if i have round 8 cubic feet will two ports be ok? two of them at 3 inche's by 21? thanks for any help guys!

if i have round 8 cubic feet will two ports be ok? two of them at 3 inche's by 21? thanks for any help guys!

not enough sq inches of port area you need 12-16 sq inches per cuft. it would be like 8 times 4 inch round ports then cut in to length per there design page listed here at link below i left a cut length sheet be low av for a 4 inch round port should be about 12.5 inch any ways there is a link above how to use the port formula. and tunes to about 30-35 i would tune it 30-33

https://ssl.perfora.net/www.ficaraudio.com/sess/utn;jsessionid=154a5d0e109ba67/shopdata/0070_Tech/0070_Speakers/0010_Tech.BTL/product_overview.shopscript

Here’s the box I build using this formula I think it works awesome cut length sheet coming soon. Box is 2.52 cuft port area 21 sq inches 18 inches long 5.25”h x 2”w x 18”L tuned to 33 hertz I still have to finish it but here is a pic of it hits every note not hesitation and with authority any ways here is that pic and formula below

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

<br />if i have round 8 cubic feet will two ports be ok? two of them at 3 inche's by 21? thanks for any help guys!<br />

If that is (2) ports 3" wide x 21" high, that is 126 sqin of port area.

Should be enough for pretty much anything you will be putting in 8 ft^3.

Brian

thanks man for ever thang!!