The "Spanische Ouvertüre" for two violins con scordatura, written in 2001, is a research project in the microtonal possibilities of a simple spectral scordatura. The eight strings of the two instruments represent the partials nos. 4, 5, 6, 7, 9, 11, 13 and 15 of a virtual fundamental F0. In order to get precise pitches, without the instrumentist having to search for them by ear, I use open strings and natural harmonics most of the time. Different perspectives on this limited material are explored throughout the piece. In the beginning, for example, my reservoir of pitches, in the form of a scale of unequal intervals, is examined step by step, starting high in register and descending (this process continuous, with interruptions, until bar 80). Chords of tight, complex intervals invoke low differential tones which develop into a second, ascending layer which exposing the pitch material from the other end of the scale. There are two attempts at this process (bars 1 -18 & 59 - 68) seperated by a contrasting section (bars 18 - 58). Contrary to this melodic, and harmonically rather complex, exposition of the pitch material, the fast intermezzo (bar 18 - 58) shows the spectral aspects of the scordatura: Pure spectra of f, c and an a (which is slightly lower than the well-tempered a) played as arpeggios, are "cut and paste" against one another before the last spectral chord convolutes, leaving a single high note. After the second attempt at descending and ascending lines, the inverse of this idea appears; single notes are morphed into spectral chords (bars 68 - 80). At the end of this glissando-section, the piece reaches the lowest note of my pitch reservoir. The following part (bars 80 - 88) refers to the spectral arpeggios of the first fast intermezzo, this time emphasizing the open strings. A melodic transitional passage (bars 89 - 94), that reflect the descending mouvement of the beginning, establishes a basso ostinato which will be the base of the following "Chorale". This "Chorale" (bars 95 - 106) explores more classical chords with "false" intonation. A Flamenco-like passage (bars 108 - 120) which uses shifting spectral chords and changing tempi (a little like analoge tape music) ends in reminiscence of the beginning.
The piece was commissioned by Kolja Blacher and premiered by Ekaterina Bolotova & Julius Bekisch.