Mixture (music)
A mixture is an organ stop, usually of principal tone quality, that contains multiple ranks of pipes. It is designed to be drawn with a combination of stops that forms a complete chorus (for example, principals of 8′, 4′, and 2′ pitches). The mixture sounds the upper harmonics of each note of the keyboard. The individual pitches in the mixture are not perceived by the listener; rather, they reinforce the fundamental pitches of the chorus, adding volume and brilliance to the sound. Historically, the mixture descends from the medieval Blockwerk concept, an organ in which there were no stops and all the ranks sounded simultaneously.
Nomenclature
Mixture stops are typically labeled with the number of ranks of pipes that they have, ie. how many pipes sound when a single key is pressed. For example, a Mixture II contains two ranks (sounding two notes), a Mixture V contains five ranks, and so forth.
The number of ranks per note in a mixture commonly increases as one ascends the compass of the keyboard. A mixture exhibiting this trait is referred to as progressive, and is labeled with two numbers (eg. Plein Jeu III-VII).
Variables affecting tone color
In addition to the standard concerns of voicing flue pipes, most mixture stops include only octave and fifth pitch levels; several historical mixtures include thirds, and some modern organs feature mixtures with other pitches such as sevenths and ninths. In some organs, the pedal division contains lower-pitched mixtures that reinforce the 16' fundamental, as opposed to the 8' (as with the manuals).
The frequency at which the various ranks in a mixture drop back by an interval (or break) as one ascends the compass determines to a great extent how the mixture sounds. If a mixture does not break, it is referred to as a harmonic mixture. Aristide Cavaillé-Coll built many examples of mixture stops labelled "Plein jeux harmonique".
Mixture breaks
The composition of pitches in a mixture may change (or break) several times across the compass of the keyboard. The "breaks" of a mixture involve the dropping out of a higher pitch at a given point within the keyboard's compass, and/or the addition of a lower pitch on the succeeding note.
For example, here is the break structure of a typical Great Fourniture IV:
Note Pitches on that note and above C1 1’1/3 - 1’ - 2/3’ - 1/2’ C13 2’ - 1’1/3 - 1’ - 2/3’ C25 2’2/3 - 2’ - 1’1/3 - 1’ C37 4’ - 2’2/3 - 2’ - 1’1/3 C49 5’1/3 - 4’ - 2’2/3 - 2’ C C C C C C 1 2 3 4 5 6 C 1/16’ |------------+-----------+-----------+-----------+-----------/| 1 - C 1/16’ B | | | | | / | 1 - B A# | | | | | / | 1 - A# A | | | | | / | 1 - A G# | | | | | / | 1 - G# G 1/12’ |------------+-----------+-----------+-----------+------/----/| 2 - G 1/12’ F# | | | | /| / / | 3 - F# F | | | | / | / / | 3 - F E 1/10’ | | | | / | / / | 3 - E 1/10’ D# | | | | / | / / | 3 - D# D | | | | / | / / | 3 - D C# | | | | / |/ / | 3 - C# C 1/8’ |------------+-----------+-----------+----/------/----/------/| 4 - C 1/8’ B | | | /| / /| / / | 5 - B A# | | | / | / / | / / | 5 - A# A | | | / | / / | / / | 5 - A G# | | | / |/ / |/ / | 5 - G# G 1/6’ |------------+-----------+------/----/------/----/------/----/| 6 - G 1/6’ F# | | /| / /| / /| / / | 7 - F# F | | / | / / | / / | / / | 7 - F E 1/5’ | | / | / / | / / | / / | 7 - E 1/5’ D# | | / | / / | / / | / / | 7 - D# D | | / | / / | / / | / / | 7 - D C# | | / |/ / |/ / |/ / | 7 - C# C 1/4’ |------------+----/------/----/------/----/------/----/-------| 7 - C 1/4’ B | /| / /| / /| / /| / | 8 - B A# | / | / / | / / | / / | / | 8 - A# A | / | / / | / / | / / | / | 8 - A G# | / |/ / |/ / |/ / |/ | 8 - G# G 1/3’ |-------/----/------/----/------/----/------/----/------------| 8 - G 1/3’ F# | / /| / /| / /| / | | 7 - F# F | / / | / / | / / | / | | 7 - F E 2/5’ | / / | / / | / / | / | | 7 - E 2/5’ D# | / / | / / | / / | / | | 7 - D# D | / / | / / | / / | / | | 7 - D C# | / / |/ / |/ / |/ | | 7 - C# C 1/2’ |/----/------/----/------/----/------/-----------+------------| 7 - C 1/2’ B | / /| / /| / | | | 5 - B A# | / / | / / | / | | | 5 - A# A | / / | / / | / | | | 5 - A G# | / / |/ / |/ | | | 5 - G# G 2/3’ |/------/----/------/----/-----------+-----------+------------| 5 - G 2/3’ F# | / /| / | | | | 3 - F# F | / / | / | | | | 3 - F E 4/5’ | / / | / | | | | 3 - E 4/5’ D# | / / | / | | | | 3 - D# D | / / | / | | | | 3 - D C# | / / |/ | | | | 3 - C# C 1’ |/----/------/-----------+-----------+-----------+------------| 3 - C 1’ B | / | | | | | 1 - B A# | / | | | | | 1 - A# A | / | | | | | 1 - A G# | / | | | | | 1 - G# G 1’1/3 |/-----------+-----------+-----------+-----------+------------| 1 - G 1’1/3 C C C C C C 1 2 3 4 5 6
External links
- Data outflows and graphics of mixtures L'Hydraule (the example above without outflow).
- Study of the Aristide Cavaillé Coll's pipework. Laurent Plet.de:Register (Orgel)#Gemischte Stimmen
