Creating Reality (2003)
is based on the songs of 32 birds, recorded in their natural environment, filtered and amplified by 36 parallel processing bandpass filters. The frequencies of the filters form a non-tempered symmetrical 36-tone tuning system with a range of five octaves.
Creating Reality was originally composed as a part of a audio-video-installation of the same name with Jungwha Jung, commissioned by the Marronnier Art Center Seoul.

Duration: 51.48
Realized, produced, released 2003 by Siegfried Koepf
CD, card cover, 12.00 €, available at Koepf's Editions and other distributors

Feedback CD 3
Bassmaschine (1994)
performed and recorded 1994 by Siegfried Koepf
Duration: 13.17
and music of Michael von Biel, Johannes Fritsch, Rolf Gehlhaar, Harald Muenz.

Produced 2003 by Feedback Studio Verlag Cologne
Released 2003 by cybele
CD, card cover, booklet, 16.90 €, available at cybele
Review by tocafi at klassik.com

Konzentriert musizieren (Freizeit) (1998)
is one of Koepf's combinatorial compositions. Its material is based on sequences of permutations of all possible valve combinations, processed by filtering and sorting algorithms. Axel Dörner then combined these fingerings with the trumpet's pedal tones, and the resulting events were reiteratively combined with themselves through the use of a real-time delay device.

Trumpet: Axel Dörner
Duration: 25.03
Recorded on June 23, 1998 by Bolko Schweinitz
Produced by Siegfried Koepf and Bolko Schweinitz
Released 2001 by textur
CD, card cover, inlay card, 11.00 €, available at Koepf's Editions and other distributors

Beuys goes Pythagoras (2000)
is the sound of Joseph Beuys' speech "which refers to the intention to found a Forum for the Active Neutrality", recorded in the 80's, filtered and amplified by 36 parallel processing bandpass filters. The frequencies of the filters form a non-tempered symmetrical 36-tone tuning system with a range of five octaves.
Beuys goes Pythagoras was originally commissioned by the Museum Schloss Moyland.

Duration: 51.49
Mixed, produced, released 2000 by Siegfried Koepf
CD, card cover, inlay card, 13.00 €, available at Koepf's Editions and other distributors
Review by Klaus Hübner in: Neue Zeitschrift für Musik, Jan./Feb. 2004

25 Jahre Feedback
Ohne Titel for prepared pipe organ (1992) (excerpt 3.00)
and music of Michael von Biel, Peter Eötvös, Clarence Barlow, Johannes Fritsch, Silvio Foretic, John McGuire, Rolf Gehlhaar, David Johnson, Michael Manion, Herbert A. Mitschke, Volker Staub.

Produced and released 1996 by Feedback Studio Verlag Cologne
CD, jewelbox, booklet, 13.00 €, available at Feedback Studio Verlag Cologne