Sidney Harman: Businessman who created the first integrated hi-fi system and later bought 'Newsweek' magazine

Businessman yet champion of workers' rights, inventor, educator, government official, philanthropist, keen student of Shakespeare and – at the very end of his life – an improbable media baron, Sidney Harman was a veritable renaissance man of modern America.

Harman gave the first serious display of his entrepreneurial mettle as a young engineer, working in New York for a maker of public address systems. He and a colleague, Bernard Kardon, wanted the company to develop an improved sound system for ordinary homes. Their boss wasn't interested, so the pair quit, raised $10,000, and in 1953 set up Harman-Kardon Inc, manufacturer of the world's first integrated hi-fi system.

The product was an instant winner: "Nobody had ever heard anything like that in his living room," Harman told an interviewer years later. When Kardon sold out, Harman ran the company himself, taking it into new fields that included microphones and amplifiers, as well as car stereo and home theatre systems. By the time he finally retired in 2007 its annual sales topped $3.5bn, and his personal fortune in 2010 was estimated by Forbes magazine at $500m.

But Harman was never one to rest on his laurels. In August 2010, on the eve of his 92nd birthday, he bought the venerable but moribund Newsweek magazine from the Washington Post. The purchase – for a sum of $1, plus the assumption of $47m worth of debt – caused much astonishment and was against the advice of almost everyone he consulted. "I've been preparing for this for nearly a century," Harman joked to Donald Graham, chairman of the Post company. "I'm in this to have a helluva good time... I'm not in this to make money."

But the development of hi-fi and the acquisition of a national news magazine were only bookends of a hugely varied career spanning seven decades. Even as he was building up his company, Harman was active in the burgeoning civil rights movement and was a vocal opponent of theVietnam War. For a year in the 1960s he taught black students in a ruralVirginia county, after local officials had closed public schools rather than desegregate them. Between1968 and 1973 he ran an experimental Quaker college on Long Island, and also found time to earn a doctoratein education.

His managerial style was equally innovative. Harman was a firm believer that the better their conditions, the better workers would perform. For some, Harman's introduction of flexible hours, special training and new incentives for employees at one Tennessee plant was naïve idealism. Others, though, regarded him as a visionary. Among those whose eye he caught was the incoming president Jimmy Carter, who in 1977 made Harman his under-secretary of commerce.

Harman served little more thana year, but long enough to meet a White House lawyer named Jane Lakes,27 years his junior. They married in 1980, and she went on to become a prominent Democratic Congresswoman, serving nine terms and rising to become her party's ranking member of the House Intelligence Committee. In 1998 Jane Harman ran unsuccessfully for governor of California in a campaign largely financed by her husband. She retired from the House in January 2011 to head a Washington think-tank.

In his later years, Sidney Harman became one of the city's leading supporters of the arts, as a major benefactor of the prestigious Phillips Collection, and donating $20m for construction of Sidney Harman Hall, new home of Washington's highly regarded Shakespeare Theatre Company. Nothing, though, prepared for the surprise of his purchase of Newsweek, by then losing $20m a year. Without Harman's intervention, the magazine would almost certainly have gone under. He had no experience in the media industry, but no matter: "He's a man who needs a project," his daughter Barbara said at the time.

The project did not stop with the purchase. Harman pushed the magazine in a radically new direction by merging it with the flashy Daily Beast website, owned by Barry Diller and whose editor Tina Brown, former editor of Vanity Fair and The New Yorker, is now at the helm of Newsweek. It was an unlikely match, but one which to Harman made eminent sense.

"Good genes, a lack of interest in eating, a great interest in athletics and staying in physical condition," was how he once described the secret of staying active into his nineties. A better explanation, perhaps, was his unfailing readiness to embrace the new.

Sidney Mortimer Harman, businessman: born Montreal 4 August 1918; married Silvia Stern (divorced; three daughters, one son); 1980 Jane Lakes (one son,one daughter); died Washington DC 12 April 2011.