The special chemistry of the roots-rock band NRBQ was seriously dampened five years ago when mainstay Al Anderson left to pursue a successful Nashville songwriting career. Group founders Terry Adams and Joey Spampinato replaced their burly guitarist with Joey's kid brother Johnny and recorded two live albums and a children's album, but it wasn't the same. It took Johnny a while to learn the band's inspired mix of elegant popcraft and irreverent juvenilia. It took Adams and Joey a while to restock the group's song closet without Anderson's help.

"NRBQ" is the quartet's first adult studio album in five years, and it finds the group back at the peak of its powers. Johnny finally sounds comfortable in NRBQ's chaotic soundscape, adding catchy, succinct guitar bits as if herky-jerky tempos and quirky chord changes were the most natural thing in the world. Joey has again written some lovely, McCartneyesque pop songs--especially "Sail On Sail On" and "Breakaway to My Dreams."

Adams applies his demented worldview and savage sense of syncopation to such topics as "Termites" and the "Puddin' Truck." Best of all is "Housekeeping," his battlefield report from the endless war between musicians and hotel maids.

NRBQ is celebrating its 30th anniversary this year. To mark the occasion, Adams has revamped the group's landmark 1977 album, "All Hopped Up," by adding four previously unreleased tracks, remixing two others and re-sequencing the 15 tracks to create a new album called "Ridin' in My Car." The new tracks include a remake of Bill Justis' rockabilly oddity "Chicken Hearted," lost songs by Adams and Joey Spampinato and a wobbly high-school-marching-band version of Anderson's classic title tune.

Appearing Friday at the Birchmere and Saturday at the Rams Head Tavern.

For a free Soundbite from "NRBQ," call Post-Haste at 202/334-9000 and press 8127. For a Sound Bite from "Ridin' in My Car," press 8128. (Prince William residents, call 690-4110.)