My grandpa was a rascal and a fiddler. Now, it’s not absolutely necessary to be a rascal in order to play the Scottish fiddle, but “attitude” is definitely required. That’s what more than a hundred musicians will be wearing – along with their tartans – as they arrive in Salinas for the San Francisco Scottish Fiddlers’ concert April 25 at Sherwood Hall. Members of the ensemble will be happy to tell you that “attitude” is the difference between a violin and a fiddle. Violinists play from the page, fiddlers learn from each other. Violinists play the notes, fiddlers bend them. Violinists perform together in orchestras, fiddlers – at least this ensemble – come together in what seems like an unruly rabble before it moves together miraculously into a complex tune at a breathtaking pace. I saw it happen last year: The stage is packed with kilties from pre-teen to codger age, whose musical backgrounds range from a few months of lessons to decades of practice, from rank amateurs to international touring musicians – some prim, others like wild-maned tribesmen just down from the hills – all galloping gleefully toward a shared conclusion. One man is holding the reins. That would be Alasdair Fraser.

“I’m inviting people to go on an exploration with me,” says Fraser. “We’re all traveling together, empowering, sharing, and I let the musicians know I’m available to go off in different directions depending on what they want to do. It’s totally exhilarating.”

Fraser came to the U.S. from Scotland about 25 years ago: “There seemed to be a hunger for this music.” He established the San Francisco Scottish Fiddlers in 1986 and the Valley of the Moon Scottish Fiddling School shortly thereafter; now he directs camps in the U.S., Canada, Scotland and Spain. He recorded numerous CDs, performed on more than 50 albums as guest artist and on the soundtracks of The Last of the Mohicans and Titanic. Fraser is considered one of the finest interpreters of the Scottish fiddle in the world: a force behind the resurgence of traditional fiddling.

“Alasdair is about expressing what you feel, playing with the music, not just playing it,” says Larry Espinosa, a Prunedale fiddler of mixed Mexican-English heritage who finds that Scottish fiddle music “takes you to unusual places in delightful ways.”

All of its forms share the conspiratorial wink behind a long glissando that takes the song into another chord, bending a note or two. It’s the music of the “folk,” where you also find the blues, Appalachian roots music, old-time fiddlers, Qawwali, Balkan gypsy music, flamenco, fado.

“I could be playing an old Gallic song in Estonia that will move the whole audience, you can feel it; we don’t have to go very deep to reach that common place,” Fraser says.

Onstage at Sherwood Hall, scores of fiddlers are joined by dozens of drummers, bassists, flautists, guitarists, harmonica and concertina players and a hearty cello section. Cellist Natalie Haas studied with Fraser as a kid in his Valley of the Moon camps, graduated from Julliard and returned. The duo made two CDs; Fire and Grace won the 2004 Scottish Traditional Album of the Year. “The cello works down there in the engine room, getting a rhythmic groove going,” he says.

It’s safe to predict during “The Night Poor Larry was Stretched” or “The Arms Dealer’s Daughter” that rhythmic groove will propel a few dozen dancers to the foot of the stage and bring the whole audience to its feet, grins in place.

THE SAN FRANCISCO SCOTTISH FIDDLERS perform 7:30pm Saturday, April 25 at Sherwood Hall, Salinas Community Center, 940 N. Main St., Salinas. $20/general, $12/children 12 and under. 758-7477, www.scottishfiddlers.org.