Originally Posted by BiGBADDABOOM
MK, a DBA has an array of subs on the front wall and the rear wall. Basically what you're doing but mirrored on your back wall as well.
That's a big oversimplification.
A system utilizing a DBA, is an attempt to address and eliminate all
room modes, and realize the actual driver/alignment simulation response, as the end user response in room. The added rear wall driver array, doesn't sum acoustically, nor does it add to the SPL capability of the system.
Briefly, a DBA is two identical arrays of drivers,...one set in the front, one set in the back. The drivers need to be placed specifically on the wall, as to eliminate modes in that direction. A typical array is one of 4 drivers per wall. The drivers need to be at the 1/4, and 3/4 point, of the wall's width and height. The same applies to the rear wall.
Like any LF source in a room, the adjacent boundaries (walls, ceiling and floor)simulate an acoustic mirror. This simulates an the effect of another LF source. This placement theoretically eliminates all room modes between the side walls, floor and ceiling.
As the front wall array fires, it approximates a planar wave. As the energy encounters the rear wall of drivers, they fire delayed in time, and polarity inverted, as to null any reflection,....hence creating an acoustic black hole behind the LP. So, in essence all directions can't be driven into typical modal behavior.
So a DBA doubles the cost of a sub install, without any typical SPL benefits.
MK, good luck with the knees,...man I cringe thinking about it. Get well soon.
Thanks, great thread