Mixture (organ)

The mixtures are organ stops known as " composés" because they consist of several rows of pipes granted in octaves and fifths. In fact the mixtures provide the sound so characteristic of the organ, that of the Full Play or Plenum which the Germans name also Blockwerk . The mixtures are recognized with their brightness and their power because their function is to enrich the sound with acute harmonics.

There exists in many ways to compose a mixture, i.e. to decide its height, of its number of rows, type of its pipes - flutes or principalisés- and notes on which the recoveries will take place. All these choices affect the sound result of each mixture and make that this one will be characteristic of an esthetics, a school and even of a particular factor.

General characteristics, common to all the mixtures

They are plays made up of several rows, that being able to go from 2 rows for a Large Supply or a small Cymbal, to 13 rows for a great Full Play. The number of rows varies according to the importance of the instrument.
In fact plays, in the traditional music of organ, never get busy only because they do not have a foundation. It is thus necessary, to use them, draw at least a basic play from 8 feet (or 16+8 if the resultant is of 16) in order to ensure a sound base to them.
In general and by tradition, the rows of mixtures are made up only by rows of octaves and fifths. There can be other positions (third, seventh, ninth, eleventh, thirteenth, quads) but they are rarer, often original and sometimes experimental.

The resultant

Any mixture, owing to the fact that it makes speak several rows about pipes granted on odd harmonic intervals, primarily of the fifths and octaves, generates resulting sounds naturally, i.e. sounds generated by additions of the sound pressures. It is about a normal acoustic phenomenon: when two continuous sounds are emitted simultaneously, it occurs a sound resulting from frequency equalizes with the difference in the two emitted frequencies.

Although the mixtures are made up small pipes, they can thus reinforce and amplify the low ones:

a mixture containing a row of 2 2/3 product a resultant of 8 feet.
a mixture containing a row of 5 1/3 product a resultant of 16 feet.
a mixture containing a row of 10 2/3 product a resultant of 32 feet.

The principle of the recoveries

As the mixtures consist of relatively acute pipes (going from 2 feet to 1/2 foot), it is not possible to go up indefinitely. It goes without saying at one time the pipes would produce sounds exceeding the threshold of auditive acuteness of the man. Moreover, these pipes becoming increasingly small are very difficult to grant and very fragile. The organ builders thus set a limit, a ceiling. It was of 1/6 of foot to the Middle Ages then was fixed at 1/8 for the traditional period to reach finally 1/16 of foot (approximately 2 cm), which corresponds to approximately 8 Khz. With each time while assembling degree in degree on the keyboard one of the pipes reaches this ceiling, one makes it set out again a quad, a fifth or an octave lower. It is this downward jump which one calls the recovery.

Although there exist some types of mixtures without recovery, the majority of the mixtures have recoveries. Except some modern mixtures carried out on an experimental basis, the notes on which the recoveries are done are always in connection with the major range of C and thus take place on C, F or the ground. They take place some times on the fa♯, only on modern mixtures.

French mixtures

In the French traditional organ the mixture term is generic and indicates indifferently any composed play, but in practice, only three names are used to indicate the mixtures: supply, the Cymbal and Full Play.

Supply

The French supply is generally a serious mixture. As its name indicates it is primarily used to provide harmonic matter to the basic plays. It is the oldest shape of mixture isolated in a clean play. There exist three kinds of supply: large supply, traditional supply and cymbalized supply.

The large supply never exists alone on an organ. Placed traditionally at the Large Organ, it is used to add to the normal supply two or three serious rows to descend the resultant. In general the large supply makes it possible to have a resultant of 16 or 32 feet.

Cymbal

Full Play

Italian mixtures

German mixtures

Use

Added to the Principal , the mixtures make it possible to obtain the plenum Orgue.

See too

External bond

a History of the Plein-jeu

Category: organ

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