Originally Posted by Kevin K
Sorry, I didn't see the link. Explain the difference in using side wall length difference than a center slot port. I'm a little confused on that.
There is no difference until you get a length that will have a bend in it, at that point you will always measure airflow at the center of the port.
So if it tells you you need 25in length of port but your box is only 25in deep. Well let's say your port is 20 tall and 4 wide. You stop the actual port wall 4 inches from the back wall. The airflow will travel 22.25, then turn go the 2in back to port wall, then .75 wood thickness. 22.25+2+.75 = your 25in length needed. Hard to put in writing