The Philadelphia Orchestra must have been the last major instrumental ensemble in the United States never to perform the complete symphonies of Gustav Mahler as a set. This was especially odd since they mounted the American premieres of both the Eighth under Stokowski and the performing version by Deryck Cooke of the fleshed-out and restored Tenth with Ormandy. One of the first acts of new music director Christoph Eschenbach was to rectify this situation. A Mahler cycle was launched almost immediately.

Although this seemed a good idea at the time, the early installments were disastrous. The Third, or at least the Carnegie Hall performance of it, was overblown and embarrassingly affected, showcasing not so much Mr. Eschenbach’s grasp of the grand totality but rather his penchant for the individual preening moment. He milked the final Adagio, and especially the “I’ll be seeing you” theme, shamelessly, while stumbling badly in the normally lilting second movement. That signature “fabulous Philadelphian” sound was also stretched beyond capacity, a phenomenon most worrying and not thus far confined to the new maestro’s Mahler performances. Those of us who had suffered through his “Tragic Symphony” with the New York Philharmonic a few seasons earlier were not surprised.

But if one falls from one’s cycle, the best therapy is to get right back up again, and this season we are being feted (or subjected) to the Ninth (January 11), and, on Tuesday evening, the Fifth. This large work, once nicknamed the “Giant,” presents a bit of a problem for concert programmers. Mahler intended the first two movements to be played with only the slightest of pauses between them, so there is no opportunity to seat the inevitable latecomers. In recent years, most conductors have opted for a short curtain-raiser followed by an intermission.

In January, Pierre Boulez will lead one of his own pieces before his traversal of this same sprawling landscape with the London Symphony; Mr. Eschenbach began his evening with an intriguing piece of contemporaneity. Long Island native Marisol Montalvo delivered a striking portrayal of ancient psychopathology in Matthias Pintscher’s colorful Herodiade Fragments, a dramatic scene on the order of “The Death of Cleopatra” by Berlioz. That same sense of footprints in the sands of time permeated this multifaceted work, which exploited Ms. Montalvo’s expressive ability to jump from one note to another. The program notes mention that she has sung the role of Alban Berg’s Lulu and I’ll wager that she is extremely adept at the part. It takes a special kind of courage to step out to center stage at Carnegie Hall; to attempt to put over this type of wild atonality to a graying crowd exhibited not only this rising star’s felicities and facilities but also her valor. Ms. Montalvo can take heart in the fact that her effort constituted, by leaps and bounds, the best musicianship of the evening.

Where do I begin to tell the story of how poor this Mahler performance was? Well, the instrumental sound seems like a good place to start. In just a short time, Mr. Eschenbach has turned that signature sound ugly. From the very first tutti chord, out of tune, blaring and ridiculously loud, this realization was irritatingly off the mark. There was virtually no decrescendo for the entire first three movements: Forty-five minutes of blowsy and blaring triple forte, with the trumpets having a terrible night throughout, in toto about as pleasant as a boom-box on a bus.

I covered the Philadelphia Orchestra for many years for another publication and realize that not all of its sonic problems are the current conductor’s fault. That “fabulous” sound, created for the bizarre acoustics of the Academy of Music, came at a price. To feature the viols, the ensemble consciously sacrificed balance, creating what I dubbed “The Great Wall of Strings” that regularly drowns out the other sections. Since the orchestra almost never sits on risers, the winds and brass are buried at the back. This makes them overcompensate by playing too loudly, causing intonation problems. The system was never perfect, but now that the strings are at an unacceptably high decibel level, the result is simply grotesque.

I have heard enough now to state that Christoph Eschenbach simply should not conduct Mahler. This music relies heavily on the contrast between the tragic and the comic, the graceful and the lead-footed, the cerebral and the banal. This conductor just doesn’t get it. He has a curious inability to conjure the Mahlerian lilt and, in this particular effort, little sense of the first movement funeral march or the refinements of the finale’s fugue-like structure. Although he produced an acceptable Adagietto, significantly for strings and harp alone, at the faster tempo that we have all come to accept as the composer’s own, I wondered as it was unfolding if it only seemed beautiful because it was such a welcome tonic for the cacophony that preceded it.

Maestro has been awarded a contract extension through 2008 for his help in securing a $50 million dollar gift for the ensemble. Fine, but what will the legacy of his tenure be for the rest of us?