Born of Swedish American parents in St. Louis in 1925, Callen Radcliffe Tjader Jr. would have seemed an unlikely candidate to become a champion of Latin jazz. But as pianist and arranger Eddie Palmieri once described him, Cal Tjader "was the Clark Kent of music."

Tjader actually started as a dancer (his father was a tap dancer) before taking up drums. In the late '40s, he joined Dave Brubeck's adventurous octet, and when the pianist reformed it as a trio, Tjader took on added duties, playing bongos and vibes. After leaving Brubeck in 1951, he freelanced and led his own groups. Two years later, he joined pianist George Shearing's quintet as a vibraphonist.

It was around this time, in a visit to New York, that he heard the great Latin bands of Machito, Tito Rodriguez and Tito Puente, was fascinated by the music and set out to organize his own Latin group. He did, leading superb small Latin jazz ensembles for almost three decades that featured musicians such as the late Mongo Santamaria, Willie Bobo, Carlos "Patato" Valdes, Armando Peraza, Manny Oquendo and Jose Mangual. (He also featured for a while a pretty good young pianist and arranger: Chick Corea.) Tjader died in 1982.

At its best, Tjader's music was both commercial and substantive, and his sound an appealing blend of West Coast cool and Afro-Cuban earthiness. He had pop hits, such as "Soul Sauce" ("Guachi Guara"), but also landmark Latin jazz works such as "El Sonido Nuevo," his collaboration with Palmieri, then a young Latin music avant-gardist. "Concerts in the Sun," a new album of previously unreleased material, catches Tjader live in 1960 at concerts in Honolulu and Santa Monica, Calif.

This quintet was anchored by Bobo and Santamaria (whom Tjader had taken from Tito Puente's orchestra in 1957), and here, curiously, the jazz and Latin aspects of Tjader's music are presented separately. Of the 10 tracks, six are straight-ahead and four are Afro-Cuban tinged, including Santamaria's classic "Afro Blue." Tjader is in fine form throughout, now elegant ("Love for Sale"), now forceful and fluid ("Sigmund Stern Groove," his own "Raccoon Straits"). Bobo, best known for his work on Latin percussion, was also an excellent drummer, and he drives the group hard behind a regular drum kit on the mainstream tracks. But when Santamaria joins in, the force of their combination adds drama and tension, raising the stakes, and Tjader goes with it with seemingly casual grace -- and muscle. Suddenly the soft-focus glow of his vibes has bite. A Clark Kent moment indeed.

(To hear a free Sound Bite from this album, call Post-Haste at 202-334-9000 and press 8152.)