Newbie needed guidance

[sean8811]

Needing*** ^^^

Hello all,

So I am trying to design two subwoofer boxes. I have all my measurements for my trunk laid out and all of the specs for my subwoofers. They are infinity kappa 120.9w run in parallel at 400 watts each off a infinity kappa one.

Any who I downloaded winisd pro. Infinity says the subs are at 27.20 htz but the sub box layout that comes with the sub calls for a round port 4 inch in diameter and 13 5/16 long fb=30htz.

So there is the first confusion.

Then on winisd the port dimensions on that are way touchy. Bigger the port hole the longer. Smaller port hole the shorter?

Then rear port velocity seems to be low and I can get it pretty low about 15 through 20 feet per second or whatever. But on the X max part it says my sub over excursions below the targeted tuned frequency? I'm so confused. Lol

Please help!

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[bbeljefe]

The box doesn't have to be tuned to the Fs of the sub. You can tune however you like depending on what your goals are and where the sub will live. And yes, more vent area means a longer vent is needed for the same frequency. Also, subs will usually unload (over excursion) at some point below tuning because the box will no longer have any control over cone movement. Making the vent smaller can help this but as with anything, there will be other negatives created such as chuffing or, vent noise.

In the end, I do not recommend WinISD Pro for novice users. It's a reasonably complicated and buggy program and if your TS parameters aren't dead on the money (which most manufacturer's published TS numbers are not) it will not present you with a very accurate picture of the driver's performance. That said, you can find a copy of WinISD Beta online but not at Linear Team's website. It's a much easier and more forgiving program for novice users and it's even good for pros. I used it for years and still sometimes do when I'm not interested in complicated data entry for a simple box.

 

[sean8811]

I did download the beta version first however it wouldn't save my specs for my subwoofer...what is chuffing?

Do you guys think I should try to build custom boxes? The sub is currently in a sound ordnance box from crutch field at 1.75 cubic feet... With two triangle vents at the bottom...