This Audio Academy link from 2019 (via Hacker News) about the Grateful Dead and its sound engineer Owsley “Bear” Stanley is fascinating. Live music amplification is mostly taken for granted these days, but it wasn’t alway the case.

It was a time when live sound problems plagued engineers, bands, and audiences equally. While rock concerts grew in size and scope throughout the 60s, audiences grew larger and louder, without the technical sophistication of amplification ever changing to meet this scenario. Screaming fans meant that low-wattage guitar amps could hardly be heard and without the help of monitoring systems, bands could barely hear themselves play. Things were so bad that the Beatles quit touring in 1966 because they couldn’t hear themselves over the audience. It was after this era that the band, the Grateful Dead, became obsessed with their sound, largely thanks to their eccentric and dedicated sound engineer.

Their solution was the famous “Wall of Sound”:

The mammoth structure was massive, made up of over 600 hi-fidelity speakers that sat behind the band as they played. It used six separate sound systems which were able to isolate eleven separate channels with vocals, rhythm guitar, piano each having their own channel. Another channel each for the bass drum, snare, tom-toms, and cymbals. The bass was transmitted through a quadraphonic encoder, which took a signal from each string and projected it through its own set of speakers. The result of each speaker carrying only one instrument or voice at a time was crystal clear audio, free of intermodulation distortion.