NEW YORK -- It seems to be in the nature of Stephen Sondheim's and Hugh Wheeler's mold-breaking, comic- gruesome "Sweeney Todd" that it breaks its own mold again and again.

	Paul Kolnik Michael Cerveris as Sweeney Todd also plays guitar, and Patti LuPone as Mrs. Lovett plays tuba. Click photo for larger image. "Sweeney Todd" At the Eugene O'Neill Theatre, 230 W. 49th St., New York City. For tickets, call 1-800-432-7250.

Has there ever been a musical so continually rediscovered? Hal Prince's original 1979 Broadway production was grandiose, an epic parable within a vast set that seemed to summon up Victorian England in all its energy and contradictions. Then in 1989, Susan H. Schulman made her name with a compact Broadway revival (memorably parodied by "Forbidden Broadway" as "Teeney Todd") that uncovered a newly intimate intensity.

So played, "Sweeney Todd" has continued to tap fresh springs of emotion, all the more poignant for bubbling up beside its robust comedy and penny-dreadful horrors.

But surely by now we realize that "Sweeney Todd," subtitled "The Demon Barber of Fleet Street," is actually meant to be small -- a comi-tragic chamber opera. It was that first epic production that was the anomaly. Subsequent directors have won critical praise mainly for revealing what was there all along.

Even so, I'm going to sing those same critical hosannas all over again, because John Doyle's current Broadway revival of "Sweeney Todd" really does -- I mean really really -- create revelation on a whole new level.

Doyle's stroke of genius is to strip "Sweeney Todd" even barer still, extending the miniaturization by doing away with the orchestra and entrusting the instruments to a cast of just 10.

I know, it sounds like a joke, or perhaps another version of the incredibly shrinking orchestra, reduced for financial reasons to synthesizers and computers. It also sounds like a gimmick, designed to attract notice, as it certainly has done. And if it becomes the precursor of orchestra-less shows by the score, it will have proved a curse, as well.

But the triumphant fact is that it works. It goes right to the heart of Sondheim's rich and still evolving work. I have never before felt so sure I was experiencing a classic, in the sense that a classic continues to reveal itself long after it has become familiar.

Yes, the actors play their own instruments. Obviously they have been chosen for this ability, and obviously there has been re-scoring to make it possible. In allowing and even encouraging this, Sondheim shows himself a more expansive artist than those (or their estates) who insist that their creations be frozen as originally conceived.

Technically, this takes a lot of skill and choreography. The 10 performers are almost constantly on stage, whether participating in the scene or just watching, and meanwhile they play accompaniment, either while they watch or even as they act or sing.

Most of them play several instruments. Alexander Gemignani (The Beadle) seems the principal keyboardist, but three others take their turn. Patti LuPone (Mrs. Lovett) plays tuba, Michael Cerveris (Sweeney) guitar and Mark Jacoby (Judge Turpin) trumpet, but all three also play orchestra bells and percussion. The especially flexible CMU grad, Donna Lynne Champlin (Pirelli), plays accordion, keyboard and flute, while Pittsburgh native Diana DiMarzio (Beggar Woman) plays clarinet. Only John Arbo (Jonas Foff), the bassist, seems cast mainly for his musical skill.

Initially, the intermix of acting, singing and playing is fascinating in itself, perhaps even distracting, but gradually you start to forget that they are their own orchestra. And then you remember, with a special thrill, as the instrument and the character suddenly merge into some new sort of creation, like a radical post-modern realization of the "total work of art," although what Richard Wagner would have made of this, I can't imagine.

The actors move their own props and build their set, as well, using simple boards and a big black coffin, pouring buckets of blood to mark each killing. Mrs. Lovett assembles and cleans her own tools (drill and bit, hacksaw, pruning shears) in a perfect parody of domesticity. They are the tale, a company of magical shape-shifters who disappear into their creation.

This merging is never more thrilling than when Lauren Molina (Johanna) and Benjamin Magnuson (Anthony) perform an aching duet of despair on dual cellos. It is all the more transporting because performers, cellos, music and words become one, right before our eyes. The same transformation happens in a more concentrated way when Manoel Felciano (Tobias) accompanies himself hauntingly on the violin.

The effect can also be satiric, as when Judge and Beadle express their self-satisfied mastery through their trumpets, or comic, as when LuPone's Mrs. Lovett tootles bumptiously on the tuba. That's a perfect expression of the noisy, awkward soul of this determined woman, as is the self-satisfied sang-froid with which she plays the bells. Both are in potent contrast to the dark ghoul of Cerveris' Sweeney.

The production is seamless. I've seen it twice, and the second time I was freer to watch director Doyle's cunningly calculated stage movement, in which everyone is always dovetailed into the present moment or preparing for the next. He is also responsible for the spare but precise design.

The overall result is like a cross between the comic horror of "Shockheaded Peter" and the grim truths of Bertolt Brecht, all driven by the silken whip of Sondheim's wit. I suppose the only shortcomings are that Act 2 never quite measures up to the brilliant Act 1 finale, "A Little Priest," and that the show must, eventually, regretfully, come to an end.

Doyle is now working on a similar self-accompanied version of Sondheim's "Company." Should the musicians' union be in arms? Should acting schools revamp their curriculum?