Regarding
beryllium (again).
Emphasis are mine.
Would you say that a tweeter/midrange, coaxial: 3.5cm beryllium dome / 14cm
magnesium found in the TAD CE1TX sufficiently diminishes the "difference between the material properties" (Be
vs Mg here), so that TAD's CST (Coherent Source Transducer) driver is "sufficiently coherent" (the coaxial CST found on the biggest model, TAD-R1, is made of beryllium for both tweeter and midrange).
On the CE1TX, magnesium (for the midrange) may not be beryllium, but it is by no means
polypropylene either (used in the Vyger's midrange); it's surely incomparably stiffer than polypropylene.
TAD CE1TX
I own a lovely pair of Harbeth M30.2 Anniversary in a second system. Very-good-but-not-outstanding textile done tweeter, and "Radial 2" midrange cone (Radial 2 is a polymer, not exactly polypropylene AFAIK). Coherent speakers indeed, but limited.
I found the TAD CE1TX with their Be/Mg CST tweeter/midrange coax driver both
much less limited, and
coherent.
@D.Duttilleux
Do you disagree ? What do you think about this Be/Mg coax ? (feel free to be direct, I'm from Northern Europe ;-)