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View Full Version : Box Construction help needed A.S.A.P

KARLEON
06-21-2004, 11:10 PM
Ok, im about to start building me a new box for this competiton friday. I have a 96 Honda accord, and my trunk isnt the biggest trunk in the world. I wanted to go with 3.5 cubic feet per sub, but my trunk will not allow me to do that. So im going to do my best to get 3 cubic feet out of it. (i might fall short of that too) But i know how some people use polyfill in sealed enclosures to make it seem as if the woofer is in a bigger box. Well, could i do the same with a vented enclosure? Like find some way, so it wont blow out of my vent. Maybe some sort of a net. Therefore air can still flow, but i dont have to worry about poly fill coming out of my vent. Will that take away from any spl? (i dont see why it would, but its a possibility)

Secondly, I have a box right now thats 2 cubic feet each tuned to 29hz, which Trixter helped me with. I know how to calculate airspace and know how to take away the sub and vent displacement. But i dont know how to calculate the tuning frequency of my vent. Like how long or short does it have to be to give me my 46hz tuning. I tried the equation but Math isnt one of my good subjects. Only way i passed that class was because i was on the football and a star defensive player. (only if caraudio was easy as football) Anywayz, i really need help tuning my box to 46hz.

Right now, the dimensions im thinking is 17H x 21D x 32W.... I might be able to find another inch or two in my width, but as of now. those are my dimensions. So someone please help me out with my tuning. Thanks

Oh and far as the look of the enclosure, i wouldnt mind going with the same look i have now. With the vent going down the middle of the subs. my pic of my current set up is in the photogallery. I'll bump it to the front page so its easier to find.

InhumanAcura
06-22-2004, 12:26 AM
www.rockfordfosgate.com
www.audiobahn.com

Use the RF site for volume and the AB site for calculating port legnth. When figuring out the port legnth all you need is the amount of port area and volume and it gives you the legnth. Both sites go to either Tech or Calculators, one of the 2. I actually have a good box design that might work for your dimensions. Ill measue it when I get home from work and post the spec's tomorrow.

InhumanAcura
06-22-2004, 12:35 AM
Well, with 60sq" of port (which is what I use) your looking at a 4.93" long port tuning the 5.335^3 (17x21x32) to 46hz. Im not sure of the disp. of the mags so you might want to double check, but even with that amount of port area it wont be but a fraction of an inch.

KARLEON
06-22-2004, 12:42 AM
i just went back outside and looked at my trunk again, i can fit another inch on my width. So instead of 32 i can get 33. How much of a difference would that make with my port length?

KARLEON
06-22-2004, 01:34 AM
Hey thanks for that audiobahn web site. It helped me out alot. Well this is what i came up with...

17H x 21D x 33W I used audiobahns website and it gave me 5.51cubic feet after displacement. and im using a box with a vent on each side with the subs in the middle. The width of the opening is 1.5inches each and it goes back 6inches. This should tune my box to 46hz. If someone has the time, please go over it just to make sure its right.

Since i have a rather small trunk, it was no way possible for me to get the 3-3.5cubic feet per sub i wanted. So does anyway have any comments on that polyfill idea? As i said, i would put up some sort of lining to make sure the polyfill doesnt blow through my vent, i just dont know how the idea sound. Or how it would be since its a vented enclosure. I really dont want to loose any SPL from it

BayAreaNB
06-22-2004, 04:05 PM
On the Audiobahn site, when it asks for internal volume to calculate port length, do you give it volume with or without the subwoofer inside?

InhumanAcura
06-22-2004, 06:19 PM
I compete with a trunk-car and have found that the port in the center of the box is loudest, not saying it wont be different in your car. If your looking to get into competing start with a single sub building boxes to where they can get in and out of the trunk easily to be modded. Its alot easier to figure out what gets the car loud when your working with half the equipment.
As far as the polyfill goes, Kicker has a diagram in the manual for a Solo X that says to use chicken wire over the port so it doesnt get blown out. It kind of throws me that you can use the p-fill in a ported box where the simulation of either more port or volume would throught the tuning off BIDK.