Instruments by SK

A replica with an unusual history


THE STORY STARTED IN 2004 with the discovery of an original Viennese fortepiano signed and dated February 1802. This instrument with keyboard compass of five and half octaves (FF to c4) was presumed to be a fortepiano by Nannette Streicher, from 1803 or 1804. The inscription, which was uncovered at the beginning of the restoration process, changed the course of events.

As it appeared, this instrument was in fact made in the period when Nannette Streicher (born Stein) was working together with her brother Matthäus Andreas. It is the earliest known fortepiano from the builders FRERE et SOEUR STEIN which exceeds the compass of Viennese five octaves instruments (to f3 or g3 in the treble) thus far known from that period.

The original instrument was restored by SIETSE KOK over a period of three years, during a unique process involving research and simultaneously the building of an exact replica, which allowed to confirm a number of theoretical bases essential to the restoration. The associated research led to the publication of several articles on the topics of keyboard compass and Beethoven. The 1802 original and its replica are being played in concerts throughout Europe.

THE FRERE et SOEUR STEIN REPLICAS WHICH ARE CURRENTLY BEING BUILT BY SIETSE KOK are a direct result of this project. They are available in the ranges five and a half as well as six octaves, and carry the nameplate D’après Frère et Soeur Stein d’Augsbourg à Vienne.


Inscription in the original instrument © Sietse Kok

d'après Frère et Soeur Stein d'Augsbourg à Vienne


Frère et Soeur Stein d’Augsbourg à Vienne is the signature of the Viennese piano builders Geschwister Stein, led by Nannette and Matthäus Andreas Stein. They are children of the famous instrument maker Johannes Andreas Stein of Augsburg, a specialist of the organ and designer of several combination instruments. Stein started making fortepianos around 1750 and the development of the Prellzungen mechanic is attributed to him.

Nannette Stein was trained in her father’s workshop from an early age. She later established herself as Nannette Streicher, founding a piano firm which she led successfully with her husband Andreas Streicher. In 1812 they created a concert venue which became a center for musical life in Vienna.

The Frère et Soeur Stein fortepianos carry the strong heritage of the Stein family and are built in the tradition of excellence for which Johann Stein was already well-known. At the end of the 18th century in Vienna, the Stein siblings were considered to be among the finest keyboard instrument makers, combining outstanding craftsmanship and musicality. The Stein-Streicher family stood at the forefront of the development of the Viennese fortepiano in the early 1800s.

More on the Geschwister Stein in Vienna? Read the research article on the Stein 1802 Project website.

d'après Frère et Soeur Stein, five and half octaves / Sietse Kok.



SIETSE KOK(1970) is a graduate of the University of Groningen in the Netherlands, where he studied philosophy. His love for musical instruments began early, and as a young student, he started as an apprentice with the organ builder Bakker and Timmenga in Leeuwarden.

He traveled through Africa in search of old church organs before settling down in the town of Haarlem, the Netherlands. He worked on late nineteenth century and modern pianos at Andriessen Pianos and subsequently specialized in the restoration of keyboard instruments from before 1850.

Sietse currently lives in the Charente Maritime region of France, between the Atlantic coast and the vineyards of the Cognac.

Planning a trip to the area? Visit Belleroq

Instruments by SK


You may call or write for more information on these instruments. Would you like to to receive a price indication? Let me know. Contact me by any of the channels below.

Sietse Kok
Aumagne – FRANCE

 +31 6 14 53 03 33

Stein fortepiano replica | Instruments by SK