tape recording was stereo 1956, LP stereo cutting 1958.
Major labels like Columbia had deep enough pockets to hire double the engineers and pay double the cost of labor to have two separate teams simultaneously working on the mono and stereo versions of an album. But Van Gelder enjoyed working alone, and Blue Note couldn’t afford such a robust staff anyway. Was there a way for the engineer to create both the mono and stereo master lacquer disks from a single session tape?
If he only recorded to full-track tape it would have been impossible to create a stereo master from that tape, and recording to two-track tape only would have initially seemed like an unattractive option since Van Gelder did not have a stereo monitoring system in his Hackensack studio.
But just when all hope for the desired simplicity seemed lost, Van Gelder, known to be quite resourceful in the studio, realized a third option: if he made both the mono and stereo LPs from a single two-track tape, he didn’t have to monitor the sessions in stereo. In other words, even if the music was being recorded to two tracks, he could still do all the recording and mixing during a session while listening to a single speaker. That way, when he went to create the mono master disk later, as long as he summed the channels together at equal volumes during the session, all he would need to do was sum them back together again the same way and he would hear exactly what was heard during the session. He called this clever method of getting two recordings for the price of one “the 50/50 system”, and on Halloween 1958, Art Blakey’s Moanin’ (BLP 4003) became the last Blue Note album ever to be recorded to full-track tape by Van Gelder.