The Chamberlin keyboard is a tape-based sample playback keyboard, invented in 1946 by Harry Chamberlin. It’s considered by many to be the first sampler, though it was primarily used as a sample playback keyboard.
According to stories, Chamberlin got the idea while recording himself playing the organ. He figured that if he could record and playback the organ, he could record other sounds and play them back, triggered by a keyboard.
Chamberlin went on to actually build 100 or more of his proto-samplers before his idea was “borrowed” to create the Mellotron. The Chamberlin has 8 tracks (Sound Effects, Trumpet, Flute, Cello, Organ, Violin, Female voice, Organ) and has stereo output.
Chamberlin’s story is featured in the excellent Mellotron documentary, Mellodrama.