Friends pointed out to me that they don’t understand my writings about building/optimizing speakers and don’t even know what to google for. Sorry, guys, I was just writing down what I was doing and not thinking about that.

The Variables (Fs, fb, ….) are so called Thiele-Small Parameters, named after two aussie guys doing research on the matter. Wikipedia provides links to sites explaining the stuff in both german and english.

Don’t let the math scare you away, you don’t need it. To build a woofer you just have to look up these values and put them in some online calculator which is spewing out build dimensions. Just make sure to get a second opinion on the results, be it through research, online forums or just asking folks…