Preparation of the Piano:
Metal screws of 5 or 6 mm diameter should be used. The screws should each be placed behind the dampers. Division of the strings into octaves by the screws is not necessary. In order to prepare the strings, they should be carefully separated by a felt wedge before the screws are inserted or removed, in order to avoid damage to the strings. Via the preparation, one of the three strings always vibrates freely, thus determining the pitch. The two strings prepared with the screw produce an alienated tone colour effect.
As large a concert grand should be used as possible (not an upright piano).
To achieve the desired tone colour, it is essential that the piano is prepared, and amplified.