The opera "Macbeth," generally attributed to Verdi, is Donizetti exemplified: bel canto melodies, sweeping, obsessive rhythms, Donizetti all the way. (Exception: those undeniably Verdian marches that sound like both the Italian and the Brazilian National Anthems - as if you could tell 'em apart.) The "Donizetti Sound" is one of the glories of West Bay Opera's new production, opened Friday night, conducted by Sara Jobin, who has marshaled rural forces to produce urban excellence. Jobin - who will soon become a "house conductor" either at the San Francisco Opera or somewhere else with an ingenious management - brought the best out of a small, fine orchestra and a small, often ragged chorus to present a fluent, cohesive, enjoyable performance, enabling the singers to rule. Rule they did, in different ways. Jason Detwiler, in spite of his youth, has been heard in the South Bay in many roles, but nothing prepared me for his Macbeth. He sang simply, quietly, naturally, with a warm, velvety voice. Top and bottom were good, but in the middle voice, Detweiler was extraordinary, bringing up blessed memories of Herman Prey singing "Pierrot's Tanzlied" from "Die Tote Stadt." Lady Macbeth came from another neighborhood - the rocks of the Valkyries, her little-known first name (no, it's not "Lady") fitting the voice: Gruach as a Wagnerian soprano. Helena Janzen is a big-voiced Swede, who made up for all of Detwiler's subtlety. Thanks to stage director Daniel Helfgot, Janzen got to sing Lady Macbeth's two great arias in a prone position, starting off as Tosca, but ending up on her back. Ending terminally, in fact, as Helfgot directed Macbeth to force some poison down her throat to conclude the sleepwalking scene, specifics not provided by Shakespeare, but what the hey?! So, on her side, face down, or on her back, Janzen still blew the house down, with a strong, broad voice and manic, jerky energy. Her low register doesn't quite measure up to the rest of her impressive performance. Adam Flowers' Macduff and Kevin Nakatani's Banquo were both well sung. The production is surprisingly good musically, and certainly is surprising dramatically. Helfgot never met an idea he didn't like. From his fertile mind came scenes such as Lady Macbeth mounting men who stretch out on their back helplessly, the devilish Gruach emptying her glass on the head of Macbeth, the witches wearing sunglasses, most of the soloists sporting a crown, whatever their rank, including - confusingly - Macbeth, even at the beginning when the crown is several murders away. On the plus side: a pithy understatement, placing the action in the program at "A land in political turmoil." A final "kick" is a risky thing in opera, meaningful, distracting - or both. A perfect example for the latter: Gotz Friedrich's otherwise excellent "Lohengrin" in Bayreuth, turning into turmoil and mush in the final minute with the arrival of Godfrey... as an R2D2 robot. Edo de Waart, in his Bayreuth debut, and the audience were amazed and shocked, discussed the puzzle then and there, paying no attention to the music. Helfgot's "Macbeth" finale is more subtle and certainly thought-provoking: Malcolm's coronation ends with a visual deja vu. As Lady Macbeth thrust a knife into Macbeth's hand at the beginning, a woman in red (Lady Macbeth's uniform throughout) hands a knife to Malcolm as the curtain falls. It could have been Gruach's ghost or a symbolic chacter standing for the idea of the Killer Wife. Jean-Francois Revon's sets on the postage-sized stage are covered over by Chad Bonaker's busy lighting, and the chorus, in Richard W. Battle's slick fake-leather (or opulent vinyl) outfits that serve witches, courtiers and revolting peasants alike... a useful device as the same handful of chorus member does all the work. No need to change costumes, just accessorize them appropriately. The area has done well with "Macbeth" - since the S.F. Opera's grand Howland-Pizzi production in 1994, Berkeley Opera (featuring Ricardo Herrera) and Pocket Opera (Marcelle Dronkers) presented small-scale, memorable performances of it. Here's the real story of Macbeth, something you won't find in Shakespeare or Verdi: Duncan was killed in 1040 while attempting to bring the rebellious Macbeth to heel. Macbeth then became king. Gruach's royal connection was fairly well established: she was the granddaughter of either Kenneth II or III and daughter of Boete who may have been recognized as tanaise to Malcolm II. Macbeth remained king for 17 sometimes turbulent years [not just for one act!]; he made a pilgrimage to Rome in 1050. (Attention Opera Quiz: What's a common element in "Macbeth" and "Tannhauser"?) Malcolm III, son of Duncan, and representing one of the three rival royal lines, finally defeated and killed Macbeth at Lumphanan in 1057. Janos Gereben/SF www.sfcv.org [log in to unmask]