View Full Version : Port length formula problem

12-28-2004, 07:18 PM
After reading the ported box tutorial, i got snagged on finding the port length...

Lv = [(1.463*10^7R^2)/(Fb^2*Vb)] - 1.463

Is the formula for finding the length, where Lv is the length, R is the minimum port area, Fb is the tuning frequency, and Vb is the interior volume of the box.

The port area i got after plugging in for dV>/=39.37*(32*305)^.5 was 3889.46 cubic inches (or 2.25 cuft). Since i wanted a 16.5" x 4" slot port, do i take the area of that instead, since the 2.25cuft is a minimum?

I want to tune the box at 32hz, the interior volume is 9813.3 cubic inches before driver displacement, and the driver displaces 305 cubic inches.

Im pretty much stuck here, since i dont know what Bass Outlaw was doing in the formula. What i think the area of the port is, is the actual area that the port takes up (minus the 3/4" MDF). Am i right? If so, how would i go on from there...?

12-29-2004, 02:01 PM
How do i get a cicumfrence out of 4inch diameter?

12-29-2004, 02:04 PM

C= pi*4 = 12.56 ;)

12-29-2004, 02:06 PM
how do i get area A=pi x radius"squared ???

12-29-2004, 02:10 PM
Volume = pi * radius^2 * height

google works ya know

12-30-2004, 12:44 AM
Im actaully done with the box designing with help from Moe Lester, so anyone can close this now, thanks!