For some inexplicable reason, Celtic music’s increasingly dumped into the catch-all bin labeled New Age, whose “soothing” instrumentals are perceived as kin to Celtic flutes and whistles. Rightly or wrongly, the Irish extravaganza “Riverdance” has long since become a punchline, so…

Who’s buying all those Celtic-flavored, New Age-y albums?

Consider “Celtic Woman,” a grandly produced collection of Irish perennials (“Danny Boy”), classical faves (“Ave Maria”), pop (Enya’s “Orinocco Flow”) and syrupy compositions by artist/ producer David Downes (a former musical director for “Riverdance”) dressed in the requisite New Age shimmering synths. Its success isn’t on the scale of “Riverdance,” but it’s a mini-phenomenon nonetheless.

Celtic Woman is an ensemble of five extremely talented and photogenic young women: single-named vocalists Chloë, Méav, Lisa and Órla and violinist Máiréad. Their album, which was released by Manhattan Records in March 2005, has had a death grip on the top spot of Billboard’s World Album chart for months. It’s spawned a stage show, DVD and popular PBS concert.

Prepackaged? You bet. Each of the women had already released solo albums and/or earned solid music and theater credits when they were brought together by Downes, artistic director Sharon Browne and executive producer Dave Kavanagh, who formulated the concept then cast the players. And, it should be noted, cast them well.

The most immediately striking aspect of Celtic Woman’s sound is the singing, which is technically flawless and so clear and pure as to sound spring-fed. Their vocal arrangement of “Nella Fantasia” is singularly beautiful, and Máiréad’s violin solos on the medley “Ashokan Farewell/The Contradiction” cause chillbumps. Most of the material, however, is a letdown, and the orchestration sounds copped from a Celine Dion record. Despite the Celtic musical canon being one of the meatiest in the world, the “Celtic Woman” song list favors more synthetic-sounding compositions like Downes’ “The Soft Goodbye” and “Someday” from the Disney toon “Hunchback of Notre Dame.” It’s not that they’re bad; they’re handsomely presented compositions that Josh Groban fans probably love. But they’re about as Irish as Irish Spring.

Anyone hungering for equally stunning singing of world-class Celtic music is advised to seek out recordings by Mary Black, Frances Black, Karan Casey, Dolores Keane and Altan’s Mairéad ní Mhaonaigh. Celtic music lovers aren’t the real target audience for “Celtic Woman,” although most of the cash cow’s CD and ticket buyers probably have at least one Enya album at home. More than likely, it’s the millions of romance-loving fans who keep vocal acts Andrea Boccelli and Il Divo in business who are flocking to “Celtic Woman.” Too bad Mom lives so far away; this is one show she could enjoy without earplugs.