With a pole receptacle that accepts a SS4-BK or SS4-BK24 on the top panel and integrated stereo pass-thru, this is the most powerful low-frequency complement to the PRX full-range systems. The addition of a polarity reverse option further enables system optimization. The low frequency driver used is the 2268FF 18" which has been used on many JBL subds in the past. It's a good sounding Neodymium speaker which is powered by a dual 500 watt Crown Class-D power amplifier. Dual-Bridge Technology directly links discrete amplifier channel outputs to each voice coil in the Differential Drive woofer. Electrical power transfer to the transducer is optimized for more power performance. A custom DSP chip is at the core of a fully featured input section, providing user selectable cross-over functionality, polarity optimization, protection, dynamic limiting and discrete component optimization. It's almost like having a mini Driverack system inside the sub itself.