Haeco-csg
From Wikipedia, the free encyclopedia
The HAECO-CSG or Holzer Audio Engineering-Compatible Stereo Groove system was an analog electronic device and method developed by Holzer Audio Engineering in Los Angeles in the 1960's during the years of transition from monaural to stereophonic popular music recording. The lead vocals and instruments in a stereophonic mix would often sound too loud to the mix engineers when they heard them playing back on monaural AM radio stations and when played on monaural record players, because when the left and right channels were added together, the lead vocals or instruments, equal in level on both channels, would add up to be 3 decibels louder than any instruments in just the left or right channels alone. The idea beind HAECO-CSG was to create stereophonic records that when played on monaural equipment and radio stations, would "fold-down" to monaural properly.
The system actually took material intended for the center and phase shifted it so that it appeared both in-phase and 90 degrees out-of-phase simultaneously, so that when played on a monaural player, the out-of-phase material would lower the center-panned material by the 3 decibels, allowing the monaural mix have to the same component levels as the stereophonic mix. Unfortunately, the system also "blurred" the focus of the lead vocals and instruments panned to the center, making headphone listening particularly un-natural sounding compared to a traditional stereophonic mix with a coherent, in-phase center, to which listeners of stereophonic material had become accustomed.
