Dear Sirs,

I have a technical curiosity.
From this forum I understand that JBL's new 476Be has extension up to 40kHz
An exceptional achievement for a driver with a 4" diaphragm.
For instance the also wonderful old jbl 375 should have a much more limited high frequency response.
My question is: what could be the main reasons of such an exceptional high frequency performance for the 476Be ?
A lighter diaphragm? a much more powerful magnet ?

Thank you very much indeed.
Kind regards,

beppe