hi all i am planning out a 6th order bp that i will be building shortly and am planning on using pvc ports and was wondering if i could use two 3 in ports in place of a 6in port or if it doesnt excactly double

thanks

No, it doesn't double. I'll be your 8th grade math teacher for a minute.

Area of a circle is pi * r^2.

3" Ports: 3.14159 * 1.5^2 = 7.07 sq. inches.

6" Port: 3.14159 * 3^2 = 28.3 sq. inches.

You'd need four 3" ports to equal one 6" port.

dont no what i was thinking but got it figured out after i posted it but what if you have to use two smaller diameter pipes that roughly equal out to what you had speced out but the pipes arent the same diameterdo you just make each one half the length of the original like a 7x30 inch port on a 3.3 cube box would tune it to 30 hz so could i use a 4 in and 6 in and make them bolth 15 inches long

No, unfortunately it doesn't work that way. I thought it did on my first ported box and I ended up being tuned to 50 hz instead of 34.

Download a program like winISD (It has an option for bandpass box so you can design it in there) or look at the port calculator on this site. That'll help you.

No, unfortunately it doesn't work that way. I thought it did on my first ported box and I ended up being tuned to 50 hz instead of 34.

Download a program like winISD (It has an option for bandpass box so you can design it in there) or look at the port calculator on this site. That'll help you.

here is the one i use it's below this. i find winisd the free down load the cut lengths are off and come out wrong. but it is a good graphical description on what the box is doing and how the sub behaves. not sure of the box calculator on this site never used it. what you got to do to get four port is divide the box into 4 section like a 1 cuft would be .25 cuft .l to get the right air space for the port. any ways here is the clac and how to use it glad i got this in word already.

http://www.ecalc.com/calculator/scientific/

use this calculator at link above

square root key look like a check with a x inside

powers of ten key looks like a y to the power of x

av =10

lv=30

vb=864

do the this part first av(1.84x10to the power of key looks like y sub x when the calculator does the y to the power of x key it will put some thing that looks like a up side down carrot hit 8 then the equal sign.

Then write the answer to all of the above down

Next do vb(lv+.823then hit the square root key put in av then write the answer down

Take the first answer and divided buy the second one

Then take and put in to the calculator .159 square root of the answer of the two this should equal 40.63716007346 hertz for the fb

Just remember you can plug any thing you want into av or lv or vb that the plug part

Av =a 2 inch by 10 inch wxh or area of vent

Lv = length of vent

Vb = volume of box

just try to keep the area of the vent less then a 9 :1 just divide like a 10 by 5 inch port in to this 5/5 and how many section of ten you get and 10 /10 and how many section of 5 you get this would equal 1x10inch and one 1x5 inch the 1x5 would pass but the 10x1 would not it to big

here are some other formulas

pie times radius squared

radius is half of a circle and this trans forms a round to a square vent real quickly

square root of “a” squared + “b” squared

hypotenuse of a triangle and how to find it in inches

Length x width x height

Divide lxwxh by 1728 to get cubic feet or even multiply to get cubic inches

Here is were the formula comes from

http://mobile.jlaudio.com/support_pages.php?page_id=165

Edited June 16, 200916 yr by sadistic_customs

hey thanks to bolth of you and i think ive got it figured out but i have a bunch of 6 in pipe but tht wouldnt give me enough port area but two 6 in pipe runs would be plenty so could i use 8.6 in a calculator as the equivilant of two 6in runs since they have the same port area