The Alton Ellis reference article from the English Wikipedia on 24-Jul-2004
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Alton Ellis

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Alton Ellis was a Jamaican musician, best known as the innovator of rocksteady music. He began playing ska at the height of the genre's fame, recording for Studio One, but he reached his period of greatest popularity in the late 1960s.

Ellis was from Trenchtown, a poor area of Kingston, Jamaica, and learned to play the piano at a young age. In his teens, Alton and Eddie Perkins formed Alton & Eddie, scoring a hit with "Muriel". Ellis launched his solo career after Perkins left for the United Sates. He moved to Treasure Isle and began recording with the back-up trio The Flames. His first hit was "Dance Crasher", a plea for peace, and followed it u with "Get Ready - Rock Steady", perhaps the first rocksteady recording. The song was recording with keyboardist Jackie Mittoo playing the bass part because the bassist did not show up; Mittoo could not keep up with the ska beat, and the tempo was slowed down to accommodate him. This allowed for a choppier rhythm that led Ellis to expand his vocal range.

Ellis' most well-known song is probably 1966's "Girl I've Got a Date"