Rosario's clarinet collection was a prominent part of the living room decor in his beautiful home overlooking Monterey Bay. Some instruments were stored in cabinets, others mounted in the rafters.

According to Deborah Check Reeves, Curator of Musical Instruments, "It was probably a short step from collecting numerous models of clarinets in various stages of development to questioning how the Boehm system could better serve its players. Thus an interest in developing and refining the Boehm system led Rosario ultimately to the development of his own 'system.' In 1959, Selmer of Paris manufactured the first Mazzeo system clarinets. This is also the same year that Mazzeo published his Manual for the Mazzeo System Clarinet. Three patents were issued to Mazzeo for his clarinet key-mechanisms, in 1959, 1962 and 1965. In 1961, Mazzeo gave Selmer the exclusive license to manufacture Mazzeo system clarinets. Some 13,000 examples were produced."

"One of Rosario's main concerns about the regular Boehm system clarinet was that the register vent was too large for the best upper register performance, yet too small to produce a rounded tone on throat B-flat. In his own words, 'Fundamentally what was sought was an improvement of the mechanism over the break of the clarinet to facilitate passage work and sonorities in the area of the break. Also, it was desired to make the sound of the B-flat equally sonorous with all of its neighbors, and not to induce embouchure manipulation which would, besides making for a general unevenness, induce degradations of sounds in this area when the B-flat was being played in conjunction with other notes. The solution as to sound was that the B-flat must be produced by its own vent hole--not the register key hole. This has the double advantage of producing a sonorous B-flat at the same time relegating the register hole to its own use as a speaker.' The awkward finger movements required by the throat B-flat also worked against a consistently good hand position and a steady grip on the instrument. Movement of the instrument, in turn, worked against the development of a firm embouchure. The Mazzeo system clarinet set about to eliminate these problems. With a new, properly tuned and full-tone side hole for third-line B-flat, many more fingerings became available for this note."

Rosario Mazzeo (April 5, 1911-July 19, 1997) was a courtly gentleman for whom no day had enough hours for all the things that he wanted to do. Born April 5, 1911, in Pawtucket, Rhode Island, he moved with his family at age four to Worcester, Massachusetts, from where, as a teenager, he made weekly trips into Boston (sometimes walking!) to study clarinet with Jack Lynch.

In 1928 he moved into Boson, washing dishes and working as a janitor to finance lessons, first with Gaston Hamelin, principal clarinet with the Boston Symphony, and then with Gustave Langenus of the New York Philharmonic, taking the overnight ferry to Long Island and returning by train.

In 1933 he joined the Boston Symphony, playing E-flat clarinet for six years and bass clarinet for another twenty seven. He was also the Orchestra's personnel manager, a job that he assumed in 1942.

In 1966, after "thirty-three truly happy years as a member of the BSO," Mazzeo moved to Carmel, California, with his wife, Katie Clare, who plays harpsichord and fortepiano. Also a serious photographer--he had his first one-man show at the Carl Siembab Gallery in Boston--Mazzeo's move to Carmel was influenced in part by the fact that Ansel Adams, with whom he had been close friends in Boston, was now living in the area. Mazzeo was also interested in ornithology and went on many expeditions to study and photograph birds.