Speaker 18 Sound 21NLW9000, 4 ohm, 21 inch

The 21NLW9000 is an ultra low frequency 21 inch neodymium high performance transducer. The transducer has been optimized for direct radiation subwoofer cabinet designs. For optimum results recommended amplifier should be able to deliver 3600 Watt program power without clipping.

Eighteen Sound engineers have obtained the best possible results with today's available materials in terms of clean and undistorted LF reproduction at a ultra high SPL, with the lowest possible power compression figure.
The transducer design features include a large displacement suspension system specifically designed for matching the carbon fiber reinforced, straight ribbed cone. The state-of-the-art 5,3" inside outside ISV copper voice Coil enables the 21NLW9000 to handle 3600 Watt program power value.
Thanks to the Triple Silicon Spider (TSS) technology, the 21NLW9000 is able to control the moving mass with high linearity, showing an exceptional stability of mechanical parameter values in the long term. Bl force factor, as well as all other electro-dynamic parameters, are linear within the working range. This, together with the high excursion design - 70mm before damage, ±14mm linear Xmax - makes the 21NLW9000 an extremely low distortion, highly dynamic transducer.
The 21NLW9000 has been developed after intense FEA and fluidodynamics simulation and testing, focusing on dissipating the heat generated by the powerful 5.3" coil. Special attention was given to the optimization of air flow into the gap without introducing audible noise. A special low density material air diffractor placed into the backplate acts as a cooling system, increasing the power handling capability and lowering the power compression figure.
The exclusive cone treatment improves pulp strength and gives water repellent properties to both sides of the cone. A special coating applied to both the top and back plates makes the transducer far more resistant to the corrosive effects of salts and oxidization.

96 dB SPL 1W / 1m average sensitivity
135 mm (5.3 in) Interleaved Sandwich Voice coil (ISV)
3600 W program power handling
Neodymium magnet assembly
Triple Silicon Spider (TSS) for improved excursion control and linearity
Single Demodulating Ring (SDR) for lower distortion
Low noise forced ventilation design for low power compression
Weather protected cone and plates for outdoor usage
Suitable for ultra low frequency systems