Three hours of raw musical energy burst across the stage in the Kennedy Center Opera House. Verdi's "Un Ballo in Maschera" is still raw stuff, nearly 130 years after its troubled premiere: a mixed bag of coups de the'a tre, dark conspiracies, the anguish of guilty love and the joy of pure, soaring melody. But in a properly vigorous production, it communicates.

The shower of "bravos" that greeted most of "Ballo's" big moments on Saturday night showed that the Washington Opera's production was communicating. Vigor, rather than finesse, marked this performance. "Belt it out" was the motto for tenor Franco Bonisolli, soprano Adelaide Negri and baritone Juan Pons in the leading roles, and this can be an effective treatment for Verdi's great melodies when the voices are good. Saturday night, the voices were variable (Pons was the most reliable among the headliners), but the power of the music came through, greatly enhanced by the forceful conducting of Cal Stewart Kellogg.

In purely musical terms, the highlight of the evening may have been "Eri tu," the aria of anguished disappointment sung by Renato (Pons) in Act 3, after he learns that his wife and the king he has served are secretly in love. The singer's eloquence rose above small technical problems and rather unimaginative stage direction to communicate directly and intensely the raw emotion in Verdi's music.

Theatrically, the opera's center of gravity is Act 2, which takes place in the looming shadow of a gallows, where Amelia (Negri) has gone at midnight to pick a magic herb that will cure her of the forbidden passion for her king. It is a fast-paced, nonstop sequence of contrived situations and emotional exchanges that grow in intensity as the stage gradually becomes more and more crowded. Amelia has been followed by the king (Bonisolli), who is followed by Renato, who warns him that he is also being followed by a band of assassins. Renato (unaware that his wife is the heavily veiled woman with the king) agrees to escort her to safety. The king slips away, but Renato and Amelia are caught by the assassins and her identity is revealed.

It requires an enormous suspension of disbelief, but the frantic pace tends to numb one's critical faculties. And the music helps this process tremendously as two impassioned arias are followed by an even more impassioned duet, a vigorous trio and an ominous chorus slowly approaching from the shadowy distance. The tense dramatic situation is finally resolved in a chorus of ironic laughter while the king's best friend and most loyal assistant decides to become his assassin. To a 1980s sensibility, it has a flavor of the ridiculous; to an ear attuned to Verdi's splendid musical rhetoric, it is overwhelming. The singing, which has to make it all worthwhile if anything can, was hardly flawless on opening night, but it had a dramatic power that (like Verdi's music) swept away objections.

The staging of this act (which presents the fewest technical problems for a director) was notably more successful than in Acts 1 and 3, which sometimes tended to be static -- at least in comparison with the Washington Opera's magnificent "Eugene Onegin." Need for more stage direction may have been the chief problem for soprano Cyndia Sieden, who sang well throughout the evening and particularly in Act 3, but did not achieve the full impact possible in the role of Oscar.

Geraldine Decker, who was scheduled to sing the short, vivid role of the witch Ulrica, has been replaced by Fredda Rakusin, making her unexpected Washington Opera debut. Perhaps the workload of singing simultaneously in "Ballo" and "Onegin" (where she stands out in a small role) was too much for Decker, who is reportedly having problems with her back. In any case, Rakusin has thoroughly mastered the role and performed it with distinction. The same can be said of Greg Ryerson and Stephen Saxon, who sang the roles of two conspirators -- named Samuel and Tom when "Ballo" is set in colonial Boston, but nameless in this production, which places the opera in a generic northern European city.

Two Washington singers, tenor Christopher King and baritone Gordon Hawkins, were given small roles in this "Ballo" as they have been in several earlier Washington Opera productions, and both performed well. King had the role of the chief magistrate who starts the plot working in Scene 1, and he filled its modest demands gracefully. Hawkins, who was singing Handel stylishly at the University of Maryland a week ago, is equally at home with Verdi as he demonstrated in the role of Silvano, the sailor in Scene 2. His vocal ability has been well known here for some time; the news in this production is his striking improvement as a singing actor.

The chorus, given some fine musical material, sang it well. Visually, it did not look like the same lively and colorful group that is currently performing in "Onegin."

Part of the good news about this production is that it marks the beginning of the Zack Brown season at the Washington Opera after two productions with scenery and costumes by others. Not that there was anything wrong with the "Don Giovanni" and "Onegin" productions, but there is a special flavor in Brown's work and it is never twice the same flavor. The "Ballo" production has been seen here before, in 1980, and is welcome back; Brown's work significantly enhances the opera's impact.