ND4015BE is a 1.5 inch exit, 4" voice coil neodymium compression driver that has been designed for uncompromised quality sound systems application. The 100mm (4in) diameter composite material diaphragm is made with a beryllium dome positioned on a polymer surround. With its very high value of elasticity modulus, beryllium is capable of double the stiffness of titanium or aluminum with great benefits in transient response and reduced distortion. The piston frequency range motion extends frequency by 25%, showing a predictable, ideal frequency response decay and avoiding high frequency spurious resonances. The edge-wound aluminum voice coil, wounded on Nomex former, completes diaphragm assembly. Thanks to its physical properties, the Nomex former shows 30% higher value of tensile elongation at working operative temperature (200°C) when compared to Kapton. The ND4015BE extremely powerful neodymium magnet assembly has been designed to obtain 22 KGauss in the gap for major benefits in transient response. The motor structure, throughout the precisely coherent phase plug with 4 circumferential slots and copper ring on the pole piece, reduces inductance effect and distortion. Four top plate air ducts have been designed to act as a loading chamber for the diaphragm, implementing mid band distortion and response figures. The custom designed O-ring creates a tight seal between the plate and the cover assuring air chamber loading. Excellent heat dissipation and thermal exchange are guaranteed by the direct contact between the magnetic structure and the aluminum cover which gives a lower power compression value. A special epoxy coating is applied to the ring magnet and the top and back plates of the magnetic structure making the driver more resistant to the corrosive effects of salts and oxidization.