Things went better last night at the Kennedy Center in the Terrace Theater's Seville than they had the night before in and around Handel's Thebes.

For its new production of Rossini's "Barber of Seville," the Washington Opera is using the excellent 1969 critical edition, taken from Rossini's manuscripts. The new edition adds some lovely touches to the familiar music. There are, among others, welcome new passages in Almaviva's "Ecco ridente in cielo," and "Un dottore della mia sorte." In addition, John Mauceri, the company's music director, has combined brilliant direction and a sense of the bubbling humor of thepiece so that scholarship is happily balanced with wit, charm and musical imagination.

Mauceri is also the excellent conductor, achieving eminently musical results except where he is handicapped by the unacceptable orchestra. The Washington Opera must find a way to use the equivalent of the orchestra that played its opening "Ballo." Last night's playing was far too often raw and thin in sound and cruelly out of tune. As on the previous night, however, the harpsichord was a constant joy. Stephen Crout was the player.

A strong cast is on hand for the 11 performances scheduled for the "Barber." Its fine points are nicely distributed. Zehava Gal restores the role of Rosina to the mezzo-soprano range and texture for which Rossini wrote it and does so with a lively wit, alluring acting and notable singing. She ranged easily from the low G sharp to several fine top Bs, taking the rapid passages with dexterity. If she would sharpen the clarity of her words, her portrait would be even more distinguished. Rossini's original Lesson Scene was of course employed, giving Gal further opportunities to show real class.

Washington has a right to take pride in the elegant, stylish baritone singing the role of Figaro.He is Patrick Raftery, born here, trained in Boston. He looks perfect in the part, moving with the kind of free-and-easy manner Figaro must have. His voice is big and round, beautifully produced, blessed with high As he tosses off as if they were nothing at all. His rapid-fire enunciation is a model as is just about everything else he does. What a star he seems destined to be.

Another real joy is Jerry Hadley's tenor in the taxing role of the Count Almaviva. Tall and handsome, he has the gift of modulating his fine, virile voice to a lovely quiet texture that is ideal for the music. He does not yet command all the notes evenly in "Ecco redente in cielo," but it seems probably that he will before long. He is a notable new singer.

These three young singers were admirably supported by Joseph McKee's outstanding Bartolo, acted and sung in the best manner. William Dansby made Basilio a vast pleasure, his "Calunnia" craftily conceived and executed. mJanet Stewart sings berta with flair, but surely the sneezing is overdone. Tony Torchia sounds well as Fiorello, though not exactly on the beat at first. Very special praise goes to Art Treichel for his miming of Ambrogio, as to Joseph Pearson's sergeant.

Lou Galterio, using restraint in his state direction, kept Beaumarchais to the fore and the bad tradition of low comedy largely out of sight. The sets and costumes of Zack Brown and the lighting of Christine Wopat were on the same high levels as on the previous night. The makeup and wigs of Charles Elsen are so perfectly executed that they are sometimes taken as matters of course.The fact is that they exist on an exalted plane that enhances everything they touch.