# combining ports question



## The_man (Nov 5, 2010)

Ok si I am looking to build a single chamber ported box for my 2 PPI Pro10 subs. The manual says to use a 3" port at 10 1/16 length. So if I wanted to do one port how would i figure out what size it needs to be? Thanks for the help


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## Patrick Bateman (Sep 11, 2006)

The_man said:


> Ok si I am looking to build a single chamber ported box for my 2 PPI Pro10 subs. The manual says to use a 3" port at 10 1/16 length. So if I wanted to do one port how would i figure out what size it needs to be? Thanks for the help


The area of a 3" port is 7.07". The area of dual 3" ports is 14.14". And then *(sqrt(14.14/pi))*2* gives you single port with a diameter of 4.12".

There are some advantages to using multiple small ports also. I'd just use dual 3" ports really. Or better yet an aero port of a moderately longer length.


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