Fear not! Even experienced organists can get confused. The Fowler Organ Company Guide to Organ Jargon will help you sort it all out!
Most organs have at least two manuals and pedal. Each of the manuals has a set of corresponding drawknobs or some other kind of switch. These controls allow the organist to select appropriate sounds for each manual. Each manual can have its own sound, allowing the organist to play a solo sound (a trumpet for example) on one and an accompaniment (principals for example) on another. Sometimes an organist will even play a melody on the pedals accompanied by the manuals!
The keyboards each have names: Great, Swell, Choir, Positiv, Solo etc. The sounds associated with each keyboard make different contributions to the whole of the instrument.
The Great, usually the lower or middle keyboard, contains the meat and potatoes of the organ: the principal chorus. Depending on the design of the instrument, it may also contain solo sounds such as a trumpet.
The Swell, usually the upper keyboard, usually contains both solo (reeds) and accompanimental sounds as well as a secondary principal chorus, somewhat lighter than that of the great. As its name suggests, the Swell is usually enclosed in a box where the organist can control openings with a foot pedal to make the sound loud or muffled.
The Positiv or Choir, usually the lowest keyboard on a 3-manual organ often contains solo and accompanimental sounds, though different from those of the swell. Mutation stops are usually found here. The positiv or choir also contains a secondary chorus. A choir is enclosed like the swell, a positive is not.
Hear the sound of Great, Swell and Positiv choruses.
The stops in an organ are designed to compliment one another's overtones or harmonics. (This is where the numbers come in!) Stops labeled 8' (say: eight foot) pitch sound at a pitch directly corresponding to the keys you play. Stops labeled at 4' play one octave higher, reinforcing the second harmonic. 2' stops play an octave higher than that.
In addition to 8' 4' and 2' stops, most organs have 2 2/3', 1 3/5' or 1 1/3' stops - these are called mutation stops because they sound pitches other than octaves above 8'. A 2 2/3' stop will pay one and a half octaves above an 8' stop (an octave and a perfect fifth). A 1 3/5' stop will play 2 octaves and a major third above an 8' stop.
There are three main families of tone to which nearly all organ pipes can belong:
Principals (a group of which make up the principal chorus) have the sound of pure "organ tone" and rich harmonic series. Different varieties of principals go by names like Diapason, Montre, Prestant, Octave, Quint. A typical principal chorus looks like this:
8' Principal (diapason, Montre...) -- The fundamental pitch 4' Octave (Principal, Prestant...) -- the second harmonic partial 2 2/3' Quint (Nasard, Twelfth...) -- the third harmonic partial 2' Superoctave (Doublette...) -- the fourth harmonic partial IV Mixture (Fournature, Scharff...) -- an assortment of high-pitched harmonics
Flutes have little harmonic development but have a beautiful pure sound. They can function both as accompaniment and soft solo sounds as well as complimenting the ensemble. Flutes come in many varieties, such as Bourdon, Gedackt, and Rohrflute. Flutes are sometimes made of stopped wooden pipes.
Reeds take many different forms, from a loud, fiery trumpet to a soft vox humana. Unlike principals and flutes which resemble whistles, reeds produce sound with a vibrating brass tongue. Reeds can be used for solo sounds or to add power and brilliance to ensembles.
There also Strings which are similar to principals but usually have a much smaller diameter (scale) and thinner tone. Strings are usually found in the swell and go by names like viola, viol da gamba, and dulciana. A string stop is often complimented by a celeste, a similar stop tuned slightly sharp to give a beautiful shimmering quality to the sound. Note that for this reason a celeste should never be used with other stops.
Couplers, such as "swell to great" link two manuals so their sounds can be combined together.
A combination action is a mechanism or computer which can store settings of all the controls on the console and recall them at the touch of one of the buttons under they keyboards. This allows the organist to make rapid and dramatic changes while playing. Until about 20 years ago, this was accomplished by complicated mechanisms. However, with the advent of microchips and computer technology, these and other functions are performed very reliably by solid state technology.
Let's look at the specification of a theoretical medium-sized organ.
GREAT 8' Principal Note the principal chorus as above. The Rohrflute 8' Rohrflute can be used alone or with the Spitzflute for a lovely 4' Octave light sound or to accompany a solo 4' Spitzflute 2 2/3' Quint The 2 2/3' adds color to the principal chorus 2' Superoctave IV' Mixture The mixture adds characteristic brightness and sparkle 8' Trumpet The trumpet can be used for a solo or to compliment the principal chorus SWELL 8' Bourdon The bourdon and viola are the foundation of the 8' Viola swell's ensemble. The viola and celeste make a 8' Viola celeste beautiful soft accompanimental combination 4' Koppelflute 4' Principal The 2 2/3' and 1 3/5' with the Bourdon make a nice 2 2/3' Nasard soft solo sound called a SESQUIALTERRA. Adding the 2' Piccolo koppelflute and piccolo to this makes a CORNET. 1 3/5' Tierce III' Scharff The Oboe can compliment the swell's ensemble or 8' Oboe serve as a medium solo sound. PEDAL 16' Subbass The subbass and bourdon give deep bass to the pedal 16' Bourdon division, giving the organ a good foundation. 8' Principal The principal and gedekt add body to the bass line. 8' Gedekt The choralbass is a principal that can be used to 4' Choralbass play a solo melody. or as part of the ensemble 8' Trumpet The trumpet functions as in the great.
This is only an exploration of an idea - every organ is different and is designed specially for the room it is built in and for the musical needs of its owner. Each stop in an organ can be used in an almost limitless variety of combinations. In a well built organ, nearly any combination of stops will sound well together.
We hope this has helped you to become interested in the wonderful art of organ building. If you have any questions, please give us a call at (517) 485-3748
Fowler Organ Company
1061 Hickory Road
Lansing, MI 48906
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