Hi Reubent,
Here's a pretty good freeware program. The vent length calculations aren't totally reliable. Box stuffing isn't accounted for, nor is enclosure wall losses, but this will get you in the ballpark:
http://www.ggimages.com/spsim/
In practice, expect that a vent slightly shorter than recommended will give the proper tuning frequency. It takes a pretty sophisticated program to properly account for the fluid flow dynamics at the ends of the vent (even if you use a flared port).
Enjoy!
Duke
Here's a pretty good freeware program. The vent length calculations aren't totally reliable. Box stuffing isn't accounted for, nor is enclosure wall losses, but this will get you in the ballpark:
http://www.ggimages.com/spsim/
In practice, expect that a vent slightly shorter than recommended will give the proper tuning frequency. It takes a pretty sophisticated program to properly account for the fluid flow dynamics at the ends of the vent (even if you use a flared port).
Enjoy!
Duke