ok so im builind this box thats 1.25 cubic feet with a pvc port. i was planning on putting the port outside the box but im thinking of how it would work on the inside. if it goes inside would i have to change the cubic feet or would it be the same?

p.s this box is strickly for spl

 

You have to make the inside of the box bigger to make up for the port displacement. Working with a port outside is much easier to tune and work with.

 

ok so all id have to do is calculate the volume of the port and add that to the box size right? im just wondering becuase i have very limited space.

 

Yes that is all you do, also remember to add the thickness of the port aswell (ex.3/8").

 

awesome thanks alot. i forgot about that. so i guess if making a slot port you would do the same equation.

 

Yes you would.

 

Just to add another question to this topic. Do you put the port flat on the wall or do you have it sticking about a inch or 2 inside the box?

 

Usually flat on the inside wall, but if you put a couple inches in the box (for room lets say) make sure you allow that extra when measuring youre internal volume.