box guidance

[yz_gt69]

hey guys,
i have a 66 chev reg cab step side, after moving the tank to the frame i have built a box 5" wide at the top sloped to 6.5" wide at bottom, running 48" wide by 16.5" tall (interior measurements) pending my calculations are right thats 3.4375 ft^3 - the .22 ft^3 my two mtx 12's will take up gives me 3.22ft^3. the WINisd says my ports should be 1 circular at 14cm x 7.4cm.
can anyone verify this, any suggestions about this setup, it would be much appreciated.

[Trixter]

Well here's the numbers I get:

The big part of the box:
48 x 5 x 16.5 / 1728 = 2.29

The small part of the box:
48 x 1.5 x 16.5 / 2 / 1728 = .34

The whole box:
2.29 + .34 = 2.63cu' total

Subtract your sub displacement and you get 2.41. Depending on tuning you still need to account for port displacement also. In WinISD, a 2.4cu' box tuned to 32Hz would call for a 4" round port to be 11" long...which gives you .08cu' of port displacement. Now you box is 2.33. (I'd just keep the port the same size as it would be in a 2.4cu' box...won't make that big of a difference.) If your looking at a round port, I suggest looking at a Precision Port...can be found at partsexpress.com

[yz_gt69]

hey thx for the help, i'll hopefully get them mounted up and the ports in to see how it works.
does it matter where the port is located on the box? logically i was thinkin between the two subs on the top of the box but what do i kno?

[Trixter]

That would be a good place. I always like to put the port in the middle if I have 2 subs.