I finally got the opportunity to fire up my Tumult this weekend and it sounds awesome. I was already using a Tempest sub and I didn’t think there would be much of a difference between the two, but I am convinced now that there is. The Tumult’s bass is much “cleaner or accurate” than the tempest (although this could be due to the change in Q for each of the drivers in the same box). Also this sub goes really really low. My Tempest was originally built from a design Adire Audio provides on their website. It is a Butterworth (Qtc=0.707) sealed alignment (120L) powered by a AVA250 Amp. I wanted to drop the Tumult into the same box, but the depth of the Tempest is around 2 inches less than the Tumult so a modification was in order. I added two more pieces of ¾” MDF onto the baffle and inserted Tumult and ta-da-to-daaa, I am now rockin’. Can you say really heavy sub woofer…definitely a two man operation to move this thing in an out of rooms. I figure the alignment of the Tumult sub is somewhere between Q=0.500 (which is what I wanted) and Q=0.577. My guess is that my sub now has a Q= 0.52. Someday soon, I will be doing an impendence measurement to determine a more accurate number for Q. But for now I am going to sit back, relax, and enjoy the melodies….