On a warm Saturday evening early this September, the classical strains of two violins and a cello resonate in the entrance to the Coop, mingling with the constant roar of Harvard Square traffic and an occasional siren. Around the Square's busiest corner, at Brattle and Palmer near the Coop Annex, a woman guitarist wails a Joni Mitchell tune into a portable microphone and amplifier in her own musical fight against the motorized bustle. The classical musicians and the lone woman each grab a portion of the nighttime crowd, but the audiences are largely transient. The onlookers stay for a song, maybe a few. They often drop some spare change before continuing with their plans, or looking for some.

But a little further down Brattle, tucked in The Gap's store front, a large gathering clots this otherwise fluid urban scene. Facing those who till the sidewalk and spill into the street, a burly, bearded man clad in a tuxedo jacket, narrow pink tie and baggy army fatigues finishes the Motown milestone "My Girl." An elderly gentleman steps forward and drops a bill into the open guitar case. "We should all learn from this man tonight," bellows the musician, mocking the voice of Sunday morning TV-gospel preachers. The crowd laughs, and some swell toward the case appreciatively. The guitarist asks those at the back to move up to the curb to avoid blocking traffic, then gets all singing and many dancing to his one-man version of the Beatles' "Twist and Shout." It is a happy inter-generational, inter-racial scene. Cars and buses scream by, and some beep.

***

Keyo Meyreles has a headful of hair now. He calls it his "winter look." And it is a sharp contrast from the bald-except-for-a-crescent-at-the-hairline style that was as much his trademark as the tuxedo outfit when he became a Harvard Square favorite this summer.

The baldness and crazy clothes characterized the New York City native, but they were not what distinguished him nightly from the myriad other performers who swarmed the Square during the city's renaissance of free, street entertainment this summer. Rather, a blend of showmanship, spontaneity, interaction with the audience and use of a talented, wide-ranging voice drew passersby and regulars to Meyreles's evening mix of popular tunes and snazzy original numbers.

On any given night through September, Meyreles might grab a woman from the crowd and lead her through dance steps, or pair couples blindly. He regularly enlisted a group of Tim Curryesque wrist-flickers to help him lead into his funky rendition of "Sweet Transvestite" from "The Rocky Horror Picture Show." And a song dedicated one night to his girlfriend might be prefaced the next by "a song for the one I used to love." Meyreles always combined uniques versions of recognizable songs or catchy originals with a fresh brand of unpredictable theatrics. And--just as dependably--he cultivated smiling faces.

But, as New England winter winds stir, Meyreles's hair is growing back, and he may replace the outfit he's worn in the streets for the past two years. "Just the other day I said to myself, this is going to end, too--this uniform. I think I'll go through a new stage," the smooth musician says, off the streets and in a coffee house. At a time when the legion of street musicians splits somewhat frantically for the subways, coveted club gigs and regular jobs, Meyreles confidently plans a departure from the street musician life, where he has made his living for three years.

He talks of putting together a "new fashion" and how he may once again have to think when he goes to the closet. And he laughs his stacatto laugh, as he often does. But he is really very serious about "the beginning of something new." Since closing his guitar case on the streets in September, Meyreles has formed a band with sidekick saxman Kent White, including a guitar, bass and drums. He wants to record an album very soon, and do what he calls "music/theater--I wrote a oneman theater show for myself. I'm a late bloomer. I'm 27. And I've only been performing three years. I haven't even tapped into the things that I want to do," he says.

Next month, "Keyo and the Essentials" plan to record a single and send it to record companies. The musician realizes recording contracts are hard to come by, but is prepared to "do it myself." His sudden success as a street musician makes Meyreles's plans for further recognition seem viable. While working in the Seattle public school system three years ago, Meyreles needed three separate invitations from a friend before agreeing to take his guitar and talented voice to a Seattle public market. "I finally said, 'O.K. I got nothing to lose so I might as well go out there.' I made my first six bucks, and never left the streets after that," he recalls.

On the streets, the musician says he is in heaven. "I used to do drugs--I wasn't addicted--but I get my biggest high from the people who watch me," Meyreles says. "It's something I've always dreamed of since I was a little boy." And so for three years, first in the Northwest and then in Harvard Square, he ignored suggestions from friends who said he should put a band together and try to leave the streets for the big time.

Instead, he stayed on street corners refining his unique style. "We already have Joni Mitchells and Bob Dylan and we have all these other people others try to sound like. It's too bad people can't express themselves, and do exactly what they want to do," he says. "If I sing somebody else's song I make it sound different. I make it sound like Keyo. If you listen to the song 'Miss You,' it doesn't sound like the Rolling Stones."

But now, despite a relatively comfortable street income, Meyreles has decided it's time to move on. "It's time to kind of bring it indoors, I can't sing forever in the streets 'cause I don't want to ruin my voice. I don't pace myself. If my voice is going to die out, then I want to make sure it dies out at least having given me a chance to try and get a better position in my field." What kind of position? "Like Madison Square Garden," he says with big eyes, and then a stacatto laugh. You see, Meyreles explains, "I've always had this dream of...well, being famous."

***

The air is cold and couples snuggle. But Keyo Meyreles is busy generating warmth for a receptive Square crowd which banters with the musician and tosses requests and quarters his way.

Most of the late September crowd seems to have heard Meyreles before. This is not the first time he's welcomed them "to Harvard Square, where you come to look for people crazier than you are." "That's why I'm out here," the musician says, peering into the audience. And the people still laugh.