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View Full Version : 2 12" fi btl's. enclosure help.



lrgnation
10-23-2006, 04:21 PM
Okay this is what i know so far.

I am going to be running 2 12" fi btl's on 2 rockford t40001bd's so its about 4500watts to each sub.

I want 4.5cubes after sub displacement and port.
Sub displacement for both is about .4 cu. ft. So that puts me at 4.9
I will be tuning to about 32-33hz.
How should I make the port? For the most part the box will be somewhat normal, although I want the port inbetween the subs rectangular or to the side of the subs. heres a quick sketchup.

http://img264.imageshack.us/img264/8096/untitled1mn8.jpg (http://imageshack.us)

I could also run arrows, just need some help on port size and length, box will be about 12" high 38wide. need to know port length.

baseballer1100
10-23-2006, 04:25 PM
What are arrows?

lrgnation
10-23-2006, 04:26 PM
oops aeros...

baseballer1100
10-23-2006, 04:27 PM
I was gonna say. haha

ultimate157
10-23-2006, 04:34 PM
I'd go with the port in the middle ... looks like a jeep wrangler. haha.

I love the port in the middle because its symmetrical :uhoh:

lrgnation
10-23-2006, 04:46 PM
i'll have some plans up a little bit later that you guys can review. It should be really close to 4.5cu ft. Its gonna have a slanted front which will actually let thebox be a little bigger. i need atleast 100 sq in of port however.

lrgnation
10-23-2006, 04:54 PM
Heres a rough sketchup before the plans and without a port.

http://img410.imageshack.us/img410/264/box1sj6.jpg (http://imageshack.us)

lrgnation
10-23-2006, 05:29 PM
Okay its 38 wide, 12high, 27long on top, and 31 on bottom.

So i got 5.656 for the 38x12x27.
I added .41 for the extra right triangle.
(4"-.75 for wood. 3.25/2=1.625x12hx36.5L=711.5-1728=.42.)

So 5.66+.42=~6cu ft. before any displacement.

subtract the .4 sub displacement at 5.6cu ft. and 1-1.2cu ft for port. puts me right where I want it. at about 4.4-4.6cu ft.

Just need the port design now.

2loud4u
10-23-2006, 05:30 PM
I got ya. just give me a bit and i will get back to you on aim.

lrgnation
10-24-2006, 10:03 AM
Okay so basically I got 4.5 cubes with 79sq inches of port.

its a 7.5" wide x10.5" tall slot port and 23.75" long. port takes up 1.1 cubes so it puts me right at 4.5cu ft. at 33hz.

saywhat?
10-24-2006, 08:29 PM
sounds good, now start building haha.

should be loud.

lrgnation
10-24-2006, 10:08 PM
sounds good, now start building haha.

should be loud.

No $$ right now, working on it...

gsxrjjordan
10-25-2006, 04:02 AM
Although it probably doesn't matter with SPL stuff, I've found that angling the subs is a bad idea... usually doesn't give the sound waves enough time to form before you hear them (usually, firing straight back, you get a clean reflection off the trunk and a nicely formed wave when it gets to the front seats). If you need to, slant the back rather than the front.

Also, if the port opening is on the slanted side, you won't have quite the right amout of port area (because the height will be the same, but depth different on top and bottom). Not sure how much that affects things, whenever I've done non-flat faces I've used Aeroports or rectangular vents on the back/top/flat surface.

If this doesn't matter at all for a set up this big, just call me a newb ~

saywhat?
10-25-2006, 08:09 AM
shouldnt be a problem as sound waves in a car dont exactly have time to fully develop anyways. also, hes firing in cabin.

saywhat?
10-25-2006, 08:09 AM
oh and, have your port on the driver side ;)

lrgnation
10-25-2006, 03:56 PM
Although it probably doesn't matter with SPL stuff, I've found that angling the subs is a bad idea... usually doesn't give the sound waves enough time to form before you hear them (usually, firing straight back, you get a clean reflection off the trunk and a nicely formed wave when it gets to the front seats). If you need to, slant the back rather than the front.

Also, if the port opening is on the slanted side, you won't have quite the right amout of port area (because the height will be the same, but depth different on top and bottom). Not sure how much that affects things, whenever I've done non-flat faces I've used Aeroports or rectangular vents on the back/top/flat surface.

If this doesn't matter at all for a set up this big, just call me a newb ~

The porting being slanted like that is no problem at all, you just use simple math to figure out how much that slant takes up. Slanting the back wouldnt help me, the reason teh front is slanted is to make the front big enough to fit the subs. the subs are 12.5" and the front of the box is on is only 12. The box will be sealed off, the cab will be sealed off from the trunk.

oh and, have your port on the driver side ;)

My port is going in the middle of the box, If i had some box making software I would show you teh design. I have different port size now. I calculated it wrong.

Its 4.3cubes at 33hz.

10.5" tall, 7" wide and the port is 32" long. The way I designed the port to angle inside the box makes it long enough, I'll try and get something posted of teh design.

iamamp3pimp
10-25-2006, 03:57 PM
port on drivers side generally makes me hear more rattles.

lrgnation
10-25-2006, 04:10 PM
Its possible I might be ordering enough damplifier, overkill, and luxury liner to eliminate 80% of the rattles. teh other 20% will rattle like hell...