It was an excellent test run. As the clowns and jugglers of the No Elephant Circus performed to the manifest delight of a youthful holiday audience, it became clear that the old Kniskern family barn from upstate New York had been given a successful new lease on life as a performance space tucked into a suburban Virginia hillside.

The Kniskern structure and a companion barn from a nearby county were dismantled more than a year ago and trucked to Virginia, where they were painstakingly reassembled to become the Barns of Wolf Trap. The transformation will become official at 8 p.m. Tuesday evening when the players of the Primavera String Quartet sound the opening notes of a performance billed as a "comedy with music."

In the summer the Barns will play a supporting role to Wolf Trap's Filene Center, the indoor-outdoor facility that opened a decade ago. For the rest of the year the 380-seat auditorium will host its own season of performances ranging from "music to mime to movies." There is no question that the space will serve those purposes, and others, beautifully, for the Kniskern barn, built in the first quarter of the 18th-century, makes an excellent, warm, intimate place for certain kinds of performances.

As the No Elephant Circus went about its engaging business two weeks ago, I was able to check out the basics: Sight lines are adequate even from under the hayloft overhang, acoustics seemed fine even in the back row of the hayloft balcony (if an elephantless circus is any kind of guide), lighting was first rate and clearly capable of doing much more, and backstage facilities are basic (simplicity will be the watchword for productions at the Barns).

However, there's more to it than this checkoff of functions implies. The space feels right. It suits its new purpose like an old glove. The aged textures of those hand-hewn hardwood beams and studs have something to do with this quality, but it's also due to space itself, almost as if Johann Peter Kniskern had something more than hay and horses in mind when he built the barn in the Schoharie River Valley near Albany more than two and a half centuries ago.

Architect Mary Otis Stevens of the Design Guild in Boston believes that Kniskern and all the early barn builders in the New World did, indeed, have something else "in mind." A serious student of early American vernacular architecture, Stevens has observed how in process and form the old barns relate directly to medieval building practices in northern Europe, and how barns in both the Old World and the New clearly resemble simple medieval churches.

This explains, she says, why barns such as this old one so comfortably house the performing arts and why their acoustics are so good. It also explains her design for the Barns of Wolf Trap, which tactfully celebrates the magic of the interior space of Kniskern's barn. In other ways the design is not so successful, but it admirably accomplishes this main goal.

The Kniskern barn, which remained in the family until sold to Wolf Trap two years ago, is a German "swingbeam" barn, so called for the stupendous oak beam with a 40-foot clear span that holds up the hayloft (and which allowed a team of horses to be unhitched and turned into stalls without obstruction). A second, smaller barn with a sharper silhouette, built by Scotch craftsmen in upstate New York about 50 years later, is attached. Equipped with a kitchen and bar, it will be used as a community room for parties and other special events as well as for gatherings at intermissions.

The idea and the money for the Barns, like almost everything else at Wolf Trap, came from Mrs. Jouett Shouse, its founder. Until she met architect Stevens through the agency of conductor Sarah Caldwell, Mrs. Shouse had intended to house the new enterprise in entirely new "barnlike" buildings. Because of her research, her love for the old structures and her acquaintance with Richard Babcock, a professional saver of old barns (among other things Babcock is assembling a museum of the old buildings in Hancock, Mass.), Stevens fortunately was able to persuade Mrs. Shouse that original barns would do the job better.

Stevens and Babcock chose from his inventory of northeastern barns because most of the pre-revolutionary barns in the Washington environs were razed during the Civil War by Union troops frustrated in the face of guerrilla strikes by Mosby's raiders. Babcock and his team took the two New York structures apart piece by piece and put them back together again at the eight-acre Virginia site on Trap Road less than a mile from the Filene Center. The interiors were the major attraction. To preserve them while adding necessary insulation and mechanical equipment, Stevens built around them, sheathing the old structures with new clapboard siding and shingle roofs.

Functional requirements, interior circulation and the sloping site determined that the smaller barn be attached to a rear corner of the larger structure. This allowed a basement under both buildings for an orchestra pit, storage, rehearsal and training rooms and other services. On the outside, two major alterations were made: Stevens punched a series of square windows into a sidewall of the Scotch barn-community room, and, while preserving the basic contour of the Kniskern barn, she added significantly to it. The stage building is entirely new. Where the old barn ends, the stage begins.

The major visible new construction, however, is the L-shaped structure that serves as a main entrance and as a passageway between the two barns. From the inside this works quite well, providing a clear 360-degree passage through the entire complex with a view into an open central courtyard. Even so, the detailing of the new construction, especially by comparison to the rich textures of the old barns, has a humdrum appearance. The passage into the theater looks almost as if it were a hallway in some low-budget schoolhouse.

On the outside this new structure is a little confusing and more than a little boring -- confusing because the main entrance is so low-key as to be almost invisible, boring because it reticently refuses to contribute anything at all to the massing of the two barns. The question arises, when does respect for the past become too much of a good thing?

One cannot help but feel an opportunity was lost here, a chance to articulate the difference between old and new. Such a gesture need not be demeaning to the old structures. Indeed, to articulate transitions in time and space, to make them self-evident and even to celebrate them, is the essence of this kind of architectural problem. Stevens was aware of the challenge. She reported by telephone from Boston that her original design proposed a low tower at the corner of the L-shaped connector building to mark the entrance and to clarify the relationships between the buildings. She lost the fight for that tower.

As an abstract proposition -- I have not, after all, seen that design -- I can say that the client's victory was our loss, for some emphatic gesture, some appropriate mark of the 20th-century designer's art, would have notably enhanced our understanding of the Barns of Wolf Trap. Stevens takes an optimistic stance. "This is not an immaculate design," she said. "It's not a concept that cannot be changed." In any case she's happy with the transformation of the old Kniskern barn, and the rest of us can share that view.