Rolf Ellmer (born 3 December 1960), also known by the names Jam El Mar, Jam, and Trancy Spacer, is a classically trained musician (concert-guitarist), producer and DJ. He has become one of Germany’s most known techno and trance producers.

Together with Markus Löffel (alias Mark Spoon), also a big name in the German dance scene, he has recorded under several monikers such as Jam & Spoon, Tokyo Ghetto Pussy and Storm. He was also a member of the group Dance 2 Trance, along with Dag Lerner (alias DJ Dag), which had great success all over the world and is said to be among the pioneers of trance music.

He also works as a producer and remixer for other artists.