Need help with a box design =]

[noct3rn4l 0]

Hey fellas.. can someone help me with dimensions for putting together a sealed enclosure for a 15" Avalanche into a 2003 mustang?

KU40 PM'd me dimensions on carstereo but that forums down.. again and i cant access my inbox =/

Im looking to put together a sealed enclosure at first.

I'd like to try 2 different dimensions...

1) that could slide in through the back seat...

therefore the max dimensions would be. 36"w x 27" d x 11" h .. upfiring and id like to try 2.2cubes after displacement

2) Id like to try to put together a 2 piece sealed box.. with a max height of 14.5" ... so this one would be like putting the "bottom half" of the box in, and then putting the top half in and then gluing the halves together in the trunk and then putting the sub in.. so max dimensions would be 36"w x 27" d x 14.5" h

Ill be powering with a HiFonics BX1000D @ 1 Ohm (1000wrms)

also, my first box for my brahma was in .5" plywood.. can i use .5" plywood again? or should i use .75" ply or mdf?

thanks

-James

[ford302redneck 15]

I wouldn't use normal plywood. PERIOD.

I'd at least do 3/4in MDF, or Birch if money permits.

1/2 is just to weak honestly.

[noct3rn4l 0]

I wouldn't use normal plywood. PERIOD.

I'd at least do 3/4in MDF, or Birch if money permits.

1/2 is just to weak honestly.

alright.. ill give mdf a try!

got any ideas on dimensions?

[BKOLFO4 29]

Sealed box is pretty easy.

Shoot for 2.5 ft^3 gross volume. That is 2.5 * 1728 = 4320 in^3.

As long as the INTERNAL W x L x D measurements multiplied together come out around 4320 you have your box design.

You have way more than enough room without building a 2 piece box. 32" wide x 16.5" deep x 11" high would work. you could also double the top layer (top of box 1.5" thick) and go 34.5" wide x 16.5" deep x 11" high.

You could also make it more of a square - 24" wide x 24" deep x 11" high with a double top baffle.

There are a lot of choices - just do what you like best.

[noct3rn4l 0]

32" wide x 16.5" deep x 11" high sounds good =]

for the bottom part, when you glue the sides to the bottom do you normally put them on the side and then screw them together? or do you do it so the sides sit "on-top" of the bottom board?

also, is liquid nails good enough? last time i used a bunch of screws and id like to avoid that this time.

do i have enough room to go ported if sealed doesnt do it for me?

Edited May 6, 2008 by nOct3rn4l

[shizzzon 461]

people do things different but this is what i do-

The bottom and the top ARE, to me, The Bases of the box.

The side walls sit on top of the bottom, so does the back wall and so does the baffle even if double baffled. The top is sat on top of everything, meaning the top is the same cutout dimension as the bottom piece.

I've built a box out of just LN before, never had problems. Just make sure everything's sealed inside like always and you are fine.

[noct3rn4l 0]

BKO, is there any reason for the double thick top, does it serve any purpose other then a "just-in-case" type of purpose?

you guys ever use polyfill?

[JimJ 11]

Use proper wood glue...I prefer Titebond products but there are others that work well.

[BKOLFO4 29]

Since the subs are mounted in the top, the double baffle just makes it stiffer so it will not vibrate with the sub.

Do as Jim said and use titebond instead of liquid nails. You can go back after the box is built and use Liquid nails on the inside to seal it up and add strength.

I nail my boxes together with an 18 ga nail gun. If the box is for high SPL, I go back and predrill holes and wood screw every 6-8". For most boxes, the wood will hold everything together. The only time I have run into a problem is when there is enough pressure in the box that it actually splits the MDF (the glue joints stays).

edit - you will not need polyfill if the box has enough airspace.

Brian

Edited May 6, 2008 by BKOLFO4

[noct3rn4l 0]

Since the subs are mounted in the top, the double baffle just makes it stiffer so it will not vibrate with the sub.

Do as Jim said and use titebond instead of liquid nails. You can go back after the box is built and use Liquid nails on the inside to seal it up and add strength.

I nail my boxes together with an 18 ga nail gun. If the box is for high SPL, I go back and predrill holes and wood screw every 6-8". For most boxes, the wood will hold everything together. The only time I have run into a problem is when there is enough pressure in the box that it actually splits the MDF (the glue joints stays).

edit - you will not need polyfill if the box has enough airspace.

Brian

I picked up the MDF today and the sealed enclosure is in progress!

If i decide that sealed isn't quite working for me and i want to go ported again, how would i calculate tuning freq/port width/length and what would be a good frequency for the Avalanche?

I'd also like to build a slot ported enclosure as well and then go with which ever sounds best. Like the sealed, the ported enclosure would be upfiring, but id like the port to fire to the rear (no round ports either).

[BKOLFO4 29]

I design mine the "long way", but it always works, and it is just how I like to do it.

Determine NET box size required.

Determine max dimensions, which will be used to determine the port height and width (using 12-16 sqin per NET ft^3 of box).

Calculate port length here:

http://www.carstereo.com/help/Articles.cfm?id=31

Add up port displacement (include the port wall), driver displacement, and net required volume.

Determine W x H x D required for the calculated gross volume (If not enough room for gross volume - rethink the net volume required and/or smaller port. If it is still too low, consider a smaller/different sub). Make sure the port and sub will fit when determining the true W x H x D.

Calculate true net volume with the port actually placed in the box. Make slight adjustments to the box size and port length as required for target design.

Finished

After you have done a few, it is pretty darn easy. I can put together a standard slot port box for daily driving within a few minutes.

Brian

Edited May 7, 2008 by BKOLFO4