Norwegian keyboarder and producer from the region Fredrikstad. In 1989, he co-founded [[artist:10664]] together with [[artist:170343]]. He only stayed for a short time, as he didn't share Groth's affinity to EBM an Industrial to form [[artist:79715]], a Synthpop band.

The relationship to Groth stayed friendly. As Groth himself tended more and more to Synthpop in the late 1990's, Martinsen again collaborated with Groth and became guest musician on some of his releases.