View Full Version : Calculator Accuracy

fasfocus00

03-22-2008, 11:11 AM

I ran across a link a while back to a site that calculates port length for tuned frequency. It asks for box Volume and for tuning frequency as well as for round, square, or slotted port.

my question on this is the given volume including the port displacement or not?

to reference here is the site

http://www.carstereo.com/help2/Articles.cfm?id=31

thanks for all the help.

fasfocus00

03-22-2008, 11:52 PM

so out of all the ppl that build boxes here, there is not a single person that can check the site and see if the port length calculator is including or excluding the volume of the port?

BrianChia

03-23-2008, 12:11 AM

It does not include port displacement. :)

bonesninja

03-23-2008, 12:15 AM

put in your net volume...meaning after subs and port

theothermike

03-23-2008, 01:28 AM

wrong....

it is asking for gross volume.

i type in all my info for a box im making.

i came out with 32.5" for the port length using the algebraic method by doing it on by hand, and came out with 32.43 using my gross volume that i used for my algebraic method

volume uses gross volume so if a box is 3.55 gross and the port / sub is 1.05 and ur net becomes 2.5 than type 3.55 in the box to acquire the port length. dont use net volume.

Mike-

BrianChia

03-23-2008, 01:47 AM

wrong....

it is asking for gross volume.

i type in all my info for a box im making.

i came out with 32.5" for the port length using the algebraic method by doing it on by hand, and came out with 32.43 using my gross volume that i used for my algebraic method

volume uses gross volume so if a box is 3.55 gross and the port / sub is 1.05 and ur net becomes 2.5 than type 3.55 in the box to acquire the port length. dont use net volume.

Mike-

That's incorrect. You must have made a mistake when calculating -- that website does not calculate the port displacement for you. You should enter the NET volume to calculate the proper length. The port displacement can't simply be calulated from the size of the port. You need to take into account factors such as folding the port, thickness of the port walls, if the port is built into a side(s) of the wall, etc.

fasfocus00

03-23-2008, 11:38 AM

Does someone just have the formula's?