polyphonic keyboard

Organistrum: new polyphonic keyboard



My reconstruction of the instrument is based mainly on a new interpretation of its musical function, considering it as a true polyphonic instrument. To this purpose I invented  a special keyboard, providing some new tecnnical suggestion in using the wheel too.


By tuning the strings  either:  A – d – a   or:  A – e – a    we get an overall extension of two chromatic octaves (minus the last semitone). Before lifting each key, the performer  can choose which string he is going to touch, simply by turning the key to the proper position: the first one allows him to act on the bass string, the second on the middle one, the third on the higher string.

Thus it is possible to play two different melodic lines simultaneously. In Santiago sculpture the hands of the musician on the right are on the third and on the fifth key. This means he is playing  -c, g -  rather than  -d, f -  bichord on bass and middle strings,  or  - g, c’  rather than  - f, d’- bichord on middle and higher strings (first tuning).


First string                              a..       a#      b     c’     c’#     d’

Middle string                         d..       d#      e      f      f#      g    

Bass string                            A..       A#      B     c     c#      d

Keys                                      0          1       2     3       4      5


 In position 4 the key is provided with two tangents so as to act on  second and  third strings (tuned either in Fifth or Fourth)  at the same time to perform  Organum parallelum, leaving the bass string as a drone.  Finally, whatever mode you play, whatever mutationes or permutationes you practice,  you will never use  the 6thkey:  Tritonus.


On the other side, the musician who is in charge of turning the crank, by a smooth, even movement of his right hand,  can  lift each string from the edge of the wheel in order to stop it vibrating with his left hand. This way you can either avoid conflicts between the voices or stop  undesired drone effects.  






I chose one big  Red Willow (Salix purpurea) planck, seasoned in nature, from which I  carved the sound box and the base of the keyboard in one piece, average thickness  8-10 mm. Flat back, flat sides as in the original. 

GENERAL MEASURES:                                                                                                             

 Total length    940mm                                                                                                           

Max width      230mm                                                                                                              

 Depth              80mm                                                                                                                

 Diapason        720mm

In the bottom of sound box I drilled a 10mm hole for the wooden axis, made of Beech (Fagus silvestris). Axis ends into another hole of 10mm drilled directly with no axle box in a wooden bar (Spruce) 15mm thick, glued between the two lobes of sound box which has been carved out of one piece of Spruce (Picea  abies) 8mm thick with no other bars glued underneath. Keyboard  box is independent from the body of the instrument and can be easily removed to modify  general level of the bars, changing their angle with the strings or making reparations. The 11 bars of the keys, diameter 10mm, are of Pine (Pinus nigra) and the 55 pivoting tangents of Beech. The problem of the distances among the bars is discussed in the present article. To avoid noise made by the bars returning to their previous position, after being pulled up to play, a stripe of cloth has been glued at the bottom of the keyboard. The carved lid has been made of Spruce, 8mm thick and is simply interlocked with the body of the keyboard without any hinge or other device.

The wheel, 11cm  wide and 20mm thick is of Walnut (Juglans regia) and forced on  wooden axis without any screw, nail, or wedge. No axle box at the end. The Beech crank , stuck in the square end of the axis, can be easily removed. The soundboard is glued to the body of the instrument , no sound pole in it. The bridge is of Poplar (Populus nigra) reinforced with a Beech edge. The tailpiece  of Chestnut (Castanea sativa) is linked to the bottom of sound box by a leather lace. Tuning pegs are of Beech, no need for a tuning key. Two light  layers of pure almond oil have  been used as  finishing . Gut strings: 0.80, 1.10, 1.40mm.



To understand the reasons of my idea about the name, it's enough to read  Guido d'Arezzo, Micrologus, XVIII, 1-18.





Congrés du CTHS, Paris 23-27 avril 2018

Congrés du CTHS, Paris 23-27 avril 2018



“Livres en pierre” c’est une denomination donnée de très longtemps aux portails des églises  romanes et gothiques. La doctrine catholique était très clairement exposée à travers la présentation des scènes bibliques, voilà donc  une effective transmission de connaissances théologiques. Mais d’autres savoirs pouvaient etre tout aussi transmis: histoire, astronomie, musique. Parfois , au moyen d’un language codé, on exposait des connaissances secrètes.

Nous avons étudié trois exemples excéllentes: les portails  des cathédrales de Chartres, Arles et Saint Jacques de Compostelle, en mettant en évidence une transmission de connaissances de musique et d’astronomie. On voit que les sculpteurs ont représenté avec le plus grand souci les instruments de musique, leur tenue, les détails de fabrication, les decorations et meme les figures des musiciens, des chanteurs, des anges, leur expression, leur attitude. Le nombre, la position des sujets, les endroits occupés dans la composition, les relations entre les personnages, tous ces eléments donnent indications et suggestions au regard  des études de théorie musicale conduits à l’époque (1143-1188): intervalles de l’exachorde et Musique des Sphères à Arles, gammes chromatiques à Chartres et à Saint Jacques de Compostelle des références à la cosmologie platonicienne et à l’astronomie, dans tous les trois monuments la présence du Tritonus ou “Diabolus in musica”.


La transmission des savoirs musicales à travers les sculptures des portails des églises était importante, car la Musique (des Sphères), liée à l’Astronomie, était considerée comme un moyen de communication avec Dieu. Quelques détails pouvaient etre compris uniquement par un public savant. Avant tout, la réponse dépende de la question qu’on pose.


AAVV, El mensaje simbòlico del imaginario romànico. Aguilar de Campoo, Fundacion santa Maria la Real, 2012

Elena Ferrari Barassi, Testimonianze organologiche nelle fonti teoriche dei secoli X-XIV.  Cremona, Fondazione Claudio Monteverdi, 1983

Boethius Severinus Manlius Torquatus, De institutione musice.

Bruce Eastwood, Ordering the Heavens. Brill, 2007

Dieu Lionel, La Musique dans la sculpture romane en France, Centre de Développement en Art et Culture Médiévale, 2006



La communication des savoirs musicales à travers les sculptures des portails des églises était importante, car la Musique (des Sphères) était considerée comme un moyen de communication avec Dieu, bien que certain détails pouvaient etre compris uniquement par des musiciens savants.




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