SUMMER ALBUM ROUNDUP : *** JOAN JETT & THE BLACKHEARTS, “Pure and Simple”; <i> Warner Bros.</i>

Plain and simple is more like it, for Jett’s music is anything but pure. Here, almost exactly as on her previous solo outings, she jumbles together a panoply of influences ranging from doo-wop to moptops, with particularly heaping measures of late-’70s punk and mid-’60s bubblegum.

What makes “Pure and Simple” so gratifying has little to do with any climactic evolution in Jett’s sound, though the collaborations with hit songwriters Desmond Child and Jim Vallance meld melody with muscle more seamlessly than she ever has before.

Rather, the record’s contemporary punch stems from the current underground celebrity of riot grrrls and their more mainstream ilk. Coming from someone else, Jett’s paean to this nascent movement, “Activity Grrrl,” and recruiting members of Bikini Kill, L7 and Babes in Toyland to write and sing with her might smack of bandwagon-ism. But as a pubescent, leather-clad guitarist of the infamous Runaways back in the mid-’70s, Jett practically invented the genre--or at least the attitude that fuels it.

True fans will want the album, CD and tape because each varies slightly, with the LP version--natch--including an extra pair of all-out rockers.

New albums are rated on a scale of one star (poor) to four (excellent).