The North Carolina Chamber Players brought a real mix of styles, periods and musical caliber to the Library of Congress Saturday. They played under the direction of guest conductor Nicholas Harsanyi, whose economy of beat is excelled only by the depth of his experience and his ability to communicate same.

At full strength, the group has 32 players, some of them from the North Carolina Symphony, and they perform widely for otherwise neglected audience throughout the Southeast. On Saturday the string section, coming unglued at the peak of some of the most exposed lines, was the weak link in an otherwise nicely groomed ensemble. It sounded, however, more like a problem of concentration than of technique.

The finest playing of the evening came in the Chausson "Chansons Perpetuelle" with soprano Janice Harsanyi as soloist, and in Harold Schiffman's well conceived and serviceable Prelude and variations, written a year ago.

Janice Harsanyi's voice is in marvelous shape these days, and, consummate musician that she is, she brought to the music of Chausson and the poetry of Cros just the touch of ennui and the flavor of sophistication the sad story needed.

Schiffman's music is a modest but honest piece that is nicely scored and that handles a few good ideas with considerable interest. The orchestra gave it a careful and accurate reading.

Also on the program were a boisterously informal early Scherzando by Haydn, the self important and cliche-ridden 4th Symphony by Robert Ward, and Dvorak's exuberantly romantic "Czech Suite."