room itself is pretty small though. Typically sat around 7ft from the Arc with a wall directly behind me and the surrounds 3ft to either side of me. Very recently moved into a bigger place so maybe see better results once I am kitted out.

Hmm.