Pipe organ

This article is a work in progress and may have some incomplete or missing content.

This article is about organs which push wind through pipes in order to create a musical tone.

For an overview of related instruments, see Organ

A German Organ

The pipe organ creates sound by pushing wind through pipes which are selected through several keyboards (called manuals) and a pedalboard played by the feet. Pipes of common timbre and force are arranged in lines call ranks, and organs typically have many ranks of differing timbre and force. Because of the continuous supply of air, the organist may hold out a note indefinitely without decay, as opposed to the piano or harpsichord, the tone of which beginning to decay as soon as the note is struck.

Pipe organs are commonly found in concert halls, churches, synagogues, and cathedrals and are traditionally used for the performance of sacred and classical music, although they are in modern times often used in the performance of secular music as well.

Stops

Stops have different names depending on the countries where they are made. Even the same names can result in a different sound. German or Dutch organs sound different than the English or later more Romantic French organs. There are several families of stops. One of the base stops is the Principal or (open) Diapason, Prinzipal (German), Prestant (Dutch), Montre (French). The name signifies these pipes stand in front of the organ. Those are the shiny ones you see at the front of the organ. Made of metal, they give a strong and solid base sound. A softer family of stops is the Flutes, usally made of wood. Both these types of stops have a similar building, like a recorder: with a mouthpiece, where the air leaves the pipe. Another kind of stop is the category called Reeds. Names like Trumpet, and Posaune (German name, usually 16' rank, means Trombone) signify the more brassy sound. A piece of wood with a metal lip before the tiny opening for the wind. When the wind moves through the opening the metal lip is going to vibrate, resulting in the brassy sound of this family of stops. They have often a loud and penetrating sound. Although there are softer stops, more to be compared with an oboe or a bassoon, the sound is always a bit nasal. Especially the French, and in a lesser degree Spanish, organs are famous for their many different kind of reeds (Anches in French).

Ranks

After a stop name is a designation like 8'. That tells something about the height of the longest pipe. In this case the lowest c pipe was about 8 feet. That is the normal sounding height, similar to a piano. The same key on the manual but with a 4' stop sounds an octave higher. Since the pipe is half its original size the frequency is the double of that of an 8' pipe. There are many stops with other designations, almost always corresponding with the natural harmonics. The half of the pipe length resulted in an octave higher. 1/3rd gives the next natural harmonic: a fifth and an octave higher. The designation is 2 2/3' (which is the exact result of 8 divided by 3) or a shorter for 3'. These stops usually have names like Quint (which is the German Dutch and French for fifth). The next harmonic is 2 octave above the base note of the 8' pipe, called 2'. The next rank is called 1 3/5, (which is 8 divided by 5), resulting in a third and two octaves above the original 8' base note.

<music> \cadenzaOn c c' g' c e </music> The first four natural harmonics

The stops are not only going higher. There are lower ranks as well. Often found in the pedal there are ranks called 16' (one octave lower), 32' (two) and on a very few organs there are 64' stops.

Reference

http://www.organstops.org/