Speakerbuilder magazine had an article in 1996 about a subwoofer made with a 55 gallon plastic drum (7.35 cubic feet). It featured a Radio Shack 15" woofer, which is currently unavailable. I actually built one of these with the correct Radio Shack driver and it works well. I wanted to build another, only to find that Radio Shack no longer sells drivers. Has anyone experimented with these?