Swell

What it means

The swell is a device on the organ that allows the volume of one or more divisions to be changed continuously, rather than only by fixed switching of stops on or off.

The most widespread form is the swell box: one or more manuals, along with their pipes, are enclosed in a box with movable shutters that can be opened or closed like venetian blinds, letting the sound project outward more or less strongly.

Musical use

The swell is operated by a foot pedal at the console, letting the organist shift continuously between soft and loud, or shape gradual crescendos and decrescendos, while playing, without needing to change stops.

The swell was developed from the eighteenth century onward, first in England, and spread increasingly across continental Europe in the nineteenth century, giving Romantic composers such as César Franck or Max Reger considerably more flexible dynamic shaping than pure registration alone could provide.

The swell should be distinguished from a stop itself, which switches a fixed timbre on or off, whereas the swell continuously varies the volume of a stop already sounding, and from the crescendo pedal, which instead adds further stops automatically and in stages.

Performance practice

Use the swell deliberately and with control to shape longer dynamic arcs, rather than moving it abruptly. Combine the swell pedal with a suitable registration so the instrument's full dynamic range can be exploited.