Help with my IB plans

[baggy]

Hi,

I've spent some time lurking here and now I'm hoping to be able to build an IB of my own, so thought it best to set up an ideas thread of my own rather than ask questions in someone elses.

Unfortunately I don't have the luxury of a dedicated room, my HT is set up at the end of our living room.
The room size is approx 31'x14'x8' (3500 sq ft)and it can be sealed.
There is an underfloor area of the same width and length with a height of approx 4' (1740 sq ft).
So I'm thinking of an underfloor manifold with the opening between the left front and center speakers.
The floor joists run across the room with a spacing of 16.5" between joists. The floorboards are oak of 8.5" width and the wifes very fond of them. Hence there is some reluctance to me cutting holes in them and the path of least resistance would be to only remove two sections.
This limits my opening to approx 16.5"x17".

So I have a room of 3500sqft and my thoughts are that an IB manifold using 4x18" would be best but my opening is probably better suited to only 4x15".
Any guidance to avoid pitfalls would be appreciated.

[baggy]

A photo of the room

[ThomasW]

Hi,

There shouldn't be any big issues.

My large IB is mounted in a floor with joists 16" OC. The opening for the manifold is a 13.5" square and it works just fine.

If you can do the 16.5"X17" opening you're good to go with 4-15"s

[baggy]

Thanks Thomas,

I thougtht that size outlet/opening would be sufficient for a 4x15" manifold.
I was just wondering if 4x 15" would be OK in a 3500sq ft room?

If not and I went for the 4x18" would they still be OK in the less than optimum outlet/opening of 16.5" x17"?

[ThomasW]

Aug 3, 2010 6:55:10 GMT -7 baggy said:

I was just wondering if 4x 15" would be OK in a 3500sq ft room?

If not and I went for the 4x18" would they still be OK in the less than optimum outlet/opening of 16.5" x17"?

You should use 15"s, we don't want a larger manifold being choked through a smallish opening.

I can't imagine 4-15"s not being adequate to the task, I suppose you could build the manifold deeper to a accommodate another layer of drivers if needed...

[baggy]

Thanks Thomas.
Lots to think about.

Would sticking with just 2x18" be a realistic alternative?
Any benefits over 4x15" and also any drawbacks?

I'd been considering the TA2400 as the amp when thinking of 4 FiIB3 18's, would that be overkill with 2 and would it still be a viable option for 4x15's?

[ThomasW]

Once again, with the smallish IB opening you need to use 15" not 18"s.

You'd need to check the T-amp powering your load. T-amps like those from Face aren't as forgiving as other amps when it comes to being bridged or low impedance loads.