Antonin Dvorak's three-act opera, "The Jacobin," was given what is thought to be its first fully staged American performance last night at Lisner Auditorium. Virtually everyone there was hearing it for the first time, and, let there be no question about it, "The Jacobin" is a very beautiful work. How this and other operas by one of the most celebrated of composers can continue to languish in obscurity is indeed puzzling. There are a number of mainstays of the repertory that, quite simply, pale by comparison.

Picture a more aristocratic folk comedy than Smetana's "The Bartered Bride" with references to Mozart here and clear hints of Wagner's "Ring" in parts of the third act. That's roughly what the combination is. And it flows along with the ease of the Slavonic Dances, the second set of which was written about the same time.

Yet "The Jacobin" had to wait for more than 90 years for this introduction, in a performance that made no pretense of being fully professional. It was done by that inveterate proponent of Czech opera in this city, Lida Brodenova, whose sane philosophy has been that Czech opera is better done on a shoestring than not at all.

Certainly last night's performance was ragged. Balances were mostly askew, to the point that singers were quite often inaudible. Violin tone and ensemble suffered in particular in the adhoc group of 45 National members who were, quite literally, sight-reading the music for only the second time.

Yet the evening was a very upbeat experience. The continuing lilt and warmth of the music kept stealing your attention. This is no polite gesture toward interesting esoterica. Take the noble bass aria of the elderly count in the third act. It deserves to be placed right up there with similar work in Mozart's "The Magic Flute" and "The Abduction From the Seraglio."

Occasionally the singing came close to real distinction, particularly, Sondra Harnes' slightly vinegary soprano in the role of Terinka.

The distinguished Czech-American composer-conductor, Karl Husa, showed an authoritative grasp of Dvorak's complex and glowing orchestral part that contributed considerably, under trying circumstances, to the success of the evening.

Brodenova plans Dvorak's "Rusalka" for next year. More power to her.