Double Bass Array concept, any thoughts?

[thadman]

Has anybody researched/investigated this concept?

http://www.avsforum.com/avs-vb/showt...4&page=1&pp=30

Heres some info
A DBA consists of two identical arrays of subwoofers. One on the front and one one on the rear side. The subwoofers have to be mounted on special positions on the wall. For example if you have 4 drivers in one array (that means overall 8) ranged in a square, their correct place is at 1/4 and 3/4 of the wall's width and height. The side walls work like mirrors and have the same effect like more equidistant bass sources. This completely eliminates the room modes between the side walls and between floor and ceiling. With this order the front array produces a plane wave which propagetes through the room. When it arrives on the rear wall the second subwoofer array creates the same signal but with inverted polarity. So both waves compensate each other and no reflection on the rear wall occur. The bass is completely free of modes!

Of course it only works, if the rear array is delayed by the time the sound needs to travel from the front array to the rear (delay = speed of sound / room length). Such a delay can be achieved by using cheap DSP equalizers like the Behringer Ultracurve 2496.
The level of the rear array usually has to be a bit lower than the level of the front array, since there is always a bit loss in real rooms when the wave propagates. But with measuring equipment the best setting is easy to find.

In theory, it should work correctly. Right? Anybody see any flaws in the concept?

How high in frequency can this effect work? It seems like a substitute for DRC and dipole

Is there a formula available (such as those made available by Jim Griffin in his white paper for Line Arrays) that will calculate how high in frequency the DBA effect will dominate the listening domain?


FYI the dimensions are not exact.

I was wondering if the rear wall was necessary for the DBA effect, or if I could place the rear subwoofers at a predetermined distance in the room and cancel them at that point? I'd love to incorporate a double bass array into my HT/listening area, but since my listening room opens up it doesnt seem very desirable. Could I place the rear subwoofers at the mouth of the HT area and achieve the same effects as if a wall were there?

I'd also love to substitute this for a dipole and run them all the way up to 300hz (RSS390HF can handle extremely high crossover points, considering the first high amplitude breakup is in the 1700-1800hz region). What would be necessary and how many would I need to reach 300hz?