What's that sound? `Apple Crisp'

Just down the block from the juggler, the man dressed up in Colonial garb, and the guy trying to free himself from ropes, Avi Fagan and his son, Jonathan , 13, get their instruments ready for another day of music near Faneuil Hall.

``You got power there?" the father asks.

``Actually, no," the son replies.

``You got power now?"

``No," Jonathan says again.

His father goes to work. This is not a problem. Avi Fagan, 40, is a sound engineer by trade. With a flick of a switch, he gets Jonathan's keyboard plugged in, and then he returns to assembling his vibraphone -- a 36-key, xylophone-shaped instrument -- while Jonathan gets their tip box ready.

This is the life of a street performer -- a life that, officially anyway, begins this weekend with the street performers' festival in Faneuil Hall Marketplace. It kicks off yet another Boston summer of one-man bands and statue people, unicyclists, and balloon twisters. There is a husband-wife team known as the Yo Yo People and then there are the Fagans, a father-son team, known as Apple Crisp, starting their second summer at Faneuil Hall.

They play contra dance music -- traditional folk music, catchy jigs, and reels -- and they are not here for the spare change that people throw their way. They are here for the music, the Fagans say, and to play together. But it would be nice if they could cover their parking costs, and maybe their meals for the day, with the tips that tourists and others offer.

And so, Jonathan sets up the tip box and pulls out a plastic bag with five $1 bills. He takes the bills one by one and then scatters them in the box. It is seed money. It is time to play. Their four-hour set begins now.

``There you go," his father tells him. ``Nice."

Jonathan Fagan began playing piano six years ago, but his mother, Susan Kline , believes that his interest in music, and in sounds, dates back to before he could even talk.

``He always seemed to be listening to something," she says. Background music. Radio sounds. Even the tunes piped into supermarkets. ``It just seemed to be who he was."

He learned at a young age to play the recorder and the glockenspiel and later started to play classical piano. But it was out on the streets with his father's Beatles cover band that Jonathan Fagan first began to play for the public, however indifferent they might have been. There, in Harvard Square, wearing his Red Sox hat, Jonathan, who now lives with his mother in Arlington, played tambourine, even a cowbell, Kline says. Anything to be close to the music.

But it soon became clear that he was too talented to be stuck playing a bell. And about 2 1/2 years ago, he and his father set out to play together as peers. They formed Apple Crisp, the pair separated by 27 years in age but joined by blood and the love of contra dance music.

``This is the kind of thing where you walk into a dance hall on a Thursday night and there are 400 stamping feet," says Avi Fagan, who lives in Watertown. ``Young people, old people, people of every age. And you talk to people and they say, `I didn't even know this existed.' "

The music is, at its core, folk dance music -- jigs, and reels, and an occasional waltz. There are dance steps to follow. Contra dancing is often likened to square dancing. Think fiddles and accordions, the sort of music one might hear in a pub or perhaps long, long ago. ``Contra dancing," one website for beginners says, ``was all the rage in 1800."

But it still has a local following. Contra dance nights can be found locally from Medford to Concord, Worcester to Woods Hole. And when Jonathan Fagan heard the music -- music his father had loved for years -- he was hooked, he says, on its sassy, lively sound.

They hit the streets, playing in Harvard Square and then, last year, in Faneuil Hall Marketplace, a location so coveted that every April would-be street performers must actually try out for a limited number of spots. This year, fewer than half of the 85 acts that tried out got accepted, and Apple Crisp, for the second year in a row, was one of them.

``We are Apple Crisp," Avi Fagan tells the crowd one recent Sunday. The band, named for a food like other contra dance groups, begins to play, father and son making eye contact over their instruments, nodding, tapping their feet, shifting keys and songs on the fly, seamlessly. People gather around and listen.

Their crowd isn't as big as the one watching the juggler down the block or even the man who has tied himself up with ropes. But people stop and listen. Children pause and want to play Avi's instrument and one mustached man keeps shouting ``More!"

``More?" Avi Fagan replies.

It's just after 11 a.m. The air smells like cookie dough. Summer has unofficially begun and Jonathan Fagan is thinking that maybe, just maybe, he could be a musician forever.

``It's what I like to do," he says. ``And what I do best."

Got a subject to suggest for Heart of the City? E-mail Keith O'Brien at kobrien@globe.com