help with box design for rockford p3 12

[Scalian]

Yes that is what I had planned this time around,

Is it worth messing around trying to loose the .03 ft^3 and gain .7hz in the tune. Or does it not make a big enough diffrence to matter when this close to the target numbers?

The box comes out to be short shallow and wide. Does the shape being a long skinny rectangle effect sound as opposed to being more square?

[Scalian]

Here is the new drawing. Does it matter that half the sub fires into the ports wall and half doesnt?

[Joe X]

You generally don't want surfaces near behind the sub or the port inner end, if you don't have an specific reason to do it like that do a deeper box, 0.7Hz is not much of a difference, if you just aim for 35Hz in your calculations with WinISD likely your real tuning will be towards 34Hz.

[Scalian]

I was trying to keept he box under the rear deck and have as much usable truck space as i could. Im not oppsed to going with a deeper box. I could go a max of 15h x 26w and as deep as needed. What would you suggest?

Is sticking with 25 in^2 for port area the correct thing. I believe i read somewhere you wanted a port area 12-16 times your boxes cubic foot volume so i just stook 1.8 x 14.

Thanks for all the help.

[Scalian]

Ok did a design using WinISD to find the port length. I set the tune at 35hz as you suggested. Port ended up at 13.5*2*30.5, 27 cubic inch opening little bigger than before but I think it will be ok. I went with my max height and a width that would fit the car well and then figured depth. External the box ended up at 15*27*14. Wight and Height could still be reduced if more depth is needed to make it correct. Thoughts?

[Joe X]

Your box is now 1.76 cubes net@34Hz with 27 square inches of port area. It looks much better to me, I don't think it needs any further changes. Internal port parts should be:

L1: 11 1/4" x 13 1/2"
L2: 16 1/2" x 13 1/2"

[alaskanzx5]

Op, thanks for trying to figure out you box specs on your own. You should get along great here.

fyi

placement of sub(s) mostly matter if its firing into the port, you can get unloading issues that way and it wouldn't end nicely. This design doesn't look like it will have any issues with that.

[Scalian]

Joe X,

Thanks for all the help first off.

Do you have a program that you use to figure out the box specs thats diffrent from what I used?

Guess all that is left to do is build it and see how it works.

I see that some people miter or round off the edges of the port corner. Is this something that is benifical and worth taking the time to do on a low power build like mine.

Alaskanzx5,

I have been reading trying to learn what I can and then apply it. Its nice to be able to put down my thoughts and ideas from what i have gathered and then get constructive advice. Always thought that was a better meathod than just saying i have XYZ what shoudl i do. One of the hard things about learning from the internet if for every person saying you should do A there is someone saying do B.

[Joe X]

Not critical in your case but it is indeed recommended to round any sharp edges inside the port, at the ends and at the turn.

[Scalian]

Woouldnt be problem or much more work to take the round over bit in the router to the outside corners. For the one inside corner do you just install an small 45 block? Or does that all have to be figure into the design. I assume that you do not want to constrict the port at the turn by adding in a 45 on the inside corner of the turn and not compensating for it on the outside and in my case keeping the 2 in spacing.