Staff Sgt. William Carr, euphonium player for the Marine Corps Base Quantico Band, introduces his tuba and euphonium choir to holiday shoppers at the Marine Corps Exchange on Monday. The ensemble performs for patrons performing classic hits like “Jingle Bells.” - Staff Sgt. William Carr, euphonium player for the Marine Corps Base Quantico Band, introduces his tuba and euphonium choir to holiday shoppers at the Marine Corps Exchange on Monday. The ensemble performs for patrons performing classic hits like “Jingle Bells.”