box for fi btl 15.

[B7L|BL4Z3R 4]

i have been working on not using the stupid ass re calc and doing everything on my own. how does this look.

height 16

width 30

depth 20

with a 4 inch wide port 33.80839511415706 inches long tuned to 32 hz.

[NB50 206]

Looks, not right. 2.93ft^3 @ 35.6Hz after all displacements.

[B7L|BL4Z3R 4]

mother fricker. could you please step by step me how you calc that?

[aimone 4]

i used sum calc last night that sumone on here made and designed a box not much different from urs

16.5 h

30 w

25 d

and that said it was close to 6ft^3 before port disp. which was 3" wide and 15" tall and like 21" long tuned at 33.08,

also with double baffle and with displacent of my fosgate power hx2 15 and 3" 45'd corners it said it was right at 4ft^3

so is it not right either?

[antonmiller 8]

im going to rewrite this some day. but this is a better one i think that i did a while ago.

this is a how to design a box

"if your doing a box that is 5 cubes you take 16 x 5 which equals your port area. then you figure out how tall you want it to be. then you figure out the port height. i would say your going to want the box to be 17" tall then you minus the double baffle and the bottom plate. so 17-2.25 which equals 14.75 then you divide that by your port area. so (16 x 5)/14.75= 5.423728 so lets say your port will be 5.5 by 14.75. (this is for a sub up port back driver side box) then you type that into this calculator

PORT Size Calculations and Formulas for WOOFER and Subwoofer BOXES

(bottom half)

so you type in 5 cubes square port, what you want your tuning to be say like 35 hz, make sure to check the slot port yes thing. then it gives you the number.

so your port will be 14.75 tall by 5.5" wide by 25.5 long. ok you have your tuning done.

now you just add your total port displacment with your sub displacment and then add the interior volume you want.

so... 5+.15(sub displacement)+ [(14.75x6.25x25.5)/1728)]=6.50 cubes total interior. (rounded)

you do the 6.25 wide because you need to incorperate the piece of wood that runs along side of it.

so you then take your 6.5 x 1728 (1ft^3=1728^3in) and you get 11232

then divide by 14.75 because thats how tall your box will be on the inside,

so you get 761.5 ish then you just decide how wide you want it or how deep you want it. dont forget this is internal volume. you need to accommodat the .75 wall thickness on each side of the box to fit where you want it to fit. so if you want the box to be 42 total outside then you minus 1.5 from that and then divide by that number.

so say thats what you want the box to be width wise, divide 761.49/40.5=18.8

so your total interior dims are 14.75 tall by 40.5 wide by 18.8 deep.

check all your math and times them numbers together and see how you came out. so 14.75x40.5x18.8=11230.65 then divide by 1728 and you get 6.4992187

very close to what you wanted! this is a good thing!

now if you think you need bracing just go and get some 1"dia round wooden dowels and put one or two in there. also put corner pieces in the corners. dont need it but it helps. yes these do remove some volume. but not enough to change the tuning too much.

now you build and enjoy the sweet sweet sound and poundage!"

I did this a while back for a kid to explain how to calculate a standard simple L-port box. hope it helps. it was for 1 15" aq hdc3.

[Kanaworm$ 292]

Dimensions all external?

If so I get 3.073ft^3 with a tuning of 34hz (+-)

[NB50 206]

In internal dimensions with the port in the box already are (Assuming .75" wood and those are external dimensions)

((23.75 * 13.75 * 14.5) + (9.942 * 4.75 * 14.5)) / 1728 = 3.1365 ft^3 - sub displacement of .21 = 2.92 ft^3

2.92ft^3 with a port area of 58in^2 and a length of 33.808" = 35.61 Hz

[Kanaworm$ 292]

In internal dimensions with the port in the box already are (Assuming .75" wood and those are external dimensions)

((23.75 * 13.75 * 14.5) + (9.942 * 4.75 * 14.5)) / 1728 = 3.1365 ft^3 - sub displacement of .21 = 2.92 ft^3

2.92ft^3 with a port area of 58in^2 and a length of 33.808" = 35.61 Hz

I didn't account for the port in the box! I added that last and was way off!

Thx for the clarification!

[B7L|BL4Z3R 4]

i am lost. i guess i just can not catch on. could someone please make me box dims.

W.42

H.17

D.20

tuned to 32hz

[caintrain 0]

Wood Thickness (inches) 0.75

External Height (inches) 17

External Width (inches) 38

External depth (inches) 20

Desired Frequency (hz) 32

Port Height (inches) 15.5

Port width (inches) 4

Sub Displacement (cubic Feet) 0.2

Sub Cut ID 14.125

Port Length 21 1/4

Net Box Volume 4.946836035

I think these will work, someone check my math.

Edited July 5, 2010 by CainTrain

[Kanaworm$ 292]

Box width is 30"

[caintrain 0]

I used the second set of dimensions he gave, which i was assuming was the maximum dimensions for his truck, the only one i changed(so i could get the volume within the recommended by the manufacturer) was the width.

[Kanaworm$ 292]

Gotcha! I missed that post!