# can't figure out port

armymp90099
Copper - Posts: 76
Joined: July 05, 2009
Location: Illinois, United States
Posted: December 13, 2009 at 9:04 PM / IP Logged
Ok this may be a newb question but say I want to have 2 ports in one chamber of a box. If I use 2 inch ports would that count as 1 4 inch port or still just a 2 inch port but add the lengths of each port. Sorry if this is simple but I'm stuck.
-ETS-
Escape The Scilence
j.reed
Copper - Posts: 716
Joined: January 05, 2009
Location: Arkansas, United States
Posted: December 13, 2009 at 9:20 PM / IP Logged
Two 2" inch ports would be like having one 4" port. It will increase you port area.
FYI, if using the port calculator on the site. Make sure you are using NET volume to figure tune. Take outside dimensions to figure your GROSS. Then subtract port volume, driver displacement and bracing to find your NET airspace.
If you need help to get the right goal of tune and volume. Just hit me up. I can walk you through it in more detail if you need it.
i am an idiot
Platinum - Posts: 13,597
Joined: September 21, 2006
Location: Louisiana, United States
Posted: December 13, 2009 at 9:22 PM / IP Logged
It will take (4) 2 inch ports to equal (1) 4 inch port.   Formula for area of a circle is Pie X (Radius squared)  2 inch circle = 1 x 1 x 3,14159 = 3.14159    4 inch circle = 2 x 2 x 3.14159  = 12,56
j.reed
Copper - Posts: 716
Joined: January 05, 2009
Location: Arkansas, United States
Posted: December 13, 2009 at 9:25 PM / IP Logged
i am an idiot wrote:
 It will take (4) 2 inch ports to equal (1) 4 inch port.   Formula for area of a circle is Pie X (Radius squared)  2 inch circle = 1 x 1 x 3,14159 = 3.14159    4 inch circle = 2 x 2 x 3.14159  = 12,56
Good catch "i am". That is indeed correct. Two 2" ports would be closer to a 3" port.
i am an idiot
Platinum - Posts: 13,597
Joined: September 21, 2006
Location: Louisiana, United States
Posted: December 13, 2009 at 9:36 PM / IP Logged

No catch i was typing when you posted.  I had no idea you had posted.

j.reed
Copper - Posts: 716
Joined: January 05, 2009
Location: Arkansas, United States
Posted: December 13, 2009 at 9:40 PM / IP Logged
i am an idiot wrote:
 No catch i was typing when you posted.  I had no idea you had posted.
In that case you should have just played it off as you had I would have lol
armymp90099
Copper - Posts: 76
Joined: July 05, 2009
Location: Illinois, United States
Posted: December 14, 2009 at 1:50 AM / IP Logged
ok thanks guys. I dont need it to be dead on balls accurate as this will be my daily driver box not competition. Ill calculate it as a 3 inch port. Then all i need to do is buy the DC LVL4 XL to go in it and ill be a very happy man. :)
-ETS-
Escape The Scilence
j.reed
Copper - Posts: 716
Joined: January 05, 2009
Location: Arkansas, United States
Posted: December 14, 2009 at 2:41 AM / IP Logged
You will want more port area then that for a DC lvl 4 XL. You will want to build a slot port box. What size sub is it going to be?
armymp90099
Copper - Posts: 76
Joined: July 05, 2009
Location: Illinois, United States
Posted: December 14, 2009 at 9:20 PM / IP Logged
Ok Well I was originally going to go with a 12 but now im leaning toward the 15. Below is a sketchup rendering of the box tuned to 35Hz. The overall size is 38W x 10H x 20D Which gave me a net volume of about 3 FT^3. The Port is 6.25W x 8.5H giving me enough port area given 16 IN^2 per 1 cubic foot. The front is cutout so you can see the port inside.
-ETS-
Escape The Scilence
j.reed
Copper - Posts: 716
Joined: January 05, 2009
Location: Arkansas, United States
Posted: December 14, 2009 at 10:07 PM / IP Logged
Its late now So i cant call, but i would send DC an email asking there recommendation for port area per cubic foot. That port area seems to be too small to me.
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