(b Darmstadt, 1773; d Holland, 1849). German engineer and instrument maker. His first invention was a friction idiophone called a Mélodion, designed in 1805 when he had established his business at Emmerich. Similar to E.F. Chladni’s earlier Klavizylinder, it was in the form of a small square piano, measuring approximately 122 cm by 61 cm, and it had curved metal bars sounded by contact with a rotating metal cylinder. Dietz demonstrated the mélodion in Westphalia and the Netherlands in 1806. He had a factory in the Netherlands before he moved to Paris, where on 18 February 1814 he patented his best-known invention, the claviharpe (see Harp-piano). This was an attempt to produce characteristic harp tone by means of a keyboard. It had a six-octave keyboard that operated plectra, which gently plucked silk-covered strings sideways. It was 2·15 metres high and resembled a giraffe piano without a soundboard and outer case. It was reckoned that even the most careful listener could not detect the difference between it and an ordinary harp. A claviharpe that Dietz made in 1814 is at Brussels Conservatory.
Dietz’s son, johann christian Dietz (ii), and grandson also made claviharpes up to about 1895, but they did not come into general use, not least because such an instrument would be extremely difficult to keep in tune and properly regulated. An article in the Harmonicon (1828) states ‘M. Dietz succeeded in resolving a problem of considerable difficulty, that of graduating and modifying sounds at will, but not of sustaining them’. The same fate befell Dietz’s other inventions, including the Trochléon (1812), described in the Harmonicon (1828) as ‘an instrument of round form, furnished with metal plates of different sizes, sounded by means of a circular bow, set in motion by a pedal’. No example of this instrument survives.
Description du claviharpe, inventé 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 (Ghent and Brussels, 1880–1922, repr. 1978 with addl material)
MARGARET CRANMER