Joachim Haas and Gregorio Karman from the Experimental Studio for Acoustic Art of
Südwestrundfunk (SWR, "Southwest Broadcasting") in
Freiburg, which had been founded on 1 September 1971 as the Experimentalstudio der Heinrich-Strobel-Stiftung des
SWF, created the OKTEG, a special piece of equipment to allow Stockhausen to realize the spatialization manually. They brought the OKTEG to Kürten in March 2007 to spatialize the piece. Other firms had done similar things for Stockhausen. For example, the WDR studio technicians built a manually driven "rotation table" for the production of
Kontakte in 1958–59, and an improved, electrically driven model (capable of up to 25 rotations per second) for
Sirius in the early 1970s. The Modul 69 B for
Mantra, was built to the composer's specification by the Lawo company from
Rastatt, near
Baden-Baden, a switcher-controller, a regulator-distributor, and two "rotation mills" for the spherical pavilion at
Osaka's World Fair, were built to Stockhausen's designs by Mr Leonard of the Firma Electronic in Zürich in October 1968. The OKTEG (
Octophonic Effect Generator) relies on a
Max/MSP patch that uses eight variable-law
amplitude panning modules. The modules are driven by individual sequencers with tempo control. An
execution queue containing the rotation data specified by Stockhausen's maps managed the messages that controlled all eight sequencers. Motor
faders allowed real-time adjustment of the tempo of each sequencer. The performance of these real-time adjustments was encoded as a
frequency-modulated audio-rate sawtooth. This signal was then recorded as an audio track in
ProTools. This audio track is then used as a controller to realize the finished audio files. ==Reception==