Re: does this sound right?
The only thing I see different is I got a port length of 22.75". But even if you go with 21.5" long you still get 32.5Hz (or so). To make thing a little bit easier for your self, just carry out to one decimal place. Often time you will find out even if the port is .25" longer, it may not make that big of a difference...maybe only like 1/8 of an Hz or something.
Example: your box 4cu'
-@31Hz port should be 24" L
-@32Hz port should be 22" L
-@33Hz port should be 20.5" L
2006 Jeep Liberty
Adire Audio, Cadence, Clarion, MB Quart
Lv = [(14630000 x R^2) / (Fb^2 x Vb)] - 1.463R
*Vb = vol. in cu"
**R = sq.rt. A / Pi (for square/slot port)