"Inside a harpsichord there are well over 1,000 separate pieces of wood and metal," says Tom Wolf. "They all have to fit together."

He and his wife Barbara stand in their workshop, the ground floor of a now defunct, turn-of-the-century Washington firehouse. The room is long and narrow, two engines across, a hook and ladder deep. There are few windows, so the light-mainly artificial-is severe. Hand tools hang on the walls. Across the cement floor table saws, routers, planers and sanders rise like tree trunks.

This is where the Wolfs make between four and six harpsichords a year. Prices range from $4,000 to $10,000. "We don't advertise," she says. "We have a four-year waiting list," he says.

Buyers include "a few rich old ladies" and an eccentric or two: "One man told us that a harpsichord was cheaper than therapy." But mainly their customers are serious musicians, and that is the way Tom and Barbara Wolf like it to be. It is clear that they wouldn't make harpsichords if they didn't care-very much-for the sound that comes out of them.

Tom was drawn to that sound ten years ago while a student at the New England Conservatory of Music. One spring afternoon he was playing bass in a baroque ensemble and happened to be standing next to the harpsichord. It was his first real taste of the lotus.

He and Barbara also happened to be "broke" at the time. So he went out and apprenticed himself to a harpsichord maker in Boston. Barbara, a piano student, soon followed. They "never looked back."

The apprenticeship lasted five years. They then came to Washington, where Tom had a two-year contract restoring antique instruments for the Smithsonian.When that expired the Wolfs set up shop.

"I consider the sound of the harpsichord freer than that of the piano," says Tom. "It is lighter and clearer."

"Why?"

"The strings are shorter, thinner, and strung with less tension," answers his wife. "Less reverberation."

The comparison is an apt one because the historic fates of the two instruments are twined. The piano is evolved from the clavichord, a stringed instrument which in its early form had a keyboard often no longer than two feet. In the clavichord the strings are struck; in the harpsichord they are plucked.

Between 1500 and 1800 the harpsichord was the predominant of the two keyboard instruments. But over that time the clavichord changed. Its keyboard widened, its strings became longer and tauter. "It got louder and more touchsensitive," says Tom. "It took on expressive possibilities." You could thump a key or you could tap it. Two different sounds would emerge. The harpsichord offered less choice. If you hit the key, it simply plucked the string.

The piano "wiped out" the harpsichord with an assist from the Industrial Revolution. Court society declined. The spread of wealth took the recital out of the salon. Larger audiences meant a need for larger halls. The louder piano could reach the patron in the back row; the harpsichord could not. Virtually no harpsichords were made during the 19th century. In France after the revolution many were used for firewood.

"People forget that many of the great classical composers grew up with only the harpsichord," says Barbara. "There's a body of music written over a 300-year span meant specifically for this instrument. That's why there are harpsichordists around today. And that's why we're in business."

The Wolfs live on the second floor of the firehouse. We climb the stairs and walk through a skylit room. It, in turn, opens to another room which, from the Eastern, urban perspective, can only be described as vast. It is a good 50 feet square, with a 30-foot-high ceiling. Light floods through two churchlike windows facing the street.

The room is the shop below-in negative. The light is soft and abundant. The machine tools have become an archipelago of three harpsichords, some chairs, and a sofa spaced across the sea of the floor. The sofa becomes our island.

Barbara says: "We see this as a lifetime job. I'd quit now if I didn't think I'd be doing better work 20 years from now." She smiles knowingly. "But I'm impatient. I'd like to do that work now.

Tom adds: "Many artists don't do their best work until their later years."

"We are each other's quality control. If one gets discouraged the other says, 'C'mon, it's not that bad.'"

"Harpsichord-making died out as an art form for 125 years. We are part of the revival."

"A lot of techniques were not written down and passed on."

"So we're making discoveries on our own all the time."

"So we're making discoveries on our own all the time."

"And some mistakes."

This conversational duet continues. It sustains itself and grows, testing the range between the light and the serious. There are jokes about savings accounts sacrificed to the god of antique harpsichord ownership and how it feels to be 30 and living in a firehouse with the plaster eroding. There are assertions about the art. Smiles about discoveries made.

I ask Barbara if she will play something. She moves to one of the harpsichords. Orange, black, and gold, it is busily baroque against the toneless plaster wall. She is wearing paintspattered Levi's and a sweater some moths have known. The rich, lucid sound fills the room. It sustains itself and grows. Barbara bends her head to the keys and her body sways with the music. Tom smiles. If we could see the notes they would be diamonds. CAPTION: Picture, no caption, By Bill Snead