George: When they invented stereo, I remember thinking "Why? What do you want two speakers for?" Because it ruined the sound from our point of view. You know, we had everything coming out of one speaker, now it to come out of two speakers, it all sounded like, very naked.
Paul: But then finally someone said "Well, you can like move things". So like then everything from then on got panned like mad, you know, everything got moved.
George: But to get to the point where you do a stereo mix and put the drums and bass in the middle, it took a while... it used to be over on the side!
— The Beatles on the invention of stereoFor a long time since the beginning of recording technology, most recordings were monaural (reproduced on a single channel), in spite of explorations by Clement Adler starting in 1881, and Bell Laboratories in the 1930s under the direction of Harvey Fletcher. The first stereophonic disc was released by Audio Fidelity in November 1957 and the technology quickly took off, by 1968 all major record labels having stopped manufacturing monaural records. This all happened at the same time that rock music was rapidly becoming very psychedelic or garagey, and as a result many people in the studio probably couldn't resist the temptation to show off with their new technology. So, we got many albums from the mid-sixties up to the early-seventies (sometimes) that isolate various tracks on separate channels, or heavily employ fancy panning effects, as if avoiding the center was a matter of life and death. This description does not mean to imply in any way that this is a bad thing. There are often good reasons to use stereo separation, such as allowing instruments to be heard more clearly than the usual lump-everything-in-the-center approach. It is a sort of musical equivalent to Science Marches On and Zeerust as this sort of production tricks aren't as widespread anymore. Plus, if you're a producer who wants to sample a bit of a song, you'll probably pray for this sort of thing - easier to get a song where the drums are on the right and everything else is on the left, sample it and cut out the left channel, than one where everything is centered and you have to use the extraneous bits as well or break out the EQ. This is also used to great effect in motion picture sound. It allows sound to be matched to moving visuals. Theater and home surround sound systems have between five and eight channels to play with; using multi-channel surround in music is still largely experimental, if only because headphones only have two channels. The intended effect can be altered by the playback equipment. Two speakers mounted side-by-side in a single cabinet have more crossover than two mounted in opposite corners of a room, and headphones have none at all. Historically, the decline of the "guitar on the right, bass on the left" type of mixing came about as albums started being recorded on 16 or more tracks, which makes it easy to double-track every instrument. When your mix already has two or more guitars playing the exact same part for the "fatness" this provides, the natural tendency is to spread them out over the stereo field. Led Zeppelin and Black Sabbath were some of the early bands to do this, although not all the time as the examples below show. Likewise, when you have enough tracks to give each individual drum its own separate stereo position, its highly unlikely you're going to mix the entire drum kit to one side unless you're deliberately trying to invoke the 1960s. Has nothing to do with the practice of critically lambasting a work without restraint, at least not inherently.