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da_bOm
07-06-2003, 02:10 PM
for dual ports could i just take the measurment i have for my one port and divide it in half for two ports? would it be tuned for the same frequency? thanks for any help

chinxtaboi
12-09-2007, 09:52 PM
i know its an old thread, but i have the same question. anyone?

BrianChia
12-09-2007, 10:07 PM
Generally speaking the length of the ports will be proportional to total port area. If you have 1 4" port at 20" long, then you would need 40" or port for 2 4" ports. If you cut the port area of the first port by half and add another port elsewhere then the length remains the same. For example, (2) 10"x2" ports at 20" would be roughly equivalent to (1) 10"x4" port at 20". However going from one 10"x2" port at 10" to two 10"x2" ports would mean you would mean both ports are now at 20" since the area doubled.

Punk In Drublic
12-09-2007, 11:07 PM
Yeah, if you cut the port area in half for each port the length and tuning will be the same I think.

BuckyBoy
12-09-2007, 11:27 PM
You take your internal volume and divide it by how many ports you want and get volume X.
Then, you find the port length to tune volume X to what you want.
You use that port length for both ports.

chinxtaboi
12-09-2007, 11:41 PM
so say i have a have a slot port that is 10" long with a port area of 4" x 12". if i wanted to make the box with 2 ports.. i would just have both ports at 2" x 12" and keep the same length at 10"?? right?

thanks

BuckyBoy
12-09-2007, 11:41 PM
so say i have a have a slot port that is 10" long with a port area of 4" x 12". if i wanted to make the box with 2 ports.. i would just have both ports at 2" x 12" and keep the same length at 10"?? right?

thanks
what is the volume of the box after sub displacement? and what tuning are you aiming for?

chinxtaboi
12-09-2007, 11:56 PM
i havent designed the box yet. just wanted to know how i could make the box with two ports instead of one.

BuckyBoy
12-10-2007, 12:00 AM
i havent designed the box yet. just wanted to know how i could make the box with two ports instead of one.
i assumed you would know how much airspace and what tuning before you worried about the ports. or do you not know what subs you are gettin yet? either way, just read my earlier post. thats how JL's site explains it.

chinxtaboi
12-10-2007, 12:16 AM
i was lookin at the calculator on re and another site to figure box and port dimensions. so i could just figure the port area to use to make two ports.

BuckyBoy
12-10-2007, 12:18 AM
http://mobile.jlaudio.com/support_pages.php?page_id=165

helotaxi
12-10-2007, 10:05 AM
Two ports with the same total cross sectional area will be longer than a single port with the combined area of the two for the same tuning. The link posted above explains it a bit.

The box calc on REs website is terrible. WAY off. There are a bunch more out there that actually give you numbers that are correct. Or you could download WinISD for free and have a pretty good calculator at your disposal all the time.

chinxtaboi
12-10-2007, 11:11 AM
ah so its not the same as just cuttin calculated area of the port and splittin it into 2.

helotaxi
12-10-2007, 11:15 AM
ah so its not the same as just cuttin calculated area of the port and splittin it into 2.

No.