John H. Steinway, 62, has known Van Cliburn since Cliburn was a kid - they occasionally "noodle" on the piano together. Rudolf Serkin - "Uncle Rudy" - is a great friend of the family. Rachmaninov used to come over to the brownstone in Manhattan for dinner - "We love to come, but please, no other guests," he would request. The young Steinway dated Rachmaninov's grand-daughter, Sophie Volkonsky. A fatherly I. J. Paderewski, after a concert and dinner, reminded the 8-year-old Steinway to keep up his piano practice. "Are you taking your lessons? Are you studying your scales?" he would ask.

Some 129 years ago, Steinway's great-grandfather, a German cabinetmaker, immigrated to New York. He had made one piano. ("It was a beautiful piece of furniture, but a terrible musical instrument," Steinway said.)

But he learned fast.Three years after working in other New York piano shops, the cabinetmaker set up his own shop with his three sons, and began making piano history, turning out what have become some of the world's most celebrated pianos, played by some of the world's most celebrated pianists.

"Slava Rostropovich has two in his home, I think," said Steinway. "Of course, Vladimir Horowitz plays them - he owns two. Van [Cliburn] has three or four."

John H. Steinway owns one. "I'm happy to say the demand for them is up, up, up. There's a great interest in the performing arts. Look at the Kennedy Center, look at the interest in music education. It warms the cockles of a pianomaker's heart."

Steinway lives "comfortably" in Manhattan, and looks the part of a man whose product has a high reputation.

And he clearly enjoys the role. He appeared in tuxedo, looking totally well-suited to it, at the formal opening of Art, Inc., an exhibit of art from American corporations currently on display at the Corcoran Gallery. Steinway and Sons, Inc., is among the corporations that lent art.

He bowed with Old-World elegance when greeting someone, speaking about pianos in his velvety smooth voice the way art connoisseurs might speak of Renoirs.

"It's the sound, the action, the touch under the finger, the control of the key," he said. "This is where we have been trendsetters."

Steinway has been an innovator, he said. It was his Great Uncle Theodore, who died in 1889, who strung the bass strings of the piano over the center section. "Every grand in the world is like that," he said.

"We don't bring out new models every year like the automobile boys," Steinway said, "but we try to refine the piano, make it more durable, tougher."

Despite concert-going at an early age, three years as an apprentice in the company's Long Island City factory, and 20-odd years of piano "badly." He shies away from talking about his own piano playing, preferring to talk about the actual pianos.

"I've tried for years to describe what tone is" Steinway said. "How do you describe that character of sound? There are many words you can use - 'full-bodied,' 'mellow,' but how do you describe that character of a Steinway?"

Whatever it is, he would know it anywhere. "I could get fooled," he said, "but I think I can spot a Steinway a mile away."

In fact, his ear was so fine-tuned after his years of apprenticeship in the business that when he was drafted into the Air Force in World War II, he could identify planes by sound. "I would be sitting in an officers' club and could tell the difference between a British and American engine in an airplane flying over. I'd hear something and say, "Oh, that's a Wellington bomber,' or 'Oh, that's a DC-3.' I guess I have developed a sense of hearing."

Good ears are two important prerequisites for Steinway piano apprentices. "We would rather not have a trained musician," Steinway said. "A trained musician wants to put too much of his own taste into it. We'd rather have a bright, intelligent guy with good hearing who absorbs from his teacher what a good standard Steinway piano should sound like."

There are some gradations in sound of the Steinways, and pianists look for them, said Steinway. "If a pianist is playing a concerto and he's up against 110 people in the orchestra, he will want a piano with guts, brilliance to cut through that."

It takes about seven or eight years to train an apprentice to make and place the hammer that strikes the strings of the piano and then adjust it for sound quality. This process is known as voicing the piano.It takes about one year to make a piano.

Since 1853, Steinway and Sons has made 456,000 pianos, all serialized. "We have number books going back to 1853," said Steinway. "We know where they were bought and who bought them."

The price of a new Steinway today ranges from $6,000 to $20,000. More is added for those with the fancy carving-like the gold eagle legs on one grand piano in the White House.

"To a professional pianist, a piano is black and plain," said Steinway. "Sometimes they come into the showroom and see these things veneered and carved and say, 'What's that?' We say, 'Oh, we make those for people with fancy homes.' But that's fine with us. We're aware people buy them as furniture too. We're just happy they like pianos." CAPTION: Picture, John H. Steinway, by Margaret Thomas - The Washington Post