EVEN THOUGH rock's basic elements are the essence of musical simplicity, there have always been those who prefer to outfit the music in ambitiously complex arrangements. For Supertramp, that has generally meant jazzy chords, lush keyboards and rambling exposition, a strategy that tended to "make the group's sound seem more sophisticated than its mainstream pop instincts might otherwise have suggested.

But with "Brother Where You Bound," the group's first album since the departure of guitarist Roger Hodgson, Supertramp's self- imposed seriousness gets in the way, because tiny ideas are all too often expected to support vast pieces of music.

"Cannonball," the first single, is an eight- minute meditation on how the protagonist's lover done him wrong, while the title track, despite some wonderful keyboard atmospherics by songwriter Rick Davies and a searing solo from guest guitarist David Gilmour, boils down to some 16 minutes of "Don't Trust the Commies."

Martha Davis of The Motels is no Nietzsche, either, but where Supertramp's Davies goes in for blunt metaphors, Davis prefers punning. "Shock," the Motels' latest album, is filled with wry writing such as "Icy Red" and "Annie Told Me," where the lyrics' sense and sound feed off one another. Such word games, though, are only part of this album's appeal, for by maintaining a sense of scale equivalent to the high-tech flash of the band's arrangements, Davis is able to camp it up without ever overplaying her part.

SUPERTRAMP -- "Brother Where You Going?" (A&M ST-5014);

THE MOTELS -- "Shock" (Capitol SJ-12378); both appearing Saturday at the Patriot Center, George Mason University.