DavisB
Spring action doesn't have inertia (to be precise it has inertia but way too low), and that is the reason it feels bad, inertia is needed to "convert" finger force into velocity (and the velocity of hammer/key is what determines volume both in acoustic and digital), simple example: in spring action with 60g downweight, when you apply 61g of force key goes down and you have low velocity (pianissimo), when you apply 70g you have high velocity (fortissimo), because of the almost non existent inertia the range is very small, so small that you can't play that way at all and instead you have to deliberately press the key with certain speed not force which is not easy and intuitive. In proper acoustic action or good digital, there is quite large inertia and if then downweight is that 60g, 61g of force will give you pianissimo1 and to get fortissimo you need 4000g of force, the range is huge and so it is easy to control, but also usually demands more strength. You don't have to deliberately move the finger with certain speed, just apply force, inertia will convert it to velocity for you,
1. this is valid for digital actions but real acoustic action usually requires at least downweight + 30g of force to produce pianissimo sound.
