Ground Zero GZIB 250XBR-ACT active subwoofer 10" (250 mm) kit.

Ground Zero GZIB 250XBR-ACT active subwoofer 10" (250 mm) kit.

Previous models of GZIB boxes were one of the most succesfull on the market. No wonder because they had superior soundquality in their price class. 
New models have new subwoofers that have been optimized with Klippel-device. Drivers have smooth impedance response, good sensitivity and good power handling. 
These features give good sound quality and a lot of bass with very moderate amplifier power. New better drivers deserve also a better enclosure. 
Previous enclosureses were so good that it was hard to make them better. Solution was to invent new port type. This enclosure uses EFP ( Enchanced Flow Port ) port. 
It has cross-section like aeroport. This gives significantly better air flow without side effects. More air throught the port = more bass! 
Despite the better air flow in same size enclosure, tuning frequency is the same than before. And it gives a very smooth bass response through whole bandwidth. 
Size of the port is more than adequate to the required amplifier power for this subwoofer. If you are looking for an active subwoofer that gives you good sound quality and a lot of bass it is here.