Albert Fuller, who died Saturday at 81, was a harpsichordist and leading proponent of the early music movement in America.

As co-founder in 1972 and artistic director of the Aston Magna Foundation in Great Barrington, Mass., he nurtured an ensemble recognized as among the pioneers of the revival of playing baroque music on the original instruments for which it was conceived, such as the viola da gamba, the flauto traverso, and the valveless trumpet. A frequent solo tourer, Fuller also recorded extensively, including the first American original-instrument complete set of Bach’s Brandenburg Concertos. The 1977 recording, made at the Metropolitan Museum of Art, became the initial release of the Smithsonian Institution’s recording program and went on to sell more than 100,000 copies.

Born July 21, 1926, Fuller grew up in Washington, D.C., where he was a boy soprano with the choir at the National Cathedral; an interest in choral music persisted and drew him as a teenager to Vivaldi, among other early music composers.

Originally trained as an organist, Fuller went on to study harpsichord at the Peabody Conservatory of Music and at Yale University, where his professors included Ralph Kirkpatrick and Paul Hindemith. He made his New York debut at Town Hall in 1957, and in 1964 joined the faculty of Juilliard as professor of harpsichord.

Although much of Fuller’s early performing on organ and harpsichord consisted of solo repertoire, he became more interested in the expressive possibilities of ensembles. In 1972, he teamed up with the Manhattan financier Lee Elman to form the Aston Magna Foundation, named for Mr. Elman’s estate in the Berkshires, which had originally belonged to the violinist Albert Spalding. Up to 30 performers gathered for several weeks each summer to work out how to produce early music on the original instruments, which were sometimes unfamiliar ancestors of more modern concert instruments. Fuller once told the New York Times that the process often went “very slowly and often by trial and error.” He compared old instruments to sports cars.

“The modern symphony orchestra demands a smoother, continuous kind of power,” he said in the 1983 Times interview. “Early 18th-century music, with its shorter breaths and its greater diversity within a phrase, requires a technique similar to an MG’s — one which can bounce around, operate in small spaces, turn on a dime.”

Yet Fuller was under no illusion that modern performers could recreate the exact sounds or mentalities of times past. “There’s a lot of talk about authenticity these days, and I think it’s nonsense,” he told the Times on another occasion. “The authenticity I’m interested in is our contemporary sense of the reality of the past, and what the music we have inherited has to do with us today.”

His affection for the music was anything but antique. Describing his reaction to a recording of Mozart’s “Jupiter” Symphony on original instruments, he once told Time magazine, “It made me feel hot inside — drop-dead, roll-around, fall-over, lava hot.”

The summer program was popular among performers, in part because the catering Fuller procured was first-rate, and the Aston Magna concerts caught on. Performances were moved into town from the estate, though townspeople were a bit suspicious of all the activity at first. The Berkshire Eagle reported that they were worried about “hot dog stands” and “hootchy-kootchy dancing.”

Fuller left the Aston Magna Foundation in 1983 over differences with the board. The foundation was already sponsoring performances in New York and Los Angeles, and he wanted to expand programs faster and wider, and move into 19th-century repertoire. He nevertheless remained close to many of the performers.

Fuller went on to found the Helicon Foundation, a New York-based ensemble that plays mostly in small venues and private homes around the city, with occasional appearances at festivals. He moved his time frame forward a bit, including performances of Mendelssohn, Schumann, and Brahms, often on 19th-century pianos.

Fuller was a longtime friend of Alice Tully, and spent a lot of time with the benefactress and classical music lover. In 2000, he published the affectionate and impressionistic “Alice Tully: An Intimate Portrait.” According to one reviewer, Fuller “uses Tully’s dislike of loud disco music to launch a four-page excursus on his positive associations with loud music, specifically, a ‘Dionysian fete’ at the Peppermint Lounge and his adolescent sexual awakening in the swell box of an organ.”

Fuller was a Chinese food fan and was on a first-name basis with some of the city’s leading restaurateurs. He often summered in the Pines on Fire Island and from a young age was fond of dancing deep into the night. But in recent years he was hobbled by an obscure foot ailment and did most of his teaching at his apartment.