Period Terz guitar - JA Schuster
After Staufer-Legnani
Vienna around 1845
Bernhard Kresse

Popularity of the Terz Guitar
In the early 19th century, the terz guitar was so popular that the majority of duets published called for the primary guitar one part as terz guitar with one normal second guitar. This is usually indicated by the notation "tierce" or various other spellings. In Vienna, the terz guitar was especially popular, and in fact many original editions of duets from Vienna in this time period do not specify "terz", but the guitar parts are often in different keys off by a third (for example guitar 1 is 3 sharps / A major and guitar 2 is no sharps / C major), which is an indication of terz guitar being required. So common was the terz guitar for ensembles, that it was assumed. The terz guitar does not seem to have been used for solo music, although there would be no need to indicate that, since any guitar score could be played on a terz guitar or a normal guitar. The terz guitar was used for ensemble situations, where its treble range and brightness resulted in superior projection: it is often found in guitar duos, piano with guitar duos, and other combinations, including terz guitar with full orchestra, as in the case of Giuliani's 3rd concerto. The...