Can someone explain how to find the square inch per cubic feet when designing port?

[Krakin]

This is the wiring diagram for an opposing dual woofer enclosure that was posted:

???

http://www.stevemeadedesigns.com/board/topic/179470-looking-for-help-designing-a-enclosure-for-2-10-for-home-use/

I fail... hard...

[osiris10012]

Alright I took all of your advise and redesigned the box with a larger port firing towards the back of the front passenger seat. It now has a gross volume of 1.38 cu. ft. It is using a 3.5"Wx5.25"Hx25.75"L port after added length for the 90 degree bend (24" long prior to added length). The only thing I am worried about with this design is that the port ends somewhat close to the rise for the tranny tunnel. Do you all think this will cause any issues? I tried putting a 180 degree bend in the port but it got confusing trying to figure out where it should/could end. After all displacement is accounted for (.1 for the driver and .27 for the port) the boxes net volume is at 1.01 cu. ft. Here are a couple pictures of it. Let me know if there is anything you would change about it. Thanks in advance.

[Triticum Agricolam]

Having the port end next to your driveline hump like that will probably effect the tuning. Its hard to say how much though. I'd probably try to have it end somewhere else just to be sure.

[osiris10012]

ah man I can't win with this thing. lol. Maybe I will try and use a 4" port to make the beginning of the port easier. Just to be sure, with every 90 degree bend I need to add half the width to the overall length of the port?

[Triticum Agricolam]

ah man I can't win with this thing. lol. Maybe I will try and use a 4" port to make the beginning of the port easier. Just to be sure, with every 90 degree bend I need to add half the width to the overall length of the port?

That depends on where you are measuring the length from. The best way is to draw a center line down the whole length of the port and measure that. You don't need to add anything for the corners, its already factored in to the center line. You can subtract half the width of your port from the total length since you are using a slot port that shares a common wall with the side of the box.

[osiris10012]

ok awesome I will go back and redesign the ones I just did. This whole time I was thinking I needed to add length. I have only been measuring the center of the port too. Well with no additional length it may be easier. Another question I had was, would it hurt to drop the tuning down as low as 32hz to make the port length easier to achieve?

[CleanSierra]

The lower the tune, the longer the port. You may be thinking of it backwards.

[osiris10012]

Yeah I had an idea in my head and then rethought that so I think I have a good game plan for the next one. Well at least I hope so.

[osiris10012]

Ok after some rethinking I believe I may have come up with a design that will work well. Let me know what you all think. The port measures a total of 3.5"Wx5.25Hx25.75"L tuned to 35hz and the boxes gross volume is 1.38 cu. ft. Will this port design work ok?

[Joe X]

Bear in mind that the port length is measured along it's center line end to end. Also recheck your calculations, tuning is calculated from the net volume, gross volume is not even worth mentioning.