RE Enclosure Calculator is a decent calc it even calculates port flare or w/e its called.... Ie it adds half the size of the port to the port lenght because of air coming out of the port in a /. But it dosnt let you input displacement so you have to do that yourself.

Also i use a 25 or so inch L port for my box for my 05 XXX it was the only way i could get the recommended 33 sq in of port area with a tuning of i think it was 32 i would have to dig up the schematics dave from team psi threw me back when i decided to try ported over sealed for a change.( and that sucker got plenty loud for a 12 playing music. So i fall to also see how over 20 is bad i mean aslong as its done right whats the problem?

me dumb

X2 I had my 05 XXX 12 in 2.2 @ 37 and the port length was 30-40". It was loud to say the least.

Are you sure it calculates for the end of the port?

"it adds half the size of the port to the port length" ???

Hows my new box look? You reckon it'll be 34.9 ish?

[QUOTE=rbgnwa45;595344]Are you sure it calculates for the end of the port?

"it adds half the size of the port to the port length" ???QUOTE]

yes if you add up the port lenghts that it calculates going from the center of the port( you cant just add the lengths on an L port) you will notice that the port lenght the calulator uses will be half the width of your port longer than you think it is.

If the port length is calculated from the center line than whatever is taken off from the first length is added to the second length, therefore it remains the same.

With any slot port that uses the outer wall of the enclosure as one side the vent behaves like there is a 45degree line from the end of the inside vent wall to the outside enclosure wall. You need to make sure the spec'd vent length is in the middle of that 45degree line.

A 1 cuft box with a 3" diameter port tuned to 30hz results in a port length of just under 19"... 33hz is only 15.25"... :dunno:

Need a 4" diameter port? (really, if you do, then you should have a box bigger than 1cuft but you knew that right?) Then you wind up with a 38hz tune at just over 20" in length. Yep, over the 30-33 you asked for but nobody's likely going to hear it.

Of course you also already knew that you shouldn't just jam a random vent tuned to a random frequency into any random size box, right? You're alignment is liable to go right out the window resulting in:

"Why does my bass sometimes sound funny...." :ohwell:

That wasn't confusing, but I don't understand.

Which color(s) would I have to measure for actual?

http://sphotos.ak.fbcdn.net/hphotos-..._3868448_n.jpg

None of the above think of it coming off the short end of the port in a \ so say your port is 3 inches wide you would add 1.5 inches to the ports actual lenght. Some calculators do that automatically and some dont.

Do you mean I would have to add 1.5 inches to the port length or does the port as-is behave as if there is +1.5 inches, meaning I'd have to make it 1.5 inches shorter for the same tune? Trying to calculate the length at 20" with 6.2" width, so either it behaves like 16.9" or 23.1".

Is it generally not recommended to use more than a measured 20" or is that with +half the port width in mind?