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View Full Version : a box plan that needs checking.

James Bang
04-26-2006, 03:56 AM
I'm trying to figure out how to come up w/ a design for a box (something new to me). This one have round ports. I feel that they're easier to design... and build.

ok here's the specs:

30" wide x 14" tall x 27" deep = 5.25 cubes external

I will be using two 4" ports. to get 32hz, i got that i need the ports to be 11" in length.

someone please correct me if i'm wrong.

-James

btnhfan
04-26-2006, 04:53 AM
Quick plugin to bassbox said it would about 30hz.

Assuming those dimensions are external, and you are using .75" mdf

tRiGgEr
04-26-2006, 11:27 AM
Close enough.

.75" construction material, external dimmensions.

30" x 14" x 27" = 5.26ft^3
2 x 4" - pvc ports 11" long = .32ft^3

Total net volume 4.93ft^3 tuned to 31.4hz

And this is not factoring in driver displacement.

3onDubs
04-26-2006, 11:42 AM
Hey James....is this box for me? If not, that's pretty similar to the dimensions for the one i need....lol (30 X 14 X 24).

@Trigger....for the area of the ports, i get the following:

PI X radius squared X length = 3.14 X 2 squared X 11 = 3.14 X 4 X 11 = 138.16

If I divide that by 1728 i get 0.08 (the area of one port).

If I multiply that by two (two ports), I get 0.16, NOT 0.32.

Am I doing something wrong?

EDIT: That port displacement gives me 5.1 cu. ft. net volume (before driver displacement)

tRiGgEr
04-26-2006, 11:54 AM
Am I doing something wrong?

Nope. I screwed up the port displacment. Ended up doubling the final figure:blush: When is this coffee supposed to kick in:cool:

5.10ft^3 tuned to 30.88hz

Thanks for pointing that out 3onDubs.

3onDubs
04-26-2006, 01:27 PM
No prob....i just used the port length calculator on http://www.psp-inc.com/

and i plugged in the following:

Volume = 5.26 (before displacement im assuming because u wouldn't know the port length)

Tuning Frequency = 32

Port Diameter = 4

Num. of Ports = 2

It gave me the following port lengths:

Straight port: 9.65

Flare port: 10.65

@Triger...your right about the 30.88....that sight rounds of to 31 (with 11" long ports)

James Bang
04-26-2006, 01:35 PM
Hey James....is this box for me? If not, that's pretty similar to the dimensions for the one i need....lol (30 X 14 X 24).

yeah it's very similar to yours, but it's for the guy that came to check out the box that didn't fit in your car..... It didnt' fit into his either. well it did, but his rear windsheild wiper on his trunk lid caused his trunk to not close. :crap:

Thanks for all the calculations guys. I really appreciate it

3onDubs
04-26-2006, 01:39 PM
He didn't take the box cuz of that?

That was a sick box...i'd rip that windshield wiper off if i were him (definitely would've been worth it)...that box would rattle it's life away anyway....lol.

I'll still take that box in addition to a new one if it's still available by that time.

mikeyboc
04-26-2006, 02:09 PM
I read about the box that wouldn't fit. Is it still available? That seems to be about what I am looking for. Because I am being lazy, can you post the specifics on it?

James Bang
04-26-2006, 02:11 PM
yeah... who needs a rear windsheild wiper anyways? :rolleyes:

Your box will be built soon. I gotta make a trip to home depot and harbor freights (they got a sale on clamps, \$5-6 for 36" clamp/seperator). ;)

James Bang
04-26-2006, 02:16 PM
I read about the box that wouldn't fit. Is it still available? That seems to be about what I am looking for. Because I am being lazy, can you post the specifics on it?
Seperate chambers. it's 30" wide x 16.5" tall x 28" bottom depth x 20" top depth with 32hz tuning each 2.5 cubed chamber.

but you're in TX :crap:

mikeyboc
04-26-2006, 02:18 PM
Yea, I thought shipping might be a bit much, but thought I would look into it anyway.

James Bang
04-26-2006, 02:22 PM
Yea, I thought shipping might be a bit much, but thought I would look into it anyway.
shipping might be as much as i'm selling it for locally. \$70 picked up. \$40 if YOU're willing to take a road trip ;)

3onDubs
04-26-2006, 02:29 PM
Road trip ftw.....SoCal weather has never been nicer....the gophers are starting to come out of their holes (whatever that means).

mikeyboc
04-26-2006, 02:54 PM
Too bad, I was out there about 2 weeks ago. With gas @ \$3+ a gallon it might be cheaper to ship than drive the Tahoe out there :)

duckfart
04-27-2006, 06:01 AM
Hey I need that rear windshield wiper with all the heavy rain we be gettign in LA. Hey james let me know when u can build me that box thanks.

James Bang
04-27-2006, 02:11 PM
Hey I need that rear windshield wiper with all the heavy rain we be gettign in LA. Hey james let me know when u can build me that box thanks.
Rain-X ;)

i'll try to build it over the weekend. I'm about to sketch it up and make a cutsheet for it right now.