Steppenwolf may have been the first if it had come out before The Kinks came out with You Really Got Me.
The first documented use of the phrase to describe a type of rock music identified to date appears in a review by Barry Gifford. In the May 11, 1968, issue of Rolling Stone, he wrote about the album A Long Time Comin' by U.S. band Electric Flag: "Nobody who's been listening to Mike Bloomfield—either talking or playing—in the last few years could have expected this. This is the new soul music, the synthesis of white blues and heavy metal rock."
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The first documented use of the phrase to describe a type of rock music identified to date appears in a review by Barry Gifford. In the May 11, 1968, issue of Rolling Stone, he wrote about the album A Long Time Comin' by U.S. band Electric Flag: "Nobody who's been listening to Mike Bloomfield—either talking or playing—in the last few years could have expected this. This is the new soul music, the synthesis of white blues and heavy metal rock."