MALVERN, PA. -- Back in the summer of 1984, when they were green and cocky and blissfully ignorant, the founders of Ensoniq Inc., an electronic keyboard manufacturing outfit, decided to go to the National Association of Music Merchants convention in Chicago to talk about their newfangled invention to the industry heavies.

They had no prototype to show, not a single piece of hardware. They had only talk -- an idea, a dream that they could create something called The Mirage that would blast into the music industry stratosphere and challenge the giants of the business, the Japanese.

Few believed them, of course, but founders Bruce Crockett, Al Charpentier and Bob Yannis, along with nine of their whiz kids, crammed inside the 10-by-10-foot convention booth and yapped on anyway, "standing there, smiling, trying to talk to dealers," remembers Robin Weber, a company marketing executive.

Nowadays dealers stand in line trying to talk to them. In four years this tiny outfit, based in an industrial park in Malvern, 27 miles west of Philadelphia, has done what no American electronic keyboard manufacturer has since the industry started booming -- risen to world-class status. "They've arrived," says industry analyst J. Peter Santo. "They've gone up against the Japanese giants and they're a contender with the best of them." Adds Paul Majeski, publisher of Music Trades, a national trade magazine, "They were just a big surprise."

To the world at large, a successful electronic keyboard might seem to be small change. But the electronic music industry, where new technology has brought down prices and a growing number of amateur musicians are widening the market base, is big business. According to figures from the Chicago-based American Music Conference, which keeps tabs on the industry, retailers sold more than $1.5 billion in electronic instruments in 1986 in the United States, nearly half of total musical instrument sales. And sales are still booming. In the first nine months of 1987, retail sales of electronic keyboards were up 43.5 percent over 1986, according to January 1988 figures from the National Association of Music Merchants.

But while sales are booming, American manufacturers are brooding. Ninety-six percent of electronic keyboards purchased in the United States in 1986 were made in Japan. Last summer, when Ensoniq opened a sales office in Tokyo, it became the first American electronic keyboard manufacturer to handle direct marketing in Japan, exporting from its Pennsylvania headquarters.

Ensoniq President Crockett is modest about his company's success. "I don't know that it matters that our competitors are Japanese," he says. "I think it's a lot of hype. Business is business. What you need to do is get the best possible product to the consumer with the most features at the best cost. When you do that, you win."

Thirty years ago, the words "electronic keyboard" conjured up an image of the organ, a home and church instrument. Then came American inventor Robert Moog, who introduced his Moog synthesizer at trade shows in 1964. While Moog didn't actually invent the first electronic music synthesizer, his was a technical marvel revered by musicians and popularized by the top-selling album "Switched-On Bach" by Walter Carlos, which showcased its ability to mimic sounds of acoustic instruments.

The Moog was followed by the ARP, created by American inventor Allan R. Pearlman in his basement in Newton, Mass., in 1968. While the ARP was also a technical marvel, it didn't change the recording industry. It was only in 1982, when a group of musical instrument makers developed the Musical Instrument Digital Interface, known as MIDI, that the electronic keyboard came into its own and the music biz took a giant technological step forward.

MIDI ties synthesizers and other microprocessor-based instruments together by converting the musical control information into a uniform code, thereby allowing several different instruments to "talk" to one another, and even to record and play simultaneously.

With the introduction of MIDI, sales of synthesizers costing more than $1,000 -- those used by professionals -- exploded from $32.3 million in 1980 to $134.3 million in 1986, according to the American Music Conference. Most were made by Japanese firms -- Korg, Roland, Casio and Yamaha International, perhaps the most prolific of Japanese music manufacturers, which makes everything from guitars to amplifiers to saxophones.

Yamaha leaped into the MIDI fray by introducing its Yamaha DX7 synthesizer in 1983, available then for about $2,000. The DX7 and its current heir, the DX7 IIFD, priced at about $2,500, remain staples among musicians, much as Gibson guitars were the staple of earlier, more acoustic (and some say better) guitar-dominated days. Then in January 1985 came Ensoniq's Mirage "sampler" and a year later (its ESQ-1 synthesizer, which have flown from the basement to the penthouse of the low-price market.

