The ND640 is a high performance 2.5-inch diaphragm compression driver with a 1.4 inch exit throat featuring the smallest size of the art technology. The diaphragm are precision completely formed from pure titanium. Voice coil assembly is designed using high temperature kapton former and it is joined to the diaphragm by RCF proprietary Direct Drive kapton technology. Diaphragm suspension is designed by extensive FEM study for low distortion and low frequency range extension.