<p>I have already requested in some of my earlier pieces that the strings of the instruments should be deliberately detuned, so that simply by playing the open strings an overtone chord can be produced. In the case of the guitar this is relatively simply achieved: one has only to tune the bottom string a whole tone lower, the third string slightly more than a semitone lower, and the second string slightly more than a semitone higher. If the remaining strings are then tuned accurately in pure fourths and fifths, the six open strings produce a chord composed of the second, third, fourth, fifth, seventh and ninth partials of a low D: D-A-d-f# (minus 1/12 tone), c’ (minus 1/12 tone), e’.</p><p>Despite this unusual tuning – and in contrast, for example, to the violin – with the help of the frets it is possible to secure relatively precise intonation. </p><p>For aesthetic reasons, the purity of sound of these open strings needs to be ‘blurred’. For this purpose the second guitar is tuned a twelfth of a tone lower than the first, the third two-twelfths (one sixth) of a tone lower, the fourth three-twelfths (a quarter) of a tone lower.</p><p>The music derives its impetus from the contrast between these ‘pure’ chords derived from the overtone series (including their ‘shadows’ lowered by a twelfth tone or its multiples) and sixth- or quarter-tone passages composed in free microtonality, which make use of the harmonic concepts of Ivan Vyschnegradsky.</p><p>Between these a kind of ‘singing’ in twelfth-tone clusters repeatedly asserts itself. This simultaneous sounding of pitches which lie very close to one another is of course no longer in unison, but at the same time not quite a chord either. Instead it creates a sound rich in beat phenomena, which is used in the composition like an expressive unison. </p><p>The <em>Quartet for Four Guitars</em> was written at the suggestion of Christian Scheib for the Aleph Quartet and Musikprotokoll 2007. </p><p><em>Georg Friedrich Haas.</em><br /></p>