View Full Version : Round Port to Slot Port

06-17-2004, 12:48 AM
Heya guys im going to be building my first ported box. It is going to be 2.5 cu ft tuned to 35hz. Now my question is if I calculate it for a round port I get a 4 inch diameter thats 8.082 inches long. Does this sound right? Also how would i make that to a slot style port? Thx for any help guys, I really appreciate it! :D

06-17-2004, 10:19 PM
The port size will also depend on the sub used. So I don't know if your port is exact.

But here is the formula for slot ports:::

Round To Square Port Conversions

Pie x R squared

For example::Say you have a 6" port that is 13" long, take half of the port size (Radius), in this case 3". Now multiply 3x3, (R squared). This is 9. Now do 9xPie, which is 9x3.14. Now you just got the square inch of your port. In this case 28.26.

Now you can design a square, rectangle, triangle or a port that is the sub logo. As long as you match the square inch.

For example::28.26 could be made into a 3"x9 3/8" opening, 13" long.

The lenghth of the port will stay the same. It determins the tuning frequency and is not effected by the conversion.

06-18-2004, 06:53 PM
ok, so while we're on this topic. im thinking of going to a square port instead, since I have the mdf already. Do i calculate the airspace of the port out of the cu/ft of the box? like I have 1.8 cubes to work with, then minus driver dispalcement, then do I take out the port volume?

06-18-2004, 07:10 PM
Go to www.audiobahn.com they have a port calculator and round to slot conversion calculators.