Thank you Old Guy. That article on the Paradise Garage was just what I was looking for. Had no idea sound science was so advanced during the Disco era; also did not realize the DJ controlled so much of the sound system ( I thought they just played records !! ). My fondest 1970's Disco memory is of going to a large, freestanding club in San Antonio Tx called "The Last National Bank" and wondering how they got that sound; now I have some idea. Thanks again...