A very cheap set of speakers I threw together in a couple of weekends. This is designed as a 4.5L enclosure with a port tuned at 65 Hz. The drivers are a pair of Tang Band 1364 I bought from Parts Express for cheap around Thanksgiving. The enclosure is entirely made from 6 inch PVC piping (the thick stuff) and the most expensive part of the whole thing was the 90 degree elbow fitting. These sound remarkably good, even if they don't have a whole lot of deep bass.