A NOTE ON THE TERZ GUITAR
The terz guitar was a smaller guitar popular in Vienna in Giuliani’s time; it was tuned a minor third higher than a normal guitar, which meant that it had a clear tone and carried well. Today, if you are not lucky enough to have access to a terz guitar or to a replica of one, there is no reason why you shouldn’t just use a small guitar such as can be obtained in Mexico to this day (strung appropriately), or just play a normal guitar with a capotasto at the third fret. It appears that Giuliani himself specifically preferred the use of the terz guitar, not the capotasto (but that doesn’t mean that you can’t use a capotasto today.)
Giuliani specified the terz guitar in some of his guitar duets and in his third guitar concerto op. 70. Diabelli specified it in all three of his arrangements for guitar and piano of Giuliani’s three guitar concertos.