Leonore Annenberg is extending her track record as the Academy of Music's most generous supporter with a $5.3 million pledge to help restore the Academy's ballroom.

Annenberg's gift brings to $11.6 million the amount raised by the 150th Academy anniversary ball and concert, set for Saturday night. (The $11.6 million is a gross amount; net proceeds won't be known until after Saturday's fete.)

Proceeds are to be divided between the Academy and its owner, the Philadelphia Orchestra - except for the Annenberg gift, which is earmarked for the ballroom.

Academy planners have spent much of the last decade upgrading building systems and refurbishing the appearance of the 150-year-old hall, but are only now turning their attention to the ballroom, inspired by the Hall of Mirrors at Versailles.

Plans call for opening up views from (currently mirrored) windows on the east side of the ballroom, and giving visitors access to the balcony that overlooks Broad Street. Leaks in the ceiling must be fixed, gold-leafing restored, and chandeliers refurbished or replaced.

The details of the project have not been set, said Linda Scribner, the Academy's chief fund-raiser. "We have not made the decisions yet," she said. "We'll work very closely with Lee Annenberg. She is very excited about the visual impact of the project. It will really have her stamp when it's finished."

Annenberg and her late husband, publisher Walter H. Annenberg, have been deeply involved in the Academy of Music and the orchestra for more than five decades, giving $18 million in capital and $15 million in endowment gifts to the Academy, according to the orchestra.

Her gifts have bolstered the endowment, helped refurbish dressing rooms, and improved rest rooms. One year she not only gave $200,000 to renovate the Ormandy Room, a formal reception space backstage, she also sent over her decorator to do the job.

In recognition of her largess, the Academy will present Annenberg with the Academy of Music 150th Anniversary Award. The presentation Saturday night will be made by Prince Charles, who will be attending the concert with his wife, the Duchess of Cornwall.