`Das Rheingold' - latest in Met's `Ring' cycle. Also, Puccini favorites `Tosca' and `La Boh`eme' continue in repertory

The major artistic preoccupation at the Metropolitan Opera these days is getting its cycle of the four operas that make up Wagner's ``Ring of the Nibelung'' onstage. Last season, ``Die Walk"ure'' was unveiled. This season has recently seen the arrival of ``Das Rheingold.'' Next February, the curtain will rise on ``Siegfried,'' and next season ``G"otterd"ammerung'' will be presented. This is not to say that opera as usual has been suspended, and indeed, Puccini's popular ``La Boh`eme'' and ``Tosca'' are on the boards this fall. But first to ``Rheingold.''

A well-cast `Rheingold'

If casting were all it took to give a full account of this opera, the Met would be in relatively good form. James Morris's Wotan was luxuriously sung; Franz Mazura made Alberich an unforgettable figure of dignified malevolence; the sheer beauty of Siegfried Jerusalem's Loge, as well has his ability to inflect the role with great character and meaning, made for an usually skillful performance of this often-problematic part. Aage Haugland and John Macurdy made the most of their roles as Fafner and Fasolt.

Unfortunately, lesser casting was not up to this standard. Gail Gilmore's Fricka was oddly characterized, and huskily sung; Anne Gjevang's Erda lacked the requisite sepulchral tones; Timothy Jenkins's stressful way with Froh's music boded poorly for his vocal well-being; Phillip Joll's burly, raw baritone hardly suited Donner at all. In the pit, James Levine was still feeling his way around this score: Some pages flashed out brilliantly; others seemed rather mechanically re-created.

Director Otto Schenk made his ``Ring'' statement last year in that new ``Walk"ure'' - straightforward, old-fashioned. Not for Schenk were bold reinterpretations, far-out settings, allegorical imagery. Ironically, Schenk and designer G"unther Schneider-Siemssen proved in their Met ``Tannh"auser'' that a traditional, literal Wagner could be refreshing visually and dramatically.

Unfortunately, the ``Ring'' seems to be shaping up as an overproduced, underdirected bore. The opening scene of ``Das Rheingold,'' set in the River Rhine, is amply effective. But then we move to the base of Valhalla mountain, and expectations are suddenly deflated. Wotan and his brood walk around on something that looks like an ancient lava floe; in the background, a cliff encrusted with gold-glittering runes and daggers is supposed to suggest Valhalla itself.

The descent to Alberich's dark kingdom of Niebelheim - which should be stunningly theatrical - is hidden by a drop with some large holes in it. In a massive and monotonous cave, Alberich chokes on the smoke that should hide his transformations but doesn't. Back in Wotan's realm, Erda wanders up out of an awkward chasm in the lava floe.

Rolf Langenfass's costumes make everyone look like like primitive hippies. Donner is dyed - beard, hair, even face - in henna red; Erda looks like a refugee from Haight-Ashbury in the '60s; Alberich resembles a Hollywood space alien. Only the giants are menacing. The Schneider-Siemssen set designs are an obvious rehash of his older Met sets.

`Walk"ure' too static

Seeing the ``Walk"ure'' a few weeks after ``Rheingold,'' gave an inkling of how static, even oppressive, this ``Ring'' is likely to be. Vocally, it was not an auspicious evening. Hildegard Behrens repeated her vocally problematic Br"unnhilde, but with a newfound depth of histrionic effectiveness. Jeannine Altmeyer - the alternative Br"unnhilde - showed signs of stress in her blandly characterized Sieglinde; Mr. Jenkins was consistently overtaxed by Siegmund's music; Waltraud Meier made an impassioned, if vocally uneven, squally Fricka. Haugland was the stentorian Hunding.

Mazura was the unexpected replacement for Hans Sotin. An Alberich voice is not one's first choice for Wotan, and indeed, there were times when the singing was a chore. But the authority of declamation, the detailed acting, the imposing stature, made for a Wotan of unusual dramatic strength. Levine was the inconsistent conductor.

A `Tosca' worthy of Zeffirelli's sets

But at least the Met is doing right by ``Tosca.'' The Franco Zeffirelli production has settled comfortably into the repertoire, and it now has a cast worthy of its splendor. Eva Marton's Tosca has grown in stature, inventiveness, and vocal prowess. It is now a complete - even a great - performance. Giuseppe Giacomini may not be a subtle or pliant Cavaradossi, but he can make splendid tenor sounds, and he works well with Miss Marton. Sherrill Milnes is a handsomely sinister, powerful Scarpia. In the pit, newcomer Christian Badea gave a competent, if rather monochromatic, account of the score.

Weak casting mars `Boh`eme'

Casting of the Zeffirelli production of ``La Boh`eme'' has always been weak. This revival is no different. Only Barbara Daniels's Musetta holds dramatic focus, and this year she has regained her freshness of voice. Roberta Alexander retains pretty moments in an increasingly problematic soprano, and her Mimi was mostly a vocal struggle.

The Bohemians all sport slick modern blow-dry hair styles, save John Cheek, who appeared to be wearing a Halloween beard and wig. None sang well, but since Bruno Beccarria was debuting as Rodolfo, it must be noted that he constantly forced his potentially attractive tenor into a strident, bleating sound. Julius Rudel presided over this dispiriting performance as well as could be expected.