Many modern sample libraries feature eight, 16 or even 32 velocity layers per note, and if your keyboard doesn't let you generate the full range of MIDI velocity values you may never hear some of these layers. This is the reason why most keyboards offer a selection of velocity curves. MIDI supports 128 different velocity values (from zero to 127) and, whichever velocity‑sensitive keyboard you choose, it should let each player generate this complete range of values smoothly as they dig into the keys, from soft to hard. However, the ultimate goal is always the same. If you come from a synth background, a weighted, hammer‑action keyboard may feel very heavy and ponderous to play while, conversely, if you're used to playing acoustic pianos, a lightweight, synth‑action keyboard may feel lifeless. SOS contributor Martin Walker replies: Some keyboardists play harder than others, while keyboard controllers themselves can vary a great deal in their mechanical resistance, action and feel. How should I go about choosing which one to use, and why is this necessary? I've just bought a new MIDI controller keyboard that has a selection of velocity curves. From left to right, the linear setting is always a good starting point, but switching to the convex curve will give you greater control over louder notes, the saturated curve will deal with keyboards that won't otherwise generate maximum MIDI velocities, and the concave curve is the one to choose if the quiet end of the MIDI velocity range feels all 'bunched up' on your keyboard.

Many MIDI keyboard controllers feature a clutch of different velocity curves, such as these.

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