Gedackt even Covered , is the name of registers the organ whose pipes are closed at the upper end. In the narrower sense, Gedackt only refers to pipes that have the same circumference over their entire length, e.g. B. cylindrical metal pipes. Closed pipes with a tapering circumference towards the closed end, e.g. B. conical metal pipes are called pointed and behave physically different.
Further, the same acoustic laws obeying be flutes as having a closed distal (distal) end Gedackt , with an half-closed end as halbgedackt designated.
The ancient Hydraulis in Aquincum already contained closed registers, like the remains from the 1st century BC. Prove. Presumably Burkhard Dinstlinger contributed in the 15th century to spread the Gedackts. Michael Praetorius (1619), on the other hand, assumed that only open pipes were built in the 14th and 15th centuries. At the beginning of the 16th century, covered registers can be found in Dutch-North German and Polish organ building, and in the course of the century also in France, Spain and Italy. For the first time, the use of the term is covered in an organ building contract from 1519 for the organ in St. Lamberti in Lüneburg. In the Netherlands the name "Holpijp" (hollow pipe) is preferred, in England "Stopped Diapason" and in France and Belgium "Bourdon".
Construction and sound
Characteristic is the construction with labial pipes, the upper end of which is closed (covered / covered). With (round) metal pipes a soldered-on lid or movable tuning hats are used, with (square) wooden pipes, on the other hand, a bung . The closing means that the tone produced by such a pipe is an octave lower than the length of the pipe would suggest. This is due to the fact that the standing wave in the pipe body due to reflection at the pipe end does not have a speed maximum (vibration belly), but rather a pressure maximum (vibration node of the sound velocity). Inside the pipe, instead of half as in the open pipe, there is a quarter of the oscillation. The wavelength of the fundamental resonance is therefore twice as large. Closed pipes can therefore be viewed as closed on one side.
Octave notes are made in the foot positions 32 '(in the pedal, in large organs rarely also in the manual), 16', 8 'and 4'. Gedackt 2 ′ over the entire range of the manual is rare, as it is difficult to produce in the high register. In some large organs there is also a 64 'stop in the pedal. However, a fully developed 64′-Gedackt register, which extends to the sub-subcontra-C, is not yet known. The fifths 21 1 ⁄ 3 '(on the pedal, rarely and only in large organs), 10 2 ⁄ 3 ' (on the pedal) and 5 1 ⁄ 3 'are also almost always performed as a dack. Gedackt 8 ′ is very common and is the only labial 8 ′ register in most small organs.
Bumped registers are significantly quieter than open registers, sound slightly hollow and flute-like and are also darker in their timbre. The overtone spectrum only contains the even-numbered overtones that correspond to the odd-numbered harmonics . The other overtones, including the octaves, are missing. A narrowly scaled Gedackt can be built in such a way that the 3rd partial tone, the duodecime, called the fifth in organ building, emerges, which is the origin of the names quintatön or quintadena for such registers. With an even narrower scale, the 5th partial tone emerges, which is two octaves and a pure major third above the fundamental and is called a third in organ building. This register is called, for example, Terzadena or Tiercina and is rare.
Gedackt registers are made of metal with a round cross-section and wood with a square cross-section. Every now and then the deepest pipes of an open register (e.g. reed flute , hollow flute , principal ) are executed in a closed manner in order to save space, weight, material or costs.
Pointed ones are tonally between open and closed registers. In contrast to closed pipes with the same circumference over their entire length, pointed pipes contain all overtones in the spectrum. The length of pointed pipes depends on the change in cross-section and is between that of cylindrical and open pipes.
Some types of flute also have a closed construction. While with most flutes, i.e. the recorders and transverse flutes , the tube end is open, the pan flute usually has closed ends. One of the rarely occurring transverse flutes that are closed on both sides is the Ibirongwe in Kenya.
The tonal difference between an open and a closed flute can be clearly illustrated with a recorder head by blowing it open once and covering the lower opening with the palm of your hand while blowing.
- Roland Eberlein : Organ register. Their names and their history . 3. Edition. Siebenquart, Cologne 2016, ISBN 978-3-941224-00-1 , p. 278-281 .
- Distinguish harmonics, partials, partials and overtones - pdf (42 kB)
- Harmonics, Partials, Partials and Overtones - pdf (255 kB)
- Eberlein: Organ register. 2016, p. 278.
- Harald Vogel, Günter Lade, Nicola Borger-Keweloh: Organs in Lower Saxony . Hauschild, Bremen 1997, ISBN 3-931785-50-5 , p. 98 .