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View Full Version : formula to figure out box tuning and cu ft?

yo0123yo
07-25-2006, 10:27 AM
can someone tell me the formula to figure out how many cubic feet a box is and the formula to figure out what the port is tuned to? thanks

ghart999
07-25-2006, 10:33 AM
can someone tell me the formula to figure out how many cubic feet a box is and the formula to figure out what the port is tuned to? thanks

volume is to measure all 3 dimensions and subtract the thickness of the wood multiplied by 2 (for each side). Then multiple the 3 dimensions together and divide by 1728.

Example: box is 18x14x26 and wood is 3/4" thick. 18 - 1.5 = 16.5 : 14-1.5 = 12.5 : 26 - 1.5 = 24.5

16.5x12.5x24.5 = 5053 div ide that 1728 and you have 2.92 ft^3

I don't know the forumla for tuning.

yo0123yo
07-25-2006, 10:50 AM
cool i just figured out my box is 7.55 cu ft, i got 2 12" L7's, now i just need the tuning formula, oh and if it involves finding port displacement or sub displacement, i dont know how to do that, so can someone explain that as well. thanks :)

07-25-2006, 11:25 AM
i believe what ever the sub displacement is you just subtract that for each sub from the calculated volume. im also trying to figure out this whole port thing.

helotaxi
07-25-2006, 11:27 AM
The formula is on JL audio's website under tutorials. Or you can just download one of the myriad free box calc programs and let it crunch the numbers for you.

07-25-2006, 11:56 AM
got a link for that box calculator?

helotaxi
07-25-2006, 01:47 PM

acreature
07-25-2006, 01:52 PM
How accurate is this compared to paper and pencil?

http://www.subwoofertools.com/forum/ported-box.asp

helotaxi
07-25-2006, 03:05 PM
All it does is keep you from using a pocket calculator. It uses the same formula and should end up at the same answer.

acreature
07-25-2006, 04:28 PM
All it does is keep you from using a pocket calculator. It uses the same formula and should end up at the same answer.