Flutes

In a general sense, all labial ranks of the organ are flutes: they have a labium like the recorder, a sharp edge dividing a flow of wind thus causing vibrations. In a narrower, organ-specific sense, however, the labial ranks of the organ are further divided according to scale and type, into "strings"with narrow, the principal with medium and the actual flutes with wide diameter to length ratio. In addition, there are the stopped pipes, which are more similar to each other in sound character than open ranks.

Organ stops containing -flute, however, occur with open, wide-dimensioned flute ranks as well as with some stopped and overblowing ranks. The name alone can therefore sometimes mislead in assessing the design of the register.

 

Flutes in organs are usually wider than diapasons. Their sound therefore has a quite powerful fundamental and relatively few harmonics. The open construction, however, primarily produces the harmonics of the octave, the duodecim and the double octave, (No. 2 to 4 to the fundamental). The resulting overall sound is clearly audible and viable, yet mild and pleasant, but without the brilliance of the principals conveyed by their higher harmonics. Similar sounds can also be achieved with other pipe constructions, for example with partially covered or overblown registers (which is why they also are labelled "flute").

 

Open flute registers - also in contrast to the always cylindrical diapasons - are often conical, usually tapered from the labium to the end of the pipe (Fig. left and right), as the original instruments recorder and transverse flute themselves. A very rare exception is a rank with pipes expanding from the labium to the end, as common in reeds and many other wind instruments, by the name dolkan/dolzian (Fig. centre) (not to be confused with the usual reed stop Dulzian). The sound character is reflected in the name, which is derived from the Italian dolce (sweet).

The most common open flute stops are the "Hohl flute" (a variety of shapes, also wide-cylindrical), which is called "Sifflöt" or similar (also eg "Sui flute") as a high rank (in 2' or 1'); also similar to "Wood flute" (narrower; also mostly 2'), as well as - despite the "horn" name - the very wide scaled "Night horn" (8').

"Gemshorn," "Spitz flute", or "Flach flute" (with a quite narrow scale) and (with cylindrical beginning) the "Spindle flute" are conical. One of the most popular ranks was  "Nasat" 22/3' or 11/3', the most important alternative to the diapason fifths. "Flute" only was often identical to "Block flute" and another open-conical rank, between the stops Gemshorn and Spitzflöte. The flute stops also include the undulating "Unda maris", of various construction. However, it was always to be combined with another flute stop. When both were pulled together, the undulation produced the effect of the "sea waves" promised by the term, with a little imagination and good will...

 This may have lead to experiments of pipes with two labia, either on the front and back of the pipes or at right angles to each other, with names like "piffara" (bifra, etc.) or "double flute", usually stopped, occasionally open. Here two pipes are united in one, vibrations arising in both labia, which, however, communicate with one and the same pipe tube. If the two labia are not exactly positioned and dimensioned in the same way, minimal beatings occur, which give the sound a particularly ethereal character by small pitch vibrations. Some organ builders simply put two pipes together back by back, and thus fulfilled the term double flute literally.

 

The differences in sound between these ranks are not very large. But what they all have in common is a contrasting character in relation to the diapasons. This makes them the most important group of alternative timbres.

v. l. n. r.: Spitzflöte und labialer Dolzian (aus Dom Bedos: L'Art du Facteur d'orgues), Spillflöte (aus Praetorius: Syntagma Musicum II) 
v. l. n. r.: Spitzflöte und labialer Dolzian (aus Dom Bedos: L'Art du Facteur d'orgues), Spillflöte (aus Praetorius: Syntagma Musicum II)
 
 
 
 

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