I have some material and design specs here:
-Midbass drivers typically handle the range of 60-2000hz
-The cones are a fiberglass composite. This material exhibits a good balance of stiffness, damping, mass and transmission speed. Unlike paper, the glass composite cone is less affected by heat/moisture, nor does it breakdown or soften. And unlike plastic cones, itmaintains its tonal character over a wide temperature range
-The shape of the cone is curvilinear much like our allow subwoofers. This adds stiffness to the cone to control breakup modes and smooth the rolloff responses. The natural tone is free of harsh peaks.
-The surrounds are again a rubber compound, and much more reliable than the common foam surrounds. The shape/thickness/compound perfectly terminates the cone edge.
-Motors utilize high-grade ferritres and quality pole components. Voice coils are over-sized and of the latest low-distortion materials.