I'm going to be building a spare tire enclosure for one 10" sub. The recommended volume for a ported enclosure is 1.25^3 ft. with a 3" diameter x 7" long port. I'll be using 3/4 inch MDF to build the enclosure. Now my question, how would I port this box? Is it a 3" X 7" vent? Also, since the top of the box will be covered by carpet, would I be able to put the vent on the side of the box? Here is a sketch I have of the box, not to scale though.

 

Yes, you can put it on the side of the box as long as its not going to be obstructed by anything.

 

port it with PVC pipe 3 inch diameter.

 

This is going to be the easiest way to do it. 3" diameter PVC pipe, 7" long in the side of the box.

Correct. You can have the port coming out any side of the box, doesn't matter as long as there is no obstruction near the outlet of the port.

A general rule is that you shouldn't have anything closer than one diameter of the port close to the outlet if that makes sense... In this case, your diameter is 3", so you want at least 3" of clear, unobstructed space at the port outlet.

I checked your dimensions and you've got it right using those external dimensions.

Just a heads up, your sub cutout will likely not be exactly 10". Check the specs of your sub and use the cutout diameter listed there.

 

Oh yeah, I forgot to mention, I would use ABS pipe instead because its thicker. Once you have the port attached in place, you can run a 1/4" or larger round-over router bit on that edge so youn can reduce port noise.

3" ports are handy and all but 9 times out of 10 they can create some port noise or 'whistle' which is a bad thing. Routering that edge is a must!

 

3" aero port will be money better spent than pvc pipe

you will not get port noise from the aero

you will hear a bit from the PVC


if it was a trunk set up than pvc would be fine

but since it is in your hatch than go aero port

like $15 for a 3" aero port