Speaker Box HELP!

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OK I need some help. I just got my 15" in yesterday and now i need to build a box. Im gonna make it ported. Its a RE SX, and RE's recommendation is it be 3.5 cubic feet PORTED. But i dont know how to find the volume of a box with the port. Im gonna use a rectangular port... not pvc tubes. And via enclosure calculators i found out that if i make a box (WxHxD) 30"x17"x15.2" it will be 3.50 cubic feet. BUT how do i find out the port, i dont know where to subtract or an equation. Dont gimme any of that GOOGLE IT, crap because ive checked and all those calculators are for circular ports. So can someone help me out please. BTW i can fit a 43" wide and 17" high box in my trunk. Thats the max. So if someone can tell me the equation or help me out, or even make some plans that would be awesome.


PS: The port im gonna make is 32 Hz. So i'd need to know the width of the port, since it will be 15.5" high and 14.5" deep.

posted by  Stem

one question - what thickness MDF will you be using....i'd imagine for a 15"...you will be using 3/4"?....

posted by  dodgerforlife

yah 3/4", the calc i was using tho incorporated that, so even with the thickness and those measurements, it still came out to 3.5 cubes.

posted by  Stem

okay, good. anything less thick would probably fall apart on you :P

anyways. are you trying to determine cubic feet with the port in the box, or port size?

posted by  dodgerforlife

port size, ive only built one box before, and it was sealed, so this whole MAKING the port thing is blowing my mind, i dont know wtf is going on lol. i mean am i supposed to make it 3.5 cubic feet and then add a port on? and if so, whats the width of the port if i want to tune it to 32 hz.

OH YAH, BTW the port im gonna make is 32 hz, per RE's recommendation

posted by  Stem

hmmm....those were outer dimensons, correct?

posted by  dodgerforlife

Alright, found what I was looking for.

If those were the outer dimensions...then you wouldn't have a large enough box with a port included...it would drop to about 3.3 cubic feet...

Your outer dimensions should be 17H, 32W, 15.2D with .75 wood

Port should be 5"x2.52" and 6.4" long. Gives you a port area of 12.6", equivalent to a 4" round port.

The measurements above will leave you with a box that is 3.568 cubic feet gross, and 3.522 cubic feet net(final). Close enough to work well.

posted by  dodgerforlife

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