That is answered in the new KEF white paper posted above. It replaces the stuffing in the tweeter chamber with a relatively expensive set of tuned absorbers plus some stuffing. Note the absence of a comparison between the old cheap lump of stuffing which will almost certainly have worked fine and the new absorber which also works fine but is more complex and expensive. The tweeter in a coaxial driver is significantly constrained by size in the radial directions but less so the axial. The reduction in size in the axial direction is of little benefit but would be of great benefit for the midwoofer of an on wall speaker for example. Here's hoping this largely irrelevant application (outside marketing) is followed by one where the advantages of the approach are used to benefit the overall performance of a speaker.I had misunderstood the material originally, I thought it was some kind of fancy absorption, but I was evidently wrong, It seems to be some magic “about the size of a hockey puck” fixed to the back of the drive unit to absorb sound above 600Hz coming from the back of the tweeter. But there seem to be many other changes too, so who knows what the meta stuff contributes.
Much better at storing books, IME.Marketing is already working. They could easily sell the same speaker all over again.
I wonder when people will realise that small bookshelves are useless for reproducing music.
Apparently this sorts the metallic colouration that spoiled the original LS50.
This issue really puzzled me, and nothing in the measurements explains why they can't convey any reach or attack to Freddie Hubbard.