What is it?A powered subwoofer housed in a bass reflex enclosure tuned for “accurate, ultra-low frequency” response.DetailsThe DVA S1521N is designed for easy integration into large DVA and DVX Series PA systems as a sub-bass unit or as a stacked subwoofer. Made of durable birch multiplex ply and finished in robust black textured lacquer, the high-quality housing provides six carrying handles, an M20 pole mount and bushings on the rear panel that accept casters. Pick-points for attaching DRK-10 and DRK-20 harnesses are built into the top panel to enable safe, easy stacking.Housing a 21” low-frequency neodymium driver with a 4.5” voice coil capable of handling up to 15kW RMS from the built-in digipro Class-D amplifier, the DVA S1512N’s quoted frequency response is 30Hz – 110Hz at maximum SPL levels of 139dB. Onboard processing is carried out by a 56-bit DSP offering crossover and delay presets, phase control and built-in limiting. I/O is via standard XLR hardware with network control provided through dual RJ45 connectors.And another thing…db Technologies also produce the DVA S1518N sub, based on the DVA S10 model but offering 50% greater output plus integrated DSP and an RDnet link.