# Dual Ports: Port Length Question

Discussion in 'Home Theater Projects' started by Brad Boydston, May 30, 2004.

Joined:
May 30, 2004
Messages:
5
0
Trophy Points:
0
On Adire's website, the Tempest in a 194L vented alignment requires two 3" flared ports five inches long. Using Unibox, I plug one port of 3" in diameter, I get five inches. When I plug two ports in, it reads two 3" ports each 12 inches long. Which is right and why?

The larger the diameter port, the longer the length required. With two 3" ports, you're basically using a 6" port. When I plug a single 6" port diameter, I get 24" which is the same as using two 3" ports of 12".

2. ### Patrick Sun Moderator Moderator

Joined:
Jun 30, 1999
Messages:
38,749
480
Trophy Points:
9,110
Actually, using two 3" wide ports is closer to using a single 4.25" wide port. You actually have to do the surface area calculation for one port, multiply by 2, and then solve for the radius of the single port with the same cross sectional area. Simply assuming that two 3" wide ports is the same as a 6" wide port is not the way to go.

3. ### minhG Stunt Coordinator

Joined:
May 6, 2004
Messages:
82
0
Trophy Points:
0
also remember that when you used a flared port like the ones adire recommends, the flares also add to the length. adire's suggestion is for the center section to be 5 inches, i think the flares add another 5-6 inches to the total length,

Joined:
Jun 30, 1999
Messages:
38,749