For an upright bass, this is pretty damn hood. http://www.drealm.info/sfz/DSmolken/ Plucked and bowed notes plus various noises, SFZ mappings, velocity layers, round robins, and totally raw samples with no EQ or compression. 252 MB of samples, and free. Next I might sample my most swagged out electric bass. It's got modern active electronics and a dead set of flatwound strings that are close to 10 years old now, which is a pretty popular setup with bassists that do hip-hop and R&B live. And it's got a fake Louis Vuitton scarf glued to the front. What more could you ask for?