Celebrating the pipe organ, the King of Instruments
March 5, 2007
G’morning. What is the relationship of “ranks” to “stops”? I assume that an organ might sometimes need two or more ranks to obtain a particular tone, say, an oboe or a string. That is, if an organist pulls a “stop”, might that require one or more ranks for that particular tone? Many thanks.
In simplest form, a ‘rank’ is a single set of pipes, one for each pitch, from lowest to highest, on the organ keyboard…which, for the sake of this discussion, would be 61 pitches…from low “C1” to high “C6” in the five octaves of the ‘standard’ organ keyboard (realize that, historically, ‘standards’ vary considerably).
A ‘rank’ is activated by pulling on the ‘stop’…which allows air to pass through those pipes when a key is pressed down. A ‘rank’ may represent any of the various families of tone…flue (principal, flute, string) or reed, and any of the various pitch levels at which ranks are specified (8′ pitch is unison, equivalent to the pitch or note relationships on a piano; 16′ pitch is an octave lower, 4′ pitch is an octave higher, etc.)
Some further illumination of this can be found on our How Pipe Organs Work page. On that page is link to Lawrence Phelps’ web page titled “Pipe Organs 101.”
Often a single ‘stop’ engages only a single ‘rank’, though sometimes a stop will activate several ranks simultaneously (these are called ‘compound stops’, such as Mixtures or Cornets or celestes). These compound stops are indicated in an organ specification by a Roman Numeral (III, V, VIII, III-IX, etc., depending on the number of ranks activated by that single stop).
The number of ranks in an organ directly relates to the number of pipes. The number of stops can, by electrical or mechanical reallocation, allow various ranks to appear in various places within an organ specification (a Trumpet on the GREAT manual might be borrowed from the SWELL division, or be playlable in the PEDAL…so that one ‘rank’ might be counted as three ‘stops’).
Sometimes, it is possible to ‘synthesize’ a sound by combining several ranks. The classical ‘Cornet’ is made up of five ranks of flute pipes at 8-4-2 2/3-2-and-1 3/5 pitches. Draw those ranks individually and you hear them as flutes; play them together and the effect is a new, nasal, soloistic tone. Sometimes an “oboe” effect can be created this way (though a synthesized ‘oboe’ stop will not have the same character as an actual labial/reed ‘oboe’ stop.)
In some orchestral organs, various ‘string’ ranks may appear as separate stops (viola da gamba, salicional, etc.) independent of their off-tuned companions (Voix Celeste, Gamba Celeste), though sometimes the celesting pair is playable ONLY on a single stop…indicated by the Roman numeral II, representing two ranks).
Hit the library, the wiki, or the various background articles available through the Pipedreams Resources page. Eventually, it will start to make sense.