THE WASHINGTON area has long been known as a guitar player's town: You can start with Roy Clark, who used to play the downtown honky-tonks in the '50s, and work right through to folks like Roy Buchanan, Nils Lofgren and Danny Gatton. So it's not that surprising that the first cover of Guitar Player Magazine in 1967 featured Charlie Byrd, Barney Kessell, Jorma Kaukonen and Jack Casady, all residents of Maryland or the District.

That was back when GP started out as a shoestring newsletter in a California guitar shop. Since then GP's narrow focus has become the model for specialized musicians' magazines. In fact, GPI (Guitar Player Inc.) Publications cloned Keyboard magazine in 1975 and Frets in 1979 (for all acoustic stringed instruments). Each covers all instruments within its category (for instance, GP includes acoustic and electric, classical, pedal steel and bass) and all styles--rock, classical, folk, jazz, bluegrass, blues and others. The company motto is "Magazines Serious About Music."

Such specialty magazines used to be hard to find, but now they're equally hard to avoid, which is pleasing to GPI publisher Jim Crockett. "We don't appeal to the general player," he pointed out during a recent College Park stopover for a seminar on career opportunities in the music field. "I'm interested in people who are serious as hell about their music and about playing as best they can. At first, GP was for people who wanted to learn how to play guitar. I changed that to people who already knew how to play, and who wanted to play better.

"I'm a musician in my heart, but not too much in my hands anymore. But I know when I pick up one of those magazines, from the first page to the last page, it's all music one way or another. I know it's dedicated to my interests."

With an estimated 16 million guitarists and 25 million keyboardists in America, the circulation (150,000 for GP, 50,000 for Keyboard and 55,000 for Frets) is solid, particularly since each copy has 2.3 readers, Crockett said. He also pointed out that several million people say they can play their instruments on a professional level.

Crockett said most of his readers regularly practice their instrument of choice (13 percent play both guitar and keyboards), so what's offered among a plethora of semitechnical advertising are instructional columns, player profiles, product and equipment evaluations and answers to the constant flood of readers' questions. The columns (GP alone has 25) are written by a virtual who's who of music professionals. Some are stars (Frank Zappa, Larry Coryell), while others are studio legends, producers, teachers and instrument builders.

"Back in 1971 we didn't have any money to pay these guys so we put their name and picture on the columns and gave them a free ad," Crockett recalls. Some of the writing has been quite professional ("Coryell studied to be a journalist") while others "know music super well but can't communicate it. They tell us what they want to do and we semi-ghost. Some guys on the road phone their columns in from airports and backstages from around the world, or they send in tapes."

Because specialized publications like to know their markets, Crockett can quote figures left and right--and enjoys doing just that (he's been doing demographic studies every two years since 1969). The readership is overwhelmingly male (98 percent for GP, 88 percent for Frets, 75 percent for Keyboard). Frets' readers also happen to be older (average age: 35 compared to 26 for the other two magazines). Almost half the GP and Keyboard readers are "people struggling to make careers in music."

When he first came to GP as an assistant editor in 1970, Crockett spent a year learning how to play guitar "so that I knew something about the mechanics involved. And I spent five years reading every available book about the guitar--history, performance, maintenance. I'm probably one of the world's truly great authorities on the instrument . . . but God forbid you should put one in my hands."