help with ported enclosure design for 12" JL W3V3

[PaulC 10+ year member]

I have done some research and designed a ported enclosure for 2 12 in JL W3's to go in my new Toyota 4runner. I have always used sealed boxes but now I finally have room and want to go ported. JL recommends internal net volume of 1.75 cubic feet tuned to 30 hz. I have saw a lot of guys recommend going about 2 cubic feet and 32hz? from what I have came up with or what I think I came up with I have right around 2 cubic feet of volume and tuned it to 32hz. I listen to mainly rap and want to have clean bass with maximum output. I did everything only using one sub and just duplicated it for the second which is what my drawing depicts. I end up with 2 of the exact same chambers next to each other but completely separate. I am looking for advice and suggestions on the build but mainly for someone with experience to double check my calculations. The tags on the dimensions are in reference to JL's ported enclosure design on their site. Thanks in advance for your time and help

SPEAKER BOX PDF.pdf

Click to read more...

 

[bbeljefe]

I come up with 2.14 and tuning of 33 hz. I would add some 1.5-2" corner braces on the wall opposite the port, lose the partition and laminate the baffle with two layers. You could just cut a huge hole in the partition and leave it for bracing and that would accommodate the displacement of the braces.

Other than those minor changes, looks good!

 

[PaulC 10+ year member]

thanks for the quick reply!! im pretty happy my first crack at this came out that close haha. what are the affects of adjusting the net volume and port tuning? am I close enough on those numbers to just leave it? and what are the purpose of the corner braces? the box will be made out of 3/4 mdf so it should be plenty sturdy. your recommending eliminating the middle wall and then doubling the thickness of the baffle(which I believe is the front wall where the speakers mount). whats the reasoning for doubling up the front/baffle?

 

[PaulC 10+ year member]

tweaked the design a bit going with bbeljefe 's recommendations. I haven't added the corner bracing or doubled up the baffle yet as I was hoping for more input to get an understanding on the need for those.

my calculations

4.894 cubic feet of volume

port is 25 x 2 so for 32hz I come up with a length of 21. 25 x 2 x 21 = 1050 cu in or .608 cu ft for port displacement

2 subs at .071 = .142 for sub displacement

4.894 - .608 - .142 = 4.144 or 2.072 cu ft per sub.

when calculating for port displacement I haven't found anything on including the material thickness, so the way I look at it the material used to create the port isn't taken into account for overall net volume?

please see attachment of a dimensional drawing of the box.

SPEAKER BOX 2ND DESIGN PDF.pdf

 

[PaulC 10+ year member]

come on guys I know some expert box builder out there wants to help me??? my head is spinning with this. I used the 12 volt calculators up to this point to figure out all that I have and when I double check those calcs on re audio's box calculator I get different results. I even contacted JL tech support and am getting different stuff from them? I want to stick more towards my first design and the only responder made me feel pretty confident with it but he had some suggestions that im not clear on and id like someone else to chime in?? PLEASE HELP!!!

 

[ancorp 10+ year member]

Non shared walls of the port should be accounted for displacement. So if the port has one wall that is not shared, you should add the .75" thickness to the width of your port. In your case 2.75" width instead of 2.0.

In fact, 2 x 25" port will most likely suffer port noise because the ratio of width to height is so great. You'd be much better off with a port that's less wide and more tall, like 4 x 12.5"

 

[PaulC 10+ year member]

ok guys this is my final design pieces will be cut today lets hope everything works out. from what ive come up with I should have just over 2 cubes of volume after sub, port, and brace displacement and hoping to have it tuned to between 32 and 34 hz.

SPEAKER BOX PDF MAIN.pdf

 

[PaulC 10+ year member]

my enclosure came out excellent! thanks to the few that had suggestions they helped out. heres a link to a new thread I made showing the install.http://www.caraudio.com/forums/car-audio-build-logs-cars-trucks-suvs/585303-2013-4runner-2-12-jl-w3v3s-planet-audio-amp.html#post8446964