I have a 2000 Toyota 4runner.. Throwing in 4 old skool 15" ROCKFORD FOSGATE HX2. Sorry, I had to put the name in caps for respect!! Anywho, I got some measurements here... I want the box 40" (width from wheel well to wheel well) x 36" (length from back seat to back door) x 20" (from bottom to top). So measurements are 40"x36"x20", outside measurements (roughly 16 cubic ft) . Here are my questions... Has anybody had 4 15" subs facing down towards the floor and had rectangle port facing up? My reason is, if you look real close at my pic, you can see 2 6x9 Kenwwods bolted on top of box. Also, I usually haul wood and crap for my work and would really hate to get a sub busted because of something dropping on it... I will raise the box 4 to 6 inches off the floor for the subs of course... OH!! Also, does anyone know what the measurements would be for the port if I want it tuned at 35 htz? Ummmm, trying to think if I need to put anything else here... 4 15" hx2, going to be pushed by 2 RF t10001bd amps, probably doubled layered where subs are bolted on, definatly have to 45 the inside corners, and will be glued, screwed, then sealed. If its not possible for subs to be facing down, I guess I can face subs upwards and port in between subs...

Do I have this topic in the wrong place???

Not in the wrong place, sorry I read this before and wasn't really sure what you were asking...

I think that the 6x9's have to go, and why not do upward firing and just design a cover for when you need it for work... You would loose soo much cargo space raising that box up 6" just to hope for enough air movement...

I'll let someone with more downward firing experience chime in on this though.

Thanks. I would love to fiberglass the 6x9 somewhere else, but I never did fiberglass work and have no place to work with it since I live in an apt. complex. How about the port measurements? How do I figure that out?

Edited February 20, 200916 yr by SLYTLYSCRAMBLED

If your concerned about wood then what about doing this....thats my box for my car its just to give an example i guess and the darker wood is supposed to simulate wood for your work i guess...

http://img527.imageshack.us/img527/5315/yeawi9.png

http://img502.imageshack.us/img502/3544/yea2tw7.png

With those dimensions, and a double baffle, you get a gross enclosure volume of 13.64 cubes.

I don't know the displacement of each of the HX's, but let's just assume .16cu ft ea - you've got 13 cu ft internal volume. Now, depending on the port size, and the internal bracing, I'm willing to bet you're going to be down to around 12.25 cubes or so.

AND - gotta agree with firing the subs up. Even if you were to raise the box up 5", that's a LOT of space to give up to be able to carry material. Some kind of cover is a must.

BUT.... Will the HX's work fine in 3 cubes each? Can you go smaller? Are you looking for Max SPL, or just good SQ? If you're looking for sheer volume, I believe a smaller box, tuned to a higher frequency, will get louder than a larger box (but I may be mistaken). If you can drop to 2.5 cubes each, you're down to 10 cu ft after all displacements, and probably somewhere in the 11.5-11.6 cu ft gross range. With the box still being 40 x 36, it would only need to be approximately 17.25" in height - Then, you COULD raise the box and fire them down - lift it just 4" off the floor, should be plenty of room for the subs to breathe.

I like that set up ADK... Didn't think of that... Thanks... Hey BIG, the hx2 will work at 2.5 cubes each and displacement is .25 each... I wanted at least 12 cubes total, but will settle for 10. (not too picky if it still can hit the lows pretty good) I mostly listen to rnb hip hop and bass tracks. I would love to have a hair trick box and everyone is telling me that 35 is a good average frequency. Can I do 35htz in the 10 cu ft box? If not, then I will just have to build some sort of cover (shouldn't be too hard).

Also wanted to say THANKS FOR THE INFO!!! I really appreciate it...

You could do 10HZ in the 10cu ft box if you wanted to, but your port would be ridiculously large.

Use Port Calculator to get you started in the right direction.

1)Figure what size enclosure you want (Cubic feet x 1728 = cubic inches)

2)Determine your tuning frequency

3)Figure how much space the port will take up (Cu in)

4)Add in the displacement of the speakers (Cu in)

5)Add the sum of 3) and 4) to your enclosure size (Cu in)

6)Divide by 1328.25 (interior dimensions of 38.5" x 34.5") = your interior height of your box.

So....using an Xmax of 19mm....

