For the last 20 years, John Colby, a Grammy and Emmy-winning composer, producer, music director and keyboardist, has created theme and background music for virtually every televised sporting event, including two Super Bowls. As ESPN’s music director (1984-1992), Colby helped shape the sound of ESPN in those early years, composing and producing music for hundreds of ESPN sporting events and television programs. All that said, Colby, 63, is perhaps best known for six simple musical notes he composed in 1989 . . . six notes of an iconic melody heard every day by sports fans around the world — “DaDaDa DaDaDa” — part of the theme song to SportsCenter.