jan 1, 1950 - Direct to Mono Recording was found here

Description:

In this era recording was quite limited tape recording was quite expensive so artists
had to record in one take.
There was hardly any post production
any production that was added to a track had to be added to the whole track
It was first recorded in stereo but because it was there was only one speaker it would be produced in mono
There was only 2 channels one for vocals and one for everything else
There was also sub mixing here where many mics were dedicated to one channel
any editing was done with a slicer ata a diagonal slant for cross fade