Groove making, generally speaking, means two or more lead players plus a rhythm section interacting in a process that at its best results in something akin to synchronicity.

Groove making, generally speaking, means two or more lead players plus a rhythm section interacting in a process that at its best results in something akin to synchronicity.

Then there's Keller Williams, the singer and multi-instrumentalist who has benefited from a longtime relationship with String Cheese Incident. Williams is easily the world's greatest one-man jamband, as he handily demonstrated yet again during a rambunctious, enthusiastically received show Sept. 24 at Tampa Theatre, the historic movie palace and concert hall.

For two-and-a-half hours, the Bonnaroo favorite enthralled a packed house of mostly 20- and 30-something manic dancers, dedicated tape traders and the merely curious with a pair of sets as rangy as they were infectious. His repertoire encompassed everything from a very silly version of Michael Jackson's 1979 dance-pop hit "Don't Stop 'Til You Get Enough" to a bluegrass-flecked take on Pink Floyd's arty rocker "Another Brick in the Wall (Part II)," released the same year.

Williams was just one guy, surrounded by a stage full of acoustic and electric instruments, including various guitars, an electric bass guitar and an upright acoustic bass, keyboards, vibraphones and, yes, a Theremin, that odd musical device capable of generating a variety of spacey, synth-like noises.

So how does he do it all? It's not as easy as it looks: a maelstrom of perpetual motion, the musician typically lays down a riff, and presses a bare foot against a pedal to generate a sound loop, moving from instrument to instrument until he's happy with what he hears. He then proceeds to sing, solo, whistle or make various horn-like mouth sounds over the resultant groove. His fingerpicking is quick, clean and dead on, and he often treats his guitars like percussion instruments.

Williams, shaggy haired and dressed in a white cotton shirt and khaki work pants, employed the above strategy for a long list of offbeat covers, including Bob Marley's "Trenchtown Rock," a two-fer Jimi Hendrix segment stitching "Castles Made of Sand" to "Little Wing" and Stephen Stills' "For What It's Worth."

For Dave Mason's "Feelin' Alright," the last song of the first set, singer-songwriter and show opener Raul Midon sang lead and aced a six-string solo doubled by wordless vocals, ala George Benson. The second set opened with the Stones' "Gimme Shelter."

The crowd also warmed to "Anyhow, Anyway," "Ship of Fools," a piano-driven ballad with a sing-song chorus, "Boob Job," "Life Without You" and the bouncy, catchy, innocently sexy "Love Handles."

Signature song "Celebrate Your Youth," sung over a bed of Djembe drums, hand drums and whistles, was heard during the encore. "Running on Fumes," a late-show favorite, was spiked with Williams' self-deprecating commentary about the tune's sprawl: "Somebody wake me when this long-ass song ends," he sang. Given the unfettered energy emanating from the stage and the herbally enhanced party that spilled out from the seats into the aisles and directly in front of the stage, there was little chance of anyone nodding off.