Bob Dylan, "The Basement Tapes Complete: The Bootleg Series Vol. 11" (Columbia/ Legacy)

It's the most famous room in pop music, its history equal parts legend and truth. In the decades since its use as a rehearsal space, this subterranean refuge has become known as the birthplace of some of America's most examined musical tapes.

As the story goes, while recuperating from a motorcycle crash and starting his life as a husband and father, Dylan and his compadres, who soon rechristened themselves the Band, recorded more than 40 reels of tape that have since become sacred texts of sorts. The most famous works are well known: "This Wheel's on Fire," "I Shall Be Released," "Tears of Rage," "Sign on the Cross." Many were traded on the underground circuit through the decades, and a two-LP set of highlights was released by Columbia Records in 1975. But until this week, the full set has never been officially issued. This new six-CD set gathers more than 100 songs or fragments. A two-CD volume collects highlights.

Taken as a single seven-hour-plus narrative, the recordings bear witness to the birth of a new Dylan. The set also stamps the moment when the most important American musician of the 1960s vanished from New York City to upstate New York. He ceased being a one-man music revolution and instead explored crevices in American music's history. Some people, though, took Dylan's retreat to be courageous. Amid the Summer of Love, within a period when Vietnam War protests and urban violence were erupting around the country, his off-the-grid move, it could be argued, was a legitimate political act.

Politics, though, weren't obviously on his mind as the musicians frolicked through "She'll be Comin' Round the Mountain" and "Wildwood Flower." Instead, variety was. Looking for the evolution of "You Ain't Goin' Nowhere," Dylan's rollicking kiss-off, he and the Band explore the song from a few different angles, experimenting with tempo, texture and phrasing. They tear through country songs by Johnny Cash and Hank Williams, turn "Blowin' in the Wind" into a death march propelled by guitarist Robbie Robertson's bluesy licks. During "One Too Many Mornings," a song that Dylan and company had beaten into an electrifying rock song during their 1966 British tour, they turn it sideways.

Hear a giggling Dylan free-associate the words "See you later, Allen Ginsberg" to the tune of "See You Later, Alligator." Elsewhere they offer a stunning version of the Impressions' "People Get Ready."

The most illuminating aspect of the set is the playfulness, witnessing songs blooming, a sound being explored with casual joy, musicians coming together in that ethereal realm that transcends theaters, studios or garages.

Randall Roberts, Los Angeles Times