Excellent detective work! I hadn't noticed that. I think a deep notch in the woofer's response at 2 kHz, as with my speculative notch filter placement, would have precluded the possibility of a suckout like that. Thanks!
I think you're right! Here are some statements about Magico's midrange cone. From John Atkinson's write-up of the M2:
"The cones of the M2's 6" midrange driver and 7" woofers use multiple layers of woven carbon-fiber, incorporating graphene, a form of carbon in which the atoms are assembled in a sheet just a few atoms thick that is said to be 100 times stronger than steel. The resulting cone is both light and stiff, pushing breakup modes well above each unit's operating passband."
And from Magico's M2 page:
"The newly designed Magico six-inch midrange and seven-inch bass driver cones found in the M2 are both manufactured using Multi-Wall carbon XG Nanographene and an ultra-stiff proprietary new carbon weave which is 20% lighter and 300% stiffer than previous cone material we used in Magico loudspeaker offerings."
So these statements are emphasizing STIFFNESS, with John Atkinson stating that the breakup modes are "well above each unit's passband". However they don't actually use the word "pistonic".
It LOOKS to me like in this new generation of midrange cones "the thickness/mass of the diaphragm is nonuniform", EXACTLY as you said. From Atkinson's write-up of the S5:
"It's desirable that a speaker cone be of varying thickness: thickest at the center and the boundary with the voice-coil former, thinnest at the junction with the surround. However, Magico used to use a sandwich core of constant thickness, because the foam material would fracture if the thickness varied. For their new generation of midrange units they developed a process in which the foam is carefully injected between the front and back carbon-fiber, to permit the overall thickness to vary in the desired manner."
And finally, from Magico's "Drivers" technology page:
"The result is a cone that displays bending strength, self-damping and attenuation of ringing that are all an order of magnitude or more higher than that of conventionally manufactured cones."
In my opinion the word "bending" implies "non-pistonic" behavior, which I would have called "breakup". And in my opinion "self-damping" and "attenuation of ringing" imply WELL CONTROLLED breakup.
[I found this online definition of "cone breakup": "At low frequencies a cone moves as a whole. This is the 'pistonic' area of operation. At higher frequencies the cone starts to flex, leading to resonances. This is what is referred to as 'breakup'."]
So maybe this is what's going on: The new cone goes into extremely well-behaved breakup and flexes just the right amount to significantly widen the radiation pattern up into the crossover region, with any "nasty" breakup peaks being well above the driver's passband. And the marketing department chose to emphasize the strength and stiffness of the cone because admitting to "cone breakup" within the driver's passband would hurt sales.
And IF this is what's going on, then in my opinion the marketing department's selective wording IN NO WAY DIMINISHES the amazing accomplishment of Magico's engineering department.
I have ZERO affiliation with Magico... but mucho admiration for their engineering department.