(b Emmerich, c1804; d Paris, 1888). German instrument maker, son of Johann Christian Dietz (i). He learnt his craft from his father, and made a claviharpe (an instrument invented by his father) for the exhibition at the Louvre in 1819. He continued the family tradition of invention and designed a grand piano with freely vibrating sides to the soundboard. He was awarded a medal at the 1827 exhibition in Paris, where he exhibited five different pianos. The one that received most approval was a grand with four strings to each note – the fourth undamped string increased the power of the instrument by providing sympathetic resonance. A few months later he invented the Polyplectron, a bowed keyboard instrument (see Sostenente piano); an account of it appeared in the Harmonicon (1828). To make the bow act on the strings like other string instruments, Dietz needed as many bows as notes. He dealt with this problem with ‘numerous bows, composed of thin slips of leather’, which circulated on a cylinder placed on the upper part of the instrument, and over pulleys in the lower part. The motion of the key brought the bow into contact with the string by means of a small, thin piece of copper. The sound could be varied a good deal according to the pressure used on the key. The instrument coped with fast passages very well and had the ability to sustain in a remarkable way, but it did not ‘answer the expectations of those who wish to trace in it the sound of a Stradivarius or an Amati’. A panel of literary men and musicians who met in 1828, of whom Cherubini was a member, agreed however that Dietz had ‘approached much nearer to perfection than any of his predecessors’.
Description du claviharpe, inventè par M. Dietz père et exécuté par M. Dietz fils (Paris, 1821)
V.C. Mahillon: Catalogue descriptif & analytique du Musée instrumental du Conservatoire royal de musique de Bruxelles, ii (Ghent, 1896, 2/1909, repr. 1978 with addl material)
MARGARET CRANMER