Speaker manufacturers or box manufacturers with off the shelf drivers?

In your years of high end speaker building, what materials have you found that work best?

kenjit-
You will need a concrete box 100 inches thick all the way round.

kenjit, you are talking about a cube of concrete 16 feet on a side, per speaker. That is 151 yards of concrete. 614,400lbs of concrete. 307 TONS of concrete. PER SPEAKER. 

Are you sure about that???

Are you sure about that???

it may need to be even thicker. Without trying it, hard to know. 

" Without trying it, hard to know."

It seems you haven't tried anything. All your musings are bouncing around in your head and for some reason, you seem compelled to release on us. How is is a benefit to anyone reading your scribble when you don't even know for sure if anything works the way you think it should? Theories don't count for much in audio.

By the way kenjit that wasn’t some totally random detached from reality flaming wild guess. "A concrete box 100 inches thick all the way around", which is what you said, really is 151 yards of concrete and really does weigh 307 tons. Its a fact. You could look it up.

But look. 100" thick all the way around is 200" wide which is over 16 feet and that’s per speaker, meaning you need a room over 34 feet wide just to fit the speakers snugly side by side! Oh, and a 17 foot high ceiling.

A full load is 10 yds. So kenjit, you are talking about 15 truckloads of concrete PER SPEAKER!

Now don’t get me wrong. I am all for mass loading. But 307 TONS!?!?!
And your reply: " it may need to be even thicker. Without trying it, hard to know."
Hilarious. Absolutely bust a gut crack me up hilarious.