Rivera builds the amplifiers that rock stars crave.

It's not easy trading riffs with the giants of the highly competitive guitar amplifier business - Fender, Marshall and Peavey, among others.

But Paul Rivera has made a name for himself and generated more than $2 million in annual sales with the equipment he builds in a small, family-owned-and-run plant in Sylmar.

Rivera's amps can roar with the raunchy growl of heavy metal one minute and sing with the crystalline twang of country-western the next.

That versatility, coupled with reliability born of relentless quality control, have made the Rivera amp the choice of a small but growing cadre of pros and Saturday-night hackers.

Rivera's customers include some of the biggest names in rock and country music - from Chet Atkins, Vince Gill and Jerry Reed to Robbie Robertson (formerly of The Band), Steve Miller, Boz Scaggs and Jeff "Skunk" Baxter, who has recorded with the Doobie Brothers and Steely Dan.

The gear isn't exactly cheap. The company's top-of-the-line amp - without speakers - retails for $2,895.

"I thought the best thing we could do was to compete on some high-end niche," Rivera said on a recent afternoon, standing beside a rack of amplifiers heating up under the scrutiny of a diagnostic computer. "I could compete on quality and tone."

Sales are up this year by more than 50 percent, said Rivera, whose equipment is sold in more than 50 countries from Australia to Thailand.

But the boyish-looking 45-year-old with shaggy brown hair says he won't claim financial success until revenues exceed the $10 million mark.

"Our image is much bigger than the size of our company," said Rivera, whose 13 employees at Rivera Research and Development include his wife, son, daughter and niece.

Rivera's is the classic story of youthful spirit and entrepreneurship. The son of a musician, Rivera learned to play the piano and the guitar at an early age and soon began tinkering with ham radios.

In 1968, at the age of 15, Rivera opened his first amplifier repair shop in the back of a guitar store in New York. His uncle loaned him the $300 for a volt meter and other rudimentary tools of the trade.

Rivera soon developed a reputation as someone who could change a resistor or alter a circuit to coax a desired sound out of a guitar amplifier, a reputation he still enjoys.

"He knows how to translate what he hears into a design," said Grammy Award-winning guitarist, producer and songwriter Jay Graydon, who helped develop a signature line of amps sold by Rivera.

"I explain it to him and he can translate that into a sound."

Rivera has been working on the West Coast since 1972, when he moved to San Diego and began designing and making a small number of custom amps.

Four years later, he moved to Tujunga and founded Rivera Research and Development out of the home where he still lives. He landed consulting jobs with Yamaha, Mesa/Boogie and other amplifier manufacturers.

In 1981, Rivera took a full-time job with the languishing Fender Musical Instrument Corp. He developed some new amplifiers for Fender. including the successful Concert and Super Champ models, helping the company to boost sales and recover some of its lost luster.

But he ended up leaving the company in 1984, after finding himself on the losing side of a buyout battle. Several months later, Rivera hopped on a plane and visited Fender's European distributors with plans in hand for his own line of amplifiers.

"I went to them and asked if they'd buy my product," said Rivera, who attended some college but doesn't hold an engineering degree. "I came back with 100 orders."

Rivera refined his designs and gathered pans for production while continuing his work as a design consultant. He began making his own line of amplifiers in his garage in 1986. Rivera rented a neighbor's garage to store speakers and other materials.

Since then, Rivera has been building his business, keeping his overhead down by using subcontractors to build cabinets and circuit boards.

Rivera designs on a computer in a crowded office he shares with his wife, where he comes up with new ideas to make a jumble of wires, tubes and metal conjure up thunder or calm.

Down the hall is a small, no-frills assembly plant. Hand-wired circuit boards wait on racks for further assembly. A box of hand-tested and matched tubes sits on a workbench ready for installation.

A computer plots the performance of nearly completed amps, which contain military-grade components. A technician finishes an amp and hauls it into a sound room for final testing. Boxed equipment awaits shipment.

Rivera moves around his plant this day in shorts and T-shirt. As his family works nearby, Rivera tells how he enjoys being his own boss, always pursuing new designs to make his amps stand out in a crowded field. He recently added several new amps to his line and says orders are brisk.

"When I see my stuff on stage used by great artists and they're producing great tone, that's my satisfaction," he said.