There are 3 main controllers that we recommend using with Spitfire Audio libraries, by default these are:
Dynamics - CC1
Vibrato - CC21
Expression - CC11
To use these effectively, it's important to know what these controllers are doing.
Dynamics are controlled by the modwheel, or CC1. This controller will crossfade between the different sampled dynamic layers (for example, pp to ff) depending on the value of the continuous controller. Depending on the instrument, this will often change the timbre and also the overall volume.
Vibrato controls which vibrato sample is triggered on the selected articulation. In Spitfire libraries, we tend to use the fader as a 'switch' instead of a crossfade. This is because 'crossfading' vibrato can often create an unrealistic performance, especially with solo instruments.
Expression is a volume controller within the library itself, and will have no effect on the timbre of the instrument. Used together with CC1 this can help you to create a more 'expressive' performance, hence the name!