Capricci per sonar solo varie sorti di Balli e Fantasticherie

The sonatas, which Castaldi calls “Sonate forastiere in habito tiorbesco” (foreign sonatas in theorbo attire), are independent compositions in a single movement, written in a style which closely resembles that of the correnti, though they are somewhat more complex.
The collection also includes six pieces for solo voice in which the theorbo plays the role of a basso continuo instrument with an obbligato part written in tablature. The works contained in the Capricci are among the most refined and technically complex pieces in the entire 17th-century repertoire for theorbo. The entire range of the instrument is utilized (in 1622, when the collection appeared, a frequent use of drones in general and of the 14th string in particular was not very common).
The composer makes use of all the typically idiomatic techniques of the in-strument, such as bells, unisons, strascini (sliding) and imitative passages in the contrabass range.