It took several years to build, rebuild, tweak, and finish this system. I'm currently rebuilding/upgrading the sub for the 4th time. It is a 7.1 with 3 amps total. I tried to load pics but they didn't show up. See it here: http://groups.yahoo.com/group/mfishmike/
I wanted good audio to match the large screen TV and couldn't find anything decent in the retail audio stores. Most of the speakers were 1/2" thick junk boxes with junk drivers and I wasn't going to pay 20k for a pair of speakers from the high end audio stores, so I chose the option to design and built my own. It took a lot of research, trial & error, and rebuilding each of them till I got them right. I'm in the process of rebuilding my subwoofer for the 4th time.
Here are some of the photos. The rest can be seen at my Yahoo Groups website.
Each design was different and more expensive. My last design in the above photo with the two 15" Sound Splinter RLS drivers and 4 passive radiators was the most expensive. I blew those 4 passive radiators shown in the above photo in the shop during testing because I had the mass loading too heavy and hit a 10 hz test button accidently. It sounded like a crankshaft coming out of an engine, pistons and all, when I make the fatal mistake. I had to buy 4 more passive radiators, and I also added a second 1400 watt amplifier. Each woofer is driven by it's own amp, giving me a 2800 watt subwoofer. Estimated rebuild cost using the existing cabinet is about $1,760.00, counting the cost of the two amps. It weighs in at 235 lbs and is extremely musical and low. I've got a little more work to do on it when I get some time, and then it will weigh in at 250 lbs when completed.