Inspired by the Nat King Cole jazz ensembles from the time of World War II, he started his own orchestra at the age of 16 in 1947, The Syncopators Band, in Sarpsborg, and he soon became a central figure in the local jazz scene.
In the summer of 2011, Karlsen was 80 years old and was celebrated with an anniversary gala at Oslo Konserthus where a large number of artist friends and partners lined up with a Big Band and choir for a musical event constituting a party out of the ordinary [REF].