LPs, it's so full of surprises and left-field humor it may keep you off balance for a little while.

Part of the reason for this is Cooder's own unpredictability and adventurousness. There's never any telling how he's going to come at you from one record to another. There are some constants, of course: the peerless musicianship, the whistle-clean and sunburstvivid production, a certain kind of easygoing funk that seems as simple as a shrug when you hear it but comes as hard as an apology when you're trying to lay it down in a studio. The musical territory Cooder passes through is tough to reckon, even when it's been charted. Sometimes, as with his Hawaiian explorations, he moves right off the map.

Cooder has endured the same fate as many originals. His struggles to avoid categorization have resulted either in critical confusion or in a frenzy to nail him down once and for all. He's been dealt many cards of identity: blues acolyte, lapsed folkie, archivist, revisionist, eccentric. In one way or another, at one time or another in his career, most of these labels have pertained. But they'll do you as much good in dealing with Bop till You Drop as a bunch of Burma Shave signs will in guiding you through the Holy Land.

It's pretty much assumed about Cooder that, because of his folkie past, he's some sort of zealot for authenticity. And that, because of his heated disinterest in most contemporary rock music, he's some kind of purist playing his lonely bottleneck to lead us through the wilderness. Bop till You Drop is resoundingly unauthentic, if your understanding of authenticity means imitation and duplication. (Leave that to George Thoro-good, Robert Gordon and the students in the blues-guitar seminars.) Cooder's after an approximation of the feeling and the texture of the originals. But what he hears in them is so unique that knowing his sources (which, on this LP, run from Arthur Alexander and Elvis Presley to Ike and Tina Turner and Howard Tate) is of no particular advantage to the listener. Cooder recasts these songs in such a radical fashion that he almost reinvents them.

When Ry Cooder talks about going for a Stax/Volt sound — as he has in relation to Bop till You Drop — he doesn't mean stalking Booker T. He wants that texture of informal dynamism, the unruffled intensity of the groove, but, finding it, he wants to push it further so it stands fr