Audio reproduction formats have been in flux since the first cylinder spun over at Edison's workshop. The mechanical "horn" system of playback, used on those early recorders and 78 players, gave way eventually to electro-mechanical contraptions using a stylus and a speaker. Doubtless there were listeners who decried this "move forward" as ruining the sound of music as they knew it. By the late '60s, matrixed dual channel encoding on vinyl led to the two speaker "stereo" system. Initially producers, engineers and artists ignored this "advancement", preferring to spend most of their time mixing the mono versions of albums and leaving the stereo mixes as late night fun for the assistant engineers. As stereo won over, engineers had to develop new ways of mixing to accommodate the dual speaker beast. Producers like Phil Spector, who had spent ages learning to coax depth out of a single speaker, suddenly had to figure out a new game plan for using stereo. Panning instruments in approximate positions of a stage appearance or crazily putting mics all over single instruments to make them "stereo" began in earnest. But quad was in the development stages. Soon there was utter chaos as hopped-up rock bands felt the need to pan solos and sound effects around and around in crazy patterns, with no regard for solid stereo imaging. Luckily this didn't last too long.