CHATHAM COUNTY To hear the Red Clay Ramblers play is to get an education, even when they’re just warming up. A recent evening found the hyper-eclectic band’s core four – fiddler Clay Buckner, pianist Bland Simpson and multi-instrumentalists Chris Frank and Jack Herrick – casually arrayed in the studio behind Herrick’s house.

Between discussions about barbecue, long-ago gigs, porcine anatomy, smallpox vaccines and the inherent appeal of Tina Fey, the Ramblers worked up some tunes for an upcoming folk-festival date, displaying impressive off-the-cuff virtuosity. First up was an old Irish reel, proceeding at an amiable lope with Buckner’s fiddle seeming to dance atop Frank’s accordion and Simpson’s piano.

“That’s ‘Miss McLeod’s Reel,’ ” Buckner said.

‘Well, that’s the name ‘over there,’ ” Frank said, referring to its Irish origins. “What’s it called over here?”

“ ‘Hop High Ladies,’ ” Buckner said, absently fiddling on the tune’s main riff.

They moved on to another tune that proceeded at more of a stately pace. After working it over some, Herrick rooted around his closet and emerged with a bouzouki, an eight-string Greek instrument. That gave it more of a droning, almost Middle Eastern flavor.

“Yeah,” Frank quipped, “that’ll be on our upcoming album, ‘The Red Clay Ramblers Play “Hava Nagila ” – all Jewish numbers!”

That was a joke, right?

“Well ... with us, you never know,” Frank said.

The Red Clay Ramblers came together in the fall of 1972 as a trio – banjo player Tommy Thompson, guitarist Jim Watson and Fiddlin’ Bill Hicks. From the start, they put a highly idiosyncratic spin on old-time music, adding elements of vaudeville, jazz, blues, music theater and whatever else struck their fancy.

Through myriad changes, the Ramblers have retained the ability to make old music seem new and new music seem old, in the process becoming a Tar Heel institution. They have played everything from Broadway stages to military bases.

Enough time has gone by for the lineup to turn over completely a couple of times. Hicks and Watson departed by the mid-’80s, leaving Thompson to carry on with replacements. One was singer/songwriter Shawn Colvinin her pre-pop-star days. Alzheimer’s forced Thompson’s retirement in the early ’90s; he died in 2003.

But they’ve been a model of stability the past quarter-century. Of the core quartet that still plays as the Ramblers (augmented by others onstage), Frank is “the new guy” – and he joined in 1987 as Colvin’s replacement. Through it all, a band-of-equals egalitarian spirit has served the Ramblers well, even if it left old-time purists confused.

The Ramblers’ first four decades have seen some disappointments, including a planned Broadway run of their musical “Lone Star Love” that was canceled after a falling out with star Randy Quaid in 2007. But they’ve had a lot more triumphs, conquering Broadway with “Fool Moon” in the early ’90s and collaborating with national theater and dance companies.

They’ve also had a long and fruitful association with director/playwright Sam Shepard. The Ramblers served as pit band for Shepard’s1985 stage production “A Lie of the Mind” (starring Harvey Keitel, among others). Shepard also put them onscreen as a medicine show band in 1994’s “Silent Tongue,” the late River Phoenix’s final film.

If all goes according to plan, more big-screen work could be down the road. There’s a feature film that Simpson is very keen to make happen, based on a North Carolina-centric book he doesn’t want to name just yet.

“We wouldn’t direct it, but get it off the ground,” Simpson said. “Find the money, producer, director. And we’d do the soundtrack, maybe more. Sam (Shepard) put us in ‘Silent Tongue’ playing bit parts, so maybe some of that. Part of the fun of this anniversary is to reflect forward, think about things we want to do and different ways to put entertaining musical narratives onstage. A musical theater piece is different from a dance piece, is different from a concert in a big hall, is different from a concert in a club.”

The Ramblers have done all of that, and more.