SR wrote:
I am interested in learning more about Quadraphonic stereos and it's music.

There is a Wikipedia site that discusses the several techniques by
which the four channels of information could be stored on LPs.

http://en.wikipedia.org/wiki/Quadraphonic

BTW, I refer to equipment that reproduces four channels of information
as four-channel equipment, not as Quadrophonic or Quad. There is a
company in England, the Acoustical Manufacturing Company, that sells
equipment with the trade name Quad, most notably electrostatic
loudspeakers.