HELP! Building tomorrow, need input on box tuning/siz tonight! Dual Sundown SA-12's.

[USAFMileHigh 10+ year member]

Sorry for the obnoxious title, but the planning has to be done today as I go off to College in like 2 days... I'm building a new box, and picking up another SA-12 (already have 1 at the moment) running off a BRZ1700.1D.

Sundown recommends 1.75cuft per subwoofer, I assume this is after displacements? The box size I am looking to build right now is 32W/14.5H/23D with a 4" slot port, which is a gross volume of 4.92 before port/subwoofer/45 displacements.

I will be sealing off the trunk of my Cobalt SS sedan in the nearish future, therefore the port will be on the front (same face as the subs). Will it matter if the port is in between the subs or if the port shares a wall with the box?

As far as port length goes, I used a mixture of the12volt.com and RE Audio box calculator to calculate tuning, and I'd like some input. I want it tuned about 32hz (up to 34hz, doesn't really matter TOO much to me, it's a daily driver). Right now, in the RE Audio calculator I have that box with a 4" slot port, 34" long. It is leaving my volume at 3.899, each subwoofer is .14 displacement if I remember correctly, so -.28 = ~3.62cuft before I add in 45's/bracing? Therefore if I use small 45's in all the corners, and maybe 2-4 dowel rods for bracing I should be about 3.5cuft and the 34" of port length should be perfect for a 32hz output correct? Did I do any of my math wrong?

Thanks //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

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[DukeNut 10+ year member]

i am getting 3.38 cuft before bracing/45s at 31.4hz.

 

[pro-rabbit 5,000+ posts]

When you take out volume for displacements it will alter tuning. Port area is based on the product and tuning is based on the application and goals as it the sub/port locations on the enclosure.