sub for $3500 or less

Horseface,

Velodyne tech support claims that in an audiophile 2 CH application, the DD-15 and DD-18 sound faster & less distorted than the smaller 10" and 12" versions. Appparently the larger cones present an easier load to the plate amp. I'm using the 15" in a 2 CH application and am pleased with its performance and ease of setup. You can buy a used DD-15 or DD-18 for $2K-$3K.

Dave

Trying to optimize deep bass in the 15hz-30hz region without a frequency analyzer and digital EQ such as found in the Velodyne is like piloting a submarine without sonar. Without such tools you can spend months playing around with subwoofer setup and still be uncertain where you're at. The system allows phase shifts in 15 degree increments, the parametric EQ has ample headroom to allow notches to be stacked up high to eliminate bulges/depressions in frequency response, the servo control can be adjusted to loosen or tighten the bass for HT or 2 CH mode, cross-over & rolloff is adjustable in fine increments, and you can see it all on your TV or PC plotted in a graphical frequency sweep. Without these kind of tools it won't be easy to harness those long 20' to 50' wavelengths in the deep bass region...

Dave