Martin-Audio CDD-LIVE 218 Dual-driver, self-powered subwoofer. The CSX-LIVE 218 achieves the ultimate in subwoofer performance for the most demanding professional applications – delivering very high output levels and superb transient performance with minimal distortion. With an operating range of 35Hz-150Hz ± 3dB, it houses dual 18” long-excursion (460mm)/4” (100mm) voice coil drivers with water-resistant cones and triple roll surrounds.