Johnny Cash, "American VI: Ain't No Grave"

The unlikely collaboration between legendary singer-songwriter Johnny Cash and producer Rick Rubin of Beastie Boys, Run-DMC and Slayer fame was an inspired final act for the career of an American treasure. Rubin's simple recordings highlighted the timeless nature of Cash's inimitable voice and a vision that consistently found God in surprising places, from Folsom Prison to the pit of despair in Trent Reznor's "Hurt." For the most part, the partnership deserves to be remembered as one of the most extraordinary in the history of popular music.

That's for the most part. Sadly, the 2006 collection "American V: A Hundred Highways," released nearly three years after Cash's death in September 2003, was a weak and disappointing coda recorded in the midst of his failing health, while he was grieving the death of his wife and with mortality hanging over every note. Rubin said at the time that it was the last installment of the series. Yet now comes another set of material from those same maudlin sessions, timed to what would have been Cash's 78th birthday.

The man in black started singing about death as a teenager, of course, and he never stopped--though he was most often railing against it, instead of rushing toward it. "There ain't no grave can hold my body down," he sings in this disc's opening line. But it feels less like a boast than a warning about grave robbers.

That once indomitable voice is often reduced to a sad and fragile croak, though as with its predecessor, the weakest part of "American VI: Ain't No Grave" is the song selection. Only three these tunes approach the strength of the best moments on the first four American Recordings albums: Tom Paxton's reflective "Wonder Where I'm Bound," Kris Kristofferson's "For the Good Times" and Ed McCurdy's enduring anti-war anthem, "Last Night I Had the Strangest Dream."

Most of the other tracks should have remained as outtakes. Then there are two downright disasters that should have just been erased: a version of "Cool Water," written by Bob Nolan but popularized by Frankie Laine, and a closing cover of the traditional Hawaiian ballad "Aloha Oe," both of which play as pure schmaltz. Yes, Cash liked to play the former in concert, and the latter also was recorded by his former label mate, Elvis Presley. But that doesn't redeem them.

After the first four volumes of American Recordings plus the five-disc "Unearthed" box set, the final chapter of Cash's story already had been thoroughly documented. One epilogue combining the best tracks from volumes V and VI could have been forgiven, if only for archival value. As it is, Rubin seems to be shifting from paying tribute to exploiting, and we can only hope that trend ends here.