Well. I was thinkin about it at work, the design and everything. I want to make a ported box, with the ports towards the top on a slant. I'm also thinking about going with a box that has approx 1.75 cubic inches. Here are the drawings I made up of it, I'm hope all my calculations are correct.



Comments? Concerns? Advice?... dare I say flaming?

 

As long as the port length and width are to spec, the angle won't really matter. Why 1.75 cu. ft? Do you have a sub in mind? Find a sub you like that specs the port length and width, and box volume, then build the box to it. The other way is to get the sub parameters and calculate it yourself, there's a lot of programs out that can do it. just don't build a box because it fits and then shove any sub in it, a mismatched box will sound like crap.

 

Right now I have the subs in my current crap box from my old SPX set up. I picked 1.75 because according to the parrameters, it'll give me a more deep bass, which is what I'm looking for. I just have a question about the port. It said the port diameter should be 3 inches. I took the area of the circular port and applied it to a rectangular port. Both have the same area, just different design. Would that be a problem?

The angle on the port is just a personal preference. I think it'd look better that way.

The specs of the sub are in the 3rd picture. Some of the things are a little hard to read.

heres a better pic of the bottem specs.

 

good luck making the ports on an angle for your first box that will be difficult. I would stick to a standard port. Make sure to seal the corners with silicone. Also use glue and a finishing nailer to secure it together. Also coat the MDF with either fiberglass resin or undercoating or something to seal the wood. Can't think of anything else right now.

 

Are you using 1 sub or 2? looks like you drew a cutout on the wood for 2, and if you're going to use 2, I hope that's 1.75' for EACH sub, for a total internal box volume of 3.5 cubic feet. That's because the spec sheet indicates 1.0 to 2.0' ported for a single sub.

Yes, 1.75' should be fine, and it'll provide better performance than if you went with a smaller box. Not just a flatter response and better low-end, but also less 'ripple' (resonant peaks) and group delay, so it's all positive.

Yes, it's fine to make square or rectangular ports instead of round, provided they're the same area, as you said. Keep the ports the same distance from the sides of the box and the sub, as the port diameter (3" I.D. = 3" or more from the outside of the port to the nearest panel and the sub), and flare both the inner and outer ends to avoid port noise. Use the length they recommend (7"), and keep the inside flare at least 3" from the rear panel.

HTH

 

yea the total would be 3.5 inches cubed 1.35 * (30.984/12) = 3.4857 cubic feet. I'm not quite following what your saying by keeping it the same distance from the sides as the sub. And what do you mean by inside flare?

 

what size subs? what model subs? what kind of power will they be getting?

with round ports you can get away with using less port area as long as they are flared ends.

 

They 12s. Kenwood KFC - W112S. Not sure on the power bit. The amp is a 400 watts.

 

hmmmm, what frequency do you plan to tune them to?

 

Honestly i have no idea. idk any of these terms or what does what. I was never into audio until about 3 days when my weak subs went out lol. What I have now is satisfactory, the two subs in a tiny sealed box. All I want is just a little bit more clean bass and I think a new ported box could do just that.

 

go over to reaudio.com and build your enclosure there. There is an enclosure builder there, put in your dimensions, port, etc....

It will give you a cut list and stuff...

 

^^ wow that's really cool. Is it necessary to have the ports go out the sides? I kinda want them to go out the top. I think it'd look cleaner.

 

If you want to do that just change the dimensions a little, like make it 30" high and 15" wide or something and when you put it in your car the port will be top or bottom....

 

try doing to http://www.klausaudio.com they have tool where you can plug in all your factors, and it will give you detailed instructions on building a box, tuned to your application, with the space constraints for your vehicle.

 

that's what I was thinkin I had to do. Very cool. Thanks for the link bro. Much appreciated.

 

tune low. NO higher than 35hz if you want it to sound musical. after using the sub/enclosure i have now, tuning low is where it's at.

 

Aright I built my box according to the specs I calculated and everything came out perfect. Box has 1.74 cubic feet. Port diameter is 3.1 Area is 7.7. Frequency is 25.7.

Here are the specs I put in:

Box Width : 16
Box Height : 16.992
Box Depth Top : 15.5
Box Depth Bottem : 15.5
Wood Thickness : .75
Square Port Width : .5

All the specs look about spot on for what I was trying to achieve. I think I'm gonna take combatsteves advice and just build a straight box as my first one just to make things easier. I'm about to head out and pick up some MDF and start working on this. Anything else I should look out for?

 

Are you sure you want to port it at 25hz?

 

I want to feel deep bass. I'm assuming 25hz would do that wouldn't it? Right now I can hear the bass but not feel it. I wanna feel it more. Also. I went to Home Depot and they had half inch MDF not 3/4 inch. Does it have to be 3/4 inch or will 1/2 inch be fine?

 

25hz is way too low. See what the manafacturer reccomends for the subs you are using... you could use 1/2, but your better off with 3/4, the thicker would be less prone to flexing and leaks...