Fokker organ

This unique organ – permanently housed in our Small Hall – was built in 1950 and completely restored in 2009. It is based on an invention by Dutch physicist Christiaan Huygens (1629-1695). The organ uses the microtonal 31-tone system instead of the usual 12 notes in a scale.

31-tone Fokker organ
In 1950, the extraordinary Fokker organ was built by Dutch organ builder Pels. The well-known physicist Professor Adriaan Fokker, cousin of the famous aircraft builder Anthony Fokker, had been trying to get this 31-tone organ built and played since the 1940s. The source of inspiration was Christiaan Huygens, who described the 31-tone system as early as 1691 in his Lettre touchant le cycle harmonique.

Also for remote playing
The Fokker organ has been the property of the Huygens-Fokker Foundation since 1960. From 1950 to 2000, it was on display in Teylers Museum in Haarlem. After its restoration in 2009, the Fokker organ – now fully modernised by organ builder Pels & Van Leeuwen – was placed above the glass wall of our Small Hall (Kleine Zaal). From then on, the organ could be played not only by an organist, but also directly by computers and online by, for instance, a musician on the other side of the world.

The Fokker organ is tuned in the so-called meantone temperament, in which thirds sound purer than in the current tuning system. The disadvantage of meantone tuning is that you cannot play in all tonalities. As a result, you cannot change from one key to another without modulation, as is possible in the current, tempered tone system. What makes the Fokker organ so special is that the 31 tones in the octave – instead of the usual 12 – do allow you to modulate to other keys in the pure meantone temperament. This is not possible on, for example, an old church organ tuned in meantone temperament.

To learn more about how the Fokker organ works and about its history, visit

Organ concerts

On several Sunday mornings throughout the season, you can hear the Fokker organ being played in our Organ concert series! Fascinating music from both the Baroque and the contemporary era. 

Melle Weijters


Ere Lievonen + Melle Weijters

Sun 6 Oct 2024 11:00 - 12:00
Ensemble SCALA (foto Michel Marang)


Ensemble SCALA

Sun 15 Dec 2024 11:00 - 12:00
Philipp Gerschlauer


Philipp Gerschlauer + Georg Vogel

Sun 12 Jan 2025 11:00 - 12:00
Maripepa Contreras (photo Deirdre Daly)

The Priest’s Paradox

Rembrandt Frerichs, Maripepa Contreras + Vinsent Planjer

Sun 9 Feb 2025 11:00 - 12:00
Ere Lievonen (photo Stichting Huygens-Fokker)

Expedition 31

Stefan Gerritsen + Ere Lievonen

Sun 23 Mar 2025 11:00 - 12:00
Julián Carillo

Julián Carrillo's 16th tone

Ernestine Stoop, Anne Veinberg + Ere Lievonen

Sun 23 Mar 2025 15:00 - 16:00
Sander Germanus en the Hallucinating Harmonists

The Pleasance of Disorientation

The Hallucinating Harmonists

Sun 23 Mar 2025 20:15 - 21:30
Laurens de Man (foto Juri Hiensch)

Mozart’s automatic organ

Laurens de Man

Sun 25 May 2025 11:00 - 12:00
 Ere Lievonen (photo Françoise Bolechowski)

Dutch Masters

Ere Lievonen

Sun 2 Jun 2024 11:00 - 12:05
Laurens de Man (photo Juri Hiensch)

Die Kunst der Fuge

Laurens de Man

Sun 12 May 2024 11:00 - 12:45
Laurens de Man (photo Juri Hiensch)

Die Kunst der Fuge

Laurens de Man

Sun 14 Apr 2024 11:00 - 12:00

Season 24-25