need some advice to build ported box

[menaztricks]

So I have been trying to figure out how to build a good box for these subs, but I have found a lot of conflicting information everywhere I look.

Winisd tells me that if I want to use a 2^3ft box tuned to 30hz using a 4" round port, the port needs to be 15.81" but on the infinity spec sheets, it says the port length should be 12.25." So that 3"+ difference confused me.

I wanted to use a slotted vent anyway, because I had heard these in an MTX box with a port that was 1.75" x 14" and I liked the way they sounded, so I figured if I made a box that was 2^3ft with the port tuned to 30hz, like recommended in the spec sheet, that it would sound even better. But after reading the tutorials on the JL audio site, it says "The cross-sectional area (found by multiplying h and W) should be the same as that prescribed for a round port. For example, if our design calls for a 4" diameter port, our duct's cross-sectional area should be 12.57 square inches." So according to that, I should use a much smaller vent than the MTX box, so winisd tells me that using a vent of 1.75" x 7.25" would give me a cross area of 12.69 and length of 15.97".

To confuse me more, I enter the sub specs in one of the calculators at http://www.bcae1.com/spboxnew2.htm to see if this sub is better suited for a sealed or a ported box, and it tells me I am better off with a sealed box.

If you were me, who would you listen to? Should I make one with a rounded port the length in the spec sheet, or using the length winisd gives me? Or should I use a port thats 1.75"x14" at whatever length winisd tells me to use, and forget what JL audio has to say about the cross area? Or should I just make it a sealed box.

Any help would be appreciated.

Also, this is the link to the specs of the sub, if anybody wanted to double check anything for me http://www.bcae1.com/spboxnew2.htm

Thanks

[boricuaso]

well if you cant figure out how to do it , i can do it for you.
check out this link for details. http://forums.caraudio.com/vb/showpo...68&postcount=1

i have done plenty of enclosure designs and all my customers have been very happy with them.