If you've never heard Bach performed on period instruments, you're in for a treat. Here's a performance of the third Brandenburg concerto by the Akademie für alte Musik Berlin.

https://www.youtube.com/watch?v=mSHLlidrZh8

Compared to "normal" instruments, you'll hear something that's a lot lighter, less monumental, more fun, a bit faster especially in the third movement. I was lucky enough to see them live a few times, and it's really great to hear how much they listen to each other, how much work has gone into their performance, and how much fun they're having, with big smiles and happy looks.