A pioneer in the Early Music field in the United States, Ritchie was born and educated in Australia, graduating from the Sydney Conservatorium of Music in 1956. In 1962, he settled in New York, where he became concertmaster of the New York City Opera in 1963 and associate concertmaster of the Metropolitan Opera in 1965.
In 1975, he joined the Philadelphia String Quartet (in residence in the University of Washington in Seattle) with which he played as first violinist and performed in Europe and the Americas, until accepting his appointment as professor of violin at the Indiana University Jacobs School of Music in 1982.
His interest in Baroque and Classical violin dates from 1970, when he embarked on a collaboration with harpsichordist Albert Fuller which led to the founding, in 1973, of the Aston Magna Festival. In 1974, he joined harpsichordist Elisabeth Wright in forming Duo Geminiani; their recording of the Bach Sonatas for Violin and Obbligato Harpsichord earned immediate critical acclaim.
Since then, he has also performed with many other prominent musicians in the Early Music field, including Christopher Hogwood, John Eliot Gardiner, Sir Roger Norrington, Malcolm Bilson and Anner Bylsma. For 20 years, he was a member of The Mozartean Players, with fortepianist Steven Lubin and cellist Myron Lutzke. In 1990, he and Wright inaugurated an Early Music concert series in Bloomington, Ind., and established a not-for-profit organization which, in 2005, become the organizational home of the Bloomington Early Music Festival (BLEMF).
As a faculty member of the Jacobs School of Music’s Early Music Institute, he has taught more than a generation of Baroque violinists, violists and cellists, many of whom now have flourishing careers in the Early Music profession. His teaching career has led to pedagogical research, and he is currently working on a method for Baroque and Classical violin.
His recordings include Vivaldi’s Op. 11 Violin Concertos with Hogwood and the Academy of Ancient Music (Oiseau Lyre); the Mozart piano quartets and the complete piano trios of Mozart and Schubert, as a member of The Mozartean Players, and a CD of 17th-century music for three violins and continuo, Three Parts upon a Ground, with John Holloway, Andrew Manze, Nigel North and John Toll, all for Harmonia Mundi USA.