Boosting the beat of a famed dance troupe's feet

Every Christmas for decades, the leggy, legendary Rockettes have tapped their way across the stage at New York's Radio City Music Hall, stirring images of drummers drumming and lords a-leaping.

But the dancers faced a perennial challenge – their tap rhythms were often muted in the 6,000-seat enormity of the world's largest indoor theatre.

Efforts to boost the beat of the feet in their signature Twelve Days of Christmas number – using, say, directional microphones or body-pack transmitters – were ineffective, awkward, or too visible.

Enter Quantum5X, a Canadian firm best known for developing rugged wireless technology to capture the crash of basketball giants and the cacophony of hockey hits and baseball slides.

The solution? To mount tiny microphone-transmitters onto the bottom of the Rockettes' tap shoes, picking up the beat so faithfully it could be amplified over the theatre sound system.

Call it Rockette science – a classic case study of how innovation is born of necessity and improvisation.

Audiences and performers have been blissfully oblivious to the small devices. "To the dancer, it is just a shoe," says Paul Johnson, chief executive officer of London, Ont.-based Quantum5X Systems Inc. "As for the complication of turning on and turning off [the mic] it is all done wirelessly."

For the past three years now, Q5X's wireless mics and remote, computerized audio controls have played a key supporting role in the iconic Christmas Spectacular, which runs from early November to the beginning of January, drawing a million people to the 78-year-old Radio City Music Hall.

It was not a huge leap from the speed and violence of hockey to 40 high-stepping dancers on stage or in the wings, with 80 mics transmitting at any one time. Consider that a Rockette might perform three shows a day, with multiple costume changes. "It is an incredibly athletic performance and highly skilled," Mr. Johnson says.

For its tap-shoe numbers, Radio City Music Hall experimented with amplification schemes, including body packs with wires running down the back of dancers' stockings to shoe mics. But nothing worked well, particularly in coping with lightning-fast costume changes.

Meanwhile, Quantum5X, founded in 2002, was gaining a reputation for supplying sound mics for baseball and football parks, and NHL hockey and NBA basketball venues, including New York's multipurpose Madison Square Garden.

"Our currency is about being very small and very rugged," says Mr. Johnson, referring to the transmitters' thin lithium-ion batteries and miniature circuit boards.

At the 2009 NBA all star game in Phoenix, some players were wearing Q5X's devices in the seams of their jerseys. That was when the Canadian company was introduced to the senior vice-president, productions, of Madison Square Garden Entertainment, whose properties include Radio City Music Hall.

When the technology was explained, the reaction was: "Wow, could you build that in a shoe?," Mr. Johnson recalls. Indeed, Q5X could, attaching 1.5-ounce devices about the size of two double-A batteries into the arch of a dancer's pump or into a flat-shoe heel.

Almost every live performance these days needs to be 'miked-up.' For female pop stars, the tiny transmitters solve a major challenge in wardrobe adjustments. "We have a system that can go in their hair or in a bra and it can become very inconspicuous," Mr. Johnson says.