Well i've decided to build my own ported box after hearing it in the sealed box i want louder so i'm porting the dual 10 in. type-r's.

-first of all i need plans and think i'm going to use that gnomeaudio guy just for the plans unless someone else wants to do them for me for free :D
-i'm going to tune it to 30Hz and the max dimensions are: W:30" L:24" H:15"
-i'm going to buy a large sheet of high grade MDF from a local sound shop (Sound Perfections), i know i'll need that Liquid Nails stuff from home depot but i'm not sure what exact nails i should use for this stuff (i know also that i have to predrill each hole).
-then after i'm done building the box i'm letting the guy at Sound Perfections carpet it for me since the stuff he uses almost exactly matches my trunk carpet.

What exact nails should i use for the box?
What kind of cutting blade should i use for the wood so i dont splinter it?
What kind of caulk should i use for the inside of the box?

Any help or tips or advice any box builders can give me would be great since this is my first box.

Ps. how many cubic feet should i go with?

I cant help u on the box plans but i know GnomeAudio is a good way to go, and if you sign up for caraudio.com ull get a discount for being a member. A good place to also ask any questions about this kind of stuff.
For supplies u put the wood together using regular wood glue, for screws i bought a box of 1 5/8" screws theyr call grip tight or something, cheap and did what theyr supose to do, hold the box together till the wood glue dries. For sealing liquid nails works good or any other caulkant like silicone. My advice to u is get a helping hand when making the box, it makes it much easier so they can hold the peices together while u predrill the holes.

One question, is the coupe trunk smaller in width than the sedan trunk? because i was able to get 32" wide in my trunk, check to make sure because 2" will make a good difference.

yeah i'm pretty sure i can get another 2 inches in i was just being on the safe side.

What kind of cutting blade should i use for the wood so i dont splinter it? .. shouldn't matter, remember MDF is particles, it can't' splinter... on that note though, cut as much as you can with a tablesaw (if you have it) for a nice straight edge. A jigsaw, or better yet, rotozip can build a whole box, but just take your time.

What kind of caulk should i use for the inside of the box? .. I find painters quick dry to work well, but MAKE sure you still give it AT LEAST a day or two to cure, or else the fumes will eat your subs.


Ps. how many cubic feet should i go with? .. the specs sheet should say. Good luck!

Here are my few tips.

Use a table saw if you know how to use one. This will produce a much truer cut than a circular saw or a hand-held jig saw. Just be sure you know how to use this safely, including using a "push stick" instead of your hands when pushing the stock close to the blade. Also setting up the guides properly. Do test cuts on spare material so you can see how much the blade wobbles side to side before you start cutting into your good stock.

Use a fine furniture blade. These blades will have very fine teeth (and a lot of them) close together. You don't need tungsten carbide or titanium nitride blades unless you are cutting something with a Rockwell 87 hardness rating.

Last, put a piece of duct tape over your cut line. This will give you a cleaner cut (even though technically MDF can't splinter). This will help give you a square edge.

I like to use screws and wood glue instead of nails or liquid nails. If you cut everything precisely, everything should fit together exactly without any need for fillers. Also will result in an airtight enclosure. I use the screws to hold everything together permanently. I don't take them out when the glue dries. Measure everything more times than you need, once you make the cut there's nothing you can do about a bad cut. Also it's a good idea to let someone else carpet it for you since too many car audio people have told me it takes a lot of practice to get it right.

Are you SURE the base of your enclosure is supposed to be 30 x 24??? That seems a bit large for an E36 trunk. You may not even be able to fit it in. Try making a mock up out of cardboard (go to your local supermarket's trashbin)before you spend the money on MDF. This will tell you how big you can go with your trunk.

i was just saying that those are my MAX dimensions, i knew they prob wouldn't fit....this is the box i'm going with

L:18"
H:14"
W:30"
Port: 12.5"H, 2"W
.....and i plan on making a port plug so i can run different freq. when i want.

if anyone knows how to construct a port plug and has any info they want to give me about building one that would be great.

