Born in Brescia in 1549, Costanzo Antegnati became the most famous and authorative representative of the noble dynasty of Brescian organ makers, who were active in Northern Italy from the end of the 15th to the second half of the 17th century. Antegnati was introduced to the family business at a very early age, so that he was able to substitute his father Graziadio at only twenty years, when he was already able, as a constructor, to emulate “his predecessors in knowledge and skill”. Reputed “the most perfect” organ makers of this time, he realized the organs of S. Barbara in Mantova (1565, in collaboration whith his father Graziadio), of S. Pietro al Po (1581) and of S. Lucia (1596) in Cremona, of Sir Alfonso Morandi (1584) and of S. Martino in Avesa (1610) in Verona, of S. Maria della Consolazione (1588) in Almenno San Salvatore, of the parish of Bagolino (1590), of S. Maria Maggiore (1593-94), of S. Agostino and of S. Grata (1607) in Bergamo, of the Steccata of Parma (1593),of the parish of Gardone and of the Carmelite of Salò (1594), of S. Gervasio (1598-61) in Trezzo, of Calcinate (1601) and of the parish (1601) and the church of Corlo (1602) in Lonato, of Mazzo in Valtellina (1604-05, in collaboration with G.C. Moroni), of S. Martino (1607) in Treviglio, the reformation of the organ of S. Marco (1604-11) in Milan, of the parish of Polpenazze (1609) and of S. Giorgio (1612) in Venice. In 1584 Antegnati was appointed organist of the cathedral of Brescia, a position he maintained for more than twenty years, until forced into disability by a sudden attack of apoplexy.
As a pupil of Girolamo Cavazzoni, Costanzo Antegnati cultivated an inclination to composition, maintaining that composition was “very necessary to the profession of making and playing organs”,especially if one wanted “to do things in the right way”. He published many works, of which today we only know Missae quaternis vocibus concinnendae, addita Missa Dominicalis alternis versibus decantando, Liber primus(Brescia 1579, Sabbio), Liber primus missarum 6 et 8 vocum (Venezia 1578, Gardano; reprinted 1587), Liber secundus missarum 6 et 8 vocum (Venezia, check “ivi” 1589), Liber XIV in quo habentur Missa Borromaea, Mottecta, Cantionesque Gallicae tribus coris concinendae (ivi 1603), Salmi a 8 voci (ivi 1592), Sacrae cantiones, vulgo Motecta, paribus vocibus cantandae quatuor vocibus (Brescia 1581, Sabbio), Sacrarum cantionum liber primus a 5 voci (Venezia 1575, Gardano), the first book of Madrigali a 4 voci (Venezia 1571, Gardano), the group of 15 songs alla francese (to be played) in the tablature of the German organ, in Johannes Woltz “Nova Musices Organicae Tabulatura” (Basilea 1617, Genath, III^ parte, nn. 25-39), l’Antegnata intavolatura de ricercari d’organo op. XVI (ivi 1608) and lastly Arte organica: dialogo tra padre et figlio (Brescia 1608, Tebaldino), one of the most precious sources for research in the field of the Italian organistic practise of the classic period. Antegnati died on 14th November 1624 and was buried in the church of Saint Joseph, Brescia.