Celestion's self-build reflex cabinet for the massive CF18VJD 1600Wrms, 5-inch voice coil subwoofer, has proven hugely popular. The video shows how we tested in.... Here's the design: http://celestion.com/speakerworld/patech/1/74/BUILD_THIS!_Ported_sub-bass_cab_featuring_CF18VJD_LF_Driver/