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Please, can you provide me with an easy definition of 'ranks' in an organ? How are the number of ranks determined in any pipe organ?

Hello! Thank you for the question. A typical organ keyboard has 61 keys. If we wanted to use the keyboard to play pipes, we would need 61 pipes. Each pipe would be tuned chromatically from the lowest pitch to the highest pitch across the keyboard compass and every pipe would maintain a particular common sound such as that of a flute. These 61 flute pipes would then be referred to as a single "rank" of pipes.

Organs typically utilize many ranks of pipes. Most pipes fall into 4 main categories of sound: Flutes, Strings, Principals (also called Diapasons) or Reeds. There are hundreds of variations of timbres within each category. Therefore there are many of types of Flutes, many of types of Strings, many of Principals, etc. Generally speaking, most organs have at least one Flute, String, Principal and Reed rank. Therefore, a minimal organ would consist of 4 ranks, each rank representing the four families of sound. A large organ having, say, 100 ranks would still utilize the four basic pipe families but offer many variations within each family. A good way to think of this is to consider all the kinds of reds, blues, yellows or greens there are.

An organist uses the available ranks of sounds much like an artist painting a picture using pigments. By mixing sound colors, the organist is able to create a vast number of sonorities just as a painter is able to create all the hues and shades needed to create just the right colors to produce the desired effect. Obviously, the more ranks an organist has at their disposal, the more colors they can create, just like a painter.

It is common for ranks to extend beyond 61 pipes. So, expect to see single ranks that number anywhere from 43 pipes to 97 pipes. This is called unification and allows a single rank to be played at various pitches.

Thank you for your answer! However, I still can't get the concept of ranks.

OK, lets try another couple angles. Imagine a shepherd out in a field who has a set of pan pipes he plays to pass the time. Assuming his set of pan pipes includes every pitch he needs to play his tunes. That set of pipes would be referred to as a single rank (meaning a complete row of pipes with similar sound at different pitches). The pan pipe was the first pipe organ. Granted it did not have a keyboard, but the musician didn't need one. Now, lets assume the shepherd becomes bored with the sound of his single rank of pipes and decides to make another rank of pan pipes which he makes differently to create a different kind of sound. Pitches would be the same so he can play the same tunes on it as the original set. Now he has appreciably a two rank organ. If he lays the new rank of pipes atop the original rank, he can play a pipe from each rank at the same time or a single note from either rank individually. Obviously, if he wishes to expand on the project of building more ranks of pipes he would quickly benefit from incorporating a keyboard of some type with stop controls to allow him to decide which rank or ranks he wishes to play when he depresses a note on the keyboard. Along with an alternative supply of wind he would have at least the concept of a modern day pipe organ. The problem being, as a shepherd, he wouldn't be able to lug the organ around with him so easily.

Now, lets consider a rather odd orchestra that has 61 trumpeters, 61 violin players, 61 flute players and 61 oboe players. Each group is lined up in a row. Each has a rather odd instrument to play because each trumpet is valve-less and can only play a single note, each violin has only one string that plays a single note with a bow, each flute plays only a single note because it has no holes. The oboes the same. The four groups of musicians make up what we can call four individual ranks. There is the trumpeters rank, the violinists rank, the flautists rank and the oboists rank. Each musician's instrument is tuned to play only one note within the chromatic scale (C, C#, D, D#, etc). Fortunately, each player is a really good counter and when their music says it is time for them to play their single note they are right on schedule...kind of like playing hand bells.

Hopefully, the above concepts are helpful. Also, I should mention a "flue" pipe is any pipe within the four pipe families mentioned that produce their tone as a whistle does...using only a stream of air to create sound. Therefore, pipes can be divided into two groups: flues and reeds. Principals, strings and flutes are all flues. Reeds are not flues because they utilize a brass reed to create their sound and not only a stream of wind.

Lovely, but I still can't explain to my students what, exactly ranks are. I think I have an idea, but, as you say, when one gets into mixtures and other combination stops, the ranks change? Here's the thing a typical music educator asks me: 'Is there a pipe for each key/tone of the 8' diapasons on the great?

The question 'Is there a pipe for each key/tone of the 8' Diapasons on the Great? The answer would be "yes". Think of a piano. Each key sounds a different pitch. If we hooked up a pipe to each of the piano's 88 keys, each pipe would need to be tuned so that they all correspond to their assigned note on the piano. The word "pitch" refers to tuning. The word "tone" refers to the timbre of the sound. Asking someone about what kind of "tone" a piano has does not mean they want to know whether it is in tune, but rather whether is it "bright" or "dull". Therefore the tone of a reed tends to be bright, with some fire, and the tone of a flute tends to be dull or better yet..."pure" or without fire.

Yes, there will be a pipe for every 4' string on the Swell. However, I need to qualify this statement and this is where things get complicated. While it is a true statement, there are two ways of designing an organ to accomplish a 4' string. The first way is to build an independent 4' string rank. This would be called a straight rank. If you reread my explanation concerning the concept of extending a rank beyond 61 pipes to 73 pipes for instance, this allows the same rank to play at not only the 8' String pitch (piano pitch) but the 4' pitch as well because there is an added top octave of pipes added to the rank that will play when the top octave of the 4' string is played. Again, there will be an adequate number of pipes in the extended string rank for the 4' string to play clear to the top note of the keyboard. This is called "unification". By taking a single rank of pipes and extending its number of pipes from 61 to 96 pipes, one can play the same rank at 16', 8', 4', 2 2/3', 2', 1 3/5' and 1 1/3'. It is only one rank but you can have 7 stops playing off it, each stop starting at a different pipe within the rank.

Lastly, as you know, a tuba is very large and has a long coiled tube. Because of the long length, the pitch of the instrument is very low. A piccolo on the other hand is very small and short. It therefore sounds at a very high pitch. The valves on each of the instruments simply adjust the length of the instruments causing them to play different pitches. Obviously, an organ pipe does not have valves on it to vary its pitch so it can only produce a single pitch. That's why one needs a pipe for every key on the keyboard.

I don't want to be difficult, but if I am understanding this correctly, then the 8' diapason and the 4' principal and the 2' principal are three ranks?

Can be IF the organ uses a separate rank for each stop. This arrangement would be called a "straight rank" configuration (three ranks, three stops). It's an expensive way to go but is also the preferred way. It requires 183 pipes to go this route.

However, if the organ designers chose to design a "unified" rank, there would be a single extended rank of 85 pipes with three stops playing off it at 8', 4' and 2' pitches (one rank, three stops). This saves expense because it requires 100 less pipes.

Remember that an 8' stop means the lowest pipe note on the keyboard is a pipe eight feet long. When you have the 8' stop down and play the bottom note of the keyboard, you will hear the 8' pipe sound. As you play upwards you will be playing slightly shorter pipes as the pitch increases. By the time you get to the second octave C (C below middle C) you will be playing a pipe that is 4' long. If you continue upward to middle C you will be sounding a pipe that is 2' long. Through electrical switching, unification allows the bottom note to play at the 2' and/or 4' pitch as well as the 8' pitch. So, you can end up playing 2', 4' and 8' pitches from the same rank.

It all has to do with the way the organ has been designed. I hope this information is helpful!