Nearly four decades after ending his songwriting partnership with John Lennon, Paul McCartney still hasn't tired of insisting that he was the more experimental of the two. Just last month, he announced that he was hoping to finally release "Carnival of Light," the "lost" avant-garde piece that The Beatles recorded at his instigation back in 1967 but never released — not least because George Harrison deemed it too weird.

Whether that helps set the record straight once and for all remains to be seen. In the meantime there's this, a revival of McCartney's studio-based The Fireman project with producer Youth that's been billed as a return to his experimental roots. Considering that "Carnival of Light" is apparently a 14-minute sound collage of distorted instruments and random screaming, however, it's fair to say that his notion of "experimental" is a little tamer these days. There are no barriers broken on "Electric Arguments," no conventions upended — but it's the most interesting thing he's made in years.

Each track was written and recorded in the space of a day, and the resulting material has a rawness and spontaneity that you'd never have expected from a 66-year-old multimillionaire. Hopping from one genre to the next, the album finds space for everything from the blues-rock holler of "Nothing Too Much Just Out of Sight" to the Underworld-style techno of "Lovers in a Dream," by way of stadium-size anthems, folk and the Nick Cave-style Gothic ballad "Travelling Light."

It's enough to make you wonder if it really matters what the final verdict is on the music that McCartney made 40 years ago. The fact that he's still able to produce records this strong speaks for itself.