Now that we've covered the various lengths and sounding octaves of the pipes, including mutations and compound stops, it's time to cover the families of organ pipes.
Organ pipes are divided into two main categories: Flues and Reeds
The sound of a flue pipe is produced in a manner similar to a recorder. Without moving parts, air blows across a sharp lip.
Within the flue pipe category are three families: flutes, diapasons (or principals), and strings.
The tone of a flue pipe is affected by the size and shape of the pipes as well as the material out of which it is made. A pipe with a wide diameter will tend to produce a flute tone, a pipe with a medium diameter a diapason tone, and a pipe with a narrow diameter a string tone. The pitch of a flue pipe is determined by the length of the pipe from the mouth to the open end of the pipe.
Hybrid stops contain one rank of pipes which attempts to combine the tones of two other classifications of stops, such as the Gemshorn which has a sound combination of Flute + String.
To which family do mixtures belong? There are two types of mixtures: chorus mixtures and solo mixtures. Chorus mixtures are generally voiced as principal stops, while solo/swell mixtures are often voiced as flutes.
Chorus mixtures are used to add brilliance to larger chorus-type registrational combinations (which we discuss in the next lesson), such as principals 8’, 4’, and 2’.
Some common chorus mixtures include:
Plein jeu VI
Plein jeu VI
Solo Mixtures are intended to be used in combination with at least an 8’ stop, unless one is included in the mixture itself, as with Cornet V. Their main function is to add color to solo combinations (where only one voice is played on one manual, and the accompaniment voices are played on another).
Some common solo mixtures include:
The sound of a reed pipe is produced in a manner similar to a clarinet. Wind is directed towards a curved piece of brass (the reed) which has a flat piece that vibrates, or beats, to create sound. The longer the vibrating portion of the reed, the lower the pitch. The shorter the vibrating portion, the higher the pitch
Unlike the flue category, within the reed pipe category there is just one family--the reed family. However, reeds are further classified as either solo or chorus reeds, depending on their blending characteristics.
Pull our your stop list--it's time to get to work! Using The Encyclopedia of Organ Stops and/or The New LDS Organist Packet, page 11, go through the stops on your organ and jot down which family they belong to. With the reeds, additionally classify them as solo or chorus reeds. If you are using an organ in an LDS chapel, its online manual may also provide some stop information for you.
On some organs, the reed stop names are red while the flue stops are written in black. Traditionally, all flue stops are listed from lowest-sounding to highest, followed by the reed stops in the same order.
Instead of beginning these lessons with pedaling and fingering techniques, I chose to provide a broad foundation for you to draw from. Now that you have classified your organ's stops, in the next lesson we can continue on to Lesson 4: Hymn Registrations, which will teach you how to register a full organ and allow you to successfully "cheat" at the organ.