The renowned Berkshires venue in Lenox and Stockbridge will offer a shortened, six-week program from July 9 to August 16 that features performances by the Boston Symphony, Boston Pops, Tanglewood Music Center orchestras, guest artists, and special chamber music and large ensemble groups. Performances will be about 80 minutes long with no intermission and take place in the open-air Koussevitzky Music Shed, which received updates to its indoor air ventilation and filtration systems. “This summer is destined to be incredibly special, as the BSO and I return to our beloved Tanglewood and concerts for live audiences,” said Andris Nelsons, the music director of the Boston Symphony Orchestra who will lead eight orchestra programs this summer, in a statement. “Among the many highlights planned, we will pay tribute to Beethoven and spotlight 18 important composers of our time, representing a beautiful spectrum of styles and diverse backgrounds.”