Today's hard quest for the true Verdi sound

There was a time in the none-too-distant past when recordings of opera boasted glamorous casts and routine conductors. Today's trend reverses the order.

Orchestrally, Verdi operas usually benefit from the scrutiny of a symphonic conductor sensitive to the demands of opera. Nowadays, the sort of voices Verdi wrote for are as common as hens' teeth, so accommodation is the key word. Of the performances in question, several represent the stage standard for Verdi today. It is not even the standard of a mere ten years ago, but often it will have to do.

In the case of Carlo Maria Giulini's performance of ''Rigoletto,'' the vocal standard is remarkably solid, while the orchestral performance (with the Vienna Philharmonic) proves revelatory. Maestro Giulini has often been accused of taking things too slowly, giving music so much detailed scrutiny that the dramatic impetus falls by the wayside. It is, for my tastes, an unjust accusation.

For ''Rigoletto,'' which has been obstinately given to the hacks for far too long a time, Giulini shows the listener that there is far more in the music than even the best conductors to date have revealed.

Curiously, ''Rigoletto'' is the sort of work most opera houses and record companies feel can get by with lackluster conducting, as long as the soprano and tenor have secure D's and the baritone a good A. Only Sir Georg Solti and Rafael Kubelik have set their views on disk: Kubelik's being the finest conducting of this work until Giulini's.

In the program book that accompanies the Deutsche Grammophon set (DG 2740 225 ), Giulini maintains that Verdi never wrote a ''King Lear'' opera because he had treated the Learean themes thoroughly in ''Rigoletto.'' The maestro then proceeds to justify this claim with a performance of such richness of drama, such variety of moods and passions, of such attention to the very specific emotions Verdi depicts in his orchestra that from beginning to end, one is forced to rethink the entire opera. Maestro Giulini ensures that the listener will never listen to ''Rigoletto'' with complacency again.

The singing is on a generally high level. Piero Cappuccilli turns in a sturdy performance in the title role. Ileana Cotrubas brings a lyric soprano's vocal weight to a role customarily consigned to squeaky coloraturas. Placido Domingo cuts a handsome vocal figure as the Duke, and Nicolai Ghiaurov makes a suitably dark, if rather wooly, Sparafucile.

Giulini's presence can command regal casting: Here we have Kurt Moll's thrillingly sepulchral Monterone, Elena Obraztsova's somewhat too-vibrant Maddalena, and Hanna Schwarz as Giovanna. It is a set that restores one's faith in the imagination of the recording industry, and restores an important opera to its full dramatic glory.

Then there's ''Luisa Miller.'' The Deutsche Grammophon production of this Verdi opera (DG 2531 229) is based on an actual performance during a run at Covent Garden in London, with the performing forces of that institution under the direction of Lorin Maazel. It has become very close to the standard ''Luisa'' cast at any international house today. Mr. Maazel rarely gives any sense of being really at home in this opera. His views are anti-theatrical, arbitrary, and not especially considerate of his singers.

The title role has had several memorable impersonators in the past decade - Montserrat Caballe, Renata Scotto, Katia Ricciarelli, Adriana Maliponte. Of these, only Miss Maliponte still gives thrilling performances of the part.

Miss Ricciarelli has a difficult time negotiating smoothly what gave her no problem a mere five years ago. The voice has spread, lost its sheen, the top flaps; dramatically she communicates little. Renato Bruson, generally a fine Verdi baritone, is overparted as Miller. The ubiquitous Placido Domingo is below form as Rodolfo, the voice sounding dry and forced. Miss Obrazstova is a better-than-average Frederica, Gwynne Howell a near-cipher as Count Walter. (The standard in this opera remains London OSA - 13114, with Caballe, Luciano Pavarotti, Sherrill Milnes, and the underrated Peter Maag the conductor.)

Miss Ricciarelli used to be a fine Luisa. She was never meant to sing Amelia in ''Un Ballo in Maschera,'' the province of a full Verdi dramatic soprano. Her work on the new Claudio Abbado performance of the work (DG 2740 251) is marred by that obtrusive flap, a tendency to sing under pitch, and a proclivity to reticence that saps her performance of any dramatic tension.

Domingo is a superior Riccardo, though he has some trouble negotiating the higher-lying phrases of the part. Bruson makes an eloquent Renato, lacking only the ability to flood the upper reaches of the role with generous tone. Miss Obraztsova is the best Ulrica - a surprisingly difficult role - on stereo records. Edita Gruberova's Oscar is equally memorable - personable, and richly sung.

The Scala forces perform well for Abbado, and he is a genuine Verdian, though there is a tendency to throttle down the climaxes, robbing them of genuine passion and tension. Still, it is a ''Ballo'' for the '80s, flaws and all - a set that amply represents the standard, for better or worse, of Verdi singing at this time.

Sir Colin Davis's account of the same opera (Philips 6769 020) looks strong in print and fails on the turntable. His views of Verdi are turgid and stolid. Jose Carreras is in bellowy voice, Miss Caballe's soprano takes on a harsh edge at the fuller moments, and she sounds uninvolved. Ingvar Wixell's wooly delivery defeats his performance as Renato, while Sona Ghazarian is the uninteresting Oscar, and Patricia Payne's Ulrica tends toward a hooting sound. But meanwhile, the Covent Garden forces perform well.

If I save Herbert von Karajan's Angel (SZCX-3888) reading of ''Aida'' for last, it is because it is such a frustrating experience. The sound is ultra-spectacular, the Vienna Philharmonic plays like no other orchestra in the world. Karajan's firm grasp of Verdian line, of panoply, aural spectacle, and limpid, haunting orchestral colors makes this, orchestrally, the ''Aida'' of one's dreams.

Were his cast even adequate, I could call this a near definitive set. But Karajan, more than any other conductor in opera, has eroded standards by allowing lyric voices to dabble in the dramatic repertoire. Mirella Freni, a lovely Mimi, is defeated by just about every utterance she makes as Aida. Carreras tries to make his Radames interesting, but his voice is in such disrepair, one is often not sure if he is singing in tune or not. Cappuccilli is a splendid Amonasro; Ruggero Raimondi a dour Ramphis.

Agnes Baltsa is very clearly a lyric mezzo who understands how to ''sell'' dramatic moments. Her Amneris is the most compelling, most exciting on records. Her voice gets lost in the orchestral climaxes (but who could sing over some of Karajan's climaxes anyway?), and she clearly is at the edge of her resourses much of the time, but what a thrill.

As for ''Aida'' on records, the best bargain remains the RCA Victrola (VIC- 6119) performance with Zinka Milanov, Jussi Bjorling, Fedora Barbieri, Leonard Warren, and Boris Christoff - a golden '50s cast that has yet to be equaled on records. For those who need stereo, the best of a compromised bunch of recordings is probably the Angel (SX-3815) featuring Caballe, Domingo, Fiorenza Cossotto, Cappuccilli, and Ghiaurov, with lackluster conducting from Riccardo Muti.