1984     Formation of the first own company: danholt, manufacture of high-end hifi-systems in Düsseldorf. Development, fabrication and distribution of high-class loudspeakers for high-end hi-fi and stage from own manufacture. 1986     Development and design of a special winder for two-sides tape for 3M Deutschland GmbH. 1987     Development and manufacturing of the danholt “bumerang” device. The bumerang is a high class turntable device for analog LP’s. Discovery of the geometrical resonance optimization as a design and construction principle in this context. The journal Stereoplay attests the brilliant metro logical values (sampled data) as a result of the geometry.