question on box design for sub

I did not see any quick answers via search, and I'm doing the math prior to building a sub box based on a 2245h from the 1983 article. I'm making sure ti build the box and get EXACTly 12 cu ft in it--> tuned to 25HZ (modeled in WinISD).

When calculating the box volume to achieve exactly 12 ft3, do I subtract the volume of the port; i.e. make the box slightly larger to account for that volume (or more likely adjust the cutout size of the baffle--> top achieve the correct final volume)??

I suppose I need to approximate the volume of the 2245H as well, which I can rough out by doing a little geometry, so that the volume of the 2245H cone penetration's into the box is accounted for as well.

Thanks in advance.
Larry

I would just build your 12 cu ft box as 12 cu ft. The fiberglass insulation should negate any volume taken up by the bracing, driver(s) and port(s).

BTW -

One can be off volume target by as much as 20% and never know it.
One can be off tuning target by as much as 10% and never know it.

the 1983 article calls for a box 21 deep x 44 tall x 29 wide (15.5 CU FT W/O BRACING DEDUCTED)

after doing the math, with the suggested bracing you get very close to 12 cu ft

I'm building it, then after the box is perfect, having it veneered to match my L100T's, complete to the same type grill cover.

However I'll take your advice to heart and not sweat the details. Z

Any comments on the design from WinISD (attached).

Also, when WinISD refers to a port length of .467 ft, and an end correction of 0.614, what does that mean exactly?

FYI I'm using a Rane pe13 to do the parametric equalization, and the sub to be driven by a Crown PS 400 bridged to mono 550 watts @ 0.05THD.

WinISD design file attached

Larry

Did you check out this article on an 8 ft3 design?

http://www.lansingheritage.org/html/.../1983-subs.htm

12 ft3 can take up a lot of room.

yup!, the design started onpage 5 of that article. Once buolt into the wall, it'll not be a problem, but you're right 12 ft3 is big, as it requires a 16.5 cu ft outside measurement with all the bracing.

I am going to build the 12 cu ft box that is the 25 hz unassisted design. For those who have reviewed the article, is it correct that this design requires a 9 inch port? If so, it is 20 inches long. Can someone tell me what an equal setup would be using 2 - 6 inch ports?

Thanks
Scott