During Bach's and Mozart's days, the orchestras weren't as large as they are today. Orchestras would eventually get louder, too, thanks to advances in construction materials for instruments (moving from gut strings to metal strings, for example). But you don't always have to play the music of the Baroque or Classical eras with modern sounding orchestras.
The Chamber Orchestra of Louisville is aiming for a lighter, intimate sound more reminiscent of the 17th and 18th centuries with their concert this weekend, while not getting too consumed with the historical performance practice weeds.
Gabe Lefkowitz, who's the group's founder and artistic director, is looking to fill a niche between the Louisville Orchestra performing something like Richard Strauss' "Alpine Symphony" and Fanny Mendelssohn's String Quartet played by NouLou Chamber Players.
This weekend they'll play the "Jupiter" Symphony No. 41 of Wolfgang Amadeus Mozart (with 29 musicians!) and the Brandenburg Concerto No. 2 by Johann Sebastian Bach, featuring soloists Julia Noone, Kathy Karr, Alex Vvendenskiy, and Chase Hawkins (one of the regions few "Brandenburg 2" specialists).