John O'Callaghan

John O'Callaghan (born 24 September 1981) is an Irish musician and DJ, who mainly produces trance music. He also produces music under the aliases of Joint Operations Centre, Mannix, Henrik Zuberstein, and Stenna. He has collaborated with fellow Discover artists such as Bryan Kearney, Neal Scarborough (as Inertia), Thomas Bronzwaer (as Lost World), and Greg Downey as well as, more recently, trance hero Leon Bolier. His best-known tracks are "Exactly" with Bryan Kearney, "Big Sky", in collaboration with vocalist Audrey... meer