The greatest cellist of his generation, Yo-Yo Ma, is drinking Starbucks coffee in the Faculty Club at Harvard. He has an hour before he must drive into Boston to collect his young teenagers, Nicholas and Emily. "These past two days, I've been the single parent because Jill, my wife, had meetings in Washington. We're very child-orientated. Touring as a family doesn't work because the children have their lives here. If I'm performing I'm not available. I've learned the hard way that being available is mental as well as physical. When Emily complains, 'Dad, did you hear what I just said?', and I've no idea what she's talking about, I know my head is somewhere else."
Ma, who draws inspiration from a wide circle of collaborators, was born in Paris to Chinese parents. He began studies at the Juilliard School of Music in New York at the age of seven. Some might describe his inspiration as gimmicky - after all, this is the cellist who joined forces with Mark O'Connor, a country fiddler, and bassist Edgar Meyer in a Sony crossover album, Appalachia Waltz. Last year he made a much publicised series of films around the Bach Cello Suites, with, amongst others, skaters Jayne Torvill and Christopher Dean. Now, for his new recording, Simply Baroque, and a series of concerts with conductor Ton Koopman and the Amsterdam Baroque Orchestra, with whom he first worked eight years ago, he has restored his Stradivarius to a condition that he calls "75 per cent virginal". He had instrument makers in London and Paris restore the bridge which lifts the strings off the instrument, and the tailpiece, which anchors them. The steel strings were replaced with gut and the instrument was tuned to a lower - in what is now largely accepted as Baroque - pitch. The end pin has been removed so that when Ma plays he has to cradle the cello between his knees rather than allowing the instrument to be propped up on the floor.
Gimmicks are certainly not what Ma is about. "My background focused on different cultures. Much of my wanting to explore new music and new ways of doing things comes from looking at life around me, talking to people who know more about their work than I do, and trying to understand different systems of thinking. We live in strange times because our world is so hierarchical, so competitive and so niche-oriented that sometimes it seems strange to have someone do a variety of things."
For Ma, variety of work doesn't necessarily mean volume. "Age and responsibilities have meant having to plan more carefully. Family time is precious. Over a long period of time, I've been able to try and figure out what works for us. Now I'm past 40, priorities have become much clearer in my mind. If there are 10 things to do, I know what takes precedence. Twenty years ago, things were much more jumbled up. It was exciting and yes, of course, I could do it all. Now I try to make space for different projects rather than adding on top of things that are already full. I plan far into the future but also recognise the need to leave some time for serendipity. The terrible thing about our profession is the Two-Year-Ahead Schedule, but if you don't allow for serendipity, you can feel in a state of arrested development. New projects take on different timelines. When I made the film series of the Bach Suites, it was a wonderful, but complicated, experience. It felt to me like going through another university education."
Yo-Yo Ma is a very private man who leads a very public life. "I really enjoy living in the environment of a university community, where most people do work which is far more important than mine." At home, for relaxation, one of his great pleasures is to make "house music" with close friends. "Two of them play in our string quartet. They love music but, professionally, one's a physician, another is a physicist. Our children come at music in their own way. We would never force them into music - they have to find their own identities."
Going some place to perform is never enough for Yo-Yo Ma. "Nothing is ever just another gig. Wherever possible, I want to be involved in a place and start some kind of relationship. It's important to me to be able to go into the schools and participate in the life of the community." He had just played a benefit concert with the Mark Morris Dance Company in Orange Country, California.
"It was a strategic alliance between a theatre organisation and the symphony orchestra - an incredibly exciting combination." He made time to give master classes and listen to a Polish cellist on an educational programme in Santa Barbara. "He's 23 and is going to be someone very special. I heard of him a couple of years ago and we kept up a correspondence. Finally, we had the opportunity to meet. Listening to young musicians isn't generous of me - it's extremely exciting."
Typically, after the concert, he caught the "Red Eye" and arrived in Dallas way past midnight. "I walked half a mile with my cello. At three am I just lay down on the floor and slept by the gate until it was time to catch the Boston flight." So, has Yo-Yo Ma found his voice? "Who knows?" he says. "But I'm much clearer about what it is - what it could be." And off he went to pick up his kids.
Yo-Yo Ma performs with conductor Ton Koopman and the Amsterdam Baroque Orchestra at the Barbican on 23 April. Box office: 0171-638 8891