"MACALLA." Clannad. RCA. There's a grave, dignified beauty swelling from every cut of this Irish family's second U.S. LP. Over the course of their last few albums pure-voiced Maire Brennan and her male counterparts (two brothers and their twin uncles) have moved beyond straight folk, introducing more electric instruments and a slightly jazzy flavor without sacrificing their music's resonantly traditional feel. Indeed, this group is special exactly because it maintains a respectful faithfulness to its roots (several songs here are sung in Gaelic, and the record's title means "echo" in that ancient language). Even the more upbeat tunes maintain an aura of sweet Celtic mystery and timelessness. Icing on an already rich cake is Bono Hewson's searing, soaring harmonizing with Maire on "In a Lifetime."