Sharon Isbin, Larry Coryell and Laurindo Almeida have this much in common: each plays the guitar. Beyond that, however, their similarities dwindle; they rely, in fact, on their dissimilarities. "We are each known as soloists in different fields," says Isbin, a classical guitar virtuoso. Coryell is a pioneer of the jazz-rock fusion movement, and Almeida plays both Brazilian bossa nova and classical guitar. When their styles and schedules converge, as they will at Wolf Trap's Barns on Friday at 8 p.m., they are the trio known as Guitarjam.

The group evolved out of happenstance. Isbin, coordinator of last May's international guitar festival at Carnegie Hall ("Guitarstream '85"), had invited Coryell to perform at her festival. Coryell and Almeida had already planned a concert after "Guitarstream '85" finished, and were looking for a third guitarist. Isbin agreed to join them. The three-guitar, three-style concert "was such a novel idea that it just took off," says Isbin. They have since recorded an album, "3 Guitars 3."

Guitarjam's program will include works by Coryell, Falla, Nazareth, Gnattali and Debussy. Coryell will play Ravel's "Bolero" -- "in a form that you have never heard in your life," says Isbin. "It is stunning. Truly stunning. And it becomes a new creation with jazz influences and improvisation."