Geigenwerk III   

Compass:C - a' 

Size: 680mmL x 564mmW x 215mmH

General description: 
The original idea was in the Leonardo da Vinci's notebook. The first geigenwerk was made by Hans Haiden in Nuremberg in 1600. Since then, a number of different shapes of mechanically bowed keyboard instruments were designed and made by different makers over the last 400 years. Since 1993, I have been challenging in making Geigenwerks and a Streichklavier. The whole purpose of this effort is to realize a keyboard instrument which can produce a profile in each tone of melodic lines, by modulating dynamics and tone pitch.

In designing this violaorganista, the key concept was to imitate the sound generating principle of a violin. The violin strings are used. The bowing position and location of the bridge relative to the string length are exactly the same of those of violin. While depressing a keyboard, the corresponding string comes to contact against the rotating friction wheel, providing dynamics modulations with the finger pressure. Mechanisms which can move the strings up and down with the rotating levers are mounted on blocks similat to the tail peice of a violin. The string moves up/down, rubbing vertical edge (strictly speaking a partial circle) of the bridge giving a slight side bearing to the bridge. To provide the lowest note of C, viola strings are used in addition to the violin strings for the other notes.

Additional tensile force to the string when the key lever is depressed results lifting sound pitch. Through previous experiences with the geigenwerk, it was recognized that providing pitch control ability to the player was too much freedom and it was impractical to control tone pitches of all tones in a harmony. Then the rotating lever, invented when the streichklavier was designed, was employed, so that the player can concentrate dynamic modulations with minute change of tone pitch.

Modulation with wheel rotation speed.Vibrato with finger pressure.Crescendo/DiminuendoMozart K.3

 AMIS Meeting Slides


Compass: C - f''' 

Size: 1572mmL x 860mmW x 260mmH

General description of the instrument

For a Geigenwerk, wich has friction material (parchment or horsehair) on a circumferential edge of a circular disk, the friction material is supported with hard material (wood or metal). Instead of using friction wheels, Streichklavier employees an endless belt like structure of friction material, which has no supporting material on the back side of the friction belt, imitating regular bow of the violin family string instruments.  The compass of four and half octaves is divided into 6 portions and each one of the friction belt is to play 9 notes.  This is because of 1. Providing slower bow movement for lower tones and faster movement for higher tones, like playing violin family instruments and 2. Preventing large deformation of friction belt when higher pressure is applied between the string and the friction belt.  A mechanism to have strings contacted to the rotating friction belt is, of course, linked with the keyboard action.  To produce louder tones, higher pressre is applied between the strings and the friction belt. A special lever structure is designed to apply higher pressure without modifying the string tension.

When a loosely set string is pulled in a direction perpendicular to its tension and the pulling pint is rotated around a point on the straight line between the bridge pin and nut pin, string tension is not changed.  This rotating motion can be used to move the string down to contact against the rotating bow.  Then, loudness modulation, corresponding to the pressure between the string and the rotating bow, can be obtained without modifying the tone pitch.

A rotating lever to move the string down to contact against the rotating bow can be found in the Truchado’s instrument and figures of Hyden’s instrument in the Syntagma Musicum by M. Praetorius.  However, if these reference materials are carefully examined, it can be found that the string tension is also modified when the rotating lever presses down the string against the rotating bow.  The axis of the rotating lever and the straight line between the bridge pin and the nut pin do not align in the same line.  Moreover, in the Truchado’s instrument, although it is also obvious from the plan view, the nut rail is positioned no less than 5mm higher than the base block of the rotating lever.  This implies the rotating lever, used in this instrument, is not with an intention of keeping the string in a constant tension when it is pressed against the rotating bow.

In order to provide an easy maintainability for replacement of friction belt, the sub-assembly of 6 friction belt units can be detached from the bottom of the instrument body. The string tension is supported with the frame structure, not with the bottom board.

