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Post by zaphod on Jan 21, 2010 16:56:42 GMT -7
in the 43,235,341 pages i read this past week on IBsubs, i remember seeing something relating the size of the manifold opening to the summed sd of the drivers.
i've looked through the docs, and FAQ and used the search engine, but can't find it. i seem to remember it being near the "How big an opening should there be for my manifold" section just after the rough calculation based on base plate distance. but i can't find it now.
did i dream reading about this relationship? have i started dreaming IB calculations?
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Post by ThomasW on Jan 21, 2010 18:39:41 GMT -7
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Post by zaphod on Jan 21, 2010 19:38:22 GMT -7
thanks Thomas!
"an opening equal to the summed swept volume of the diameters "of the drivers being used."
must be what i was thinking of - although i thought i saw somewhere that explicitly referenced the "Sd" measurement by those two letters.
is the summed swept volumes the same as Sd? i didn't think so. how does one find/calculate the swept volume of a driver?
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Post by zaphod on Jan 21, 2010 19:47:48 GMT -7
is the summed swept volumes the same as Sd? i didn't think so. how does one find/calculate the swept volume of a driver? okay, did a quick google and found the swept volume is actually Vd - the Sd times the Xmax. but thats a volume (duh  ) in cubic units, not square units. but the manifold opening is a measurement in square units. now i'm no further ahead... |
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Post by legend3215 on Jul 25, 2010 7:32:40 GMT -7
Generally, in most cases... since manifolds are rectangular and drivers are round, the opening to the listening room will be adaquate, even though it's 2 to 1.
Real world example (mine): manifold house eight AE IB 15's
each IB 15 Vas= 830 sq cm= 128.65 sq inches x8= 1029.2 sq in
My manifold's inside (to the room) dimensions:
19x64= 1216 sq inches
but even @ the typical 14.5 inch manifold = 928 sq inches
If that short amount bothers you, adjust the manifold height to
71 inches. Matter of fact, that made me think of a helpful hint:
In my particular case, the manifold height is just barely enough to house the woofers. Because of this, it makes it extremely tedious to work with the mounting bolts. If I had to do it over again, I'd extend the dimensions by say, maybe 3 inches on the top and bottom to avoid this. p.s. my width is 19 only because I had the luxury of not being confined to an existing wall. More about that, you will have to find me at my assigned spot Legend3215. I have already cheated by posting here, hope I don't get into trouble !
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