# Question about UNIBOX



## nuno (Sep 5, 2007)

Hello!
I'm building a 3 way system using 2 x Extremis + 1 CSSwr 125S + 1 Usher Audio 9950 C15 (which is the Exodus Audio 2641 kit).
I want to build two boxes for each channel (WATT PUPPY/V. Speakers style), one bass relex for the bass and another sealed for the medium/tweeter. I'm using UNIBOX program to simulate the boxes.
When I was modeling the bass box I notest that if one maintain a given box volume (physical Vb), and the given diameter port, changing only the system tunning frequency (Fb), the frequency response of the box changes, besides all the other parameters remain constant.
I don't know which parameters Fb depends on to change the frequency response.
So, my question is-In the real world with a real box, and with a given physical Vb and inside port diameter, whow does the box "knows" what Fb (system frequency) do we want? 
Thanks for your help.
:huh:


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## Geoff St. Germain (Dec 18, 2006)

In the case you're describing Fb depends on the length of the port (when Vb and the port diameter are kept constant).


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