Research and development at Grotrian has resulted in several patents. It also linked the name of GROTRIAN very closely with the history of piano building as a whole. GROTRIAN for example was the first piano manufacturer to construct an instrument using an iron frame connected only at the back frame which enables free vibration of the inner system and produces the unique tone of the GROTRIAN. This technique is still used in the current uprights. Further developments are the homogeneous soundboard with accurately balanced timber and a string scale that allows the hammer to strike each string at the optimal spot, and let’s not forget the patented star-shaped back-frame.