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Organ with an open swell box below the main work
Balancing step of the swell (right)
Detail view

The term Schwellwerk describes a part of an organ , the volume of which can be regulated by an additional device. The pipes of this part of the work are in a locked wooden box, the swell box , the front of which can be opened and closed with the help of various techniques. Sometimes the narrow sides and the top can also be opened and closed.


Normally the blinds are opened and closed using a foot controller, the swell step . This balancing step is located a little above the pedal keys, usually around the middle of the small octave, large organs can have several swell steps. Other designs are also possible, such as the so-called spoon step of the Cavaillé-Coll organ in St. Sulpice (Paris) . This step is not balanced and there are three lockable positions: The swell box can only be closed, half-opened or fully opened. Of course, this causes considerable difficulty in achieving a homogeneous crescendo or decrescendo. Similarly designed steps can also be found on instruments by Friedrich Ladegast .


One of the most common locking elements (also called rocker panels) are wooden blinds (known as blind rockers ), but there are some other systems such as wooden doors that slide or fold to the sides, exposing the entire front.

The box itself is particularly soundproof, which varies depending on the organ builder. Probably the most effective method is to create two walls from several layers of wood, with sand being poured in between them. The wooden blinds should also be made of several layers of wood and their edges should be provided with felt strips, for example, to ensure a tight seal. For even volume control, it is advisable to connect the swell step mechanically to the blinds and set it so that even the smallest change affects the volume.

Since the 19th century, organs have been built in which several swell boxes can be operated mechanically at the same time, so-called collective swell boxes . As a result, a considerably larger number of sounds can be made to swell together.

Sound effect

A swell with folding doors ( Albiez organ from the late 1970s in St. Verena, Lindau )

With the help of the swell mechanism, the otherwise unchangeable dynamics of individual registers or register combinations can be changed, and the rigidity of a partial work can be largely eliminated. Registers that by their nature sound soft, such as the vox coelestis, can, provided they are placed in the swell, be reduced to the minimum pianissimo and thus produce almost spherical sounds. In addition, closed swell doors dampen the high overtone spectrum more than the lower partials, so that in addition to the dynamic effect, there is also a change in the color of the sound. A tutti of the registers in the swell box with the blinds closed forms a powerful, albeit subdued sound spectrum , the dynamics of which increase when the swell box is opened and has something downright majestic about it. For this purpose, the swell is usually equipped with plenty of registers, often the largest part in terms of numbers. If enough reed voices (16 ', 8' and 4 'if possible) are used in the disposition , the crescendo effect is particularly intense.


Historically, the swell was widely used in the course of the romantic epoch. Although the concept of swell boxes was already known (in Spain there are some significantly older models to be found), they were not used to regulate the dynamics during the game, but for echo effects and dynamic gradations that were retained over the course of the piece and have not been changed. Wing doors had similar effects on many organs of the Renaissance , which remained closed during Lent and thus muffled the sound.

The first swell mechanisms with today's functionality were constructed in England around 1720. It was not until the 19th century that swell mechanisms were also built for continental European organs. In 1801, Abbé Vogler describes that the Neuruppin organ was to be used as an attempt to put the pipes in a large box with a movable roof that could be opened with a kick. In the offer for the new organ in the Paulskirche in Frankfurt , Eberhard Friedrich Walcker referred to Vogler's ideas. This organ, which he completed in 1833, was the first with a large swell that could be operated with a kick. In the period that followed, however, very few individual instruments in Germany received a swell.

The first swell made by Aristide Cavaillé-Coll is located in the organ built in 1838 in the Paris Notre-Dame-de-Lorette church. The organ built by Walcker in 1845 in the Protestant church in Hoffenheim was given a physharmonica register , the sound cover of which can be operated with a kick and is originally preserved.

The swellable breastwork built by Friedrich Ladegast in the organ in Merseburg Cathedral in 1855 is possibly the oldest swellable structure in Germany.

It was only after 1890 that a swelling device for the 2nd or 3rd manual could be established in Germany.

See also

Individual evidence

  1. Behind the decoration (gilded pipes) all sounding pipes are locked in a box with a cubic figure of 18 Rhineland shoes [...] [The setup] prevents the bass pipes from sending their tone directly into the church and overriding the treble . The box has two roofs, a movable [sic!] For the bass pipes and a movable one for the treble pipes, which the organist can open and close with a kick. In: Allgemeine Musikische Zeitung, Volume 3, pp. 568f. https://books.google.de/books?id=YBVDAAAAcAAJ&pg=PA523&q=Orchestrion#v=onepage&q=schwellkasten&f=false , seen on April 14, 2020.
  2. Willibald Gurlitt: The Frankfurter Paulskirchen-Orgel from 1827. In: Frankfurter Zeitung of January 7, 1940. http://blog.ef-walcker.de/wp-content/uploads/2009/01/gurlitt.PDF , seen on April 14, 2020.
  3. In Walcker's workshop book it says crescendo box for III. Clavier and crescendo footsteps z. III. Clav. http://blog.ef-walcker.de/wp-content/uploads/2009/01/opus01_ffm.PDF viewed on April 14, 2020.
  4. A sketch of the gaming table shows four steps: https://gewalcker.de/SpieleischWeb/00000098ab0919101/5360859847100c101/index.html seen on April 14, 2020.
  5. Photo see: https://www.orgelbau-lenter.de/projekt.php?id=94 , seen on April 14, 2020.
  6. The disposition of the large Friedrich Ladegast organ in the Merseburg Cathedral. Friends of Music and Monument Preservation in Churches of the Merseburger Land, accessed on March 31, 2020 .