Thursday, March 19, 2009

Why clarinets?

Let us examine next the second hypothetical question:

Why would somebody want to investigate the acoustics of clarinets, and let alone of a contrabass clarinet? Surely there are nice of-the-shelf instruments to be bought, played and enjoyed.

Just to start with, the acoustics of clarinets is unique. It is the only modern woodwind instrument that features a cylindrical bore with an air column that behaves as a cylindrical pipe closed at one end. Other than the clarinet, only its grandfather the chalumeau or a medieval instrument called rackett, feature cylindrical bore. Considering that the pressure along the tube has a node at the closed end and an antinode at the open end, a closed cylinder will produce resonance of odd harmonics (no even harmonics are produced) and the fundamental frequency is an octave lower than the one produced by an open cylinder of the same length. Another interesting feature is that the air column will overblow at a twelfth, since when opening the register hole, the fundamental frequency is cancelled and the third harmonic is produced.

Other woodwinds as the flute, for instance, behave as an open cylinder. Conical bore instruments, on the other hand, feature varying cross sectional area along the air column. The pressure wave is not plane as for a cylinder but spherical. In short, it can be said that for conical bore instruments the fundamental resonant frequency is the same as for an open cylinder of similar length. For open cylinder and conical bore, all harmonics are produced, odd and even. Instruments that behave as an open cylinder overblow at an octave, meaning that the same fingering with the addition of opening the register hole, will produce a frequency twice as high, since the second harmonic is produced.

Summarizing, the main features of the clarinet acoustics differing from all other woodwinds are the following
  • produces only odd harmonics (chalumeau register). This originates the particular timbre characteristics
  • overblows at a twelfth. This enables such a large range spanning over 4 octaves
  • the same air column length produce frequencies an octave lower than open cylinder or conical air columns. This feature allows the contrabass clarinet to reach the same register as the contrabassoon (Bb0; 29.14 Hz) with half the piping (about 3 meters instead of 6)
These acoustical characteristics are valid for all clarinets. Why then a particular interest in contrabass clarinet?
The chalumeau register in the standard Bb soprano clarinet has that warm and full tone that is characteristic. Since I was specially interested in deep voices, my next step was Bb bass clarinet. The chalumeau register of this instrument is truly majestic, which such a dark tone. Bb bass clarinets usually feature a range down to written Eb (sounding Db2). Only professional instruments have a longer body (about 23 cm longer) with three additional semitones, down to Bb1. This feature is quite interesting, considering that the range of the bassoon and cello reaches Bb1. Since the solo literature for Bb bass clarinet is rather scarce, with this extended register a whole world of possibilities for playing bassoon and cello literature are opened. Of course, a professional Bb bass clarinet, say a Buffet Crampon 1193 of about 6-7 kEuro, was not fitting well within my budget, therefore I decided to develop an extension for my old and trusty Evette - Buffet Crampon. At some point in time I will be also discussing some experiences with this project. The next step in the search for deeper clarinet voices is, of course, a Bb contrabass clarinet.

Ok. It is clear why the interest in contrabass clarinet. But
what about buying a nice of-the-shelf instrument? A selection of the best woodwinds acousticians of all times have been dealing with issues of tuning, intonation, flexibility, responsiveness, multiple automatic register keys, etc., etc, for contrabass clarinets for over a century: Adolphe Sax, Besson, Houvenaghel, Leon Leblanc, Robert Carre, and more recently Eppelsheim. Why should somebody bother about it? Selmer and Buffet Crampon manufacture in the traditional straight shape in wood and metal respectively. Leblanc manufactures in metal both the straight and the "paperclip" down to written C and to Eb. Eppelsheim manufactures a metal version folded in a way resembling the paperclip, yet different, down to C.

My reasons are the following,
  • The motivation of the project is to learn and experiment in clarinet acoustics in a systematic way, with a project proposal that is new and was not yet explored, as far as I know. I am not just eager to play modern compositions of electronic music or contrabassoon repertoire.
  • I do not have some spare 10 kEuro to spend in an Eppelsheim instrument
  • Just to show it can be done

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