After Wayne posted the Hemlholtz formula and the recent questions
I've seen go by about ports for this box or that, I wrote a perl
script that will calculate (if I didn't screw it up) a port for
a given box volume and desired resonant frequency. Its non-GIU
and runs on *nix systems and probably Windows if you have a perl
for that. Example output:

./portcalc.pl 32 3.5
Freq of port: 32.952 Hz
Port diameter: 4.000 in
Port length: 5.125 in

I suppose it could be attached to a web page form also...

You can get Perl to run on most web servers and even the public web hosting services usually allow Perl executables. In fact, this bulletin board system is written mostly in Perl. Just upload your program to your server's cgi-bin directory and have the server's Perl path in the first line of your program.

Do you have a service provider? If not, I can host it on the π Speakers website. So just let me know.

Port Calculator

Let me know if its useful and if the values match the other
programs in use. If you get an error message, maybe your Fre
is too high for the size box (make it smaller) or maybe its
too low for a too small box. Its not real graceful about
this. There is a limit of port diameter of 1" to 8", and box
depth is assumed to be 10", and the port can't be any longer than
70% of the depth. I guess that needs to be another input.

Chris