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Ganassi - Kynsecker - Bressan - Denner 

Structural differences and  their effects on musical practice

Lecture held at the ERTA Symposium, Karlsruhe 1994         English translation by Terry Simmons, Warrnambool, Australia        

1 Fundamental of Recorder  acoustics

The aim of this paper  is to examine recorders regarding different building methods: the structural  and constructional side, how structural differences affect the musical characteristics; and ranges of application of the instrument.

1.1 Relationship of Bore  Profile to Tone Colour

We will examine the various factors-determining the instrument’s sound, beginning with the different profiles of the bore. Here the differences are e.g. between a Renaissance recorder, shown at its clearest in the Ganassi building method.                

From elementary physics or from organ-building, we know the difference between open and stopped pipes. We know that for a given frequency, a stopped pipe is only half as  long as an equivalent open pipe. Also the tone quality is different. We know that the sound of an instrument consists of the fundamental plus different  partial tones. After the fundamental as the basis, the octave follows as the  second, above that the fifth in addition (and/or the twelfth to the  fundamental) as the third, as the fourth the double octave, as the fifth a third above that as the sixth again a fifth above the double octave and so on.                

We remember that whereas  the sound of an open pipe consists of all of the harmonics, the sound of a stopped pipe is comprised of the odd-numbered harmonics only: the fundamental, fifth above the octave, third above the double octave , etc. We call this rather nasal-sounding tone picture “stopped tone quality”.                

Stopped pies also  differ from open pipes in their over-blowing behavior. Stopped whistles can  be over-blown only into odd-numbered harmonics. The typical representative is  the clarinet, which cannot be overblown into the octave, but straight into the  twelfth.                

Between these two extremes are pipes in which the bore more or less strongly contracts towards  the bottom end. In such whistles the even-numbered partials are suppressed -   completely, but clearly weakened compared with the odd-numbered, so that such pies have a tendency towards a nasal or “stopped: tone quality, even though it is generally easily possible in all rule to over-blow them to the octave over a wide range.                

A further factor is the bore diameter compared to the its length. The narrower the bore, the more strongly pronounced are the higher harmonics and the more easily the instrument can be overblown. In extreme cases it may be difficult to produce low notes  because of the instrument’s strong tendency to over-blow.                                                By contrast, an instrument with a relatively wide bore has, by virtue of its large air volume, a large sound, is rather poor in overtones and perhaps rather difficult to over-blow into higher harmonics.


1.2 Other sound-Determining design  features

Naturally there are other  design factors that play a large role in determining the sound of a recorder.                

There is first the design of the “cut up”. Generally one can say that the higher it is, the louder and more direct the sound becomes. (The cut-up is the distance from the wind-way exit to the edge.)

This is particularly relevant in relation to the bore diameter. This becomes clearest, if one looks at the extreme. Thus a wide bore together with a low cut-up results in a dark,  intimate sound, while a narrow bore, combined with large cut-up results in strident instruments with fast, nervous speech.

As well, there are clear differences in the direction of the wind-way in relation to the instrument’s length axis. Generally a wider bore needs to be stimulated stronger than than more narrow bores. Consequently with Renaissance instruments the windway is almost always angled slightly inwards, while with the usually narrower-bore  baroque instruments they are normally parallel or even angled slightly outward  the instrument.


Stephan Blezinger
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