2-3 Weeks. 45 Day Lowest Price - 100% Satisfaction Guarantee. If the convenience of a self-powered subwoofer is preferred, JBL offers the JRX118SP, which incorporates a specially designed amplifier with 500 watts peak and 300 watts continuous power output into the same driver as the nonpowered version. It offers dual inputs with balanced XLR connectors, a built-in stereo crossover network and peak limiter to protect the amplifier and speaker from clipping.