Duplex scaling.

A system of Aliquot scaling introduced by Steinway to provide sympathetic resonance to enrich the treble register of the piano. In the ‘octave duplex’ piano by Hoerr of Toronto, each note had four strings, of which two, three or four might be struck by the hammer depending on one of four pedals being depressed (see ‘The Octave Duplex Piano’, MO, xxi (1897–8, 842 only). Steinway’s duplex scale was anticipated a half century earlier by an experiment undertaken by the German piano maker Wilhelm Leberecht Petzoldt, in which a small bridge was placed behind the normal large one in an attempt to exploit the potential additional resonance of a sympathetically vibrating extra length of string.