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I shall be soon building a pair of subwoofer enclosures fairly similar to the one in the attached image. The one on the photo is shown flipped 180 degrees onto its backside, with its "belly" facing up. (Normally the driver faces down.)
The pair that I'm going to build will be designed so they can be stood "firing down" exactly like the one in the photo; however, I plan to turn them 90 degrees so they lie on their sides, with the woofer cones perpendicular to the floor. This is because I plan to place them underneath my audio equipment rack -- with THOROUGH ISOLATION of vibrations! -- and the height of my main speakers will be perfect if they are placed above the subwoofers lain on their sides.
The two subwoofer enclosures will actually be touching each other (not along one of the long faces, but rather along one of the short faces -- the cones will never face directly toward the listener). What I'm trying to figure out is, do I want the cones facing away from each other and firing in phase, or do I want the cones "almost kissing" and firing out of phase in a sort of push-pull arrangement?
I already know one obvious answer: "Try them both ways and see which you prefer." The only reason why I am asking is, if it turns out that the latter "almost-kissing-push-pull" arrangement is better, then another question arises: would it be good to design the "legs" so three of the four leg-walls on the two enclosures mate in fully flush contact with the other cabinet? Doing so would leave just a single opening from which the sound could emanate. That might give me maximum efficiency; however, would I need to worry about that opening functioning as a port? (I don't need any Helmholtz resonator with these subs.)
It occurs to me that one thing I might need to worry about with the drivers working in a push-pull arrangement is double the force attempting to move the enclosures and make them "dance." If I have the drivers facing away from each other and firing in phase, the vibrations of the two subs will always tend to cancel each other out. (The two subs would be solidly linked together.)
As far as bass reinforcement is concerned, does anyone see a significant relative advantage in any of the arrangements I have outlined above? Or are they all going to yield pretty much the same results since I'm way below one-quarter wavelength regardless of which I choose?
Many thanks!
Christopher Witmer
Tokyo
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