Desperate for box design help!!

[phantom240 5,000+ posts]

Okay, ive run into a HUGE problem designing my box. My hatch area is UBER shallow... which means my box will have to be under 14 inches, and if i make it long itll have to be 12 inches for the hatch to shut. gay. So my box is gonna be 12 inches. Gay. The box dimensions are gonna be 12"(tall)x30"(wide)x20"(long) That means that instead of having the drivers and the port facing foreward or the drivers facing foreward at all is not an option so ill have to make the drivers face up. Thats not a problem. The problem comes with designing the port. I was shooting for a slot port facing foreward ont he bottom side of the box. The calculators i was using warned against the height:width ratio as the port would have been like 28.5"x3 or 4"... and the port would be like 40 some odd inches long... which i dont have room for unless i build a snail shell box... which isnt TOTALLY out of the question just yet, but the driver depth would be an issue. SO I thought i could build a box with the drivers facing up and a slot vent on the front of the box with the slot vertical on one side of the box... measuring like 4"x10.5" tall. That seemed to work.. except when i went to draw it up on graph paper.. the box isnt wide enough for that. So im thinking about round ports but i know next to nothing about tuning with round ports... can i get some help with these ports?

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[xluben 10+ year member]

what subs is it for?

i came up with this:

http://www.subwoofertools.com/forum/ported-box.asp?Ew=30&Eh=12&Dia=6&Xmax=9&Vd=.1&NumW=2&Vb=2.3&Fb=32&Qts=&Vas=&Fs=&CE=0

but it's WAAYY too small and the port is probably not wide enough either.

i just don't think you have enough room for two subs ported. and round port won't help, either. i think they'd actually be worse. to get the necessary port area and length, you'd definitely need to do 90 degree turns (which is much easier with a slot port).

 

[phantom240 5,000+ posts]

well with one of the online port calculators, i came up with 2 4" ports approx. 13.75 inches long, which fits in the box and such... and thats tuning to 32hz in a 4.1 cube box.

BTW its for 2 memphis M-Class 12s, the 2005 black chrome models...

 

[xluben 10+ year member]

well, considering that box (if made out of 3/4" mdf) would only be 3.2ft^3 before displacement, i don't think that's right.

using those outer dimensions and two 4" ports, 13.75" long, i get about 2.8ft^3 tuned to 39Hz, BUT if you're using two 12's you should really have four 4" ports and probably closer to 4ft^3 total (after displacement).

 

[phantom240 5,000+ posts]

hmm... good point. Well im tired of having to do more than double my subs' RMS power to each of em to make my car shake.. im so addicted to bass.... //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif Would this box be suitable for a single 12" RE SE? ill have to modify my amp to run it... but if it would be louder than my 2 memphis subs were Sealed?

 

[phantom240 5,000+ posts]

Well i COULD make a bigger better box... but it would render my backseat useless... ever seen a 240sx with a 6cube box in it?

 

[phantom240 5,000+ posts]

WEll i went outside and measured again and i think i can fit a box 36"x 24"x 12"...

That leaves me with 6 cubes TOTAL, and im not sure how to figure net volume. That WOULD leave my backseat intact too. SO i might be able to do a box like off of RE's website!

 

[xluben 10+ year member]

with a 4" wide slot port (10.5" tall), i think you can get about 4ft^3 net with those dimensions.

 

[phantom240 5,000+ posts]

gay.. my car wasnt meant for spl //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif

Thats before port and driver displacemnt right? gay. BUT that might be enough to increase my boomage. Would that make a decent box for those subs?

 

[phantom240 5,000+ posts]

The port would be about 20 inches long... This box now seems do-able.

 

[xluben 10+ year member]

that was after displacement (hence the term 'net').

you never did tell me what subs it was for.

if it's for two 12's i think 4ft^3 net with a 4" wide port tuned to the low 30's will sound quite good. it's probably about what is recommended for most subs.

i think the port is going to have to be closer to 30" though

 

[phantom240 5,000+ posts]

Its for 2 2005 model Memphis M-Class DVC 12's... 15-MC124D

Why would the port have to be 30" instead of 20"? Im not really big on port calculations...

 

[dru 10+ year member]

do you drive a 240sx fastback by any chance? I drive the same car btw and a box for it is an adventure in itself

heres a pic I used/made

 

[reneeb7363 10+ year member]

This thread is GAY!!! How many times can you use the word GAY? Do you even know what GAY means... isnt that from like the 80's or something! what are you a 13 yrs old?... grow up! Go to school...

On to the problem...... why not fiberglass the base of the box, maximizing avail airspace, then build up chambers/port with MDF?

 

[phantom240 5,000+ posts]

hmm... .cuz fiberglass is EXPENSIVE, time consuming... and making a ported fiberglass box is GAY. and GTFO of my thread... ur GAY. And yes, i do drive a 91 fastback. So my box plan wont fit in my car? i want to go with as simple a shape I can get awaywith, as this is my first box...