Geigenwerk II      

Compass: C - f''' 

Size: 1430mmL x 871mmW x 300mmH

Aim for the new version

When the first prototype was made in 1993, several potential capabilities of Geigenwerk were pointed out: long tone sustaining, forte/piano expressions, vibrato and fine adjustment of tone pitch.  Although all of these features could be demonstrated, the instrument still had some problems to be improved: difficulties in playing fast passage in lower tones, unstable starting up of sound and impracticality of instantly adjusting pitches of all individual tones of a chord, based on natural harmonics.  Moreover, from one of the descriptions of the instrument made by Hans Haiden (or Hyden)*1, it seemed to be able to quickly control forte/piano and could emphasize any part in a harmony. Adding these features is also included in the aim of making this new version.



1.Mitsugu Yamada: "Bach and Lautenclavier  -seeking lost instruments-" Symphonia Co., Ltd. March 2001, p.72 to 73 (sorry, Japanese only)




Results of modifications:

With the modifications described below, significant improvements are observed in the area of:
1. Dynamics expressions corresponding with depth of keystroke.
2. Emphasizing any single part of a chord.
3. Playing fast passage in lower notes.
4. Stable start-up of sound.
However, with the sliding nut pin, dynamics and tone pitch cannot be controlled independently and it is inevitable to raise small amount of tone pitch, when the key is depressed deeper to increase dynamics.


Major modifications after the first prototype: 

 1. Parchment replaced with horsehair

Rotating friction wheels, covered with parchment, is good enough when used in a hurdy-gurdy mode, where strings are already in contact with the friction wheel when the wheel starts rotating.  However, in the Geigenwerk, where strings come in contact to the rotating wheel to start producing sound, it was not so easy to produce stable start up of sound, which might be due to uneven friction coefficient of parchment.  Instead, horsehair show very stable start up of sound over the entire range of the compass.  In the maintenance point of view, however, sometimes horsehair drop from the rim of the friction wheel.  Once the horsehair dropped, they tangle each other,  and require entire bundle of the horsehair need to be replaced.   In order to avoid this problem, thickness of the friction wheel was increased.  


2.Cat skin on the strings

A sharp start up of sound is available with a thin small piece of cat skin adhered on the strings where the circular bow with horsehair is applied.  With the cat skin, tremolo and fast trill can be played with no difficulty.  The thin cat skin is originally prepared for a Japanese authentic plucking instrument, Shamisen.  



3. Sliding nut pins 

In the previous prototype, tone pitch adjustment and vibrato were controlled by changing string tension, keeping the constant pressure between strings and the friction wheel.   In this configuration, though rather stable tone quality could be obtained, dynamic expression was only controlled by tangential speed of the friction wheel.  To provide a wider dynamic range, it was experimentally found that changing pressure between string and the friction wheel works much better than changing the rotation speed of the wheel.   To adjust pressure between the string and the friction wheel, either moving the wheels or the strings up and down is necessary.   If the wheel was moved, dynamics of the chord could be controlled but single part of the chord can not be emphasized.  A mechanism was invented to slide the strings up and down on the nut pin.  When the string is pressed down, string goes down, rubbing the nut pin, where the string is acoustically terminated. (Click here for drawing)


4. Minimal down bearing 

In the most of keyboard instruments, both down bearing and side bearing are applied by geometrical positions between bridge pins and hitch pins.  In the case of R. Truchado's instrument, flat hitch pin rail, like one for harpsichord, is used.  In such configuration, each string, in a set of string group for one friction wheel, has different down bearing.  Typically in the center of the convex soundboard bridge, down bearing is as mush as 35 to 40 mm.  The clearance between strings and a friction wheel is typically 1mm and large down bearing may cause the soundboard bridge to sink down, causing miss alignment between the circular friction wheel  and strings more severely in the higher notes. Though it is inevitable to have small amount of moving up and down of the soundboard bridge due to humidity change, minimal down bearing, as little as 1mm, is applied with circular shaped hitch pin rail to prevent bridge from sink down due to the string tension.  Acoustical coupling between the strings and the soundboard bridge is applied mostly with the side bearing.


5. Tangential velocity of friction wheel 

In the previous prototype, all friction wheels are rotated with the same tangential speed.  As a result, strings could not smoothly start vibration in the lower notes, because of too fast tangential speed of the circular bow.    On the other hand, in higher notes, rather faster speed is needed to have smooth tone quality.  Thus, as seen in R.Truchado's instrument, sizes of the pulleys are adjusted to provide fast rotation for higher notes and slower rotation for lower notes.   Typically, the rotation speed of the friction wheels are 70% of that of immediate next right of the one.  


