Produced by Butterfield keyboardist Mark Naftalin, Strawberry Jam showcases the group's live heat in a series of nightclub performances from 1966 through 1968. Butterfield was a powerhouse, a percussive harpist and disciple of Little Walter and Magic Sam. He was a master both of speed and of clean, stinging tone.

His growling vocals here are marvelously engaging, while his band keeps pace with fierce intuition. The Butterfield band was grounded by the bass of Howlin' Wolf alumnus Jerome Arnold – check his fleet fingers on the rollicking "Cha Cha in Blues" or on Butterfield's signature tune, "Born in Chicago." The ensemble shines on a stately, chiming-guitar version of Willie Dixon's "Tollin' Bells" and credibly revives such war horses as "Rock Me" and "Mystery Train."

Butterfield could also work his harmonica like a jazzman's horn, as demonstrated on the standout title track. The 11-minute "Strawberry Jam" spotlights a young David Sanborn heading the brass section that often accompanied Butterfield in the late '60s. And throughout the album, Elvin Bishop delivers the feisty guitar that later earned him Southern-rock hits. A vital intro, Strawberry Jam reminds us that the blues remains unbound by time and circumstance. Instead it's the swing of the thing that counts.