Strictly Stereo
Trade: Strictly Stereo
You really need a minimum of an 18inch driver for the really low bass. 24inch are becoming the new standard, with 32 and even a 50inch driver available. Multiples of these drivers is the ideal way to go, but other methods like infinite baffle or the rotary woofer are said to be the ultimate.
The rotary woofer doesn’t seem to be particularly room friendly...
https://www.soundandvision.com/content/eminent-technology-trw-17-rotary-subwoofer