IB LA Against Wall

[novice]

Before I start an incomplete "My Project" thread/introduction without all the info for a proper post....quick question.

Looking to do a similar installation from this thread, ibsubwoofers.proboards.com/index.cgi?board=projects&action=display&thread=1457

Particularly this image (amazing sketchup skills btw)



My question is, can the LA be 12" from the back wall, vented up through the stud bay cavity, into a truss style ceiling?

This is the screen wall/ceiling. I thought about sistering the 2x4 with 2x12 to move it out enough for a LA mount.


Or will the rear wave bounce back into the subs? Could a 45* angled piece of wood help the wave move up through the bay? I'm the biggest n00b here when it comes to this stuff. I believe I have over 3000 liters in the trusses.

My other thought was a LA of 8 12" Fi subs, firing down into the room mounted in the trusses. Only 12" of clearance between the trusses (11.125" cutout ID) That also raises the issue of the rear wave bouncing back into the sub :\

The room is roughly 30x16x10, with a 8' entry in the rear right of the room with heavy curtains for movie time. Also the opposite wall of the screen wall has a 6' by 14' opening for a "pass through' bar, also with heavy curtains.

Once I get more information on the setup, I'll try to post a decent my project thread. Thanks!

[chrisbee]

Unless you already own the 12" drivers I'd seriously consider using 15" or 18" drivers. The thread you linked to (by a useful coincidence) has a list of suitable drivers.

Angled boards have little or no effect at low frequencies.

Leave the back of the baffle wall open and the space becomes deeper by the depth of the studs.

You have an interesting roof structure. All the timbers appear to be lying on their sides.

[novice]

I have not purchased anything yet, and definitely want to use the Fi 15s or 18s.

Those trusses were actually prefabbed offsite and brought in, that is the ceiling/floor between the basement and the first floor.

The bluefoam/insulated part is brick/poured concrete wall.

You think 12" (4" between the magnet and the concrete wall with the 8" mounting depth of the 15") is deep enough for the wave to escape up the stud bay and into the trusses?

Leave the back of the baffle wall open and the space becomes deeper by the depth of the studs.

What do you mean by this? I need something to mount the drywall of the front wall to, are you suggesting not using entire 2x12 and just 12x12 sections of it for a nailer? I'm open to any ideas

I'm waiting on measurements of the truss system to see if I could fit a pair 2x18" manifolds up there, but then I see pictures fall off walls in the rest of the house more so, compared to attaching to the concrete floor of the basement

[chrisbee]

Aug 13, 2010 11:34:09 GMT -7 novice said:

I have not purchased anything yet, and definitely want to use the Fi 15s or 18s.

Good.

Those trusses were actually prefabbed offsite and brought in, that is the ceiling/floor between the basement and the first floor.

I have never seen a truss which placed the timbers flat. They are usually placed on edge so that the greater depth carries the applied loads.

You think 12" (4" between the magnet and the concrete wall with the 8" mounting depth of the 15") is deep enough for the wave to escape up the stud bay and into the trusses?

Provided the cross sectional area is large enough and the space does not become a tuned port.

What do you mean by this? I need something to mount the drywall of the front wall to

I just meant that you should cover the front of the baffle wall. Not both sides.

I'm waiting on measurements of the truss system to see if I could fit a pair 2x18" manifolds up there, but then I see pictures fall off walls in the rest of the house more so, compared to attaching to the concrete floor of the basement

Pictures fall off walls because the wall flexes to LF cyclic pressure waves. Where you place a manifold has little impact on pictures on walls.