View Full Version : Car's Standing Wave And Box Questions

06-12-2007, 09:25 PM
Ok here we go. I am currently running 2 JL Audio 13W3V3-2and 425 clean watts per. I have a 2001 Dodge Durango so if i want to keep the 3rd seat i am very limited in my box size. I built a slot ported box to the max i can and it sounds ok but i am losing a little. Currently it's hitting at a max 128.2 db but i have lost some low end notes an responce:verymad: . The box is tuned to 27 hrz and JL recomends 25 hrz. I have come to realize I must lose my back seat and build the box to the 5 qubic feet and not the 4 that it is now. My question is I know the is a way to figure the standing wave in hrz of your car, and you can tune the box to it. The problem is I do not remimber how to calculate this other than measuring from the back to the from glass. I am also looking for any suggestions or help.

06-13-2007, 12:52 AM
Are you only looking for a one note box to get loud? Going slightly bigger and tuning lower isn't going to get you any louder, in fact you will probably lose a bit of output in the low 30's region. No reason to tune to 25hz in a car anyway. If you're looking for output I'd be more inclined to tune in the 30-35hz range.

06-13-2007, 12:55 AM
yeah tune to 32htz and see what kinda size you can work with

06-13-2007, 08:06 AM
The 5 qubic feet and 25 hrz is what JL says to build it to. I am not really looking fo just ultra low. When i first got these they were in a sealed box. With the sealed box it was not as loud overall and dropped lower. I switched to the ported in hopes of gaining overall. I have read articals that if you tune your box to the standing wave of your car you will get better sound. But i do not know how to figure that out.

06-13-2007, 09:08 AM
I agree with the respnce above... tune the box to ~ 32Hz @ about 3.5 cu/ft per sub will poerform very well.

5 cu/ft @ 25 Hz is more of a design for a home theater application.

06-13-2007, 10:06 AM
The standing wave in you car is going to vary with the positioning of the sub and box. It is also going to be much higher than 25hz. Probably more in the neighborhood of the mid 40s. You'll lose all the lows by going that high.

06-13-2007, 01:08 PM
are we saying "standing wave" instead of "resonant frequency"?

when you tune to the res. freq. your not going to increase sound quality. this is done to increase spl. a box tuned as high as the res. freq. will not sound good for normal listening.

jl may say 25hz....whatever...that would be good in a house. go for the low 30's and keep you beack seat too.

06-13-2007, 09:19 PM
Your syaing tuner it to 30hrz and 3.5 cubic feet per? I think that the box is about 4 qubic feet. I think if i cut 4 inches off the port it will tune the box to 32 hrz.

06-13-2007, 09:32 PM
Well that's a little small for your subs. How much port area do you have?

06-13-2007, 09:37 PM
What song are you playing in video 2?

06-13-2007, 09:55 PM
Click the "more" button in the description.

06-13-2007, 10:21 PM
Ok so here is what i have come up with and my question. I am not so bright when it comes to this

2 JL Audio 13W3V3-2
425 watts per

Box 7 qubic feet ( 44 X 18.75 X 18 )
3 inch port 12 inches long
tuned to 32 hrz

Question 1: Does this look right?
Question2: I understand tuning the box to a higher hrz but why more air space than the mfg suggests? What is the benifit?

06-13-2007, 10:53 PM
Thank you for your help. I am trying to learn

06-14-2007, 07:11 AM
That looks terrible actually. List your max dimensions and I will draw something up for you later.

06-14-2007, 08:07 AM
46 wide
20 tall
30 deep

06-14-2007, 04:28 PM
Hey did you forget about me?

06-14-2007, 07:04 PM
No, I was just at work from 8:00-6:00 so I couldn't draw anything up.

Here is what I came up with:

If I wasn't so tired, I would have actually done a little different design but that one should work for you. It's 7.5 cubic feet tuned to 32hz.

06-14-2007, 08:50 PM
so what do i gain from the same hrz but larger air space?

06-14-2007, 09:04 PM
The low end you said you didn't have. My sub in 2.2 cubes tuned to 32hz drops lower than a 1.5 cubic feet enclosure tuned to 30hz that I have. Size does matter in speaker enclosures.