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DaGh0st
12-09-2005, 12:49 PM
ok im gonna start building my box for my 15"sx 4ft3@45hz i need to know if this looks right.
2 round ports 4in x 5.44 =43.52 sq in
Box (internal) 15 x 24.5 x 20.5 = 7533.75
7533.75 -43.52 = 7490.23 / 1728 = 4.33
so then i take off .18 for sub dis placement and its at 4.15ft3 does that look ok?

psych0ticnemes1
12-09-2005, 01:22 PM
are you SURE 45 htz is where you wanna tune it? it will sound like a massive fart machine.. i own an sx i know

DaGh0st
12-09-2005, 02:24 PM
ok im gonna start building my box for my 15"sx 4ft3@45hz i need to know if this looks right.
2 round ports 4in x 5.44 =43.52 sq in
Box (internal) 15 x 24.5 x 20.5 = 7533.75
7533.75 -43.52 = 7490.23 / 1728 = 4.33
so then i take off .18 for sub dis placement and its at 4.15ft3 does that look ok?
ok i changed the ports to 4 x 13.61 @32hz 54.33 sq in but do i have to mutilply 54.33 by 2 since theres two ports?

saywhat?
12-09-2005, 02:30 PM
Lv = Av*1.84*10^8/[Vb*1728*(Fb/0.159)^2] - 0.823*sqrt(Av)

bimma85
12-09-2005, 02:30 PM
where you get 4 x 5.44?

Moe Lester
12-09-2005, 02:32 PM
umm 2 4" round ports = ~25 sq in of port....

DaGh0st
12-09-2005, 02:34 PM
where you get 4 x 5.44?
http://www.carstereo.com/help/Articles.cfm?id=31
thats were i got it from but now i have it at 4 x 13.61

DaGh0st
12-10-2005, 12:09 PM
do you have to mutiliply 4 x13.61 twice. since there are 2 4in ports or just once?
exmaple 4 x 13.62 or 2 x 4 x 13.61

bimma85
12-10-2005, 12:12 PM
do you have to mutiliply 4 x13.61 twice. since there are 2 4in ports or just once?
exmaple 4 x 13.62 or 2 x 4 x 13.61
you are looking for area of a ports? (4"/2)^2*3.14*2(if ya have 2 of em) for a 4" circle

DaGh0st
12-10-2005, 12:16 PM
you are looking for area of a ports? (4"/2)^2*3.14*2(if ya have 2 of em) for a 4" circle
so its 25.12 sq in of port?

DaGh0st
12-10-2005, 12:17 PM
how much should you have? is 25 enough?

bimma85
12-10-2005, 12:18 PM
so its 25.12 sq in of port?
i dunno the exact off hand but year 2 4" round ports would have an area of about 25 square inches.

DaGh0st
12-10-2005, 12:21 PM
so the lenth has nothing to do with the area right? its just for tuneing?

Moe Lester
12-10-2005, 12:22 PM
2 4" ports isnt enough, 4 minimum and you would wanna flare them.

DBfan187
12-10-2005, 12:25 PM
25.2" sq. if you want to be technical.

saywhat?
12-10-2005, 12:26 PM
id do six if possible. doesnt have to be aeroports, but flar the box side of the port.

DaGh0st
12-10-2005, 12:26 PM
ok so 4 4in ports should give me 50 sq in? and then its good? flared does that mean to kinda curve the ends so i dont have port noise?

saywhat?
12-10-2005, 12:30 PM
ok so 4 4in ports should give me 50 sq in? and then its good? flared does that mean to kinda curve the ends so i dont have port noise?



yes , its right around 50. but again, IF you can fit it go for 6

amartin_72
12-12-2005, 09:51 AM
To make the correct box for your SX if you are using round ports, to figure out the tuning you take the total net box volume after port and driver displacment divided by the number of ports you will be using, then use that number for the net box volume and use the area of ONE of the ports for your port area. Use the common tuning equation from JL audios website or whatever site you found the one your using now. I think moe lester is right two 4" ports is not enought for a 15" sub with decent power handling, that thing will be moving alot of air you need at least half of the cone area for port area., Four 4" ports would be better for SPL. But 3 4" ports on a 15 sounds great with music, tune to suit your personal taste.