Bourdon (organ pipe)

Bourdon, bordun, or bordone normally denotes a stopped flute type of flue pipe in an organ characterized by a dark tone, strong in fundamental, with a quint transient but relatively little overtone development.

The Bourdon is also frequently found at 8', especially in French organs, and is equivalent to the German Gedackt and English Stopped Diapason, which give a similar sound.

They are thick-walled and generally square in cross-section, with a high mouth cut-up to produce the fluty tone.

This makes the tone one octave lower than a pipe of open construction (they are only one half the length of an open pipe of the same pitch), and also eliminates the development of even-numbered harmonics ("squaring off" the timbre), helping to create the characteristic tone quality.

'Bourdon' has many spellings and German organ builders will often use "Bordun", or even "Untersatz" (typically when it is in the pedals) on the stop knob for this rank.