since i can't find what i want, i'm going to build my box for my subs. i need .65 cubic feet of airspace and want to know how i can figure out how much space i have or need. i'm putting a pair of 8's in an angle cut box in my xa and this is what i have to work with. i need the box to be no taller than 12", no longer than 36", and the bottom depth can not exceed 9". i have yet to determine the top depth since i pretty much started taking measurements last night in the dark.

i'm planning on using 5/8" mdf since from what i've read, it should be more than sufficient for my application. any help would be appreciated. thanks.

 

google dat _____

 

i did. but i couldn't find an equation that took an angled box into consideration, only a flat box.

 

Length times width times height (measured in feet)= cubic feet. for a speaker enclosure you need to measure the inside of the box or be sure to subtract the MDF thickness from the calculation.

 

for an angled box, use the calculations provided just divide the box into 1) a cube and 2) a triangle. Then add them together to get total space.

 

for the triangle portion it's half of the base times the height times the depth

 

bird, what do you mean by divide the box into a cube and a triangle?

so i don't need the top depth in order to get my final number? what i was looking for was a formula since i thought i would need the top depth for sure. am i mistaken or what?

 

an angled enclosure is essentially a box with a (3D) triangle on top. so find the air space of the box, then the airspace of the (3D) triangle and then add them together to find the total air space...

and as someone else has already pointed out, the basic equation for a (3D) triangle is:

 

that's where i get a little lost. since the depth is different at the bottom of the box than it is at the top, what number do i use?

 

found a link on another forum that answered my question. thanks for your help guys.

http://www.rockfordfosgate.com/rftech/boxcalculator.asp

 

the formula is Length times Width times Depth (Height is the same as depth) and yes you measure most easily by measuring the box in sections. Cube sections are easy LxWxD. Leaving one or more triangular sections. Each triangular section (if they are right triangles can be measured by measuring the sides adjoining the right angle side1 x side2 x depth divided by 2. If you have an oddball triangle that does not have right angles simply measure it in sections. Divide it into 2 parts where both are right angle tirangles and measure as above. When you have measured all the sections (you did write your numbers down yes add up the total. From the overall spoace you listed above your box is likely to be perhaps large. One way to fix this is to make the whole box less deep which is going to change all the volumes you just measured. another way is to build the box the overall size you planned (but the vlume is still too big) and then put interior walls making the sub spaces smaller to achieve the .65 cu ft you want. Your 8's require .65 each?? Do they need to be in seperate sealed chambers? Do not forget to subtract any dividing wall between them from your calculations

 

ted, thanks for the heads up but according to the calculations i got on the rockford link i posted earlier, i'm right where i need to be including the dividing wall. i'm ok with numbers but i'm glad i was able to use that link. it saved me a lot of trouble. now all i have to do is build and carpet it.

 

There ya go!! Good luck. Pics when done.

 

i have so much work to do it's not even funny. between the amp rack, box, components, wiring, screens, back up camera, and sound deadening ,i won't be done for at least 2 weeks. but you can be sure once i'm done, pics are coming. lucky for me i have friends that are willing to lend a hand.

 

You might also try this site www.the12volt.com


John

 

http://www.bcae1.com/ go to #110 on the list to the right. this is an awesome site!