Vented Box help!!

[blahblahblah]

Sup, Iv made over a dozen boxes, All sealed. Im going to be making a box for two PA FBX-15s. Im going to make a vented box this time. Iv been looking at all the tutorials and it helped a little. But I have no clue on how to get the tunning thing down. Any help would be great.

Thx............

[POS carb]

basically you need to remember this:
longer ports lower the frequecy (deeper bass)
narrowing the ports lowerers the frequency (deeper bass)
the problem is that a port that is too thin will sound like crap at high volumes so you want to get a port diameter based on how loud you will be playing (like a 4" port for 12 or mild 15 is a good start) and then you lengthen that 4" port to get to the right frequency

the best way to go is to research what the manufacturer recommends for a box volume and then go from there

I have a pair of JBL 12" GT series in a 3.6 cubic foot single chamber box with a trio of ports and I swear that box craaaaanks but the lows aren't as good as my 2 15's in sealed chambers. If I lengthen the ports it would help but I may lose some punch. Ported boxes sound best in hatchbacks in my opinion

also if say your box is 12" deep but your port requirement is 16" you can put a bend in it, just measure the lengh from the center of the pipe

[POS carb]

also if say you want to go crazy with your port designs you need to keep the port area the same.

say your manufacturer recommends a single 4" port 12" long
i.e. a pair of 2" ports is not the same as 1 4" port because:
area = 3.14 x radius squared
2 squared = 4, 4 squared = 16
so really i think that works out to like quad 2" ports = a single 4" port
keep the length the same

[NXRacer]

there's a shop around here that makes all their boxes with round ports. I swear, he can make ANY speaker bump like crazy. I forget the name of the port right now, but if you can find plans to make a box for those ports, i'd do it. You can buy the ports online i believe. They're not just the usual round ports either. They're shaped in a way to encourage sound waves to move in a way that give the best sound.

[POS carb]

aero ports
you can get them on crutchfield.com

[blahblahblah]

2.2 cu. ft., tuning 34Hz, port size 4" (d) x 12" (l)?????

[Ludi Mali]

i've heard a half dozen brands of subs in this box http://diamondaudio.com/products/pdfs/Dual%2015%20in%20Vented%2005.pdf
and they all sound amazing

[Strugglebucket]

go here and download winisd pro.

http://www.linearteam.dk/

very good basic box designing program which should help you a lot. don't know if your subs are already in the database or not but you can always manually insert the parameters.

[Vanilla Sky]

yes, i was gonna direct you to the WinISD program... since it's been brought up, i'll go ahead and let you be lazy and tell you how you need to build the box...

those subs need a crazy big enclosure... the only way i could see them used in a car without having no rear seat would be to run them isobaric... even then, they still need a crazy big box...

for the isobaric setup:

4.572 cubic feet
1 4.02 inch by 12.33 inch port

that tunes the box to 22.09 hz

that's what i would go with, unless you had a van or an SUV

[blahblahblah]

There going in an 86 S-10 blazer. You sed a 4.572ft^3 box..Is that for both? Thier webpage sed 2.0 at 35hz(33hz for better SQ) for each sub. And I got the winisd and Im messing with now. I think Im getting this know......

[Vanilla Sky]

tuning the box like that isn't gonna give you good sq, but it will give you the boomy shit sound most people want...

for a single driver, you would require twice the listed size... makes it a bit over 9 cubic feet each driver... you'd have no rear seat, even in something as large as a cargo van or a suburban...