Before the birth of the digital sampler in the 1980s, the only way to get the sound of a genuine acoustic instrument was by using the Mellotron, which was born in 1962. The Mellotron could provide the sound of violins, cellos, choirs, horns, and many other real-world sounds by using strips of magnetic tape, a pinch roller, tape head, pressure pad, and a rewind mechanism for each note on the 3-octave keyboard. The tapes were installed on large frames that dropped down into the instrument and each frame could hold three sets of tapes. To change the sounds, a different frame would have to be substituted that held recordings of other instruments. To hear a sound, players would press a note on the keyboard, which would trigger the mechanism that pulled each tape strip across the tape head, which would then reproduce the sound prerecorded on the tape.
Because of the way in which the Mellotron produced its sounds, there was a limit of about seven or eight seconds of sound per note, after which the tape rewound itself to be ready when the same note might be played again. Thus the Mellotron was best suited to slower music, since the delay between the end of a note and when it was again able to be played was a limiting factor. However, shorter notes resulted in shorter delays, as the tape had a shorter distance to rewind. You can hear the Mellotron on almost every song on the Moody Blues albums, as well as The Beatles’ “Strawberry Fields Forever,” and on many albums by Genesis, King Crimson, Yes, and Led Zeppelin.