The organ will soon be on permanent loan from the Städtische Universität MUK in Vienna.
The Enharmonic Pipe Organ has been built in 1979 by the organ builder SCHMACHER, Eupen, Belgium according to the plans of Prof. Dr. Martin Vogel of the University of Bonn. It has 328 pipes, that is one continuous rank of flute pipes, stopped in the lowest octave, the tone colour changing to the sharper tone quality of a principal stop in the high register (60 % tin, 40 % lead). The lowest tone is F1, the highest D7 (midi note names). The organ provides 48 tones per octave, which are tuned in just intonation. It is possible to add 8 intervals as parts of a mixture sound to the basic flute sound: 1.) octave as a 4 foot stop 2.) the twelfth as a 2 2/3 foot stop (fifth above 1.)) 3.) the second octave (2′) 4.) the third partial above 3.) (1 3/5′) 5.) the fifths partial above 3.) (1 1/3′) and 6.) the sevenths partial above 3.) (1 1/7) 7.) the third octave (1′) and 8.) the nineth partial (9/8′) above 3.) The concept of the organ intends to open a variety of microtonal intervals in different ratios up to eighth tone steps for composition and performance. The keyboard consists of two normal twelve-tone manuals , a special manual (F1-D4) and a pedal (F1-D3). The pipework is played by an electric action with magnetic valves, being connected with the keyboards by a MIDI cable.As the whole instrument is midified, it can play together with MIDI instruments. Within the pipe case (oak), which can be taken to pieces, the pipes taken apart are divided into five blocks. The pipes of each block are grouped exactly according to the tonal system of 6 x 8 perfect fifths, a major third apart. On the normal twelve-tone manuals the player can choose a special selection of twelve tones by aid of a special program. In the present state of implementation the keyboards are midified, so that in the near future different programs for microtonal music and mutating tonalities like e. g. MUTABOR can be used to determine choices of specified tunings while playing on the manuals. The pedal plays the lower notes of one of the normal manuals. A switch box allows the player to decide whether the upper or the lower manual is connected with the pedal or whether a toggle function is used, where the actual struck keys of one of the manuals causes the toggling between the two tunings.
On the special manual all tones can be played directly. This manual allows firstly rich melody line playing but restricts polyphonic performance It shows a chessboard-like construction including the depth dimension. The grouping of 8 rows of scales in whole-tone step distance one above the other in a slanted position to the right allows the player to use the same fingering within each tonality. A hierarchy of intervals corresponding to the complexity of ratios is demonstrated through the use of different sizes and types of woods for the keys:The octaves and fifths (walnut wood) and have the width of normal white piano keys. (For mechanical reasons their lengths had to be divided into two halves) To the left and the right side of these major tones the chromatic half tones upwards (ivory) and downwards (ebony) are placed. They have the width of the black keys of a normal piano keyboard. Regarding their musical function they are at the same time also the major thirds of the upward major thirds (ivory) and the minor thirds of the upward minor thirds (ebony).The minor thirds (acajou wood) and major thirds (box-tree wood) of medium widths are placed in the middle between the chromatic half tones.The sevenths are formed like accordion knobs and grouped laterally above and below the other intervals in approximately a sevenths apart. Between 1994-99 the organ was placed on loan in the studio of the composition teacher Klarenz Barlow in the Royal Music Conservatory Den Haag, Netherlands for study and research purposes. There it got a complete MIDI-connection. On 4th November 1999 the organ was presented in a concert of students in the big concert hall of the conservatory. Then until 2005 she stood in the kath. parish church St. Petrus Canisius in Köln-Buchforst, where she was played in a concert on 12th december 1999 together with the choir “Capella Piccola”, conducted by Thomas Reuber.
Here a detailed information on microtronal music with sound samples