6. Pressed down strings and location of the keyboard

With normal keyboard, when key is depressed, the other end goes up.  It is not easy to use this type of keyboard for the geigenwerk, which requires strings to go down against the friction wheel, when key is depressed.  Though a special mechanism was designed for the previously made prototype, this time, keyboard is located above the strings, eliminating the complex mechanism.  With this configuration, more direct feedback from string vibrations to the player's finger is provided, allowing more direct contact between the player and the instrument.   When the key lever is depressed, string is pressed down with a push rod, which is hanging on each string, then the string contacts with the friction wheel.


7. Monolithic soundboard bridge 

Instead of having four soundboard bridges corresponding to the four friction wheels, a monolithic soundboard bridge was designed.  It helps leveling soundboard deformations, which are due to string tension, temperature and humidity changes.  




8. Driving mechanism of rotating wheels

In the previously made instrument, a bicycle pedal like treadle was used to rotate friction wheels and as mentioned in the above section 2, tangential speed of the friction wheel was assumed to be a factor of musical expression.  However, it was found to be impractically difficult for players to adjust the speed of the wheel, while playing a manual keyboard.  This time, rotation  speed of the friction wheel does not contribute to musical expressions and dynamic expression is given only by changing the pressure between strings and the friction wheel.  A flywheel, just like a wind chest of an organ, is employed and an old sawing machine like pedal is used to provide torque to keep the flywheel rotation. 

Geigenwerk Prototype       

Compass: F - f''' 

Size: 1280mmL x 770mm W x 257mmH

REPORT: Making a Bowed Keyboard Instrument 

1. Emanuel Winternitz, Leonardo da Vinci as a Musician (New Haven and London: Yale University Press, 1982) 

2. Michael Praetorius, Syntagma musicum, Vol.2: De organgraphia, trans. and ed. by D. Z. Crookes, Early Music Series, no.7 (Oxford: Clarendon Press, 1986) 

3. Ferdinand Joseph De Hen, "The Truchado Instrument: A Geigenwerk?" in Keyboard Instrument: Studies in Keyboard Organology, ed. Edwin M. Ripin (Edinburgh: Edinburgh University Press, 1971) 

4. Sibyl Marcuse, A Survey of Musical Instruments (New York: Harper & Row, 1975) 

5. Carolyn W. Simons, "Some Nineteenth-Century Mechanically Bowed Keyboard Instruments in European Museums," a paper presented 15 May 1993 at the National Meeting of the American Musical Instruments Society in Nashville, Tennessee 

With kind support by Mr. Nicola Meeus, the curator of the Brusseles Conservatoire Museum, the builder was given an opportunity to investigate detailed interior of the instrument made in 1625 by Fray Raymundo Truchado. 

Model: This instrument is not a replica of any historically existed instrument. 
Though it is regularly performed by string and wind instruments players, there is no single keyboard instrument which can allow the player to perform all of the below mentioned very important music expressions including, sustaining the tone as long as necessary, increasing the dynamics after the tone released, performing vibrato and making fine adjustment of pitch. Geigenwerk has a great potential to satisfy all of these requirements at a time. 

The historical origin of this instrument can be traced back to Leonardo da Vinci. Leonardo drawn several sketches describing the idea of this type of musical instrument and named them as Viola organista. 

Simons categorized this type of instruments in three groups for its tone generation mechanism, such as, Geigenwerk, Streichklavier and Piano-quatuor. 

Since Leonardo da Vinci drawn the sketches, about 90 people attempted to make it or applied patents in the last 500 years. Curiosity about the performance possibilities and general practicality of the Geigenwerk, the builder designed and constructed an instrument based on historical examples. 

Unfortunately, at present, with the issues mentioned below, the quality of the instrument is not good enough to motivate composers and players to make music. 

1. It is difficult to play fast passages in lower tones. 
2. Build-up of the tone is not always stable and reliable.
3.Considerable skill is required for players to instantaneously adjust tone pitch of harmonies. 

The work of making this experimental instrument was presented in May 1993 at the national meeting of the American Music Instrument Society in Nashville, Tennessee.  Since then, the instrument has been continuously modified for improvement.