Easy to build, with complete plans, drawings, photos, step-by-step instructions. This sub has substantial output to 20Hz. Awesome addition to your audio mixing/mastering station, home theatre or HiFi. We bought a commercially made sub for $400 and it would not adequately reproduce sound below 50Hz. This one sounds far better, and cost much less. Can be built in a couple of evenings from 1/2 sheet of plywood. Cost? less than $150 for everything, including the driver and amp! more info and complete plans at http://acoustiwave.com Click on website link below