Rectangular and round ports

I understand that you can convert the area of a round port and get the dimensions for a rectangular port. My question is: I've seen a lot of posts saying that the round port should be 3" away from all sides of the box. Why then can the rectangular port run along the side of the box? Why would the 3" rule not apply?

Thanks for humoring me LOL

Makes zero difference as far as I am concerned.

Reason:  as a safety net against at least these two potential problems -

• a plastic or PVC tube extended along the wall could possibly clatter or resonate audibly along its length if touching the side wall, and
• the termination of the port tube has to remain some distance from another object (see acoustical port length).  The rule of thumb is generally that it be the diameter of the round port.

The biggest difference in the two types being that the slotted port construction is a glued-to-top-and-bottom solid wall, and the PVC port is in free air.  The airspace at the terminal end of the port is still needed in all cases.

Port noise is definitely annoying. Should the slotted port be rounded with a router as well? Or would it matter much?

I was thinking about using FG to get the front uniformly painted...the rounded front would look better I think.