This is a guest post by Barry Gardner, the mastering engineer who operates SAS audio mastering services.
The first stereo records were made in the 1930’s and yet it took a long time to popularize the new format and release such recordings for mass consumption. Mono recordings were the standard for many years whilst various attempts were made to advance stereophony. In music production itself there has almost always been a mono button built into the master section of large format stereo or quadraphonic mixing consoles. It was there for good reason as stereo recordings had to maintain sonic compatibility with AM sound systems and monophonic broadcasts amongst other reasons.