How do you calculate a PORT for a sub box

[rick374]

I bought an alpine type r 12", 1000w rms sub. I want a ported box and the alpine
site doensnt give clear port 1ength. The box dimensions are 23" wide, by 12.5" tall by 14" depth. its suggests vent displacement is .23feet squared. i cant figure out how to get a proper port made up. any help would be appreciated.

[PaulD]

Are you familiar with math ? (not trying to be insulting) 1 ft^3 = 1728 in^3 (12X12X12)

So 1728 X .23 = 397 in^3 (cubic inches). Surface area of a circle is pi X r^2, so for a 4" pipe, 3.14 X 2^2 = 12.56 in^2. To get the desired length - 397 in^3 / 12.56 in^2 = 31.6 in (a little too long for that box). This is how you do the calculations. You can go to WinIsd and download the free application. Your sub may already be in it, if not remember to follow the directions TO THE LETTER on enetering the info.

[dbfreak147.5]

better off to use a calculator, ive been in this stuff for a long time and thanks to paul that is the first time ive seen the math.... also hi paul, long time no see

[PaulD]

hey db, what the heck have you been up to ?

[shahbaz]

RE Audios box calculator can help you . All you have to do is take out the red numbers and type in what your specs for your box are. It will tell you what you need to know