2. THE PARTS AND THE ACTION OF THE ORGAN
The organ case is the outer part of the organ that can be well recognized from outside. The front of the case can be richly decorated especially the ones from the Baroque period. The case hides the sound making constituents: the pipes, the wind chest that makes the pipes work, and the pallet system. The sound generating system can be divided into separate units (works, Werke), which are independent small organs controlled from a specific manual. (Picture 3, 4)
The great organ (Hauptwerk) is the most frequently used part of the organ. It is controlled from the lowest manual and provides monumental sound effect.
The positive (or choir organ) (Rückpositiv) can be found in a small case inside the organ and evokes a quiet, intimate sound that is characteristic to its size.
The Brustwerk is placed in the middle part of the instrument and the Oberwerk is placed on its highest point.
The swell organ can be found in a smaller case. A separate balanced swell pedal controls its dynamics from time to time.
The pedal work consists of the leg-controlled, deep intonation pipes which are usually placed at the sides of the organ in the pedal towers.
The console is the controlling system of the organ. This consists of the manuals, stops, prepared settings, technical solutions. The organist sits here and plays the manuals from here. The manuals are hand-controlled keyboards of 56-61 keys, and they are placed above each other in succession. There can be 1 to 9 manuals on the console but the most frequent type is the four-manual organ. The only leg-controlled keyboard is the pedalboard where 30 or 32 longer pedal keys can be found. Here are the toe pistons (stop controlling devices) which belong to separate manuals and their combinations. The stops make the rank of pipes and their combinations sound at one time. The manuals can be connected (coupled). (Picture 5, 6)
All these are called the technical devices, which influence the amount of the sound and the colour of the sound force.