Update: Went to Bill Fitzmaurice and got plans for a Tuba HT, and built one in a 30" wide version. I used a 15" Ultimax UM15-22 driver, and powered it with a Dayton Audio SPA250 DSP amp. The build took a couple months, including coating the finished THT with Duratex. The result was unbelievable. First of all, this thing is huge...its a monster. Super efficient too, it takes very little power and low gain setting to literally shake the house. It easily reaches the infrasonic ranges of low frequency effects in movies, and adds a huge new dimension to the experience. We added 2 additional R-120SW subwoofers to our setup to blend the lower ranges, so we have 2 subwoofers on the front, left and right of the center, one more in the back of the room in the left rear corner, and the THT in the right rear corner, facing the wall. Tuning took a little time, but the result is amazing...the sound is crisp and clean all the way down to crazy low frequencies (took a while to find all the things that rattle in the house), but now every movie is a whole new experience...better than any movie theater we can go to. Scary at times. They say low frequency effects can instill a fear-like quality, or a feeling of dread, and i now believe that. Something primal about it. Watching the Cave Troll attack in "The Lord of the Rings", "The Fellowship of the Ring" was spectacular...freaked us out. And we watched "The Greatest Showman", the Hugh Jackman musical movie...and OH MAH GAWD...the very first scene is a number called "This is the Greatest Show"...and the stomping feet on the grandstasnds were like we were really there...the room shook with authority...Wow...
If you guys want a crazy powerful sub, and have decent carpentry skills, i highly recommend the THT...a few hundred buck in plywood and about 5 hundred in audio parts...sounds like a $5,000.00 sub.
Thanks for reading Audio Brothers and Sister, have a Blessed and wonderful day 😎