Divided slot port Ratio

[Cj Kumz]

Hey people I am doing a box for 2 12s. Got a little confused over calculating the port area. Here is the box

So when calculating the port ratio is it 23:3 (assuming total width minus the divider in the middle) or 11.5:3?? And also do I total the port width when calculating tuning??

[bbeljefe]

It is 3:11.5 twice so the ratio is 3:11.5. And yes, you need to consider total vent area when calculating tuning.

[Robert8252]

If the box is perfectly symmetrical cut it in half. If it's 10 cubes with 100 inches of port instead find tuning using 5 cubes with 50 inches of port.

[bbeljefe]

If the box is perfectly symmetrical cut it in half. If it's 10 cubes with 100 inches of port instead find tuning using 5 cubes with 50 inches of port.

Why? All you're doing is adding a function to the equation, which isn't necessary.

[Robert8252]

Because he is technically running two ports. You don't have to do it that way. Just how I roll. Personally I'd recommend a single port instead. Adds deebeez

[bbeljefe]

Doesn't matter if he's running ten ports with respect to total vent area and length calculations.

And in this instance, a single vent would be wide relative to height.

[Cj Kumz]

The box is a single chamber with two ports. The reason I did this is because I hear the port should be as close to 1:1 as possible to get best airflow. So I figured the port was quite long as 1

[bbeljefe]

One to eight is the ratio you want to stay below so you did fine. 3:24 would have been okay too but a lower ratio is better.

[Triticum Agricolam]

If the box is perfectly symmetrical cut it in half. If it's 10 cubes with 100 inches of port instead find tuning using 5 cubes with 50 inches of port.

This is the correct way to do it. You divide your net volume by the number of ports and then calculate how long each port should be like they are all in their own box. I know it sounds like it would be the same as just taking the total port area and total volume, but you do end up with a little different result. JL Audio has a tutorial on it, look towards the bottom of the page here: http://www.jlaudio.com/header/Support/Tutorials/Enclosure+Ports/Tutorial%3A+Enclosure+Ports/287541