1)10 cubes = 17280 cu in desired space

2/3)35hz requires a slot-loaded port displacement of 4942 cu in

(38.5" wide port x 6" high x 19" long, 231 sq in of cross-sectional area, slightly smaller than the 277 sq in recommended)

4)If you say .25 cubes displacement, then X4 = 1728 cu in.

5)Total interior space required = 23950

6)Interior height of box = 18.03"

Note: does not add in the space required for crossbracing, or for 45'ing the corners!

Without crossbracing, the enclosure would be 20.25" in height, assuming a 1.5" double baffle, made from 2 layers of 3/4" MDF

Edited February 23, 200916 yr by BigDaddy13440

THANK YOU!!! That really helped out a lot... I greatly appreciate this!! People in SSA are FREAKIN AWESOME!!!

GOT SOME PICS!!! Not all that, actually looks like a big box LOL!! Ummmm, how do you post pics on here???

Upload to a hosting site (tinypic.com, imageshack.com, photobucket.com) and copy/paste the links with the [ img ] tags in your post.

Pieces cut

Had to make sure I cut them right LOL!!

Had to recheck and move a couple sides around for perfect fit...

Glued and screwed...(Got a lil happy with the glue there!! )

The fiberglass thats ganna be resined inside box instead of double layer or bracing.

(hope it works)

Thanks Adrian!!

Edited March 9, 200916 yr by SLYTLYSCRAMBLED

Ahh I love it when newer members are like this, totally open and helpful. I also love the fiberglass, nothing beats the smell of resin in the morning

awesome build

good luck dude!! i want final pics

Ahh I love it when newer members are like this, totally open and helpful. I also love the fiberglass, nothing beats the smell of resin in the morning

Chea, but I can't do the fiberglass myself... . I live in an apt complex and the smell would overwhelm everybody (not in a good way)... I will post more pics when I get more done...

The fiberglass thats ganna be resined inside box instead of double layer or bracing.

(hope it works)

Resin is used to smooth out the interior of the box for air flow but fibreglass inside a box doesn't work as bracing.

With a box that big, you would be better off chucking in some bracing.

The fiberglass thats ganna be resined inside box instead of double layer or bracing.

(hope it works)

Resin is used to smooth out the interior of the box for air flow but fibreglass inside a box doesn't work as bracing.

With a box that big, you would be better off chucking in some bracing.

Bracing... Would that be 45ing the corners or is that throwing the all thread from 1 side to the other or both?? Boy!! Did I get the wrong info from the fiberglass guy!!! :puzzled::puzzled:

45's in the corners decreases dead areas at the intersection of the box walls.

bracing would be side wall to side wall and most likely top to bottom if you have 4 subs on top.

check the fisher customs boxes in the manufacturer section for ways to brace the box.

Otherwise chuck a couple of 2x2"s or threaded rod in there to brace.

Oh.... So fiberglass inside will not help with the flex?? I will do 45s and brace it with with the 2x2 then... Thanx. I'm glad I got this before I went and glassed it!!!

No fibreglass will not help to reduce flex.

If the box did flex, the fibreglass would most likely crack.

Definitely use the bracing

No fibreglass will not help to reduce flex.

If the box did flex, the fibreglass would most likely crack.

Definitely use the bracing

It will help, but don't use it as your sole means of bracing. Definitely do a double baffle and add some extra support in there. Fiberglass will never hurt.

EDIT: Adding fiber glass to the corners will help. It won't really do too awful much on the flat surfaces.

Edited March 10, 200916 yr by abxx

For fibreglass to be used to reduce flex, you'd have to be using around 10mm worth minimum and even then it still wouldn't be that effective. Its a neglible addition that shouldn't be advocated as its the wrong way to build a box.

It is also not a cost effective solution, would reduce the box size and change the port calucations.

Its one thing to increase air flow within a box. Its another thing to try a brace it with bad knowledge.

You also have to consider the bonding between the mdf and the fibreglass

Fibreglass and resin needs a rough surface and even holes to ensure the best bond. Just slapping in fibreglass and resin doesn't work.

Edited March 10, 200916 yr by DeeCee

Chea, I will be bracing it then, but first will add more glue in corners for better seal... Also, it will be baffled on top definatly... I have 2 top pieces cut but no port or holes in it yet... Thanks a lot peeps!! All info and opinions are more than welcomed!!