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Board of Directors and Administration

Sabrina Ellis — President

Sabrina Ellis has been a Calliope member (alto) since 2015. Previously she served as the clerk on Calliope’s board. Sabrina attended New England Conservatory and Harvard University and has years of experience singing as both a soloist and a chorister. She was a member of Chorus Pro Musica and the Coro Dante in Cambridge and performed with choruses in New York and in Italy.

Sabrina has administrative and managerial skills and worked at the Harvard Medical School. She is the music director of an exciting company in Verona, Italy called Opera Talk Italy.

Colleen Martin — Board Member

Colleen Martin has been a Calliope member (alto) since 2013. She was the section leader for the altos for two years and the recipient of the Kathy Koniuto Chair in 2015. As a marketing professional with experience in marketing planning, research, communications, project management, and strategic planning, she has worked in both for-and non-profit organizations. In 2019, Colleen was recognized by the Massachusetts State Legislature for her Civic Engagement and Community Service. Currently she runs her own company, CRM Marketing services.

Robert C. Adams — Board Member, Treasurer

Robert Adams spent his career in non-profit management, including positions in project management, marketing, and strategic and business planning. Bob was a choral singer and soloist with the Dedham Choral Society for 13 years, also serving as Vice President and President; he also sang in Boston's Back Bay Chorale as a chorus member and soloist for 11 years. He was a founding member of Calliope from its beginning in 2006 and sang with the organization until 2009. He has served as treasurer from its beginning.

Nathaniel Adams — Board Member

Nathaniel Adams is an associate at the Boston office of an international law firm. His practice focuses on corporate transactions, primarily mergers and acquisitions. Before becoming a lawyer, he worked for three years as an editor and writer at the Improper Bostonian magazine. He has substantial musical performance experience, primarily in voice and piano, as well as formal training in music theory and composition. A Boston native, he is a graduate of the University of Virginia (B.A.) and Columbia Law School (J.D.).

Yanko Sheiretov — Board Member

Yanko Sheiretov joined Calliope as a clarinet player in 2008 and the board in 2017. He is very active in the Greater Boston avocational music community and has played with many symphony orchestras and opera houses. He currently holds the principal clarinet positions at the Wellesley Symphony Orchestra and at Calliope. Yanko holds a Ph.D. in electrical engineering from MIT and is currently employed in the medical device industry.

Rob Mathis — Board Member

Rob Mathis has been singing with Calliope (bass) since 2015. He has many years of experience in numerous choral groups. When not singing, or sometimes while singing, he enjoys riding his bike, doing science, and going on real and imaginary adventures with his friends. Rob has a PhD in biology from MIT.

David McSweeney — Advisor

David is president and founder of Tenor Technologies (, a consulting company that provides new-media solutions for arts organizations. Before forming Tenor Technologies, he held numerous executive positions in Massachusetts high-tech companies, and he has 20 years’ experience in the technology sector. As a freelance singer, David appears regularly with several local ensembles, including Boston Baroque, Emmanuel Music, Blue Heron Renaissance Choir, and the Handel & Haydn Society. He has also appeared as a soloist with the Arlington Philharmonic Society, Boston Cecilia, Monadnock Music, and the Wellesley Choral Society.

Julia O’Toole — Founder, Artistic Director Emerita

As founder and Music Director of Calliope, Julia delighted in the opportunity to lead musicians from a variety of Boston area choruses and orchestras. Having worked with several of these organizations previously in the capacity of vocal and performance coach, familiarity with the passion of their members inspired the dawn of Calliope. She earned a BFA in vocal performance from Boston University, a Master's Degree in Musicology from Brandeis University, and a PhD in Historical Musicology from Boston University. She taught voice throughout the Boston area, substituted as conductor for local organizations, and regularly teaches, publishes, and presents on various musicology topics.


Patrick Valentino — Former Music Director & Conductor (2019-2020)

John Verkuilen — Interim Music Director (2018)

Jacques Dupuis — Former Music Director & Conductor (2016-2017)