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Discussion Starter #1
I'm going to build a ceiling mounted IB subwoofer. I (believe I) have 22" between ceiling joists. The speakers I'm going to use are two Fi IB318's. A 2-in-a-line array is (barely) possible and would require twice as big a hole in the ceiling, and somewhat simpler construction. The alternative is two facing each other in a box above the ceiling.

Any thoughts on why (besides the aesthetics of a larger hole in the ceiling) I would prefer one over the other? And if there's a difference, how much of a difference would there be?

-- Alan
 

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Have you checked out the Cult of the Infinitely Baffled yet? Lots of good info there.

I just installed two of the IB318's in my wall, on a 1 1/4" MDF panel. I added four 2x4s between the wall studs and the roof rafters to keep the wall from vibrating too much. After that, I had very few room rattles to deal with. And don't buy the MDF at Lowe's or Home Depot. It's not very dense. I looked around at some local lumber/veneer suppliers, and found "industrial" MDF. Same price, same machining qualities, but a much denser, heavier substrate.

The other option is a manifold (box). This takes more time to manufacture, but it won't stress your ceiling structure as much, as the vibrations from the speakers are self-cancelling (assuming you mount them on opposite walls of the manifold.) I'm pretty sure the IB318's can be mounted horizontally, but I would check with FI first.

As to which option sounds the best, I can't really say. I know my setup, in a 2300 cu. ft. room, is amazing. If your room is larger, you could add two more IB318's to the manifold without too much trouble. I left myself the option of installing two more IB318's on the opposite wall, but after running REW, I'm flat down to 5 Hz, with plenty of SPL. Another nice thing about IB subs in general is that they don't require much power to drive them. I'm using a Monolith 7x200W amp, which isn't being taxed, as the output from the MiniDSP is less than the input sensitivity of the amp. So even if I turned the Master Volume all the way up, the amp won't get enough input voltage to run at 200 watts. (350 watts, actually, as I bought the 4 ohm version of the IB318.) I'm running each driver with its own channel of amplification.

Hope this helps. I think you'd be happy with the Sound Quality going either way.
 

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That IB came out nice as h3ll! Did you make a cover or added trim to the edges?
 

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Discussion Starter #4
Since I posted the question here, a friend of mine mentioned that mounting large speakers horizontally (parallel to the floor) introduced distortion because motion in the down direction takes less energy than pulling the cones upwards. In addition it seems likely that they would sag over time. So, for my ceiling mount situation, it seems that the manifold (box) option would be better.

But I gotta say, your setup looks amazing with pretty amazing results!
 

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Thanks. I made a 1x2" oak frame and covered it with speaker grill cloth. My local Woodcraft store had some magnet and cup assemblies that I attached to the frame and the wall. The cup has a countersunk hole in it to screw into the wood, and the magnet just plops into the cup. They're plenty strong, and they leave an 1/8" or so gap between the frame and the wall so I can get my fingers behind the frame to remove it very easily. I also had to get some of those small metal plates with countersunk holes at Lowe's to secure the drywall to the wall studs and the top cross piece. You can see them in the second pic, below. The drywall was rattling against the studs. The plates fixed that.
 

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I like how the bookshelf speakers and floor trim match!
 

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I'm going to build a ceiling mounted IB subwoofer. I (believe I) have 22" between ceiling joists. The speakers I'm going to use are two Fi IB318's. A 2-in-a-line array is (barely) possible and would require twice as big a hole in the ceiling, and somewhat simpler construction. The alternative is two facing each other in a box above the ceiling.

Any thoughts on why (besides the aesthetics of a larger hole in the ceiling) I would prefer one over the other? And if there's a difference, how much of a difference would there be?

-- Alan
it is nice:devil:
 
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