I have a ported box built for a Rockford T2 12. It has a 2.25 net volume and is tuned at 40Hz (Termpro)...Actual in car is said to be 37Hz. I just ordered a new Fi Q 12 dual 1ohm and was wondering if it will work in my current box or do I need to change the tuning of the box?? How do you know how much to add or remove from the length of the port to get the Hz I'm looking for?

I have attached a pic of the box that I have. Any help on this would be GREATLY APPRECIATED!!!

Edited January 4, 200916 yr by shamisc

holy crap its tuned at 40??????? that is hella high!

my enclosure is similar to that, at 2.26 net, the port is 3" wide and it goes all the way to the end of the wall 3" away. its tuned @ 32 hertz

40hz is high for that woofer.

Tune at least around 35hz or lower and it'll really wake that sub up.

If you extend the inner wall of the port from it's current 14.25" to about 24" (9.75"), you're going to be giving up almost .25 cu ft of your net enclosure volume. I'm guessing (and only guessing, that is!) that at 2.0 cu ft, the port at 35.5" in length would probably give you a tuning frequency in the 30-32hz range. It might be lower than that, I'm not all that sure of the formulas for port tuning.

As you extend the port along the back wall, you are shrinking the enclosure volume. Find a compromise between the two - you may only need to extend it by 4", and have a 2.1 cu ft enclosure, ......

holy crap its tuned at 40??????? that is hella high!

my enclosure is similar to that, at 2.26 net, the port is 3" wide and it goes all the way to the end of the wall 3" away. its tuned @ 32 hertz

Is there a way you could show me some sort of drawing? Could you tell me what your demensions are? I'm not above building a new box, I was just hoping this one would work!

*** ALSO, I found a website called Klaus Audio that builds boxes fairly cheap. Are they good boxes or do you recommend others?

Edited January 4, 200916 yr by shamisc

Edit for my previous post -

Found a port length calculator program, plugged some numbers in.

http://www.mobileinformationlabs.com/HowTo...20lenth%201.htm

Extending the port to 35.5" at 2.0 cu ft, based on the existing dimensions - you'll have an actual tuning frequency of 36hz, lower in-car.

Now, if you want to shrink the width of the slot from 3" to 2", you'll end up with a port tuning frequency of approximately 32.6hz, but possibly at the expense of increasing port noise.