Generally, we don't expect a lot of oomph when a soap-opera star records an album. And, if the songs are from the series itself, maybe we expect a commemorative album rather than serious music. But when Colombian crooner Carlos Vives cut 40-year-old loves songs, nobody blinked. Vives didn't leave his audiences yawning in Madrid, nor at Radio City Music Hall in New York. And his first-album sales of 1.5 million are remarkable even by rock standards. Vives put a folk music called ''vallenato'' on the international scene, riding the wave of successful Spanish-language singers in the United States. His tour to promote his new album, ''Tierra del olvido'' (''The Land of Forgetting''), will hit Hispanic-population centers, tapping the 20 million or so Spanish speakers in North America. Vallenato was a marginalized folk music from Colombia's predominantly black Caribbean coast until the Vives phenomenon struck. Although vallenato has always promised virtuoso accordion playing and striking poetic lyrics, it rarely found its way into upper-class living rooms and was instead appreciated in more bohemian venues. Colombian author Gabriel Garcia Marquez is also from the Caribbean coast. A vallenato aficionado, he once called his Nobel prize-winning ''One Hundred Years of Solitude,'' ''a four-hundred-page vallenato.'' Vives is from the coastal city of Santa Marta and grew up humming a lot of the angular vallenato melodies. He added a rock beat, a drum kit, and a guitar to the traditional scraper-accordion-drum trio. The fact that he is white is not missed by many. Vives's fair complexion gave the vallenato just the touch to make the music crossover into the compact-disc crowd. Bob George, at the Archive of Contemporary Music in New York, says that parallels between Vives and Elvis Presley, who commercialized the blues, are obvious. ''Someone brings their own magnetism, their own style, to a music that was pretty much created by another race, and because they are white or European, manages to sell it to a larger audience. He looks like a rock star, but he's playing vallenato,'' George says. Does Vives see himself as the Elvis Presley of the vallenato? ''I wish!'' Vives said at a rehearsal for his tour. While Vives does admire Elvis's success, he plays vallenato for sentimental reasons. ''It comes from the heart of where all this music was born. Maybe for the lack of technological revolution, there's a certain conservation of traditions, certain ways of treating people. If you come to a little town, it's important to that town; they take care of you, they put you up. If there is no hotel, they put you up in someone's home. There are a lot of things in these towns that are expressed in their music. It's different - it's the provinces, it's the third world.'' Few resent Vives's success, nor the changes he has made to the music. Instead, he is credited for unlocking the power inherent in the vallenato and showing it to the world. Vives played the role of Colombia's greatest vallenato composer, Rafael Escalona, in the soap opera ''Escalona,'' which has been syndicated in the Spanish-speaking world - including Spanish stations in the United States - and even China. Escalona's life typified the hard-drinking, womanizing vallenato musician. His lyrics - which, like the blues, pay little attention to political correctness - sing of the hard lives of Colombia's coastal smugglers or sugar-cane cutters and of the beauty of the land. Escalona said that this music was created as a means of expression in an area that is for the most part illiterate. He chose to be a composer because he was one of the few people who could read and write. The vallenato musicians were troubadours who sang the news. Escalona says he still writes songs that way. ''In my provincial town, there was no radio nor television. The news was by word of mouth. And it's still that way, and it's the story of the lives people live - or lived.'' From the perspective of a world-beat musician, the globe is a salad of musical ideas, to be pilfered at will, renewing and mixing local music with faraway influences. African musician King Sunny Ade plays with Stevie Wonder, or soul gets mixed with calypso to make ''so-ca.'' The vallenato qualified as ''world music'' even before the term was invested. The accordion came to Colombia from Germany and is still imported from there. The single-headed drum was contributed by Africa's descendants. The coastal Indians donated the ''guacharaca,'' a metal scraper played with a wire fork that drives the music as does the Cajun washboard. For the Colombians, these three instruments are a metaphor for the great cultural mix that is the Americas. It is to a degree why few take exception to Vives's success. r Vives will appear at the Masonic Theatre in Los Angeles, Sept. 2 and 3; the National Auditorium in Mexico City, Sept. 9; Gimnasio Nacional in San Juan, Costa Rica, Sept. 14; the Hotel Panama in Panama City, Sept. 16 and 17; and San Juan, Puerto Rico, Sept. 29 and 30 and Oct. 1. Vallenato was a marginalized folk music from Colombia's predominantly black Caribbean coast until the Vives phenomenon struck. Before then, it rarely found its way into upper-class living rooms and was instead appreciated in more bohemian venues.