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View Full Version : Dumba$$ needs help, thanx



ngsm13
08-01-2003, 05:48 PM
ok, yet again i am a *******! I am too stupid to figure out winisd...so if sum1 could help me out on 2 box designs. the first one is a daily driver for a 15" jl. the External dimensions: Width=32", Height=17", Deep=14". Need a slot port tuned to 35hz.

This box is very important...it will be my competition box, and if i get the design soon (thanks a tons to you guys) it will be put to use next sunday the 10th at my next competition! External dimensions: Width=30", Height=34", Deep=15". As for the port...the box will be but in the back of an ext. cab dodge dakota...look at my gallery to see the way my current box is. This one will be the same...cept taller and ports will be different. For the port...the front face at the very top of the box, So that it will fire forward and be above the front seat. So, i am new to competition box and i know port area counts...so can have it 3-4"and span the entire length of the box if needed. So, 3"or4"x28.5" if needed...and lengths to tune it to 45hz or 47hz. Thanks so much! i owe ne1 who helps! peace

NG

Trixter
08-02-2003, 10:24 AM
SPL box:
From what I got, if your box is:
28.5 x 13.5 x 32.5 / 1728 = 7.24cu'

I went with a port that is 24.5 w and 3 t:
(4 t and 28.5 w got messed up #'s. You always want to keep a 9:1 ratio to limit distortion.)
So:
A port that is 28.75 L x 3 T x 24.5 W will tune to 39Hz with a peak of 7.8dB @ 46.5Hz.

So:
(16.5 + 12.25) x 3.75 x (24.5 + 1.5) / 1728 = 1.62cu'
(Add 12.25 to the length for port correction factor. Add .75 to the h to compensate for the external height. and 1.5 for the external width.)

I don't know the sub displacement but I left .12 for it (Prob not enough but maybe close?):
5.5 + 1.62 = 7.12.....7.24 - 7.12 = .12

So: 5.5 air space, 1.62 port disp., .12 for sub disp.

Hope this helps, and, as always...have these #'s double checked.

ngsm13
08-02-2003, 06:23 PM
SPL box:
A port that is 28.75 L x 3 T x 24.5 W will tune to 39Hz with a peak of 7.8dB @ 46.5Hz.

So:
(16.5 + 12.25) x 3.75 x (24.5 + 1.5) / 1728 = 1.62cu'
(Add 12.25 to the length for port correction factor. Add .75 to the h to compensate for the external height. and 1.5 for the external width.)

Hope this helps, and, as always...have these #'s double checked.

thanx so much trixter....glad some1 could help. Just need a lil explanation on the port part. Ok, total length needs to be 28.75 and my box is 13.5" deep internally. But...the .75" from the front face can be part of the port, so...looking at the front face i'll make it 3"x24.5' and make *** long as i can to the back of the box leaving 3". So, it would be 3"x24.5"x10.5" (or11.25" including .75" front face mdf) Then, how long do i make it extending down parallel from the rear face? How many inches from the top of the box...thanx for helping me out. Just need to be filled in on the specifics of the port design and the whole correction thing part...measurements. This should be a kick *** comp box. thanx, peace

NG


p.s.- my aim sn is ngsm13....so if ya see me on, IM me.

Trixter
08-03-2003, 12:05 PM
Hopefully this pic can help you out. If not, I can explain some more. For port correction factor go here:http://jlaudio.com/tutorials/ports/index.html

ngsm13
08-03-2003, 03:07 PM
Hopefully this pic can help you out. If not, I can explain some more. For port correction factor go here:http://jlaudio.com/tutorials/ports/index.html

ok, i understand better now...and it will be for 2 12k's (03 e logo) and that pic is showing a cut-away looking at the the side of the box, right? Thanx so much for the help...looking to put up some good numbers with a box that is actually FOR spl instead of my daily box. thanx again man, peace

NG

if u happen to be bored...could u give me port measurements for that first box...then i can pic up the mdf at the same time to build his. thanx

Trixter
08-04-2003, 09:43 AM
Yep. It sounds like you got it all under control.

I suggest printing the pic so you can see how the boards are joined so you get the measurements correct...don't want .75" longer or shorter. The other thing you may want to do is brace port wall that runs parallel with the back of the box. maybe a cross member from the front to it or even something angled from the other port wall.

Trixter
08-04-2003, 10:05 AM
As for the other one....

Go with a vertical port on one side on the box. It should be 15.5" tall, 2" wide, and a total of 23.25" long.

The box is 3.42cu' total. Air space is 2.5cu'. The port is .75cu'. This leaves you with .17cu' for sub displacement.

It will pretty much look the same as the other one if it were laying on it's side...(and if the port was it's entire width.)

Hope this helps...if not...let me know.