"It's kind of a gumbo," says McGuinn. "The Beatles' Revolver gave us the inspiration to go in that direction."

As for the stylistically unhinged Dr. Byrds and Mr. Hyde and Ballad of Easy Rider, both released in 1969, McGuinn's comments move further toward criticism.

"Those two were [made] after Hillman left, and I was stuck with the band name on my own," he says. "Basically, they were sort of a searching thing. We carried on a little bit in the country-rock tradition, we experimented with a little more synthesizer. It was kind of a hodgepodge; we got a little too democratic. We probably should have named ourselves something else, but we didn't."

Roger McGuinn began his folk career not as a singer/songwriter but as an interpreter, and he still prides himself on that fact. A native of Chicago, McGuinn was barely out of high school when he landed his first gig as a sideman for the Limelighters in California. In the early 1960s, McGuinn went by his birth name, Jim, which he changed to Roger in '67 at the urging of an Indonesian guru. You had to be there to understand, says McGuinn, who was just as caught up in the spirit-magnifying hubbub of the '60s as anyone else in his line of work.

By 1963, McGuinn had diverted temporarily from folk's customary path, working as a songwriter churning out tunes in New York's fabled Brill Building. He even co-wrote a surf single, "Beach Ball" (a version of which he performs on Live from Mars), with Bobby Darin. But it wasn't long before McGuinn felt the pull of his roots. He returned to the West Coast and began performing solo at the Los Angeles folk institution the Troubadour. It was there in 1964 that the core of the Byrds came together.

Among other things, the Byrds can take credit for being the first pop band to electrify folk music on a national scale. Their harmony-rich, Rickenbacker-embellished version of Dylan's "Mr. Tambourine Man" was a hit before Dylan shocked purists with his rock and roll debut at the Newport Folk Festival in 1965. Even so, McGuinn prefers to credit Dylan -- and the Beatles -- for changing the way people viewed the folk idiom. The Byrds, he says, were just following their lead.

"Blame it on [them] for [moving] the genre of traditional folk songs into the singer/songwriter era, which we're still in now," McGuinn says. "Before, it was a sort of unwritten law that it was too commercial to write your own material -- that you were not being a folk purist if you wrote your own songs, or had any electric instruments or even drums on your recordings. Not only did it have to be pure, but it had to be a valid version of that folk song. You couldn't even change around the words to suit your whims. Then Dylan came along and shattered all of that. Now you're not a valid artist unless you're a singer/songwriter."

That's precisely why, McGuinn says, he's pitching in to preserve the interpretive tradition. Last year, he created a World Wide Web site called the Folk Den. Enthusiasts can access the Folk Den through McGuinn's home page (www.mcguinn.com), and those users with sound capability can download and listen to his traditional interpretations of standards such as "Sailor Lad," "Alberta" and "Old Paint." The music is accompanied by related artwork and an information capsule on the tune, lyrics and guitar chords.

"I was getting requests from people who wanted me to do a folk album," says McGuinn. "There's probably not a big market for that, so somebody suggested I just put it on the Internet."

McGuinn quickly made the Folk Den one of his passions. Each month, he prepares a new package in his home studio and ships it off to the University of Arkansas, where a computer technician launches it into cyberspace. Add the web site to a list of projects McGuinn has assigned himself to kill time when he's not on the road. But it's more than just a diversion, he says.

"What it boils down to," McGuinn says, "is that nobody really knows what folk music is anymore."

And few are better qualified to educate the masses than rock's most resilient Byrd.

Roger McGuinn performs at 8 p.m. Sunday, April 6, at Rockefeller's, 3620 Washington Avenue. Mikael Martin opens. Tickets are $10 to $25. For info, call 869-