Best Big Sub? or duals?

Is that the Nelson-Reed top of the line where he used ATC midrange in the mains and eight Volt 12" woofers in a pair of subs? I believe he claimed 120 db SPL at negligible distortion...WOW.

I use a Bag End Infrasub 18. Very nice reviews. Wish i had room for two so i could have one next to each speaker. Excellent IMHO. Don't know if this is out of your price range but i saw a very nice one used a week or so ago for around $900. A very unique and great sounding sub. Good luck on the down low.

The best sub I've ever heard was the jl audio gotham. Musical, acurate, fast, goes as low 15hz, and has as much slam as a concert at a coliseum. Probably a fathom 113 would do the job right but if you want overkill the gotham is the way to go!

Shadorne, yes , it is. I use to have the 804s as well. I was a dealer for them in the distant past. Their factory was destroyed in the San Fran. earthquake and they never rebuilt. I don't think there is anything quite like them on the market now. Probably cost prohibitive as 8 12" Volts are a considerable expense. My REL Stadiums use one 10" Volt and do a great job, but of course will not play at anything like the same level.

Unfortunately this site http://www.servodrive.com/ is down. ServoDrive uses belt driven motors to actuate their cones. These are not self powered or crossed over and they require much less power. Ask around, these are the loudest cabinets by a large margin.

Meyer Sound has a nice selection of bins and powered units. There stuff sounds much better than their specs would have you believe.

Bag End ELF systems are typically in sealed enclosures and they also require less power and come in many sizes. Their designs may seem dated but they go lower than most anything out there, they simply work. There were two 18" cabinets, processor, and an amplifier for sale here for $1200.

12K for a sub is a joke. Do your homework. Whatever you select use a Velodyne SMS-1 then let any HT room correction take it from there.