It is a challenge for instrument builders and players of low-brass, to get copies of the cimbassi Verdi used. To begin with the 'Bas-valve' horns were derived from 'Basson Russe' until the tuba formed 'Trombone Basso' as used after 1867 until Otello/Falstaff (1884). Another challenge is, following the initiative of John Eliot Gardiner, to accompany 19th century operas, including Verdi's juvenilia and early period pieces until his mid-life period, to perform with a 'Period' orchestra. This includes the most discussed instruments of that era, also used by Verdi, the cimbasso / low brass instruments, and the 3-string contrabasses described by musicologist Bonifazio Asioli in about 1820s. The cimbasso in its original form as developed by Verdi and atelier Pelitti, included the diapason A4 on 430 Hz instead of the norm around 1848, 435 Hz.