Help! 4 BTL 18's in a wall

[JASON123 1]

I've built boxes for at least 15 years. But, i've never built a ported box like this. This box is gonna be 31.18 cubic ft 52 in wide x 37 in tall x 28 in deep. Trying to figure out how to fit all the subs and where to put the port. My guesstimations on the port size would be 15 in x 20 in and port length would be 8.13394050 ??????????I put the width and height in on a port calculator and it comes up with this length. What is that? I don't understand the length part. Don't even know if I can make a port hole that size with those subs in there. I was thinking of slotting the port either at top and bottom or on the sides. Sides would be better i'd have more room. I've never built a box like this so i'm clueless. Always built sealed boxes. Please help.

[JASON123 1]

Oh yeah by the way i'm trying to tune to 34 or so hertz

[lee 2]

what port calculator did you use?

[KU40 173]

What don't you understand about the length part? if it needs to be 8" long, you put a board inside the box that's 8" long (minus front baffle thickness) from the port opening. You don't need to build it exactly 8.1248i48392923823lkadsfj inches long or whatever it gave you. getting to the closest quarter inch is close enough. The program just uses an equation to figure out the port length, so it probably has an infinite number of decimal places. They just didn't cut it off very much.

In order to fit those you'll have to stagger them a bit so that you can scrunch them height-wise. so for instance, in a square mounting configuration, you'll have to have the center of the bottom sub offset maybe 4" to the right of the center of the top sub. That will allow you to move the bottom sub up due to the round cones so that you can fit two subs together height-wise. If you slot your port all the way to one side and use all 35.5" of inner height on that box, you can probably make the port 8" wide. That'll give you about 70 square inches of port area per sub, and that's probably the lowest amount of port area you should do.

You should make a life-size drawing of the front baffle with how things can be configured to make them fit. Maybe use chalk on your driveway or something. Or you could scale it down and put it on a regular piece of paper. But chalk sounds like more fun to me.

[JASON123 1]

O I see that makes a lot of since.duuuuuuuuuuuuuuuuhhhhhhhhhhhhhhh I do appreciate it.

[JASON123 1]

ku40 thanks for the help. Helped me out alot. Couldn't figure it out I must have been brain dead. But now the box is gonna be alot wider than I thought. Gonna strip the back of the truck down and that will give me close to 70" wide but the same heigth. hopin to put a 15x20 port in the middle at the bottom and that would give me a port length of 10"?. gonna be using for daily but would like to take it to some shows and want to open my own fiberglass shop so I want it to look good for customers.I want it to be really loud but sound good. That's why i'm trying to stay in the 33 hz area. i've never messed with 18's or a ported box. This is a first for me. I want to be able to pull the port out and go to 40 some hz. Been reading lot's of other posts to get ideas but there doesn't seem to be too many people that have done this in a explorer or just run a wall with 4 18's. i'll figure it out one way or another. any help by anybody is appreciated about how to do the ports and the optimal cubic feet that i should try to reach. thanks, bigjay

[JASON123 1]

come on now 156 pep looked 2 replied

Edited January 13, 2009 by BIG JAY

[danieln_88 0]

is that 31.18cu.ft. before of after displacements??

[JASON123 1]

it could be either now that im gonna gut the back out i got a lot more room i was thinking 31 cubic feet after though

[danieln_88 0]

it could be either now that im gonna gut the back out i got a lot more room i was thinking 31 cubic feet after though

thats only going to give you 9.67sq.in. of port per cu.

i think you need more port.... atleast try to get that up to 12sq.in. per cu.

[JASON123 1]

how do you come up with that im trying to learn so would 20x20=15.5 Port Length right would that be enough thanks

[jaynanspl 17]

Do you have to have it at the 70" width?

[danieln_88 0]

how do you come up with that im trying to learn so would 20x20=15.5 Port Length right would that be enough thanks

15x20=300sq. in. of port and divide that by your 31cu.ft....

what is your complete dimensions you have workable in the truck?

Edited January 13, 2009 by danieln_88

[JASON123 1]

cool i see but i have 68.5 wide 37.5 high and i dont wont to go no deeper than 33 deep

it will probably be 53 wide 37 high 31 deep that gave me 31.25 so 30 cu ft is it after the drivers then got some bracing

Edited January 13, 2009 by BIG JAY

[danieln_88 0]

you could go port on driver side at (rough estimate dont how thick of wood your using) 11"w X 35"t and that comes up with a little under 12.5 sq.in. per cu.

[jaynanspl 17]

This is what i have come up with for you, was not sure if this is what you had inmind.

[rushnrun 14]

cool i see but i have 68.5 wide 37.5 high and i dont wont to go no deeper than 33 deep

what year/type of explorer?

how are you planning on getting this in there?

Building inside the vehicle?

I only ask because the size of box you're posting won't just slide in through a door or a hatch... Make sure you know what you're getting into...

**explores get real loud without walls

[JASON123 1]

yeah how does that sound with a port coing out one side. I'd really like to have it up the middle but I know i'd have to stagger the drivers to make them fit.

[JASON123 1]

the box is cool but the drivers will have to be staggered off centered a bit because they are 18's. i like the way you did the picture of the box. what program is that? thats cool. its a 1998 explorer i think i know what im getting into Ill build it in it. lol

Edited January 13, 2009 by BIG JAY

[danieln_88 0]

cool i see but i have 68.5 wide 37.5 high and i dont wont to go no deeper than 33 deep

what year/type of explorer?

how are you planning on getting this in there?

Building inside the vehicle?

I only ask because the size of box you're posting won't just slide in through a door or a hatch... Make sure you know what you're getting into...

**explores get real loud without walls

i agree..... if this is your first ported box, then i think you should just take one btl for now and build a ported box for it.... do some testing, find your pros and cons, then go from there....

[JASON123 1]

I want to build a wall too keep the back seat in and it is a 1998 4 door explorer. i think i got it now. thanks for everybodys help. took me a minte to realize what you were saying on the ports. went back and read again. now i got it. why run 1 when you can run 4. i like to be different and difficult.thanks again Big Jay

[jaynanspl 17]

Here is another way you could do it, I know it don't have the port in the middle like your wanting, but it might help give you some more ideas.

[diablo_331 23]

no point in building a wall behide the second row of seats

[rushnrun 14]

re-measure.... in the 96(I believe it's pretty much identical to the 98) it's 42" from fenderwell to fenderwell.... I couldn't imagine that the 98 is 18" wider... above the wells you may have 60 but......

I don't know all the measurements because:

A.) I don't have a 4dr and

B.) I only care about width and seat height for regular street class building

You're going to be doing a little more than building a regular rectangular box to make the woofers and port fit..

Good luck with your build either way.. walls are a whole lot of work..

[JASON123 1]

sure there is. like i said i lke to make stuff difficult. anybody can rip out the backseat and put a bunch of subs in something. i'm trying to put a bunch of subs in something and make it look like it came that way. thanks for the drawings. they look really good. that's what it's gonna look like eventually. once it warms up and got some room in my shop. but i do believe i got it. i'll post a build on it when i get it started. it ought to be a creation. Big Jay