View Full Version : Rule of Thumb

03-25-2008, 06:06 PM
How many sq inchs of port area are you supposed to have per cube ft of air sapce?

03-25-2008, 06:09 PM

03-25-2008, 06:11 PM

03-25-2008, 06:14 PM
12-16 square inches of volume applies per cubic foot of volume

03-25-2008, 08:56 PM
Port area depends way more on the driver used and the amount of power applied than it does on the box volume. I've used less than 8in^2 per cubic foot and I had no port noise! I have also had 15in^2 per cubic foot and gotten port noise!

It's a terrible rule of thumb coined by DD to be used with their subs. If that's what they feel is needed, then great, but it does NOT apply to all subs or enclosures.

03-25-2008, 09:02 PM
ok well sub is a level 4 DC 12", box is going to be 2.75 before displacment of sub and bracing, Im going to tune it to 32hz, ? if I start at 30 hz cant I cut out port and raise the tuneing?

I just found this...http://img23.imageshack.us/my.php?image=275cubes30hz39sqin0gn.png
I can use this one? I am also going to kerf the front part of the port... does this just mean that I add 1.5" to the port lentgh?

03-26-2008, 12:04 AM
box in sig only has 36 sq in and it works just fine.