Recently (late last year?), Yamaha introduced CX Series to replaced its C Series. It’s Yamaha’s attempt to upgrade its grand piano line from “Asian” sounding pianos to a “European” sounding pianos. They reached the goal. I was invited to test-drive the new line: The C and CX sound very differently. What makes that happen is the use of different materials. Mainly in the following areas:
Thicker back posts;
Other than acoustic difference, there are cosmetic changes, too. But they are not something I am interested. You may ask the dealer for more details, or visit: http://usa.yamaha.com/products/musical-instruments/keyboards/grandpianos/gp-cx/?mode=series#tab=feature
The model numbers are a little confusing. They are not CX3, CX5, etc., but they are C3X, C5X.