Does anyone ACTUALLY know this?
From looking at the exploded diagrams of both noting the Ultra’s driver shapes, especially being that its chassis is slimmer, I asked and thus got ChatGPT’s partial answer:
“The mid woofers on the Sonos Arc Ultra are traditionally shaped, following a circular cone design. This design aids in producing accurate midrange frequencies for crystal-clear dialogue and balanced audio output.”
And we already know there are only 6 of them on the Arc Ultra (which will arrive here either tomorrow or on Wednesday the 4th). So if they are circular, what are their diameters? (And of course the size of their magnets and voice coils make an important difference, too. But I doubt even Sonos knows what the “magnetic flux” is, which is measured in “Tesla”s.)
The Arc, as we’ve known for years has 8 elliptical midwoofers, so what are their measurements (height and width)? And I’d like to know the size of the voice coils and magnets here, too.
I think these diagrams will give everyone a kick. This is the front speaker layout of the Arc and Arc Ultra:
Arc:
T • W ——— T • W • W ——— W • T
(The other 4 midwoofers are facing the sides and upwards, so the cabinet is getting more overall midrange resonance.)
Arc Ultra:
T • W • W ——— W • T • W ——— W • W • T
(All 6 of the midwoofers are facing the front. Of the 4 remaining tweeters, 2 are upward firing and 2 are side firing. What’s left is the four-motor actuated, dual-cone, force-canceling woofer, which is likely why you have a 15th digital amplifier as two amps are likely relegated to each force-canceling cone.)
I can see this array being superior for music listening combined with my wall-mounted Era 300 surrounds and two Sub Gen 3s (as the soundbar will be a more forceful presence so long as you don’t have the speech enhancement turned way up or the treble turned way up), but I just wonder how forceful the center channel’s dialogue will be when listening to TV or movies. I’m hoping the woofer really does its job well! It’s also a good thing that one of my subs is only inches away from the left side of dresser the Arc Ultra will be on (currently Arc), with the port facing the 400lb. wooden dresser which injects it with lots of bass resonance; my other sub is inches away from my right wall with a walk in closet behind the wall which acts as a resonance chamber, while the sub itself is so sturdy and you can hardly feel any bass when you touch it due to the force-cancelling drivers. The subs have their own ported resonance chambers with openings on the top and bottom between the drivers, where each one funnels around one of the drivers in a clever design.
What worries me about the Sound Motion
woofer is that there is not enough space between each cone, and from what I can see in the enlarged, animated video of just that woofer module, it looks like both cones are wrapped in a sealed piece of rubber where the cones move towards each other pushing the bass inwards in a sealed, rubber enclosure with a phase of 180° instead of the cones moving apart from each other at 0° phase. I hope I’m wrong about that though.
Anyway, if “there is anybody out there” 
that knows the driver sizes for both of the Arc’s and Arc Ultra’s midwoofers AND silk dome tweeters, I’d be very interested in doing some math based on the acoustics to find out exactly what I’m getting and if it will need constant adjustments for music and movie listening.
Thank you!
