Ha. Custom 18" driver (Fs 25hz, xmax 12mm), box tuned to 22hz via 2 6"
ports, measures flat to
20hz in room, subsonic filter at 18hz. Powered by a QSC PLX amp and EQd
by a BFD. It will go above and beyond the capabilities of my Choruses.
On low bass-heavy music, the floor shakes in huge waves and everything
moves. It modeled with extremely low group delay for a vented box
(under 20ms to below 20hz) and sounds like it. Cost me all of $900 to
build.