View Full Version : Desperate for box design help!!

09-07-2006, 04:48 PM
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?

09-07-2006, 05:47 PM
what subs is it for?

i came up with this:


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).

09-07-2006, 06:07 PM
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...

09-07-2006, 06:11 PM
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).

09-07-2006, 06:47 PM
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.... :crap: 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?

09-07-2006, 06:48 PM
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?

09-07-2006, 06:53 PM
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!

09-07-2006, 07:15 PM
with a 4" wide slot port (10.5" tall), i think you can get about 4ft^3 net with those dimensions.

09-07-2006, 08:20 PM
gay.. my car wasnt meant for spl :crap:

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?

09-07-2006, 08:24 PM
The port would be about 20 inches long... This box now seems do-able.

09-07-2006, 11:31 PM
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

09-08-2006, 04:56 PM
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...

09-08-2006, 05:06 PM
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


09-08-2006, 05:58 PM
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?

09-08-2006, 06:16 PM
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...

09-09-2006, 04:02 PM
91 fastback... trippy, I have the same

follow the dimensions up there and you should be safe

09-09-2006, 07:39 PM
Are you wanting to still use you rearview mirror(not sure if your other box is tall enough)?

Mabe Wall it off:up2somet:

09-09-2006, 10:20 PM
Wall + hatch at like a 35 degree angle = bad. Plus its round as hell in there.

09-09-2006, 10:36 PM
wow this is a tough box build u have here

09-10-2006, 10:41 AM
Yeah. I find that im not like most people on the forums here, who try something easy the first time they do it. Like building a box. They might build a sealed box that fits well within their dimensions of allotted space.. whereas im building a large ported box that pushes the limits of what i can fit, in a very ahrd to work with space. This is also true about the interior of my car. I re-covered the insets of my door panels. Ive never worked with any kind of fabric in my life, no upholstery, no sewing, nothing. I dove into it head first, using logical processes that i thought fit what was supposed to work. And this is how the driver's door came out (camera phone, and need to get a pic of pass side too). I also did the glove box.


And I wont stop till it works. No matter how much mdf i use, no matter how many times i **** up and cut my self trying to make it work.... It WILL work...

09-10-2006, 10:45 AM
nice interior work? id get someone to build the box for you.