[DaveC113]

Again, whole different ball game ... 6 inch voice coil vs 3.9 inch, 1000 watts continuous vs 150, 10.5mm xmax vs 2.3mm.  The PD woofers are top of the food chain for high output HT bass.

For sure, I just thought the Fostex looked cool. 

[Vapor Audio]

For sure, I just thought the Fostex looked cool. 

It's definitely cool, this is 'murica, we like big  

[Pete Schumacher]

Well, long shots occasionally pay off.  I actually have a space that is about 2 feet deep by about 18" across that extends the whole length of the room.  One side only.

It is about 12 feet off the ground though.  My ceiling is from 14' at the sides to 16' in the center.

You could mount a couple of subs in that space in an opposed orientation to eliminate mechanical vibrations and have them play out through wall vents that would completely hide the subs.

[SoCalWJS]

You guys gotta understand, the subwoofer I was talking about - a stacked ply TL with the Precision Devices 21" woofer - is in a whole new league compared to anything else mentioned here.  A 21" subwoofer that can handle 4000 watts continuous with only 2db of power compression!  Seriously, there's no finished subwoofer available that uses a driver of that level.  We're going to be using a couple of them for an install in South Carolina soon.  The customer asked what's the best you can imagine, let alone build ... well that's it. 

Precision Devices does make a 24" woofer too, but the volumes needed for that are just into the ridiculous category.

Sounds like it would be very impressive! I'd imagine it's a fairly large enclosure.