Ask the Argentine drummer Daniel 'Pipi' Piazzolla about the role of claves in his music and you shouldn't expect an answer so much as an exuberant lesson. Piazzolla, the leader of the celebrated Buenos Aires-based sextet Escalandrum, loves claves—the way they "naturalize" complex time signatures; the infinite rhythmic possibilities they present; the mathematical derring-do of fitting the square-peg of a clave inside the round-hole of a given meter.

"I lived in Los Angeles for a year," Piazzolla tells me in the middle of our interview turned impromptu rhythm class, "and they would make us play [the claves] of our friends' telephone numbers. For example, [my friend's] number is 765-3243. We'd play a clave in seven, then a clave in six. Five, that's the Mission: Impossible theme song. Have you ever thought that it was in five?"

When I reply in the negative, he starts singing and tapping out the famous melody. "It sounds natural," he says, "that's a clave."

"If you have a tune that's in 11/8, you don't have to count out 'one, two, three, until eleven.' What you do is you make the measure into six and five, which gives you eleven. Then, you can divide the six into three and three, and you can divide the five into three and two. When you structure rhythms that way, it's much easier to feel them. It'll end up so that you might think that it feels like it's in 4/4. It sounds natural because of [the clave]...the music of Escalandrum really got going when we started to use these kinds of things."

Escalandrum—whose name is a portmanteau of "escalandrún," the Argentine name for a sand shark (the Piazzollas are avid shark fishermen), and "drum"—formed in 1999 as a group of six friends who hung out with one another nearly every day and thought it high time to collaborate. Their first album, Bar Los Amigos, featured a shark-themed design (Escalandrum's website still has a menacing dorsal fin motif) and a Latin jazz feel, employing Afro-Caribbean percussion, an electric guitar, and an electric bass.

Then, in the space of two months in the spring of 2002, Escalandrum's sound underwent a sea change. It often takes a while for a band to find its most compelling voice—whether it's the Beatles ditching their mop-cuts for shag, or Miles Davis' first classic quintet working its way out of bop and into a new modal vocabulary. For Escalandrum, the change (documented on its second album, Estados Alterados) meant going acoustic, moving past more typical Latin claves into a more complex and global rhythmic conception, and committing itself to an Argentine voice that owes a debt to the tango and folkloric traditions.

Piazzolla was playing in the band of the Argentine pianist and composer Guillermo Klein when the seed was planted for the new Escalandrum sound. Klein, like Piazzolla, is a clave fiend, using fresh takes on typical Argentine rhythms like chacarera and candomble to propel music that owes a heavy debt to the jazz tradition. Klein's style of phrasing jazz with a modern Argentine accent excited Piazzolla enough that he resolved to change what he was doing with his own group.

While Piazzolla cites Klein as one of the crucial influences in his musical maturation, he also—as lovers of tango or Argentina will likely have guessed by this point—comes from a rather distinguished line of musicians. 'Pipi' Piazzolla's father, Daniel, is a noted tango pianist, and his grandfather Astor was one of the most celebrated musicians in Argentine history, occupying a position analogous to Ellington or Stravinsky in the world of tango—the sophisticated modernizer, the gentleman-rebel.

From the time he was very young, Piazzolla was regularly attending his father and grandfather's shows—Daniel and Astor regularly played together—finding it natural to scamper around backstage at the Teatro Colón, Buenos Aires' most famous concert hall. Yet, Piazzolla is quick to dispel the notion that he was groomed to follow in the footsteps of the man Argentines call "the great Astor." "Neither my father nor my grandfather ever gave me a single lesson...In my house there was music playing all day long, and that's the way I got into it, there wasn't any pressure [from either of them.]"

Piazzolla tells a story about the moment when he fell in love with music. He was four-years-old, sitting in front of the TV, when the jingle on a commercial suddenly struck him. He got up, walked over to the grand piano in the living room, and tapped out the melody that he'd just heard. "It was like playing Playstation for a kid today," he says grinningly.