Does the space taken up by a port affect the volume of an enclosure or just the materials that are used to make the port? Also what about these boxes I see with ports sticking out of the box? Does that volume need to be added to the enclosures volume? Thinking bout making a new box or adding a port to an existing one and was just wondering how this works. Thanks

 

If a port is inside a box than the port is obviously taking up space, think about it. A ports behaviour doesn't change the volume of the box. It doesn't make a difference if a port is in or outside of a box, you just don't calculate for its displacement if it's outside the box.

There's a lot to explain. A port isn't just a hole.

Port area is how much air can come out of a box at a time, you're either choking or letting a sub breath too much. Big subs need lots. Too little port area can cause port noise.

You need to figure out how many square inches of port area a subwoofer needs to reach it's full x-max (carstereos.coms' calculator).

You then play with the length of the port for the tuning (the 12 volt.coms' calculator). I was told told not to go over 20", but sometimes that's hard to do for the tuning you want.

Try not to go past a ratio of 1:3 for square inches of port area (IE 4 x 12 is 1:3).

Make sure you use the right amount of NET space.

You need the sub to be loaded in a ported box. Loading keeps the subs voice-coil from moving too far in either direction. There has to be pressure or else it moves too far. Try to face it towards the closest flat wall.

There is also port end correction. When measuring the port length, you measure it from the center line. If a port uses the side of the box as a wall than you add half of the port width (the smaller number) to the calculated port length, as in you may have it calculated to 30", but it will act like 35" if your port is 10" wide, because the end of the port acts like it's slanted up the wall of the box. You then add the same space in cubic feet (the other half of the slant) to the NET space, so that every area in the box is accounted for as either port or NET space.