subs on flat baffle instead of W or H ?

[MEXXX]

Well, it seems i will probably never build my arrays because I keep changing my mind on how I want to build them.

My latest design hangup is how I want to implement the subs. I've decided that I don't really want a seperate W or H due to limited space so I want to put them right in the arrays.

My arrays are going to be 3 peices connected with piano hinges with a narrow middle baffle and two different size side baffles.

I want to use 4 12" woofers per side and wanted to know how well mounting them on the array baffle at an off axis angle will effect the sound. Also, will a baffle width of 25-30" and hight of 6' be big enough for a 12" with a Fs of 30hz?


P.S.- I just realized that the thread name looks like it should be in the subwoofer forum. I don't think it does, but if a mod thinks so please feel free to move it.

[johninCR]

I would put 2 drivers in a W manifold at the top and the same at the bottom. Also, I'd go wider with the wings at the bottom at least for stability, plus you get the benefit of added distance the rear wave must travel.

How many of the 4" drivers do you have? Ideally you want the main array to be as tall as possible (unless you have a small room) with the drivers as close together as possible. If you go with 8ft of total hieght with 1ft at the bottom and top for the woofers and a 6ft main array where your ears are in the plain of the array standing or sitting then you should get good results and remain in the nearfield for array purposes unless you have a very large room.

The reasons I'd suggest the W manifolds are that they take up the least space, are easy to construct, cancel out mechanical vibrations, damp higher frequencies, enable push/pull alignment which decreases distortion that is more important for lower quality drivers, and results in a wider effective baffle width.

The reasons I suggest top and bottom mounting of the woofers is to gain some line array effect in the 150hz and down range that you need from the woofers and a double stack at the bottom would lift the bottom of the main array up too high and give you no line array benefit. At a 150hz upper limit the center to center spacing of drivers can be up to 90" although I'm not sure how much only 2 point sources will act like an array but in theory you should get some distance vs SPL gain.

The baffle width issue is complex because a flat baffle is not the same as an equal amount of wood with folded back wings. Folded back wings adds substantial additional distance that the rear wave must travel to get to your ears. The greater that additional distance is, the lower the starting point of the 6db/octave dipole bass rolloff.