Help finding a Sub w/ quick punch down to 20hz

JL Fathom F212, and the F113 as well. They are very fast and also go to 20 Hz. If you can settle for 21 Hz, you can save some money with the F112 ($3100 instead of $3900).

09-02-12: Irvrobinson
If you want real 20Hz response at low distortion you're going to need a fair-sized sub.

The REL F110 is about 13"x15"x17" and is good to at least 25 Hz. If you have a strong enough magnet, tight enough tolerances, and enough internal power, you can get to near 20 Hz *and* have serious volume in a relatively small package.

HomeTheaterReview's review of the F110 revealed that a single one could flap the reviewer's pantsleg at 10 ft.

09-02-12: Johnnyb53
The REL F110 is about 13"x15"x17" and is good to at least 25 Hz.

Oops, I meant the JL Fathom F110, but you guys probably figured that
out by now.