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View Full Version : Need box design please! (2) JBL W12gti MkII



mrjoeyjiffy
02-18-2008, 09:48 PM
I was hoping someone could make me a sealed box design for 2 JBL W12Gti MkII subwoofers, they are going in the back of my 2001 tahoe (3rd row removed) and will probably be getting around 600-800 watt rms a piece(depending on which amp i end up going with) I want something reasonably loud, but tight hence the reason im going sealed and not ported. Here is a data page with all the T/S info, and as far as size limitations, i think about 40 inches wide and no more than 16-18 inches tall depth isnt really a concern but if i had to put a cap on it i guess i would say about 30 inches. Thanks in advance! http://infinityreinforcing.com/W12GTi_rev_f-1.jpg

mrjoeyjiffy
02-19-2008, 10:01 AM
Ok well I went out on my own and did some research :eek: and I believe I've came up with a pretty good box, comments suggestions are greatly appreciated!

Width 30.5"
Height 17"
Depth 29 3/4"

Vent height 15.5"
Vent Width 4 1/2"
Vent Length 21 1/2"


http://infinityreinforcing.com/portedbox2-19-08.jpg


The idea was to make the location of the port provide "bracing" for the box so that no additional bracing would be necessary, is this a good idea?

Atimm693
02-19-2008, 04:27 PM
I got approx 7 cubes after port tuned at ~30 htz. Is this what you wanted it to be?

The port will add some bracing.

mrjoeyjiffy
02-20-2008, 08:15 AM
yes i might make the box a dat bit shorter in depth, but its pretty close to what i want, should this box work well without any additional bracing?

Atimm693
02-20-2008, 08:16 AM
With that box bracing shouldnt be needed.

mrjoeyjiffy
02-20-2008, 04:07 PM
will that be too much airspace? i want it tuned around 30 hz, the manufacturer says 2.25 cubic feet per sub in a ported box, but im thinking theyre saying the low end because most people are confined for space, would 7 cubic feet(closer to 6 cubic feet after port/driver displacement) be too much?

Atimm693
02-20-2008, 05:40 PM
will that be too much airspace? i want it tuned around 30 hz, the manufacturer says 2.25 cubic feet per sub in a ported box, but im thinking theyre saying the low end because most people are confined for space, would 7 cubic feet(closer to 6 cubic feet after port/driver displacement) be too much?

3 cubes net each, should work, and if you do make it too big you can add stuff to the inside of the box to make it smaller.

BuckyBoy
02-20-2008, 05:40 PM
will that be too much airspace? i want it tuned around 30 hz, the manufacturer says 2.25 cubic feet per sub in a ported box, but im thinking theyre saying the low end because most people are confined for space, would 7 cubic feet(closer to 6 cubic feet after port/driver displacement) be too much?
If they recommend 2.25, then I wouldn't make it any bigger than 5-6ft^3 net.

mrjoeyjiffy
02-20-2008, 05:42 PM
yeah they actually reccomend 2.25 including sub and port displacement, back to the drawing board...

mrjoeyjiffy
02-20-2008, 06:45 PM
Alright I think I have this down, JBL calls for 2.25 cubic feet per sub gross, which would be 4.5 cubic feet for 2 subs, this box should have a gross volume of 4.7 cubic feet.

Box:
Width 28"
Height 14"
Depth 26"

Vent:
Height 12.5"
Width 3"
Length 18.4"

Should be tuned to right at about 30 hz, I think this should work well, any suggestions/comments/criticisms are welcome.

http://infinityreinforcing.com/ported2.jpg

THUMPPER
02-21-2008, 06:12 PM
stick with the recomended internal volume (2.25cf3) per sub plus
sub and port displacement and give it lots of port area

mrjoeyjiffy
02-22-2008, 06:32 PM
will the 3/4 inch of space around the smallest parts around the edge of the subwoofer be enough to support it?

mrjoeyjiffy
02-24-2008, 08:14 PM
for anyone who cares im nearly done with the box, just a few more things to do, here are some photos. Note to anyone who lets the guy at lowe's cut your mdf watch them, this lazy piece of **** would cut through it then come back through it with THE SAW STILL RUNNING, 2 belts on a belt sander and a half an hour later and i have them close enough to fit together but definitely not perfect. Anywho here are some pics http://infinityreinforcing.com/almostdonebox1.jpg
http://infinityreinforcing.com/almostdonebox2.jpg

yuske
02-26-2008, 08:35 PM
That looks good post the pics when all done i want to see.
By any chance how should i do a box for 3 w12gti subs at 2.25 tuned for 30hz i am trying to figure out where do i put the port since its 3 subs?

mrjoeyjiffy
03-08-2008, 05:34 PM
ttt i have another question.


I've since decided on building a new box with that same design just a bit taller and a bit wider so i can achieve nearly perfect (at least to the manufacturer's specs) airspace, port, etc. And also because everytime i look at it i get pissed at ol ******* will at my local lowe's for cutting it so terribly.

ANYWAYS, my question is without a double baffle and these subs being as heavy as they are(nearly 40 lbs from what i understand) should i build some sort of support for the back of the woofer? thanks in advance.

djvi0lent
03-08-2008, 11:59 PM
Double baffle ftw!

MTXman
03-09-2008, 08:32 AM
Looks good man, your cuts seem to be right on point.


That is going to sound awesome and be pretty loud.