port area

[bvr_j_0969 10+ year member]

im looking at building a wall in my truck for 4 re sr15's

the box is going to be 13.1 cft gross before any displacement.

does anyone know what kind of port area i need so i wont have any port noise?

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[psych0ticnemes1 5,000+ posts]

Minimum port area = (Net Volume x 12)

13 x 12 = 156 square inches of port

I usually use 15 as my base for port area so that I can be sure that I will not have port noise.

 

[bvr_j_0969 10+ year member]

thank you this helps alot, ive had people tell me like 10 square inches per cubic foot was a good rule but i guess they were wrong.

 

[01 S 10 10+ year member]

NET volume, so dont multiply 13.1 by anything. estimate a port that size to take up to 2cf, then bracing and sub displacement, you should be just over 10cf net

you should figure out how much net volume you want (or can fit) and adjust the size of your wall to accomadate the port/subs/bracing displacement

so 10cf net + port, etc, etc

i have 160 square inches of port for a 9cf net wall, a little on the high side, but 15 square inches per cube would be ok, so 150 square inches of port for your 10cf net wall

 

[Rashaddd 5,000+ posts]

The thing I don't like about going based on box volume, is it implies that if you use a smaller than recommended box you should use less port area...and with a larger box you should use more, which really should be the opposite, considering if you put a sub in a box smaller than it should be, what happens to the pressure inside the box? what therefore happens to the speed of the air in the port? what therefore needs to be done to compensate? More port. not less

People tend to forget (or never even knew/realized) that an increase in port area is correlated to an increase in box size, but neither cause eachother, they are both increased by a third variable, which is the sub's potential displacement and the amount of power we are putting to that sub

 

[bvr_j_0969 10+ year member]

i done the port area buy 11 cft,

10 for the subs, .64 for the subs displacement, and .34 for the braces. and a port of 10" wide and 14" tall and 28.5" long come out to be 1.99

so that come out to be 12.9 if you think those .2 cft will mess up anything to bad i can always just screw a small block of wood inside to take up those .2 cft