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Details (Google translated from German):
"The Hohner Electronium pi is an old key board from the year 1950 that the concept almost resembles a Clavioline. The basic sound of both instruments is however very different, since the tone generator of the Electronium pi produces a saw tooth wave shape, while it is with the Clavioline a square wave form. Roughly expenditure-press sounds the Elektronium pi rather like a trumpet and the Clavioline rather like a clarinet. The equipment is developed complete in tube technology and offers from tubes admitted sound. One can call these only extremely alive, warmly and nobly. It is one of the instruments, with which the well-known composer Karl Heinz stick living invented and justified the electronic music in the year 1954 in Cologne Studio of the WDR."
This was sent in via Ivan of Squeezytunes. You can read more about it here.