Philadelphians were getting primed last week for an unusual event by the Philadelphia Orchestra: music director Riccardo Muti's first full operatic performance (albeit in concert form) on these shores. The opera? Verdi's ''Macbeth.''
The Italian maestro Muti was appointed music director of the Philadelphia in 1980. His career has been meteoric, from the days he emerged as an acclaimed opera conductor, through his taking over of the New Philharmonia (later Philharmonia) Orchestra of London, and the landing of an important EMI recording contract. Since taking over the Philadelphia, he has dropped all other prominent musical posts to devote his time to his orchestra and to special guest engagements around the world.
Before the performance, to help Philadelphians better understand ''Macbeth,'' Mr. Muti held a mini-symposium on Verdi. He invited Andrew Porter, a respected Verdi authority, opera translator, and The New Yorker magazine music critic, for a one-on-one discussion in the ballroom of the Academy of Music.
Now Mr. Porter has not been a universal admirer of Muti's work over the years , and Muti must have known this. Nevertheless, the conductor thought a respectful interchange of ideas from two differing viewpoints might be interesting.
Mr. Porter feels strongly that while Verdi was explicit in what he indicated in his scores concerning tempos, dynamics, and accents, as a singer's composer he expected singers to relax a tempo now and then to better project the words and mood of the moment.
This is not to say that Mr. Porter feels Verdi encouraged interpolated high notes, excessive liberties with the musical line, or other tasteless intrusions, but rather that phrasing is an individual thing, and the conductor must give singers room for expression.
On the other hand - as illustrated on his five Verdi recordings - Mr. Muti feels that the composer's markings are ironclad and that singers must fit into that uncompromising framework. If a brisk tempo is indicated, Muti feels Verdi would not have approved any relaxation; Mr. Porter demurs.
If a series of extreme dynamic markings is indicated, Mr. Muti asserted in the symposium, Verdi would be expressing a specific desire and vision.
Mr. Porter countered that the dynamic markings were exaggerated so as to force the generally inattentive orchestra players of the day to approximate his dynamic intentions: If Verdi wanted a quiet piano sound, he would write two or three ''p's'' (pianissimo or quieter).
Frankly, I was not expecting to discover that Muti is as adept as he is at articulating his viewpoints - and in such clear English. Most foreign conductors who head American orchestras simply have not taken the time to become particularly fluent. They know enough English to make their points, but not quite enough to expound upon them.
Muti mentioned that during one of the preliminary rehearsals for the concerts - heard last Thursday and Saturday in Philadelphia and Tuesday in Carnegie Hall - someone came up to him during a break and said, ''Maestro, it is so interesting to hear in a tragic opera music of humor.'' Muti told the audience: ''I almost fell down! The fault may have been with me; I need to make the right color to make the difference between humor and tragedy.''
He mentioned the chorus of assassins, which Mr. Porter observed was a startling novelty in its day, though now, in this post-Gilbert and Sullivan era, that novelty is wrongly interpreted as poor taste on Verdi's part.
Muti demonstrated at the keyboard the difference between comedy and mystery in this music: If he punched out the bass line and ignored Verdi's staccato marks and dynamic indications, it sounds like a hurdy-gurdy; however, when he lightened the texture and stressed the dynamics and accents as written, the music assumed a nervous, mysterious, even fear-ridden quality.
In the same vein, the much-maligned witches have usually been made to sing in a hurdy-gurdy style, whereas Muti demonstrated how to make their music sound frightening and ominous. Muti stressed that the instructions over their music demand, ''Do not forget that these are witches who speak.''
I go on in such detail about what Muti said because the man behind the image is so refreshingly candid, so unexpectedly unlike the matinee idol one might expect. EMI, his recording company, has mounted a dazzling ad campaign that has turned this man into a superstar. Somehow, one expects banalities to trip off his tongue, as is the case with too many photogenic artists today.
Yet, hearing him talk so articulately, intelligently, and caringly about music has forced me to reassess the man. I now believe that Muti ponders his scores minutely, worries about bringing details to life, frets about the meaning of every fff or pp, every accent in a Verdi score, and really wants to make a performance come to life.
Unfortunately, his recordings do not carry on that image. He binds his singers in musical straitjackets, denying them the chance to instill character into a role by means of pliancy and emotional shading. Perhaps this is not the case in live performances.
Then there is the current problem in Philadelphia, where the sound that Stokowski established and Ormandy nurtured for so many years is no longer audible unless Ormandy is on the podium. Clearly, Muti wants something else, but the why or wherefore of that ''something else'' remains an elusive thing.
But back to the symposium. It is supposedly not chic today for a conductor to become an educator for his public. Muti clearly wants to change that; he seems to want his public to learn more about music. He also seems to want to make his orchestra more meaningful to its subscribers and to its city. This is cause for the highest praise.