17 June 2010

Messing About in Harpsichords: DIY Ceramic Plectra

T    he sound of the harpsichord resembles that of a bird-cage played with toasting-forks... No, it is more like two skeletons copulating on a corrugated tin roof.”
  —  Sir Thomas Beecham, British conductor (1879-1961).
S omtimes I cannot leave well-enough alone. An amateur guitarist friend at work was showing me his nice, new pick—made of some exotic ceramic material. The manufacturer of the pick is very mysterious and non-forthcoming with regard to what the “specially-formulated”, lubricious, hard material is. But junior Archimedes that I am, I go and measure it—measure its density, etc.—and I suspect (but do not know for certain) that it is boron nitride.

I  think: “That is really cool! But why should guitarists have all the nice toys? What about harpsichordists?”

 van Dijk, ‘The Bookkeeper’
T here are all sorts of other technical materials that are used for musical instruments that are specially selected or constructed so as to achieve physical properties that vary by desirable amounts, in desirable directions.

T hink graphite violin bows: how far they have come in the past 20 years. Think Michel Wegen graphite-epoxy composite guitar picks. Think ceramic composites in jet engine turbines. Think exotic dental composites and orthopedic surgery ceramic composites. Think yttria-stabilized zirconia cutlery in your kitchen!

I n one of my former lives, I did some semiconductor engineering and physical electronics. I have a slab of silicon nitride lying around. I look up the Young’s modulus (elastic modulus) and other physical properties of the silicon nitride and compare it to the properties of Delrin™ and of bird quill. Hmmm. I go down to my basement shop at home and begin slicing up my little left-over silicon nitride slab into plectra-shaped bits.

T he machining of the plectra is pretty straightforward, if you are a rockhound and have some lapidary and faceting tools and some diamond bits for your Dremel MotoTool™ (or comparable 20,000 rpm flexible-shaft hand tool). I used 400-grit diamond for most of the cutting, and 14,000-grit and 30,000-grit cerium oxide powder for the polishing work.

T he ceramic surfaces are polished to nanometer smoothness so that they will not abrade the harpsichord strings.

 Analysis of cantilever beam / plectrum
H ere is a drawing of my ceramic plectra:

 McNair silicon nitride harpsichord plectra
T hey are quieter and slipperier than Delrin™ plectra. The sound of the harpsichord tongues and jacks would not be at all affected by these exotic ceramics. The “ceramic vs. Delrin™ vs. quill” noise differences I’m talking about are only about the noise of the plectrum tip itself, just as it slips against the deflecting string before the plectrum excursion (or string deflection) is large enough that the plectrum releases the string.

I  think the only person who can possibly hear the “scritch” of Delrin™ acetal plastic against the strings is the performer a few inches away. With nitride, there is no plectrum-against-string noise at all.

T o everybody else, the pleasant harpsichord “action-falling” sounds with ceramic plectra like these should be identical to the ordinary mechanism quilled with conventional plectrum materials.

 Delrin™ plectra
R emains to be seen, but I suspect these technical ceramics may give much lower “wear” compared to Delrin™ or quill? Much less frequent need for re-voicing and re-quilling? Other advantages?

 Pilkey, page 184
I  do suspect that plectra made out of such ceramics will, in general, give a “brighter” sound—maybe brighter than purists would find desirable, who knows? But the toughness of these materials might open up new horizons of harpsichord dynamics and expression.

A nd I have no doubt that the “springiness” (nitride elastic modulus ~ 200 GPa, compared to Delrin™ and bird quill elastic modulus ~ 3 GPa) will give a ‘faster’ action than Delrin™ or quill.

 Stiffness equation
H ere is a little Excel spreadsheet I put together, modeling the stiffness of Delrin™ plectra of different dimensions. (I have a similar spreadsheet for my silicon nitride plectra.)

 Spreadsheet model of Delrin™ plectra stiffness
W hat else? The nitride materials do not undergo ‘work-hardening’. They do not get brittle like Delrin does with elapsing time and more playing. And the nitride composites have very low coefficients of friction (somewhat lower than zirconia, as I recall). Other advantages, too.

A nyway, the possibility of helping to advance the state of harpsichord technology intrigues me. Why is the ‘business end’ of the harpsichord sound-producing mechanism still stuck with Delrin™, same as Hubbard and others used 50+ years ago!

A lso, you may want to give a look at Lorna Gibson’s new materials science book, on composites (link below). More ideas for innovative plectra materials! No reason why homogeneous, nearly-isotropic (same properties in all directions, along all axes) like Delrin or ceramics is the only way to go.


