The Choprical Fish: a Human Powered Party Bike

Step 9 Create a speaker port in the positive form

I mentioned the Bazooka bass tube earlier. It's a ported subwoofer with excellent thump for its size and cost. Ported speaker cabinets can sound up to twice as loud at certain frequencies as sealed cabinets. However, if you don't tune the port correctly, you can have a system that sounds boomy or damages your woofer. The length and cross-sectional area of your port need to be calculated to the woofers and cabinet size. The manufacturer of the subwoofers you use should be able to provide you a data sheet on recommended port settings. Use it!

At this point in my process, I didn't know the exact volume of my cabinet. I measured it later by filling it with styrofoam peanuts.

So I created a port that was longer than I needed it to be. Later I would cut it down. I created a foam plug (again, longer than I needed). I made sure the port and the plug matched perfectly.