The ND940 is a ultra compact size, high performance, high power handling 4.0-inch diaphragm compression driver with a 1.4 inch exit throat. A thin copper ring is precision pressed on to the pole piece in order to modify and lower the inductance characteristics of the magnetic circuit and voice coil providing a controlled extension of the acoustic frequency response. The voice coil assembly is designed using a high strength, high temperature Kapton voice coil former and edge wound copper clad aluminium wire directly joined to the diaphragm by RCF proprietary Direct Drive kapton technology. The ND940 features a 4-slot, optimised geometry, phase plug design. Extended computer assisted mathematical modelling and testing has resulted in a geometry that provides a balanced acoustic performance controlling and lowering air distortion and maximizing output. || Features || 4.0 inch, Kapton former, edge wound aluminium voice coil || 280W continuous program power handling || Frequency range: 500Hz - 20kHz || 4-slot optimized geometry phase plug || Titanium diaphragm, Polyimide surround || Safety agency : CE compliant || Thiele - small parameters || Bl factor (Bl) (T x m) : 17.60 T x m || SPECIFICATIONS || Exit Throat Diameter : 1.4 inch / 36 mm || Related Impedance : 8 ohm || Program Power (watt) : 280 W || Power handling capacity : 140 W || Sensitivity : 110 dB || Frequency range : 500 - 20000 Hz || Diaphragm Material : Pure Titanium || Suspension Material : Polyimide || Suspension Design : Flat || Minimum Impedance (ohm) : 8.50 ohm || Voice Coil Diameter : 4.0 inch / 102 mm || Voice Coil Winding Material : Edgewound Aluminum || Voice Coil Former Design : Direct Drive Kapton || Number of layers : 1 || Kind of layers : outside || Flux Density : 2.0 T || Phase Plug Design : 4 slot || Phase Plug Material : Aluminum || Magnetics : Neodymium || Voice Coil Demodulation Ring : Copper || MOUNTING INFORMATION || Overall diameter : 140 mm / 5.51 inches || Overall height : 60 mm / 2.36 inches || Mounting : 4 x 6 mm threaded holes at 90° || Weight : 2.72 kg / 6 lbs || SHIPPING INFORMATION || Package Height : 79 mm / 3.11 inches || Package Width : 169 mm / 6.65 inches || Package Depth : 171 mm / 6.73 inches || Package Weight : 2.87 kg / 6.33 lbs ||