Haeco-csg

The HAECO-CSG or "Holzer Audio Engineering-Compatible Stereo Generator" system was an analog electronic device and method developed by Howard Holzer, Chief Engineer at A&M Records in Hollywood. His company, Holzer Audio Engineering, developed the system in the 1960's, during the years of transition from monaural to stereophonic popular music recording.

The reason for the process was the stereophonic/monophonic compatibility issue: the lead vocals and instruments, appearing in both the left and right channels of a stereophonic mix, would often sound too loud to the mix producers when they heard them playing back on monaural AM radio stations and record players, because when the left and right channels were added together, the lead vocals or instruments, being equal in level on both channels, would add up to be 3 decibels louder than the mix in Stereo.

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 worked by actually taking the right audio channel and shifting it electrically 90 degrees out-of-phase with the left channel, so that when played back in mono, the mono mix would cancel out the center instruments and singers by the corresponding 3 decibels.

Unfortunately, the system also "blurred" the focus of the lead vocals and instruments panned to the center, making headphone listening particularly un-natural sounding, as the lead vocalist or performer's audio waveform would be attempting to partially cancel itself inside the listener's head, confusing the brain's audio positioning sense.

Of special note is that the system did not employ a delay; instead, it electrically rotated the phase of the waveform amplitude by 90 degrees, treating all frequencies equally.

Many A&M releases during the period (most Sergio Mendes and Brasil '66, Herb Alpert and the Tijuana Brass, for example) were released with this audio process. Other labels soon followed suit, and an estimated 10% of all stereophonic albums released during the late 1960's and early 1970's employed the system.

The system was applied at the master tape mix session; therefore many Compact Discs of those albums still are "encoded" with the system, causing a "blurring" effect, even on modern digital players.

The system can be removed in a re-mastering session by digitally re-rotating the right channel back 90 degrees. Specialty remastering services such as Penteo specialize in performing this process. The automatic phase-correction tools in programs such as Adobe Audition are unable to properly detect this system and are unable to remove the system's encoding on their own.