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View Full Version : 15" bl box port too small



rain377
01-06-2008, 10:22 AM
i built a box for a 15" bl but like an idiot forgot about port area and i only have about 29 sq in. i'm building a new box today how do these specs look correct any if wrong. 20" wide 25" tall 25" deep port is 3.5 tall 18.5 wide about 37" long . box is 4.2 cuft tuned to 30 hz. speaker up port across the bottom facing back. looks like about 64 sqin of port.

rain377
01-06-2008, 10:33 AM
someone help me out with the math i'm not that great at box design.

themommyvan
01-06-2008, 10:39 AM
Why not just make the port all the way across the bottom?

rain377
01-06-2008, 10:41 AM
thats what i'm doing. box is 20" wide so with 3/4" wood port would be 18.5 wide.

themommyvan
01-06-2008, 10:43 AM
My bad looked at it wrong

rain377
01-06-2008, 10:47 AM
does that look like it will work though. dimensions, cuft, port area? i'll be buying the wood i a few hours maybe i'll post a biuld log.

themommyvan
01-06-2008, 10:50 AM
I used the RE calc and came up with something different. 34 port length and 4.6 before sub displacement. Tuned to 30.5

profundus-sanus
01-06-2008, 10:54 AM
that doesn't come out right..

comes out to about 3.6 net tuned to 35hz

rain377
01-06-2008, 10:56 AM
so sould someone throw me a design that will work. i can go 20" wide because i want to eventually add a second sub and i have 40" wide to work with. i want about a 30 hz tunning and i can go about as high and deep as i need.

profundus-sanus
01-06-2008, 10:58 AM
you trying to make it so you can just build an identical box for another 15 to put in next to it?

themommyvan
01-06-2008, 10:59 AM
http://reaudio.com/speaker_box/LPort_Box_Calc.html

rain377
01-06-2008, 10:59 AM
yeah basically

rain377
01-06-2008, 11:00 AM
i've done the re calculator the only thing with that though is i have to make the height the width because port will be across the bottom not the side.

profundus-sanus
01-06-2008, 11:00 AM
well, do you have any desired height?

themommyvan
01-06-2008, 11:01 AM
yea Ive done that with my last box. It was for 4 18s

rain377
01-06-2008, 11:02 AM
i'd like to keep it to about 24"

looks like i can go 20" wide 24" tall and 25" deep port 3.5 by 18.5 39.75 total length

profundus-sanus
01-06-2008, 11:10 AM
i screwed up....

its actually more like 4 cubes net @ 33.5(the original one)

rain377
01-06-2008, 11:11 AM
4 cubes is what i'm looking for but i'd like tunning at closer to 30 or will 3.5 hz make a diff?

rain377
01-06-2008, 11:13 AM
btw this is going in a grand cherokee where i used to have 4-12"s so i'm not worried too much about taking up space

themommyvan
01-06-2008, 12:03 PM
build start yet?

rain377
01-06-2008, 12:09 PM
not yet my wife has a doctors app and then i'll start. i'll post pics when i get started it's 40 here today so should be a nice day for a build.

themommyvan
01-06-2008, 12:14 PM
Im in southeast Mi also. Lot better today than what I was building in yesterday.

rain377
01-06-2008, 12:40 PM
where abouts in se MI

themommyvan
01-06-2008, 12:42 PM
Dearborn Heights

profundus-sanus
01-06-2008, 01:58 PM
4 cubes is what i'm looking for but i'd like tunning at closer to 30 or will 3.5 hz make a diff?


you should be fine.
You could also drop the height down to 24, up the depth to 26.5, and increase the port length to 38.75. It won't make a huge difference but you'll be at about 4.1 @ 32.4hz .

rain377
01-06-2008, 07:09 PM
build is done and istalled. I only have build pics though camera phone died.


26501316

26501317

26501318

26501319

26501320build is done and istalled. I only have build pics though camera phone died.

rain377
01-06-2008, 07:09 PM
26501321

rain377
01-06-2008, 07:10 PM
all i have to say is this thing hits friggin low. i never thought i could get that loud and that low with one speaker.

ugs92
01-06-2008, 07:15 PM
how much power u givin her?

rain377
01-06-2008, 07:17 PM
i'd say close to 1200 watts. i have a hifonics bx1500d. soon to be upgrading to a 2607d as soon as i get the money.

rain377
01-06-2008, 07:17 PM
**** thing fits a little tighter in my jeep that i thought though

themommyvan
01-06-2008, 07:18 PM
Should have done a wall. LOL

rain377
01-06-2008, 07:19 PM
when i get the 2nd sub i might.

themommyvan
01-06-2008, 07:21 PM
Didnt take me to long to build mine. I did most of it in 1 day.

rain377
01-06-2008, 07:23 PM
well maybe when i do a wall i'll have you help me. that was only the second box i've build so obviously i've never done a wall

themommyvan
01-06-2008, 07:24 PM
Are you going to be able to fit another box in there for the other sub?

rain377
01-06-2008, 07:26 PM
ummmm...... i think so. i kept this box so its 20" wide so i should be able to. say goodbye to the back window though.