Unlike the Yamaha DX7 synthesizers, which mimic the sounds of acoustic instruments through digitally precise frequency and tone modulation, the Mirage is a sampler. That is, it has the capacity to "sample," or record, a sound -- a trumpet, a bass guitar, a chair scraping the floor, a human voice -- store it in computer memory and then replay it, saving it on a floppy disc for later retrieval. The keyboard is used to determine the pitch and tone quality of the replayed sound. Thus, for example, a sampled human voice can be played back at middle C, or as a harmonized chord, or in any number of ways.

Sampling is not new. But the current retail price of a Mirage -- around $1,295 -- is. When it was first introduced at $1,695, the only sampler that compared was the Emulator II (made by E-mu Systems Inc., based in Scott Valley, Calif.), which then sold in the $8,500 range, while a top-of-the-line Kurzweil 250 (manufactured by Kurzweil Music Systems of Waltham, Mass.) retailed for $10,000 to $20,000, depending on features. Other top-end brands can cost up to $300,000 or more, but those are created for the Stevie Wonders, the filmmakers and the jingle writers of the world. The Mirage, although used by professionals such as Prince and Herbie Hancock (who has a promotional deal with the company), is primarily aimed at the anonymous, bread-and-butter musician who works wedding gigs, bar mitzvahs and bars. "There's only one Stevie Wonder," says Crockett, "but there are a lot of people who play Hyatt hotels and Holiday Inns."

While its price makes the Mirage available to the journeyman professional and the amateur who enjoys tinkering with sounds and music, the big boys know a good deal when they see one. "We use their equipment real heavily," says Matt Larson, road crew chief and electronic technician for Prince. "The ESQ-1 is just a great keyboard. I have four Ensoniq Mirage keyboards and three rack mount units {the Mirage computer without the keyboard}. It's a real good versatile unit. We've had {them} on two world tours and they've taken a fair amount of abuse on planes, and we've had no big problem with them."

In 1985, the first year Ensoniq shipped products, it raked in profits of more than $1.2 million after taxes on revenues of $10.7 million. In 1986 it pulled in $1.96 million after taxes on revenues of $22.6 million. Company officials say 1987 sales were up 10 percent, but even larger than the sales margin is the margin of respect Ensoniq has won from industry sages.

"Ensoniq has cut out a market niche for themselves," says Moog, 53, now a vice president of new-product research at Kurzweil Music Systems. "The Japanese are much more active on the manufacturing end. The few Americans that got into it are holding on by the skin of their teeth. The only exception, at their end of the spectrum, is Ensoniq."

It was founded by Crockett, 46, a former manufacturing design vice president at Commodore International Ltd., who with design engineers Charpentier, 34, and Yannis, 30, helped create one of that company's most popular home computers, the Commodore 64. The three left Commodore in mid-1982 to form a personal computer outfit, but opted for electronic keyboards when the personal computer industry tottered. Of the three, only Yannis is a musician. "We're a technically-driven company searching for a marketplace where we can apply our technology," says Charpentier.

For the Mirage and the ESQ-1 (which at $1,395 has eclipsed the Mirage as the company's top product in sales volume), Charpentier and Yannis developed a microchip that took the place of 120 chips used in other, comparable, but more expensive keyboards. As technically advanced as their product was, the founders had difficulty convincing venture capitalists that their idea was a safe investment. "We took everything we had," says Crockett. "We financed our houses, our cars, everything." And with a million in savings from a previous consulting project, $350,000 they managed to obtain from a venture capitalist and a $100,000 bank loan, they "went after it."

Today, unlike most American electronic keyboard manufacturers, Ensoniq has "a full custom integrated circuit design capability." That is, it has the in-house expertise to design chips specifically for its musical instruments, while other companies must venture outside their own walls to hire or buy chip expertise. Ensoniq also designs its own print circuitry and hardware, and manufactures the keyboards in its 71,000-square-foot headquarters. Its 185 employes do everything from developing new keyboard sounds to testing and packing the keyboards.

"The workers here are superb," says Crockett. "The Japanese owned the music business when we went into it, but it's not important that I take out ads that say, 'We took on this giant and won.' But it's important for me to say that {our} employes came here and put their hearts into this venture. In my opinion, everyone comes to work wanting to do a good job."