Just saw this on the new JBL 2269H dual 4" V.C. differential-drive 18" pro sub with 3.5" peak-to-peak excursion:
http://www.jblpro.com/pressroom/VT4880_06/VT4880_06.htm
http://www.jblpro.com/vertec1/VT4880...ec%20Sheet.pdf
(But how does it sound?)
John