Stramp was a Pro Audio manufacture out of Germany in the early 70's, founded by Peter Strueven (hence the name Strueven Amplification or "Stramp") They were known for their sound reinforcement equipment (mixers, amps, etc.) as well as their guitar and bass amps. Some have compared their amps to those of Marshall, both in sound and quality. They did make one synth that we know of, the Syncharger 2.
Unfortunately Stramp was eventually bought out by Dynacord who evidently redesigned their amps for the worse. Peter Strueven is still in the business though, with his own company, Peter Strueven Audio Sales.
