The dB Technologies Sigma S218 Active PA Subwoofer is designed to deliver powerful, low-ranging bass frequencies, perfect for supporting dB Technologies' Sigma series full-range speakers. The S218 features two high-performance 18'' low-frequency drivers with 4'' voice coils. The S218's Digipro G3 Class-D amplifier delivers 1800W RMS, and a huge 2700W peak, with a switchable crossover frequency from 90Hz to 100Hz. The robust enclosure is crafted from plywood with heavy-duty surfaces, and features polypropylene reinforcement/protection frames in the top and bottom. This powerful active bassreflex subwoofer is as versatile as it is dynamic, providing exceptional compatibility with dB Technologies' other audio products to create a truly professional-grade PA system.