Alright, I **** at ported boxes...

[IDSkoT 5,000+ posts]

I was thinking of having a box with internals of 13-1/2" D X 16-7/8" W x 14-1/2" H

That's roughly 1.91 cuft. The specs call for 1.79... but whatever.

I want it tuned to 40 hz, so I was thinking a 1.5" Wide port going back 12".

That should be tuned to ~41 hz..

I tried to use:

http://www.bcae1.com/spboxnew2.htm

But it's bobo.

It's telling me the port length is 1.415 inches...

RE's box calculator is giving me the same stuff.

Any insight?

Click to read more...

 

[iowaaurora 10+ year member]

try it whith a 2.5"@ 3.5 Wide port see what you come up whith

 

[IDSkoT 5,000+ posts]

2.5" long...?

 

[Lothar34 10+ year member]

Which sub are you using? If it's any kind of thumper then you'll need a bigger port. Probably 3.5" dia minimum.

 

[azimuth 5,000+ posts]

Which sub are you using? If it's any kind of thumper then you'll need a bigger port. Probably 3.5" dia minimum.

the power of the sub doesn't matter as much as box space as far as dictating port area.

 

[IDSkoT 5,000+ posts]

Well, I'm using a RF P3D212... it's 500 RMS, with 2-Ohm DVC. I'm gunna wire them in Series/Parrallel onto a G&S G--something. I'm not even sure of the specs. It was just a cheap 1000@2-ohm amp I found from someone selling it on here.

BADASS SUB.

Posting picture because it's the biggest sub I've worked with:

And if you're wondering, it's going into a '92 Integra LS.

 

[tommyk90 5,000+ posts]

After port displacement that box will be TINY.

For a 12" of that caliber I would shoot for 1.8-2 cubes AFTER displacement. All your numbers are BEFORE displacement.

 

[IDSkoT 5,000+ posts]

Well, on the paper that comes with it, it says 1.79 gross.

So, I think the subs call for a small enclosure?

Normally, I'd say "Fck it! I'll try both!" But I'd be borrowing the table saw, and don't have much money for wood. So, this box is the only box for these subs... 'til she sells them to me (hopefully)

Or should I throw this thing to the wind?

The "Optimum vented enclosure size is:

14" H x 25" W x 12" D

So, it's a pretty tiny box.

 

[Lothar34 10+ year member]

the power of the sub doesn't matter as much as box space as far as dictating port area.

If they're moving a lot of air, you'll get whistling in a port that's not big enough.

 

[IDSkoT 5,000+ posts]

So... what's a good formula to find port length?

'cause these calculators **** the D.

 

[iowaaurora 10+ year member]

http://www.carstereo.com/help/Articles.cfm?id=31

you are gonna need a wider port then 1.5

try whith a 3.5 " wide

 

[mcsoul 10+ year member]

Here's what I came up with using a speaker displacement of .12

total port, port wood and speaker displacement .95

total box displacement 3.73 cuft

net airspace 2.75 cuft

dimensions 14" h x 30" w x 19" d

port 4" w x 12.5" h x 24" d (L-port)

Go to RE box calc

input the box dimensions

Leave it .75 (and use .75)

use 4" for port width

add 5" for port length 2

should say box volume (ft3) 2.974

should say the box is tuned to 37.7133......

Use the listed cut outs.

RE is incorrect about the tuning, it will be 40Hz or very close at 2.75 cubes net.

I could redo the box for 2 cubes net at 40Hz with 3.5x12.5 port if you want.