01 June 2010

Christoph Maria Moosmann: Minimalism Is Relative

 Christoph Moosmann

T   he melodies themselves go from sound to sound, but the internals are empty abysses—because the notes are lacking in sonic energy. The inner space is itself empty.”
  —  Giacinto Scelsi.
T he ways that the organ emulates the human voice are familiar enough. But minimalist, textural compositions can lead us to re-examine what is the voice, what is the self? Exhibit “A”: Christoph Maria Moosman’s 2009 recording (link below) of pieces by Giacinto Scelsi, Arvo Pärt, and John Cage.

    [50-sec clip, Christoph Maria Moosmann, Giacinto Scelsi, ‘In Nomine Lucis’, 1974, 1.6MB MP3]

T here are sudden variations in the dynamics and texture, giving a sense of suppleness and surprising vitality. The beat-frequencies of minor seconds leave impressions of quarter-tones. Frequently there appear string-like vibrato effects and pulsations within a single tone. These qualities mimic ‘vocal’ improvisations—things that piano and other instruments simply could not do. It isn’t plausible that Scelsi created these improvisations with certain ‘models’ in mind, even ‘ritual music’ of Tibetan Buddhism.

T   he creation of music is an event full of differentiation and multiple transfers. The composer intuits something ungraspable, as yet not definable and gives it a sort of shape. The result, the musical score, isn’t music yet, is not audible yet. If a person is able to imagine the soundscape that is hidden in a sheet of music, to ‘hear’ in his/her mind the sound and rhythms as yet to be expressed by instruments, then that person is capable of a feat that hardly anyone can master. We are utterly dependent on mediators who transform the visible-but-not-audible sheet of music into an audible-but-not-visible music.”
  —  Christa Maysenhölder.
W e might naturally assume that, if Scelsi was deliberate in his improvisations, he must have had some plan or sketch or idea of what he was aiming to create. Yet this ‘In Nomine Lucis’ and other pieces lead us to suspect otherwise: the music generates itself, its own form, its own trajectory. We know that it is the product of human creative activity, but it is, despite this, more like a natural object, a stream, a branch of a tree, moving but subjectless.

A fter Scelsi’s improvisations were recorded, he typically had collaborators help him realize and notate the final product: Scelsi believed that the processes of transcription and notation were not jobs for the ‘artist’ but should be instead given over to ‘craftsmen.’ He collaborated with various trusted friends and colleagues—Roman Blood, Sergio Caferro, Alvin Curran, Frances-Marie Uitti, Vieru Tosatti, others. Third-party transcription as a fundamental part of his method: Scelsi’s compositions feel even more ‘organic’ or more distanced from the composer on account of this.

F or me, this evokes the same sort of distancing or suspense that we feel when we hear laryngectomees using electrolarynx prostheses. The pitch and timbral variations that TruTone™ and Servox™ and other digital prosthetic devices are now capable of are considerable. But their nuances are still inevitably less than the natural voice would have. The prostheses embody restrictions, road-blocks, performance risk.

A nd these features lead us to discover in the boundaries-pushing, constraints-challenging, indomitable performance under duress: new dimensions of the person—of the ‘subject’, of embodiment, of ensoulment in the living body.

A    t the end of the nineteen-fifties, Giacinto Scelsi, a self-taught Italian composer and erstwhile playboy Count who had dabbled in Eastern religions and Theosophy, had the extraordinary idea of writing an entire work—the ‘Four Pieces’ for chamber orchestra—that consisted of only single tones, one for each movement. Scelsi was not the first to hit on this concept: Elliott Carter had ventured it in his ‘Eight Études and a Fantasy’ in 1950. Nor is the scheme followed literally—the instruments often bend away from the parent note, shifting by microtones, semitones, or larger intervals. But by the end of the work a paradigm shift has taken place: the Tone is all-powerful once more. Music returns to its primitive origins: melody formed from noise.”
  —  Alex Ross.
C hristoph Maria Moosmann was born in 1960 in Riedlingen, Germany. He studied Catholic Church Music at Freiburg Conservatory and subsequently studied for the Kapellmeister diploma in Basel and Zurich. From 1982 to 1988 he was organist at University Church in Freiburg and Artistic Dirctor of Musiktage at University of Freiburg. From 1988 to 1994 he served as organist of the City Church in Wil, Switzerland, and since 1995 he has been the principal organist of the Church Maria Frieden in Zurich-Dubendorf.

 Giacinto Scelsi