structural:reformatting
Enclosure and expression pedals

Enclosure refers to a system that allows for the control of volume without requiring the addition or subtraction of stops. In a two-manual organ with Great and Swell divisions, the Swell will be enclosed. In larger organs, parts or all of the Choir and Solo divisions may also be enclosed. The pipes of an enclosed division are placed in a chamber generally called the swell box. At least one side of the box is constructed from horizontal or vertical palettes known as swell shades, which operate in a similar way to Venetian blinds; their position can be adjusted from the console. When the swell shades are open, more sound is heard than when they are closed. Sometimes the shades are exposed, but they are often concealed behind a row of facade-pipes or a grill.

The most common method of controlling the louvers is the balanced swell pedal. This device is usually placed above the centre of the pedalboard and is configured to rotate away from the organist from a near-vertical position (in which the shades are closed) to a near-horizontal position (in which the shades are open). An organ may also have a similar-looking crescendo pedal, found alongside any expression pedals. Pressing the crescendo pedal forward cumulatively activates the stops of the organ, starting with the softest and ending with the loudest; pressing it backward reverses this process.