It was 1 a.m. Tuesday, and Narciso Yepes was in Washington with his 10-string guitar, scheduled to perform with the National Symphony Orchestra through Friday. That was the good news.

The bad news was that there was apparently a revolution going on in Spain, where his children were, and his wife -- en route to Washington to meet him -- was nowhere to be found.

Earlier that evening, Yepes had charmed the National Press Club with a 90-minute discussion of his unusual guitar, never revealing his unease. After that, he'd finally managed to get a call through to his son Ignacio in Madrid. Ignacio was watching King Juan Carlos on TV, dressed in full military regalia. Then Yepes had set off for Dulles airport to meet his wife, but was delayed 40 minutes by a rainsoaked traffic accident. When he got there, the airline people assured him that Marysia Yepes had already arrived, and taken a taxi to his hotel.

So now, at 1 a.m., Yepes sat in his room at the Watergate Hotel, waiting.

The phone rang. It was Marysia. No, she was not downstairs. She was at Kennedy Airport in New York -- delayed not by a coup but by bad weather.

"Yes, it was very disturbing," Yepes said the day after, at lunch at the Watergate Hotel, Marysia beaming by his side (despite only two hours' sleep) and the coup at home successfully squashed. "I was also on tour in the United States when Franco died," he said. "We thought it was almost a miracle then that orderly government continued."

Yepes shrugged. He is a Spaniard, with a proud artistic tradition. In fact, he even looks the part -- sharing with his well-remembered countrymen Picasso and Pablo Casals a robustness somehow accented by his diminutive stature and glabrous pate. His instrument, however, is the 10-string guitar. Most guitars have six strings, which makes for difficulty in playing music written first for the lute, which usually has seven or more.

"When I first went to the guitar-maker Ramirez, in Madrid, and told him what I wanted, Ramirez said a 10-string guitar was impossible.

"'Difficult,' I said, 'but not impossible.'

"'No,' Ramirez said, 'impossible.'

"'All right, then I'll go to Barcelona and have my 10-string guitar made there.'

"'Okay, okay -- difficult,' Ramirez said."

Since the guitar came of age as a serious instrument several decades ago, a number of virtuosos have emerged, beginning with Segovia, and continuing with John Williams, Julian Bream, Christopher Parkening and others. But among them only Yepes has the 10-string. It has become the signature of his image, and now, at the height of his powers, can be heard on 30 recordings, and in more than 130 concerts a year.Reviewers have praised his impeccable taste and "dry sherry" style, and the beauty of his programs, which frequently include the works of Spanish composer Rodrigo and de Falla. (His debut Tuesday night with the NSO, conducted by countryman Rafael Frubeck de Burgos, was received this way by The Post: "Ole Frubeck! Ole Yepes!").

But if Narciso Yepes, at 53, is not yet a household name in America, he certainly is in the Yepeses' new household outside Madrid, on the road to Escorial. It is very much a musical house, crammed with his collection of guitar tablature, and the telescopes of an astronomy hobbyist, and a family house as well. The housewarming was announced with a drawing rendered by 13-year-old Juan de la Cruz Yepes, containing five versions of one message: Nos mudamos de case, nous demeageons, wir umziehen, przeprowadzamy sie, and "we are moving." The Polish was for Mrs. Yepes, who was born in Warsaw, but moved to Madrid when her father was named ambassador from Poland.

Yepes began his study of the guitar at age 6, and as a young teen-ager studied under the Spanish pianist Vicente Asencio. Asencio relentlessly criticized the guitar, saying that perfectly rhythmical legato scales could not be performed on it, and suggesting that Narciso choose another instrument.

"He said it was impossible. So I labored very hard to learn the scales perfectly, just as he did on his piano. And when I finally demonstrated for him, all he said was: 'Ah, so it is possible.'"

Yepes' big break, although he would not call it that, came in 1952 when the French director Rene Clement asked him to compose the score for "Forbidden Games." After viewing the movie 32 times, he did. And when "Forbidden Games" quickly attained the status of a classic, so did his music. His theme became so well-known that he now must decline to play it.

"What really changed my life was Nadia Boulanger," Yepes said, "and I hope she has also changed the life of my children." Boulanger, who died in 1979 at age 92, was the mentor of several generations of American and European musicians, among them Aaron Copland and Virgil Thomson. "I met her in 1950, and she had a system of teaching that was different from anyone else's," Yepes recalled. "She had a way of answering questions that you had not even thought to ask. Once, we sat down to analyze a prelude of Bach. I was with her three hours, and we never got past the first eight beats. She explained the entire conception of the piece in those first eight beats.

"My children, you know, were the last students she ever had. At the end of her life she gave very few lessons, she was nearly blind, and confined to a wheelchair, and was very tired and almost without movement. But she was still very clever. Up until three years ago we lived in Paris, all of us, just so the children could be with her, and have a chance for those special memories.

Yepes himself now has about 12 students, "scattered all over." He says they wait for him to return to Madrid from his tours, and then descend upon him. In addition to teaching, he also intends other work in Spain, where the world of the guitar is divided between the written compositions of "serious composers and the national popular music of flamenco, which is traditionally taught by ear.

"Flamenco can be written down," Yepes said. "Why isn't it? Because even if you do, the flamenco players cannot read it. But I feel I must, because if someone does not, much that is wonderful may be forever lost."

Yepes, who plays flamenco songs only privately, marveled at the memory of a time in Cordoba when a popular flamenco singer performed informally in a cafe. t

"His name is Antonio Mairena, and he was to perform, but his guitar player was late. So Antonio said he would sing without him. The song was a siguiriya , which is in 7/8 time. He kept time by tapping his hand on the table, and was very good. Then the guitarist arrived, apologizing for being late. And he began to play the siguiriya in 6/8 time. It was the most amazing thing, because Antonio did not miss a beat. Together they went on, and every 42 notes one phrase ended and the other began, and Antonio did it perfectly. It was unbelievable, really; there's not a conductor in the world who can feel 6/8 time in one hand and 7/8 in the other, as Antonio was doing.

"Now what will happen, if I don't write that down? Flamenco singers will just do the song in 6/8 time, because it's easier. And something wonderful will be lost."

Yepes looked over at his wife, who was nodding in assent.

"You know," he said, clearly engaging the cogs of an old family joke, "at first Marysia didn't even like the guitar. We met when she was 17, at a concert in Madrid.

"I almost didn't go to the concert, because it was a guitarist," Marysia Yepes said. "I met Narcisco afterward, when he was autographing programs. My friend said, 'Hand him your program -- he'll sign it.' I said, 'No thanks.' And Narsisco looked at me, then.

"It was Sunday, Dec. 13, 1953," Yepes said, his memory a lesson to husbands everywhere. "One week later, on Sunday, Dec. 20, 1953, we decided that she should become my wife."