ported box for 2 15" audiopipes

Four 4-inch ports is really close in size to two 6-inch ports. We are only talking about 5 sq in of surface area difference. (yes, two 6-inch vents is still a little larger)

The difference is minimal so you can use four 4-inch vents.

You might even consider a slot vent. As long as the surface area (the area of the opening) is about 55 to 58 square inches the length will remain the same

 

Take your time and it will turn out good.

 

Absolutely, the ported will be louder. There is a thread here somewhere where someone documented the building of a ported box. It would be a good idea to check it out. In fact I'll go look for it.

 

Check out this thread

http://www.caraudiotalk.com/audio-forum/subwoofer-box-custom-fabrication/5250-kicker-cvr12.html

Go to pages 10 and 11, he is using a slot port. Which is what I suggested considering instead of trying to cut 4 round holes for the port.

But all is not lost. Put the ports in using either 3/4 or 1 inch screws. And then use silicon to seal it up from the back side. If you look at the pic I posted earier you should be able to make out the screws in the port.

Or it might not be too late to switch to a slot vent.

 

Tell me again what the final dimensions of your box are and I'll get back with you shortly.

 

OK lets give this a try, we need a slot that is 20.5-inches tall by 3-inches wide. The port needs to be between 7 and 8 inches long to get you around your 37 Hz tuning.

 

Well lets see. I do make mistakes.

We have an inside area of 7.5 cu ft (I'm rounding off), we are gonna subtract about a 1/2 cu for the port, that leaves us with an internal volume of 7 cu ft

Now a port that is 20.5 x 3 has a cross sectional area of 61.5 sq in which is equivelent to one round port with a diameter of 8.85-inches

Actually we were both wrong, the port needs to be 10.79-inches long. Just shoot for 11-inches. I made a mistake with the calculation but your result should still be closer to mine. BassBox can take into account things that I can not. But our results should still be closer.