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View Full Version : Box plans...anyone care to check for mistakes?

arizona
06-11-2008, 10:42 PM
So I finally figured out the dimensions and I'm attempting to figure out the port dimensions.

The external dimensions of the box will be 40wx16.5hx25d so the internal are 38.5x23.5x15

This gives me 7.854 cu. ft. to work with. According to bassbox 6 a port 15hx4.5wx18.5d gives me a 33.03 hz tune. The port would displace 15x5.25x18.5 = .843 cu ft. (the 5.25 is 4.5+wall thickness. Is this correct?)

Sub displacement is .303 each so .606 total. So box volume is now 6.405 before bracing displacement.

My port area would be 4.5x15= 67.5 inches right? DD recommends 66 sq inches of port area...is this per sub or would it be the same because I am running 2 DD 2515's. Do I have sufficient port area?

So if I made a mistake please tell me what it was. I think I might mess with the dimensions a bit more later to get some more space if I did this right.

JG903
06-11-2008, 10:59 PM
I believe the sub displacement is off. I remember checking my DD 9515's and the number was odd as well. It should be more around like .16 each or something like that.

arizona
06-12-2008, 12:12 AM
Thanks...I thought it was a pretty big number. Other then that is the port right though?

JG903
06-12-2008, 12:35 AM
I think you need to let them have a little more port area. Somehwere around 15 sq in. of port per cu. ft. You have 6.4 ft net so it should be around 100 sq. in. of port.

arizona
06-12-2008, 01:05 AM
The formula for that is HxW of the port right?

JG903
06-12-2008, 01:10 AM
The formula for that is HxW of the port right?

Yes

arizona
06-12-2008, 01:26 AM
It looks like I am going to end up doing a L shaped port then...

What is the minimum distance from the back wall of the enclosure that the port wall can get if you only have 1 interior port wall instead of an L. If its like 3in or less I can just make 34-35hz box instead of 33

JG903
06-12-2008, 01:36 AM
It looks like I am going to end up doing a L shaped port then...

What is the minimum distance from the back wall of the enclosure that the port wall can get if you only have 1 interior port wall instead of an L. If its like 3in or less I can just make 34-35hz box instead of 33

I believe the minimum distance needed is the same as the width of the port

arizona
06-12-2008, 01:39 AM
So how much of a difference would say 75-85 inch of port area make vs 100?

JG903
06-12-2008, 01:41 AM
100 is better, but I think you could get away with about 80.

arizona
06-12-2008, 01:42 AM
I can come up with 86.25 without it starting to **** with things....do you think this will work?

JG903
06-12-2008, 01:43 AM
Yeah, go for it.

arizona
06-12-2008, 01:43 AM
Btw with 86.25 of port area the net volume is now 5.9xx so I am only 4 inches off of your 15 sq in per cu ft.

JG903
06-12-2008, 01:45 AM
When you build it be sure to take pics and let us know how it sounds.

arizona
06-12-2008, 01:45 AM
Alright man thanks for all the help :). This is my first box I will actually be building myself and the port was the only thing that was kinda giving me doubts. Thanks for clearing up my question about the port area... I had no clue about that.