It's a state-of-the-art, globally recognized industry giant, but Mapes Piano Strings keeps its multi-million dollar secret tucked away in the Appalachian foothills. Operating out of Elizabethton, Tenn., Mapes dominates the market in piano wire and guitar strings, to the tune of $23 million a year. The piano string industry isn't a big one, but according to Brian Majeskie at Music Trade magazine, "They're sort of it, so it's as big as they are."

Mapes is also the oldest company of its kind in the United States. The Schaff family has been making piano wire and supplies since the mid-1800s, supplying customers like Steinway and Gibson. Many manufacturers and restorers use Mapes wire exclusively, and its high quality product has become the benchmark, competing with giants like Germany's Raslow brand. Despite this global reputation, Mapes keeps the company private and close to home. Three generations of Schaffs make up most of the principals.

The town of Elizabethton knows Mapes more on a personal level than as a major company. Though local officials describe Mapes as "good corporate citizens," they admit that the family keeps a low profile. Quietly sponsoring civic improvement projects and local events, the Schaffs "go about their business privately—not one to toot their own horns," says David Ornduff, civic planning director.

Even the process of wire production is a hands-on, personal procedure. Each string is hammered out by hand, and the youngest winder at Mapes has 15 years of experience. The labor-intensive and precise nature of wire production makes this niche all the more constricted, and Mapes' dominance all the more secure.

But music strings only make up 40% of the company's business, according to Andy Wilson, the string shop supervisor. The majority of production goes into spring wire for use by everyone from toy companies to the military. Having branched out into a more diversified field of production, Mapes is already becoming a major competitor in the spring wire industry. The move is intuitive; "There is no higher quality wire than piano wire," explains Alex Kapteyn at Central Michigan Piano, one of Mapes'exclusive clients. For customers like Kapteyn, there is no higher quality wire than Mapes. Most customers have never seen the facility that makes 12 to 15 million pounds of wire every year, but this reclusive Tennessee company makes big ripples in their market.