The organ intended for the chapel was to be prestigious. It was to have 59 stops spread over 6 tonal departments, two manuals and pedal. The case got sumptuous design - exhibiting an exuberance - unusual for that period of the declining Renaissance and the first stirring of the Baroque. This organ was meant to arouse amazement and admiration as much for its sonic language as for the work of its cabinet makers, painters and gilders. It was to become the most important organ in Germany for the number of its stops and the richest decorated. The erection required the years from 1592 to 1596 and ten organ builders were involved: the master organ builder David Beck and nine assistants. The price of the instrument amounted to 10 000 Reichsthaler.
The festivities for acceptance and inauguration of the instrument on the 2nd of August 1596 arranged matched the standard of construction. In a famous event unique in the history of music 53 of the most illustrious organists in the world were invited by Duke Heinrich Julius to Gröningen. Coming from all over Germany they exhibited their talent and the endless possibilities of the instrument for a whole week. The expenses for pay of the organists amounted to 3000 Reichsthaler und the participants propagated the fame of the instrument what they had tested and accepted and also the fame of the Duke throughout the whole country. Also Michael Praetorius took part in this gathering and was charged with play and maintenance by the Duke.
In 1603 the famous organ builder Esaias Compenius entered the service of the organ by Duke Heinrich Julius without altering anything of the conception. In 1605 he was appointed as the royal Braunschweigisch organ and instrument builder by the Duke and was entrusted with the building of a second organ construction. This second organ was assigned for the castle in Hessen, the birthplace of the Duke, located between Halberstadt and Wolfenbüttel and he donated this instrument his spouse Elisabeth.
The “Companius-Organ” - a chamber instrument - is considered as the pendant to the Gröningen organ, in contrast the pipes consist of various lumbers, additional the prospect pipes are veneered with ivory. Michael Praetorius had a large share in design and building and gave the composition of this organ in his “Syntagma Musicum”. About the instrument itself he wrote: Its unusual, soft, subtle and delicate sonority cannot be truly described.” The Hessen organ was finished in 1610, but after the death of the Duke in 1613, the duke-widow Elisabeth gave the instrument to her brother Christian IV., the king of Denmark, as a present. Compenius, commissioned to transfer the organ in 1616, installed it in into the chapel of the castle in Frederiksborg. After completing the work he fell seriously ill and died, and was buried in Hillerod. This instrument is the only original survived and still regular plaid Renaissance-organ.