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 eed pipes
The " tongue and shallot" in a reed pipe correspond to the reed and mouthpiece on a clarinet or a saxophone. As the air moves upwards to the resonator, it causes the tongue to vibrate against the one flat side of a small copper tube called the shallot. The vibrations produce the sound. Such pipes have a powerful piercing sound, very bright. The names of the different reed pipes in the Saint-Michel organ are Trompette 8, Clairon 4, Cromorne, and Voix humaine (refer to stop nomenclature).
Flue pipes: a flue allows the passage of air between the lower lip and the upper lip (which, cleverly enough, is placed in the same way as a flutist's upper lip) and causes a disturbance in the column of air, which begins to vibrate.
Stopped flutes, whether metal or wooden ones, make it possible to produce the same sound as an open pipe, only with a shorter pipe length. Placing a cap (metal pipe) or stopper (wooden pipe) produces a note an octave lower; for example, a stopped 8' Bourdon will produce 16'.
 ound
The sound is produced by the air, or "wind". The air from the lungs of the flutist is what makes a flute "sing"; similarly, an organ "sings" when air generated by one or more manually operated pumps - or by an electrically operated blower - fills a cast-iron weighted reservoir. The sound is transmitted when the pressurized air enters metal or wooden pipes and strikes the upper "lip", making the column of air in the pipe vibrate at the pitch associated with the particular pipe size. The organist has a number of acoustic configurations available in the form of divisions of the organ case - one for each keyboard. These divisions are called Grand Orgue, Positif, Récit, and Echo, among others. Together, they cover a range of ten octaves, which correspond to the sound spectrum that is audible to the human ear. The music is written in 8': a 16' stop sings an octave lower; a 4' stop sings an octave higher; and a 2' stop sings two octaves higher.
Each case division is operated from the console which is located between the main case (Grand Orgue) and the Positif division. The organist sits down at the organ bench facing away from the audience, with four keyboards and a French-stype pedalboard in front of him/her.
Musical literature from the fifteenth to the eighteenth century made do with a figured bass (sustained), and the pedalboard keys were played with the tips of the toes.
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egistration of
the instrument (principles)
The organist can control the balance of tone in the case divisions through selection and adjustment of the specific stop (or stops) as a function of the musical sound to be produced. The air that is admitted into the pallet box rushes into the chosen key channel and escapes through the open slider hole(s) into the pipe(s) corresponding to the note played on the keyboard. The chosen musical sound develops as long as the organist chooses (duration of the note).
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top and key action
This is manipulated by a knob within reach of the organist. Through a system of trackers, stickers and rollers, all equipped with small levers, the knob communicates across the instrument with the slider that corresponds to the particular stop. |
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 rackers
The key is connected to trackers which eventually pull to the valves that open to admit air from the wind chest into the pipe. The distance is sometimes quite long between the note selected on the keyboard and its corresponding pipe. In this case the roller, a wooden rod, is used as its rotation can accommodate the irregular angles. One end is attached to the key and the other is attached to the valve directly, or trackers which lead to the valve.
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imbre
The timbre (tonal properties) of a pipe is partly a function of the material used for the construction of the pipe - usually metal or wood. One of the materials is a mixture of lead and tin. The sound of the pipe changes as a function of the casting admixture. If more tin is used (about 50%), the mixture is called "spotted metal"; if less is used (the average is about 28% tin), it is called "common metal".
In the different case divisions, you'll find timbres that will blend, and those that are complementary or will carry on a dialogue. These timbres are produced by metal or wooden pipes that vary considerably in length, width, diameter, and shape (see photos). The scale of a pipe (the ratio of its length to its diameter) constitutes its "size". Larger pipes give a warmer tone.
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 ind chest and accoustic components
The wind chest, which receives the pipes constituting the stops, distributes the air that comes in from the pallet box to the key channels and allows the air to escape into specific pipes when the slider opens and aligns the pipe with its key channel through the toe board.
The wind chest is the "meeting place" where the pipes (acoustic components), stop controls, key controls, and the wind (or air) needed for emitting sound all come together. It also serves to support the system of pipes. Special pipes called Postages carry the air to pipes that are not supported directly on the wind chest, such as the Montres (the facade pipes), or the lower registers.
It is into this box that the compressed air flows from the reservoir. The levers to the valves pass through a sheepskin, which prevents loss of pressure. The valves themselves are kept closed by springs, and the pulling action, provoked by the pressing of a key, opens the valve and allows the air to pass through the corresponding groove and leave by the selected pipe.
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