The English Concert, performing Wednesday night at the Kennedy Center Concert Hall, occupies a special place among those groups committed to the performance of music on period instruments. While others have branched out from the movement's baroque roots, moving through classical and into the romantic period, the English Concert has been truer to its origins as a chamber ensemble.

"The English Concert remains a small chamber orchestra," says harpsichordist Trevor Pinnock, the Concert's founder and director. "We do a lot of classical music as well as baroque, but we don't blow up to the size that we could to do Beethoven symphonies. This is a principle of the English Concert, that we're very much a chamber music group. And chamber music is {like} a musical family working together."

If other original instrument groups have been the explorers, pushing onto to Beethoven, Schubert and Brahms, the English Concert has been a colonizer, offering listeners a broader repertoire of each composer, especially through their recordings. In 1985, the ensemble completed its ambitious five-year recording project of the complete orchestral works of J.S. Bach and Handel, honoring the tercentenary of both composers.

"Of course, the more music one plays of a composer, the more aware one is of the similarities running through their works. And there is a feeling of being at home with that music so one becomes a part of that creative process," says Pinnock.

Wednesday night's concert begins at 8:30. Tickets range from $14.50 to $26.50. For more information, call 393-3600.