Yep, double the port area and leave the length the same.
You may need to modify the volume of the box slightly to compensate for a different port displacement also, depending on how it's built.
Just by going to a 6" [circle] you'd be more than doubling your area.
4" port has an area of about 12.57 square inches.
6" port has an area of about 28.27 square inches. That's 2.25 times the area.
As far as length, I'm not sure if it should be the same length or not. Maybe change the length to compensate for the larger area, but I don't know port calculations very well, just math...
Hope this helps figure port size.
Port size is a function of the volume of the box, port diameter, and the tuning freq. It has nothing to do with the number of drivers.
The formula is ((14630000*(D/2)*(D/2))/((Fb*Fb*Vb*1728)-(1463*(D/2)))) where D is diameter of the port, VB is box volume, and FB is tuning freq.
For example, if you have a box that is 1 cu/ft and you want to tune it to 35 hz using a 2" round port, that port would be 5.448 inches long.
Now if you doubled the size of the box, 2 cu/ft and you wanted the same 35hz, you would need a 2" round port of 1.992 inches long.
If you used a 4" round port for a 2 cu/ft volume, the length of the port would need to be 10.896 inches long and 24.71 inches for 1 cu/ft.
Slotted ports are a little different, but are still a function of port volume, box volume, and tuning freq.
Of course this does not take into account the volume loss due to the port itself which would also need to be calculated and subtracted from the box volume. It also does not take into account tapered ports.
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Related Threads
?
?
?
?
?
DIYMobileAudio.com Car Stereo Forum
3.2M posts
130.9K members
Since 2005
A forum community dedicated to all mobile audio enthusiasts. Come join the discussion about capacitors, amplifiers, subwoofers, marine and automotive audio, troubleshooting, and more!