The sound of California business success came to my ears the moment I stepped through the door of Fender Musical Instruments Corp.'s 3-acre manufacturing plant in Corona, 70 miles east of downtown Los Angeles.

It reached me as riffs and scales on electric guitar, audible over the thud of metal stamping and the grind of band saws that one might customarily hear on a factory floor.

But this is no ordinary plant. The last step in Fender's quality-control process requires an experienced musician to play every note on a finished guitar, listening for a stray vibration or tuning flaw to be corrected before any model, including the American Standard Stratocaster that is the plant's bread and butter, reaches a dealer.

Fender's Corona shop is a testament to how U.S. manufacturing — California manufacturing, especially — can survive in a world where even complex products such as microprocessors can be turned out by the millions by unskilled laborers overseas.

The secret is to marry assembly-line efficiency and hand-tooled precision. Much of Fender's manufacturing process, including the rough cutting of the guitar body and the stamping of the metal parts (some still based on dies cut personally by Leo Fender, the company's founder), is at least partially automated. But there's no substitute for the hand-finishing, polishing and tuning of the hundreds of American Standard Stratocasters and Telecasters, along with other high-end guitars, produced each day by a workforce of 600 in Corona.

Not even Fender is a California-only manufacturer: The firm makes most of its amplifiers and entry-level Fender-brand guitars in Ensenada, Mexico. But its executives say their core manufacturing is in California to stay.

"California is hewn into Fender's DNA," says Justin Norvell, director of marketing for the electric-guitar lines. "Leaving would never happen."

In part, that's because of its experienced workforce, which can't be casually relocated, much less replicated, somewhere else. The average tenure of a Fender employee is 15 years, and turnover is less than 1 percent, says David Maddux, the firm's senior quality-assurance technician and a 35-year employee.

Guitar-making in California also helps preserve the company's link to its late founder, Clarence Leonidas Fender, who opened a Fullerton radio shop during the Depression and tinkered with amps and electric guitars on the side. The first Fender-built guitars appeared on the market in the mid-1940s.

Fender guitars have long been identified with the California car-and-surf culture — Leo personally gave Dick "King of the Surf Guitar" Dale one of the first Fender Stratocasters, with the directive to "beat it to death." Dale worked Fender's amps so hard that some burst into flame, according to legend.

So it's no accident that Fender's $1,590 American Standard Stratocaster, the heart of the catalog, is made in Corona. And that's not to speak of the models produced by Fender's eight master builders, elite craftsmen who can spend anywhere from several days to several months building a guitar in the Custom Shop.

Collectors commonly demand the products of particular master builders, and artists sit down with their favorite builders to extract just the right sound from the hand-tweaked electronics and build of a signature guitar.

Ask him about his work, and a master builder will respond not with an engineer's precision but an artist's subjectivity. "There's a sound in my head I'm trying to chase and yet remain true to what Fender's all about," Mark Kendrick, 51, told me. Kendrick has worked at Fender since he was 18. He struggled to put his goal into words, then said, "It's really tough to describe the tonal quality of a Fender. ... It's the very definition of rock 'n' roll."

Kendrick has made instruments for Eric Clapton and Merle Haggard. To meet a customer's specifications, he'll do everything — hand-wind copper wire around the pickup magnets as well as select the wood of the guitar body.

"I can water the tree if I have to," he said.

A few cubicles down, John Cruz showed me the replica he fashioned from Swedish guitar-virtuoso Yngwie Malmsteen's 1971 Stratocaster. It's a heroic reproduction, down to the original's cigarette burns and tooth marks, not to mention its strip of tape with the words "Play Loud" and electronics that achieve what Cruz called a "1-to-1 match" sonically.

Fender then turned out 100 replicas, sold for a list price of $12,500, to Malmsteen devotees — plainly a group that puts the "fan" into "fanatic."

Yet you don't have to follow any individual artist to admire Fender guitars. Like its nearest rival, Gibson Musical Instruments in Nashville, Fender is part of every rock fan's heritage. Fenders have been the instruments of choice for Clapton, Steve Miller and Stevie Ray Vaughan.

I remember the great blues guitarist Roy Buchanan making his Fender Telecaster wail like a heartbroken lover on "Sweet Dreams" during a New York appearance in the early '70s. That's a white Strat that Jimi Hendrix seemed to stretch to its physical limits in his unforgettable battlefield rendition of "The Star-Spangled Banner" at Woodstock in 1969. If you're looking for "a definitively sublime Strat moment," guitar historian Tony Bacon says in "The Fender Electric Guitar Book," you could do worse than David Gilmour's operatic solo on Pink Floyd's "Comfortably Numb."

Collectors of Strats can be as particular as collectors of Strads, endlessly debating the relative quality of those manufactured during Fender's three historical periods — the Leo Fender years (1946-65), the period following its 1965 acquisition by CBS and its renaissance after a 1985 buyout by its CBS management, led by William Schultz, who established a corporate headquarters in Scottsdale, Ariz., but opened the Corona manufacturing facility and launched the Custom Shop there. (The instruments produced under cost-conscious CBS have long been scorned by experts but have lately begun a modest rise in collector esteem.)

Many guitar experts believe Fender is today experiencing its golden age, but that doesn't mean the firm is immune from economic woes. It cut back to one shift from two about a year ago, when the recession made $1,000-plus guitars look like dispensable luxuries.

Executives say dealers have finally begun to report hazy indications of resurgent demand.