Driver Calculations for Infinite Baffle in a Large Room

[AaronDC]

Hi. I have a very large room: 8,000 cubic feet (227 cubic meters). I also have Klipsch La Scalas, which start to roll off at 100Hz. I can't have a subwoofer in the room. I can install an infinite baffle subwoofers in two locations in a ceiling and use a attic space as the enclosure. I'll do a dual-opposed manifold to mitigate driver vibration. This is for music only. I've done exhaustive research into this and can only find anecdotal information about number and size of drivers. It would seem that getting a driver Vas and driver quantity recommendation should be very straightforward. I feel like I should be able to punch in specs into a formula: room volume, desired max SPL at 30Hz, distance to room boundaries, the fact that it's infinite baffle (with 10x Vas enclosure), the fact that I'll do 4 drivers, and I should get a minimum driver Displacement (Vd) to achieve my specs. I take that number and go shopping. Right? I think WinISD would only help me find the right kind of drivers, and I don't see any sub specs in the REW room tool. Can someone point me in the right direction? Thanks!

 

[Flaesh]

Just do it!))

in two locations in a ceiling

They may be not optimal.
You don't need to think much about anechoic frequency response. You may get real RTF (room transfer fuction) using any sealed speakers in this location.
RoomSim is quite suitable for preliminary modeling, especially if the room is rectangular and without large openings.
What are linear dimensions and construction of the room? Any acoustic measurements?..

For example:

 

[Flaesh]

I should get a minimum driver Displacement (Vd) to achieve my specs. I take that number and go shopping

Buy as much Vd as you can. Buy as less distortions and especially rub and buzz as possible.
What drivers are you going to buy?

I'm not a fan of "special" hi-Q woofers. For example, in the front wall of a friend’s attic, 2 pcs normal pro 21" woofers without any EQ, with speakers:

One of old mine in the front wall in small room, 2 pcs normal pro 18" woofers without EQ\XO, without speakers:

p.s.: last measurement taken @ ~3m 2.8V , 4.8x4.2x3m room