What kind of music do you enjoy?
August 10-12 is Al'Arme Festival in #Radialsystem, https://www.alarmefestival.de/program. Haven't been before, but will go this year as CM von #Hausswolff is playing.
Haus der Kulturen der Welt, or #HKW, https://www.hkw.de/ has a new director who is doing interesting stuff. It's also a nice place to meet friends in the beer garden by the water (it's located in the middle of the city in a huge park).
And off the main tourist routes is Pfaueninsel.