(Fr. Fourniture; Ger. Mixtur).
An organ stop with two or more ranks of pipes comprising, most commonly, intervals at octaves and 5ths but also 3rds and (occasionally) 7ths and 9ths. As the pipes usually sound at higher pitches than the other individual stops, when the ranks of pipes in mixtures reach a certain pitch (the shortest length of pipe that has seemed practical has varied from country to country) the ranks must ‘break’ to a lower pitch even as they ascend through the keyboard's compass. Since the middle of the 19th century, ‘Mixture’ has meant in English organs the same as Mixtur, mixtuur or mistura: the chief compound stop of the Diapason chorus. However, before then (with very few exceptions) the term indicated a combination of stops rather than a specific stop; nor was it then used, as it is now, as the term for compound stops in general. The number of ranks of pipes in each Mixture stop is usually given in Roman numerals in brief stop-lists, e.g. ‘Sesquialtera II’ or ‘Cornet V’.
No stops have better represented makers' and players' attitudes to organs and their music throughout the history of the instrument than the compound ones. The block-chests of the early monastic organs (see Organ, §II, 5) were probably large undivided mixtures whose intended effect is probably still to be discerned in the largest surviving monastic mixture in the organ at Weingarten Abbey (1737–50), whose 48 pipes sound simultaneously from the C pedal key, and whose name ‘la Force’ indicates the yearly explosion of natural vitality and power associated with spring and Easter. With the medieval invention of stop- and key-actions, the lower ranks were separated from the Blockwerk, so that the overall pitch of the compound ranks rose. As they were further separated during the Renaissance, a great variety of Mixtures were experimented with (e.g. Mistura, Locatio, Hintersatz, Zimbel and Fourniture), and makers of the Baroque period added a repertory of wider-scaled solo or colour mixtures, often with 3rd-sounding (Tierce) ranks (e.g. Cornet, Hörnli, Sesquialtera, Terzian and Carillon-Mixtur). As organs became more forceful with mechanical aids to playing and winding, and were more generally tuned in equal temperament (which is particularly ill-suited to Tierce mixtures), there was a Romantic reaction to the use of mixture stops, which were sometimes tolerated only as a means of ‘compensating’ for the perceived shrillness of extreme treble tessituras (Compensationsmixtur, Progressio Harmonica, etc.). Some mixtures, such as Rauschpfeife, were chorus stops at one period, solo at another. Too often, in extreme reaction, modern organs have loud and bright mixtures in no particular style; the planning, content, scaling and voicing of compound stops should distinguish between national organ ‘schools’ as well as testing the skill, aural discrimination and patience of makers.
See Organ stop.
MARTIN RENSHAW