View Full Version : External pvc port with no flare?

04-09-2010, 09:03 PM
Let me start off by saying I am not trying to gain any benefit over using a slot port. This is more of a just for looks box, but I still want it to be tuned right. I'm not sure about what subs yet, but I think it will be 2 Memphis PR 10's in a Ford truck with no extended cab. How do you do the math for 2 round pvc ports sticking about 1 foot outside the box and what's the best box program to use for this?

04-10-2010, 12:18 AM
the math is the same as a port inside the box, you just dont have to worry about the displacement the port takes up inside the box, what is your net volume?

04-10-2010, 02:36 AM
Are you saying the box should be smaller when the ports are on the outside? Are you saying to subtract the cubic feet that the ports take up inside the box, and make the box that size? If so, what's the math for figuring how much space cylinders take up? I don't know what the net size will be because I don't know what size and tuning Memphis recommends yet?

04-10-2010, 02:49 AM
You do not have to subtract the ports from the volume of the box if they are outside. So yeah. Just redesign the box with the ports outside, but the formula is (radius^2)*(pi)(Length of the pipe)

04-10-2010, 03:08 AM
Ok, lets assume I'm using a box program that only designs boxes with internal ports. Tell me again exactly what math wise am I redesigning to keep the same tuning? Sorry if I'm catching on too slow!

04-10-2010, 03:12 AM
You would have an issue and would need a new program haha. Just design a sealed box... Then go to a good online calc and get your lengths!

04-10-2010, 06:10 AM
I still don't get it? Is there a program for what I'm trying to do? If I make a sealed and put the ports in later, how do I know if the box is tuned low as I want it?

04-10-2010, 07:53 AM
How is he tuning this?
YouTube - subwoofer demo **** (http://www.youtube.com/watch?v=GgGRSv1eZRQ)