This is the second in a series of articles about the four families of tone in the pipe organ. In succeeding issues I will explore flutes, reeds and strings, but will begin with the most important family called Principals.
Principals have been a fundamental part of pipe organs for centuries. Using various names and a variety of shapes, these open pipes have been at the heart of pipe organ design and sound.
Importance has not guaranteed uniformity or predictability of sound, and Principals may range from narrow scaled (small diameter) and stringy, to wide scale fluty sounds, with everything in between. The term Principal carries such a rich assemblage of subtleties that a well trained ear could distinguish several hundred differences in color, power, attack, resonance, harmonic structure, stability, decay and ambience in as many different ranks. The indescribable sound of Principals, open to a wide range of personal perception, and the fact that no two organbuilders voice in the same manner yield unending and subtle variations.
What's in a name? Most organbuilders encounter the frequent problem of trying to explain the differences between Diapason and Montre, Prestant and Principal, Prinzipal arid Octave, Oktav and Doublette, as well as the many other names for mixtures which are all part of the Principal family.
Where do all these names come from, and how do we begin to understand what they really mean to the sound of an organ? The main problem comes from a lack of agreement on what each name implies and that all of these names refer to a single well defined type of organ pipes, viz., cylindrical open pipes, usually made of metal, and producing that full "organ" sound which can only be demonstrated by playing it for the ear to hear. Fortunately there are no rules requiring all Principals to sound the same or assuring that their names denote certain sounds. One listener's Diapason is another's Principal and is a third's Montre.
The names are ancient and come from the many different nationalities of organbuilders. Montre is a French designation for Principal pipes, but not if they are enclosed in a swell box. Praestant or Prestant (from the Latin Praestans) is a Dutch word for the same type of pipe, but Prestant is a French word for them if played an octave higher. Flautado is the Spanish word for Principal, which adds confusion since one could easily assume that such a name would signify a flute voice. Principale is Italian and Prinzipal is a somewhat generic Northern European word for the same. Diapason is a very old Greek word which has been Anglicized and is frequently used in England and the United States. It is unfortunate that the name "Diapason" acquired a bad reputation in the 1960-80 era, but brave organbuilders now use it again without fear of ridicule.
An added problem is that each name carries certain implications of history and sound. When we see "Montre" on a stoplist or drawknob, we usually think of a large round sound; Prinzipal can imply a thinner, somewhat fizzy sound; Diapason will mean a thick, big, heavy sound to those who know the organs built in the era 1910-40, but a gentle singing sound to those familiar with old English organs.
To those blessed (or cursed) with hearing and memory acute enough to hear pipe organ sound in a highly sensitive way, no two instruments sound the same, and no two ranks of Principals sound the same. It is similar to the world of the violins, where no two instruments sound alike, even from the same maker, and each famous violin has its own name and recognizable character.
The sound of Principals has been a part of organbuilding for centuries, and the majority of their characteristics were in place by the year 1600. Since then, refinements have continued and the emphasis of certain musical styles has produced alterations in both the architecture of the sound and the arrangement of these ranks within the organ. There are also subtle variations in the construction of Principals, such as being made of wood rather than metal, rectangular or square rather than round, slightly tapered rather than cylindrical. These variations are subtle, with only slight alterations to the basic sound. The analogy with the violin again applies, where there have been historic and contemporary changes to the instrument, but never to the point that the violin became a flute or an oboe. Principals have undergone such changes but still remain within the tonal boundaries of the family.
The physical data on a normal Great Principal 8' is that the cylindrical resonator is about 6" in diameter and 8' long at low C. This would become about 2" if in diameter and 2' long at middle C, and about 1/2" in diameter and 3" long at top C. These diameters (but not the lengths) would be altered slightly to compensate for room acoustics, placement in the instrument, and the builder's taste and purpose. The Principal family has the least tolerance of any tonal family for errors in design; slightly too big and the sound is fluty; slightly too small and the sound is stringy. Indeed, one can easily think of many flutes and strings as just bigger or smaller Principals.
Principal pipes are usually made of metal, and most builders have strong feelings about the type of metal to be used. Though large bass Principals are usually made of zinc, copper, wood or aluminum, when a size under 4' long is reached, the preferred material is a mixture of tin and lead. This is not a true alloy since the metals do somewhat separate from each other, creating a soft, heavy, limp material which is ideal for organ tone. Above 70% tin, the metal is lighter and smooth, giving a sparkle to the sound. In the range around 50% tin-lead the metal has spots and a very irregular density, giving a warm purr to the sound. At high-lead contents, the sound is dark and heavy. Each has an important use in the organ.
The Principal family is the source of the most characteristic and most important sound in the pipe organ. Its members are all related in shape and sound, and come from a wide background of nationalistic sources and periods. The Principal sound is found only in the pipe organ (it does not exist in nature or the orchestra) and can neither be ignored nor eliminated in thoughtful designs. It is the heart of the instrument. Next installment: Principal Pitches and Mixtures.