Port Question
 

I've got a quick question which I hope someone can provide some insight on.
If I wanted to go about converting a slot port into a cylinder port is there some formula to do it.

I'll give you the scenerio.
If the port was to be slotted it would of been (H) 8" x (W) 2" x (D) 20"
Since it's not an option now and the enclosure is already made with a
4 inch whole already cut out how do I determine the length of the 4inch port.

thank you in advance

If the slot was 8 by 2 then a 4 inch port is to small, your depth would still remain the same if you converted it right, you need a 5 inch port in your box to stay at twenty inches long. Also is your box long enough to have twenty inches of length of port in it, plus 4 inches from the back wall. I say square off the circle 4 by 4 and keep your depth at 20 then it is the same as, 8 by 2. Better yet just measure your boxes width by depth by height, and how thick the wood is. Also what sub/s you are using for it, then someone can help you out more with your decision. If you screw up on your port your box will sound like farts.

What's the net volume of the box? What tuning frequency are you looking for? It'd be easier to just plug these numbers into an online calculator like this than to piss around with converting port area and displacement from an old slot equation. Just scroll down and toss in your figures with "round port" selected and it'll spit out the length you need to achieve the tuning you're looking for with a 4" port.

thanks to the both of you.
in particular Worldwind, I'm going to try the port calculation website.

thanks again