Les Paul, the U.S. guitar virtuoso and inventor, died Thursday, 94, in White Plains, N.Y., of complications from pneumonia.

The Gibson Robot Guitar is shown in this undated publicity photo released to Reuters November 13, 2007. In what is described as the world's first robot guitar, the electric guitar not only keeps itself in tune even after string changes but also allows players to access six nonstandard tunings at the push of a button. After 15 years of research, Gibson Guitar is launching a limited edition Les Paul Robot Guitar next month that has set players abuzz with both enthusiasm and skepticism. [Xinhua/Reuters]

Paul remained an active performer until his last months: He put out his very first rock album just four years ago, and up until recently played every week at a New York jazz club.

"He was truly the cornerstone of popular music," said Henry Juskiewicz, chairman and CEO of Gibson Guitar, which mass produced Paul's original invention.

"At least he realized that he was legend in his own time while he was alive" said Richie Sambora, Bon Jovi's guitarist and a friend of Paul's.

Paul was born Lester William Polfuss, in Waukesha, Wis., on June 9, 1915. He began his career as a musician, billing himself as Red Hot Red or Rhubarb Red.

Paul joined Fred Waring's Pennsylvanians in the mid-1930s and soon moved to New York to form the Les Paul Trio, with Jim Atkins and bassist Ernie Newton.

He started out as an accompanist, working with key artists until he struck out on his own. His first records were released in 1944 on Decca Records. Later, with Ford, his wife from 1949 to 1962, he earned 36 gold records for hits including "Vaya Con Dios" and "How High the Moon," which both hit No. 1.

Paul had made his first attempt at audio amplification at age 13. Unhappy with the amount of volume produced by his acoustic guitar, he tried placing a telephone receiver under the strings. Although this worked to some extent, only two strings were amplified and the volume level was still too low.

His work on recording techniques began in the years after World War II, when Bing Crosby gave him a tape recorder. Drawing on his earlier experimentation with his homemade recording machine, Paul added an additional playback head to the recorder. The result was a delayed effect that became known as tape echo.

Paul's next "crazy idea" was to stack together eight mono tape machines and send their outputs to one piece of tape, stacking the recording heads on top of each other. The resulting machine served as the forerunner to today's multitrack recorders. Many of their songs used overdubbing techniques that Paul had helped develop.

"I could take my Mary and make her three, six, nine, 12, as many voices as I wished," he recalled.

Paul's use of multitrack recording was unique: Before he did it, most recordings were made on a single tape. By recording each element separately, from the vocals to instrumentation on different tracks, they could be mixed and layered, adding to the richness in sound.

In 1954, Paul commissioned the first eight-track tape recorder, later known as "Sel-Sync," in which a recording head could simultaneously record a new track and play back previous ones.

In the late 1960s, Paul retired from music to concentrate on his inventions. His interest in country music was rekindled in the mid-'70s and he teamed up with Chet Atkins for two albums. The duo were awarded a Grammy for best country instrumental performance of 1976 for their "Chester and Lester" album.

In 2005, he released the Grammy-winning "Les Paul & Friends: American Made, World Played," his first album of new material since those 1970s recordings and his first official rock CD. Among those playing with him: Peter Frampton, Jeff Beck, Eric Clapton and Richie Sambora.

Paul was inducted into the National Inventors Hall of Fame in 2005.

(Xinhua/Agencies August 14, 2009)