After three decades at the helm of Music of the Baroque, conductor Thomas Wikman is stepping down. When he founded the ensemble, as a Hyde Park church choir in 1971, the Baroque repertoire was largely neglected. In the intervening years, MOB has grown into one of the most respected ensembles in the city (outclassed only by the Lyric Opera and the Chicago Symphony Orchestra), not to mention its now-crowded specialty. But since the early 90s, Wikman has drawn criticism for not paying attention to the “authenticity” of his approach. He trains his vocalists to sing bel canto–which emphasizes mellifluous tone and natural, expressive phrasing–rather than in the more florid and overtly virtuosic Baroque style. He has no use for the period instruments that are de rigueur in many Baroque groups, or for the small ensembles and relatively sedate interpretations believed to reflect the way Baroque pieces were first performed–he prefers large lineups, brisk tempos, and the brassy, vigorous timbres of modern instruments. According to MOB’s executive director, Wikman is resigning, but his supporters claim he’s been ousted–not for any of this, but more likely because the organization’s new management wants a conductor with an international reputation to take over. The program for these season finale concerts, assembled well before Wikman knew they’d be his last, consists of three works from the early classical period, which succeeded the Baroque. The centerpiece is Mozart’s 41st and final symphony, known as the Jupiter; also on the bill is the Violin Concerto in D by Bohemian composer Josef Myslivecek, performed by longtime MOB concertmaster Elliott Golub. And for the evening’s vocal showpiece, Haydn’s Arianna a Naxos, Wikman has booked a superb guest soloist, Chicago-based mezzo-soprano Susanne Mentzer. Sunday, May 20, 7:30 PM, First United Methodist Church, 1630 Hinman, Evanston; Monday, May 21, 8 PM, Grace Lutheran Church, 7300 W. Division, River Forest; and Wednesday, May 23, 8 PM, Old Saint Patrick’s Church, 700 W. Adams. 312-551-1414.