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Post by rlspach on Apr 15, 2007 9:12:47 GMT -7
I'm thinking of building an IB system in my new home theater. I'd like to build the speakers directly into the front wall (no manifold). The space behind the front wall is approx 14' wide by 9' tall, but only about 12" between the front wall and the concrete basement wall.
It seems the volume is workable at about 3500 liters but I want to make sure I won't have any issues with the concrete wall being within 12" of the actual back of the speakers.
Any thoughts or experience with this?
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Post by ThomasW on Apr 15, 2007 9:45:14 GMT -7
Can you build a bumpout that spaces the drivers further out from the wall?
If so go with a manifold.
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Post by rlspach on Apr 15, 2007 11:06:43 GMT -7
Thanks for your reply. I don't want to bump out since the room dimensions are very carefully determined to minimize modes. I could go the manifold route but doing so makes an extremely tight fit if I used 12's sideways in a manifold. There is exactly 12" between the back of the studs and the concrete wall.
I'd hate to have to use smaller than 12's.
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Post by ThomasW on Apr 15, 2007 13:32:39 GMT -7
A few inch bump-out for clearance will have no impact on in-room performance of the IB. And doing that will give you enough space for 12" or larger driver mounted perpendicular to the front wall in a manifold (firing to the sides is better than firing to the back when the space is so shallow)
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Post by mashaffer on Oct 1, 2007 17:35:15 GMT -7
How about a V or W shaped manifold? This should allow larger drivers and still point that backwave at an angle away from the back wall.
mike
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Post by chrisbee on Oct 2, 2007 0:58:04 GMT -7
An "outie" manifold looks like a good option here. It can sit on the floor or be suspended at any height from the front wall (to taste). Allow for a minimum of 17" protrusion into the room using 15" drivers on each side.
Using 12" drivers would probably be more expensive than using 15" or 18" drivers for the same displacement.
But, with careful design, it should be just possible to fit a manifold with 12" drivers into the space available.
You could use the concrete basement wall as the structural rear wall of your manifold. Just close off the back of the manifold with thin plywood to keep it all in shape and to ensure the manifold is sealed.
Once you are happy with your install you can put a few screws through the plywood back into the concrete wall to stop vibration. The idea is not to use up any more depth than necessary to allow your 12" drivers to fit in the space between your two walls.
You don't have a lot of rear volume to play with so choose low Vas drivers for a low total Vas.
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