Chris, it's late at night and I have a buzz on, but I was around in 1979 when the sub-woofer thing was starting. The best was called the Dalquist 12 inch woofer. I used ACE AUDIO crossover at 100 Hertz, and it was affordable, 100.00? Compact disc's had not yet come, so ACE made a sub-sonic filter to go with the crossover so that LP record warble at 30 hertz and on down would not make your tonearm bounce off your turntable. Janis and Altec and Visonik were the pioneer sub's. Also ............ Cerwin-Vega, who started the whole thing with the movie (EARTHQUAKE). My computer is going out of control, Chris, I'll get back to you... Mark