Dunster House is sponsoring an excellent chamber group doing Bach this Friday afternoon. If you go, be sure to get there early. Comfortable places on the Library floor disappear rapidly.

Keeping with something of a tradition, the Harvard-Radcliffe Orchestra has a big-name guest solist, cellist Janos Starker. Though Vivaldi concerti are not everyone's favorite, the Dvorak should be an exciting piece; and the inclusion of Stravinsky's Petrushka was a good choice. Class consciousness has returned to Harvard: seats at Sanders will be sold for $4, $3, $2, and $1.

Paul Rosenbloom is one of the best pianists in the University and a gifted composer. Joe Conte has played Rosenbloom's compositions before, so their joint recital at Holmes on Sunday should present the contemporary pieces in the best possible light. The remainder of the program is worth hearing, too: Mozart, Schumann, and Brahms.

BUSCH-REISINGER MUSEUM. Brian Jones, organist, in recital. Free. Thursday, November 1, 12 noon.

DUNSTER HOUSE LIBRARY. Bach: Cantata Es ist genugn, and two ricercares from the Musical Offering. Free. Friday, November 2, 5:30 p.m.

SANDERS THEATER. Harvard-Radcliffe Orchestra. Stravinsky: Petrushka; and Janos Starker, cello soloist, in concerti by Dvorak and Vivaldi. Tickets: $4-3-2-1 at Holyoke Center Ticket Office. Friday, November 2, 8:30 p.m.

DUNSTER HOUSE LIBRARY. John Nicolson plays harpsichord works of Byrd and Bull. Free. Saturday, November 2, 5:30 p.m.

CURRIER HOUSE SCR. Cynthia Healy Ellis, soprano; Susan Gordon, piano; Marion Haffenreffer, violin. Chamber music of Bach, Beethoven, Molst, Walton, and Barber. Free. Saturday, November 3, 8:30 p.m.

TRINITY CHURCH (Copley Square). Sunday evening service with Brahms Requiem. George Faxon, choirmaster. Free. Sunday, November 4, 8:00 p.m.

HOLMES HALL LIVING ROOM. Joseph R. Conte, violin; and Paul Rosenbloom, piano. Chamber music of Mozart, Schumann, Rosenbloom, and Brahms. Free. Sunday, November 4, 8:30 p.m.

SANDERS THEATER. The King's Singers. Tickets: Free from Peabody-Mason Music Foundation, Box 153, Back Bay Annex, Boston 02117. Wednesday, November 7, 8:30 p.m.