21-in High Power Woofer w/Water repellent cone and epoxy coated plates 4-Ohms

97 dB SPL 1W / 1m average sensitivity Dual 115mm 4,5 in Tetracoil Aluminum Voice coil 4000 W program power handling Ultra linear suspension behavior for excellent sound clarity Symmetric flux density and inductance behaviour Low noise forced air cooling design Water repellent cone and epoxy coated plates Suitable for vented, horn loaded and bandpass applicationsThe 21NTLW5000 is a 21 inch diameter next generation high performance subwoofer, specificallydesigned for high SPL very low frequency applications in either a reflex, bandpass or horn loadedconfiguration. For optimum results we recommend the usage of power amplifiers able to deliver4000W program power without clipping.The 21NTLW5000 uses Eighteen Sound proprietary Tetracoil technology, where two different, axiallyseparated magnetic gaps and two inside-outside 4.5'' diameter aluminum voice coils are wound onthe same former and suspended evenly in the two magnetic gaps.The Tetracoil design key advantages are:1 a symmetric flux density versus displacement behavior, that minimizes the even distortionproducts;2 a very symmetric and flat inductance curve;3 the equivalent voice coil diameter of a 4.6'' Tetracoil speaker is greater than 6''. Consequentlyheat dissipation occurs over a larger surface area, driving AES power handling up to 1800 W.21NTLW5000 design features include a large displacement suspension system which, in conjunctionwith a fiberglass reinforced, straight ribbed cone allows an ultra-