The newly opened Barns at Wolf Trap celebrate their first sold-out concert this afternoon with Trapezoid, a wonderful Appalachian string band that has expanded the parameters of its music to include jazz, swing, Irish tunes and chamber music. The sellout gives the promise of a quick return, but the band's synthesis of styles can also be heard on the marvelous "Now and Then" album on the Flying Fish label.

Paul Reisler, Lorraine Duisit, Freyda Epstein and Ralph Gordon have been evoking the spirit of that influential British group, Pentangle, without confining themselves to a particular type of music. For instance, a recent piece has been adapted from African kora master Ali Bai Konte; Trapezoid has transposed it for bowed psaltery, cello, dulcimer and violin. "We westernized it by organizing it," explains Duisit. "Konte's version is more flowing, rhythmical and changing, but with the string parts that we've worked out, it almost sounds classical."

Trapezoid also utilizes guitar, hammered dulcimer, mandolin, bass, mandocello and mandola and, according to Reisler, "We've all had some classical training and the combination of instruments gives us that unique sound." It also allows Trapezoid to cast a variety of American musics in a manner that is at once progressive and traditional. "The fact that we choose a lot of different musics reflects our different interests," Reisler says. "We choose material that works with our instruments, but for us it's really the texture rather than the surface of the material that matters."