18" Powered Subwoofer 800W RMS/1,600W Peak. When you want that low end reproduced with all the chest-hitting thump you've got to have, but with precision and definition to go along with it, the Mackie HD1801 is your pick. This is an 18" high-powered subwoofer designed to complement your Mackie HD loudspeakers. It's got 800W RMS/1,600W peak power, with an incredible 133dB SPL max output, and it'll pump out those big, long waves down in the 35Hz-to-155Hz frequency range. As were Mackie HD speakers, the HD1801 subwoofer was designed and tuned for complete system optimization by the experts at Eastern Acoustic Works. You want the best? Get it, with the HD1801.