Douglas Wheeler, managing director of the Washington Performing Arts Society, gave the audience what amounted to an apology Saturday night in the Kennedy Center Concert Hall. It came as the intermission was ending for the Washington debut concert of the Academy of Ancient Music, with Christopher Hogwood conducting.

"You're looking at a man," said Wheeler, "who had the wisdom to say, 'Let's see how the Academy of Ancient Music does before we book them again.' " He held up the freshly printed WPAS brochure for the next season and looked at it a bit regretfully. "They won't be here in '86-87," he said, "but you may be sure they will be in '87-88."

Wheeler should not be too hard on himself. Hogwood is already a familiar figure in Washington, and no doubt his orchestra should have been brought here years ago. But it takes time for a mainstream, big-name-oriented organization like the WPAS to realize the dimensions of the audience for such seeming oddities as a chamber orchestra that plays old music on antique instruments tuned a bit flat.

That audience turned out in force Saturday night; it knew exactly what to expect and its expectations were superbly fulfilled. Barring a few momentary lapses of intonation or emsemble, the Academy of Ancient Music in person matched the exalted standards of its familiar recordings. The program was superbly balanced. Two blockbusters, the Mozart Clarinet Concerto and Haydn's "Farewell" Symphony, were paired with two smaller, less familiar but highly attractive works: Mozart's bright, vigorous, youthful little Symphony in G, K. 129, and his Andante in C for flute and orchestra, with the orchestra's principal flutist, Lisa Beznosiuk, playing an exquisitely graceful solo.

Antony Pay, who is featured on the ensemble's recording of the Clarinet Concerto, was also the soloist Saturday night, playing a reconstructed basset clarinet that looked, from a distance, something like a large, elaborate recorder but sounded rich, mellow and deeply soulful.

The only grounds for complaint might be the reticence of the fortepiano from which Hogwood conducted. For those who were not seated down front, this instrument's participation in the evening was purely visual. It is not strictly needed in post-Baroque music, of course, but one does like to hear what one is seeing. The solution would be to book Hogwood into the Terrace Theater or the Wolf Trap Barns when he returns. But to accommodate his audience, he would have to be booked for at least a solid week.