L 18"
H 14"
W 30"
Port 12.5"W X (28.2 devided by 12.5)L

Gross box volume = 2.9 Ft3
Net box volume = 2.5 Ft3
Port Length = 23.2 Inches
Port Area = 28.2 Inches2
Port Volume = 0.38 Ft3
Tuning Frequency = 33hz
0.5 Ft3 taken into account for subs displacement and braces

Go to home depot or lowes to get the wood cut
Remember to predrill and countersink, then a little wood glue and some screwing and you're done
too much talking does nothing, Just do it
ah.. that wine

so how big should i make the port for 30Hz in that size box? i dont exactly follow the 12.5"W...hmmmm......yeah about that wine! just messin'

30hz.=16.88"
32hz.=14.21"

are those numbers right?
and is that box area the right size?

if you make your box
L 18"
H 14"
W 30"
your should make your port 12.5" X 2.25" (thats your port area, the opening of the port) and it should be 23.2 inches long
that should tune you to 33hz.
Taking the wood, port and subs into account, you got 2.5 gross cubic feet left for your subs to work. (the airspace you get from your LxWxD is NOT the airspace you have)
if you want to tune lower, then the port would be quite a bit longer which i dont reccomend since its going to take up more space in the box leaving the subs less air to work with causing more trouble .

16.8" doesnt tune you to 30hz in that kind of box... i dont even have to check it, i built enough boxes so far to say that i'm 2k% positive

clear enough?

ok i even made you a little drawing in paint, i suck at paint but it doesnt get easier than that
anyone care to host?

could you email it to me? if so that would be great!

um... where

twinkieC405@hotmail.com

or

jjpriceless@earthlink.net

sent

awesome thanks!


*i'll be going to home depot tomorrow to pick up all the wood, nails, and glue/liquid nails....i cant wait to start.

you mean wood, screws and wood glue (the white one)
oh, a couple of drill bits and a countersink thingie

what exact kind of screws should I use?

um... up to 2 inches long and... well dunno, 4 or 5mm thick
DONT forget to predrill before you screw and DONT forget to countersink, that and the wood glue is what keep the box togeather. if you dont predrill the wood WILL split (keep in mind, you can only notice the wood spliting on the edge of the board so be carefull) and if you dont countersink and try to put the screw all the way in you will also split the wood.

tell the guy at home depot to give you 2 or 3 sizes of drill bits with the right countersink add ons (tell him you're predrilling and also tell him what kind of screws you're using).

go home and try the bits on a piece of wood, predrill and screw all the way in, then unscrew and pull as hard as you can. the bit that doesnt split the wood and that comes out the hardest way (or doesnt get out for that matter)... well use it

dont forget to share the result
good luck

i plan on documenting the whole process and sharing all my likes/dislikes of the new box, thanks a million again.

I took all my measurments and drew myself up a good sketch (front, front angle, and top).....
http://www.we-todd-did-racing.com/wetoddimage.wtdr/wNDYwOTQ5NnM0MTNkZmQzMXk1NDE%3D.jpg

*bump* for no one looking and appreciating my wonderful and time consuming work. :mad:

Pretty nice design bud! I am thinking about building a ported box to see how it would sound with my solobaric and I was wondering how a port actually functions and how it is constructed. Is a ported box merely a 'slit' of an opening on one of the sides of the box? Does the port have to be in a specific location in relation to subwoofer placement? Also, does anyone know of any good websites that explains in depth the concept of ported boxes? Thanks

Do you know what Bass Box Pro 6 is?
It lets you input all your info...driver stats, dimensions, volume a/d, frequency, etc. Then it makes a box for you and shows you each piece that is required to make the box, along with said dimensions of each structural element.

IM me on qwertyuiopp1 and I can file send it to you.

the less input you give a program the less the chances it has to screw things up.
port length can be calculated with just the internal airspace of the enclosure ,the port area and your desired tuning frequency... the rest is 1st grade maths.
that formula all these programs use can be found in jl's website

too bad that's the formula the prog. uses.
I have a copy of LEAP 5.0...you're telling me that that program will make an inferior box to a hand-calculated box?

