Sinclair has been the Music Director of Orchestra New England from 1974 to the present.
Sinclair is notably a specialist in the music of Charles Ives; he has "spent [his] whole adult life devoted to the music of Charles Ives.
"[1] He has published A Descriptive Catalogue of the Music of Charles Ives[2] with the Yale University Press and served as music director for a number of PBS documentaries, including A Good Dissonance Like a Man, about Ives.
He is currently an Associate Fellow of Berkeley College and oversees the Charles Ives papers, as well as those of pianist and Ives scholar John Kirkpatrick.
As a conductor, Sinclair has recorded a number of Ives works, as part of a complete set of Ives' orchestral music projected to be in nine discs for the Naxos label.