Generic sealed box question

[Reggie Lives 10+ year member]

I'm going to be building a simple/small sealed box for a CSS SDX10. I'm under the impression that the dimensions of the box aren't that important providing it A) fits the car and b) has the internal volume recommend by the manufactorer.

Given that A and B are met, are there any other overall dimensions that are preferred? I was thinking that if it was perfectly square, the waves might cancel each other out to a degree. Is more of a rectangle recommend? What about a wedge vs rectangle?

Another thing; I don't know how to determine the volume displacement of my woofer. I was going to just use a generic number of .05ft^3. That sound about right for a 10" woofer?

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[profundus-sanus 10+ year member]

the golden ratio is something you could go by. there used to be a long write up on it, that i've since lost... but happened to memorize the formula. Its supposed to be the best to eliminate standing waves..

the one i use is (cube root of desired box volume x 12) = internal dimension 1

(int dim 1) x 1.2599 = int dim 2

(int dim 1) x .7937= int dim 3

 

[Reggie Lives 10+ year member]

Thanks alot, that's exactly what I was looking for. What about wedged vs rectangle?

On a side note, the manufacturer recommends a .848ft^3 box with 16oz polyfill for a Qtc of .7

I wasn't plannign on using polyfill, and WinISD gave me box volume of 1.021ft^3 for the same Qtc. It's probably nitpicking (especially for a sealed box) but would it be best to build a bigger box to achieve the optimum qtc and to compensate for the lack of polyfill?

 

[BrianChia 10+ year member]

The shape makes an insignificant difference for most applications. Standing waves in the box aren't really a problem in auto subs. While the golden ratio is ideal, feel free to make a box that fits your car/trunk, as long as you meet the required airspace. You can go on the larger side and increase box damping instead of using polyfill.