You're out of your mind...

i recently built a crx box for a solo x 18running off 5000W... it was 10 cubes after displacement with 175 sq inches of port tuned @35... well, all the programs i've used gave me different port length that the one i've used, but the one i've used actually tuned the box right at 35hz, we played sin waves from 25-40hz and the sub was moving the least @35 which means it was tuned right there
i'm not saying i have a phd in box building ,i was a bit lucky that i actually got 35 to begin with because no program can be more accurate than trial and error, and however you calculate and tune your box, it doesnt always come out the way you want it. i learned that the hard way
now that i think about it... did you ever built a ported box according to those programs? and did you ever test that you were actually tuned where you were suppsosed to? or did it just sound good...

I have built numerous boxes.

Paragraphs are your friend, btw.

Gnome Audio uses LEAP 5.0 extensively...

I would also suggest slanting one wall of the box.

the wall that faces the seats is always my choice, angled to the same angle of the seats, so it slides up there close. this helps to break up the sound waves a little inside.

I have one 15"sub tuned to 15-20hz.

I assume it is tuned to this, because it plays the loudest at this frequency range at the same volume on the system. I have never heard, nor tried looking to see how much the speaker moves at this frequency. To do so you would have to be IN the trunk with it closed :help .

You have to remember car audio is not just the box itself. It uses the trunk as part of the inclosure. this is why rear firing inclosures in a trunk sound better, and hit lower.

Even filling the rear trunk hollow areas with self expanding spray in insulating foam makes a diffrence.

(I have no port in my current setup though)

I have built numerous boxes.

Paragraphs are your friend, btw.

Gnome Audio uses LEAP 5.0 extensively...

if you did and actually tested them then you'd know what i'm talking about... :stickoutt

if you did and actually tested them then you'd know what i'm talking about... :stickoutt

Um, no. Not really :rolleyes:

If a prog. uses the same formulas, the boxes come out being the same.
Additionally, Gnome Audio, which makes ridiculous boxes uses LEAP 5.0 extensively. It must work pretty damn well then.

so souroull do you think that port lenght will give me somewhere around 30Hz? if not how can i test it and change it to lower if need be?

so souroull do you think that port lenght will give me somewhere around 30Hz? if not how can i test it and change it to lower if need be?

the initial tuning freq of your box was 33hz but i didnt use end correction, and the fact that its an L shaped port will actually tune the box quite lower than that (hint: programs can't calculate this, only real life testing of the specific box)

to test it you record a cd with single frequencies, say from 25 to 40, play it on moderate volume, and see at what frequency the sub moves the least, that should be your tuning freq. (keep in mind, it wont sound the loudest)

if you like it leave it as is, if you dont, test it and extend or shorten your port accordingly

since i dont have a ssf shouldn't i be a bit cautious about playing really low freq. or is that just bass testing songs?

you'll be fine
oh, another thing, turn the crossover of the jbl all the way down and then set it in horizontal position ( from / to - and just a tad more)
your gains will prolly need to be turned up too

am i better off letting a shop do that or can it be done by someone who KINDA knows what their doing?

am i better off letting a shop do that or can it be done by someone who KINDA knows what their doing?
to tune an amp? tuning is simple and its the fun stuff. dont let a shop do it. And what deck are u using? i wouldnt use the Xover on the JBL it kinda sucks...use the LPF on the deck if u have one.

i dont have a deck cause i'm poor :(

so did you build that box already?

i picked up the materials today, and going to start when i get back from camping....dont worry i'll have a whole bunch of pics when i'm done.

UPDATE: box almost complete have to cut out the circles for the subs, i did them originally but i cut the wrong size, but looks like i wont be carpeting it yet cause the local audio shop burnt down the other week....i'm excited to get it done. i'll post pics of finished product in a few days.