The fifth iteration of the Big Ears Festival, which focuses on avant-garde, ambient, and improvisational music of all genres, took place in Knoxville, Tennessee over the weekend. Indie rock heroes Yo La Tengo performed twice, but neither performance was a usual Yo La Tengo show. During one set, The New York Times reports, they joined forces with Nashville alt-country veterans Lambchop, and in another, they teamed up with the National’s Bryce Dessner, the Sun Ra Arkestra’s Danny Ray Thompson, the Necks pianist Chris Abrahams, and harpist Mary Lattimore to perform 90 minutes of ambient improvisation. Watch footage from both collaborations below.