These are generic names for a 4' string stop. Audsley maintains that the Violetta is of small scale with an imitative tone of medium strength. Sumner describes it as a 4' Viol, while Irwin considers it to be a synonym for Octave Violin. Williams gives the following definitions, with which Grove concurs: I Spanish regal, very often horizontal, with short open conical resonators and a tone like a soft trumpet (18th-cent. cathedrals). At Segovia Cathedral (P. de Echevarría, 1796), Violin was the bass half and Violeta the treble half of a horizontal regal-stop. II In Italy about 1800, Violetta could be either a 2' bass regal, or a small-scaled open stop of Dulciana tone.
Osiris contains six examples of Violeta, all of which are at 2' pitch and appear on the left-hand side of manuals in Spanish organs dating from 1691 to 1802. All but one are reed stops. Osiris contains six examples of Violetta, none of which are reeds, one at 8' and the rest at 4'.