During his years in Boston, he formed "Bostonian Friends", a musical partnership with Swiss saxophonist Fritz Renold, which produced jazz recordings ("Starlight" 1996) and classical commissions ("The 6 Cycles" with the Thai Symphony Orchestra 1999, and "Helvetic Suite" 1998). Although having renounced the classical performing circuit for jazz, Jacob has maintained ties with the classical world through projects such as these commissioned works. Renold introduced Jacob to the Swiss Youth Jazz Orchestra, for which he was an arranger and educator throughout the 1990s. From 1992 to 1994 Jacob also served as Director in Residence of the "Orchestre Regional Jazz de Lorraine" in Nancy, Meurthe-et-Moselle, and composed their inaugural commission.