Faintly you hear the sound of a guitar being tuned. Then the cymbals count out the tempo—one, two, three—and the massive guitar, pounding bass, and ethereal keyboards join in, launching into a riff that grooves as violently as a pack of boozed-up Hell’s Angels.

The standing audience, comprised of mostly middle-aged men, cheers as it sways awkwardly to the music. The smell of marijuana smoke, both new and ancient, permeates the sold-out venue. This is a Gov’t Mule concert.

Gov’t Mule is a jam band that blends elements of rock, blues, jazz, reggae and bluegrass. Notable albums of theirs include Dose, Deja Voodoo, and High and Mighty, the last of which features the single “A Million Miles From Yesterday.”

While you won’t find them on MTV, they are well known in jam circles for their outstanding live performances, which generally go on for three or four hours.

Gov’t Mule is coming to the historic Fillmore Auditorium in San Francisco for two shows on Nov. 21 and 22. Tickets are $36.50 from Ticketmaster.com. As of press time, neither concert is sold out.

The band is comprised of four supremely gifted musicians: singer-guitarist Warren Haynes, keyboardist Danny Louis, drummer Matt Abts, and bassist Jorgen Carlsson. Thus Gov’t Mule has the courage to explore musically and the skill and experience to do so successfully.

The band got its start in 1994 as an outgrowth of the legendary Allman Brothers Band. Haynes and former Allen Woody played guitar and bass, respectively, for the Allman Brothers beginning in 1989.

When the Allman Brothers stopped recording new material, Haynes and Woody left to start Gov’t Mule, adding Matt Abts on drums. Woody mysteriously passed away in 2000, so in 2003 the band added Andy Hess on bass and Danny Louis on keyboards. Hess left the band this year, and Jorgen Carlsson replaced him this fall.

Over the course of their 14-year history, the band has done over 1,300 concerts and has sold a million records.

I have seen Gov’t Mule in concert twice, once in the Fillmore and once at the High Sierra Music Festival, and both shows were stunning tributes to the raw power of rock ‘n’ roll.

Few songs lasted less than six minutes, and several stretched out to 10-15 minutes. Alongside mostly earth-shaking originals were tasteful covers of Jimi Hendrix and the Beatles.

If you keep your radio dial set at 102.5, you’ll probably want to pass this up. But if you dig classic music from the ‘60s and ‘70s and you’re up for the drive to the City, you owe it to yourself to experience Gov’t Mule firsthand.