Organ pipe

Metal pipes are usually made of lead; for increased rigidity it is alloyed with tin along with trace amounts of antimony and copper.

In addition, high amounts of tin give a gleaming and long-lasting polish, which may be desired if the pipe is clearly visible.

Cost considerations may also lead to the use of the inferior rolled zinc especially for the lower tones that take a lot of material.

In addition, pipes have been made of many metals, including copper, aluminium, gold electroplate, silver, brass, and iron.

Metal pipes are generally made by first casting the desired lead alloy onto a long flat surface.

The low melting point, solderability and malleability of the organ metal makes the construction of pipes relatively easy.

The image at left shows the Wilhelmy American Flag Glass Pipe Organ that was created as a part of a Memorial Proposal for Ground Zero after the events of September 11, 2001.

Certain organ pipes are also mounted horizontally in the shape of a trumpet horn so as to project the sound farther.

However, when such a commanding tone is desired but it is impossible to mount an en chamade on the case, a hooded reed is used.

This type of pipe stands vertically and has a 90-degree bend at the top which acts to project the sound outward in the same way an en chamade does, but can be placed in the interior of an organ.

The sound of a flue pipe is produced with no moving parts, solely from the vibration of air, in the same manner as a recorder or a whistle.

Then the process works in reverse, with a low pressure region forming over the Labium which pulls the airstream to the other side again.

Flue pipes generally belong to one of three tonal families: flutes, diapasons (or principals), and strings.

A partial vacuum is created by higher velocity air flowing under the reed which causes it to be pulled closed against a hard surface called the shallot.

Because the resonator is partially stopped/closed by the reed, odd-numbered partials/harmonics are dominant (in the hollow tones of Krumhorn and Clarinet stops, for example).

If the resonator pipe expands outward to conical, the geometry allows the production of both even- and odd-numbered partials, resulting in the fuller tones of Trumpet and Oboe stops.

Possessing a powerful bass groundtone, the pipe is generally made of wood and can be voiced at various wind pressures.