Note-off velocity?

QuasiUnaFantasia it? When a physical key is let go in an acoustic, gravity pulls, and the damper drops, where does velocity play a part?

MIDI was not designed to capture the events of digital pianos but to interconnect synthesizers and computers. In a synth, the note-off velocity can be used to control the Release component of the ADSR envelope.

In an acoustic piano the velocity of releasing a key has impact on how fast the key damper touches the strings and therefore on the sustain. This can have a noticeable impact on sound, especially in slower pieces that do not rely on the sustain pedal. Have a listen at András Schiff playing the WTC at the BBC Proms 2018 for several examples. But one could argue that this effect is minor when considering a wider repertoire.

In a digital piano, the note-off velocity can be a constant value or represent the release velocity at a given point. This feature requires measuring the time difference between a pair of key sensors - and this is the reason why DPs that rely exclusively on hammer sensors cannot implement it. As @CyberGene pointed out, some implementations, notably Yamaha's, represent the key release not as a single event but as multiple events. This better simulates the key damper mechanism of the acoustic instrument. Improvements to how series of note-off events are managed is actually one of updates to the MIDI 2.0 spec. In any case, the primary use case of note-off velocity is to control the Release of synth sounds.

Gombessa , on the NV-10's sound engine the note off velocity seems to affect the volume of the release sample as well as the volume of the hammer noise. I couldn't tell any difference in the nature of the sample itself.

The CA98, which has the engine as the NV-10, processed the note-off velocity by changing the sound volume of that note. It can tested with a MIDI file designed for this purpose. Do not remember the impact on the hammer noise. But why should they also change the volume of the hammer noise? In an acoustic, the release velocity only impacts the damper and the action of that key, not the overall hammer movement, including how the hammer returns to its rest position.

arc But why should they also change the volume of the hammer noise? In an acoustic, the release velocity only impacts the damper and the action of that key, not the overall hammer movement, including how the hammer returns to its rest position.

Well, actually in an acoustic grand the key release has a (small) impact on the noise the hammer makes when returning to its rest position from either the checked position or from its escapement position. If you want to be totally realistic the digital piano should also take into account which ones of these two positions the hammer was before releasing, hence if the previous note was loud (checked) or soft (escapement). In my opinion this is too hard to implement right compared to the provided enhanced realism. So I agree that the main thing to take into account is the way the sound is dampened.

arc As @CyberGene pointed out, some implementations, notably Yamaha's, represent the key release not as a single event but as multiple events. This better simulates the key damper mechanism of the acoustic instrument

Yes, in fact in theory the damper might not damp completely, and then be raised again creating a number of effects. Not sure how common this is done by competent pianist, but I can attest that it is besides the capabilities of the average pianist, also because the average piano is seldom well regulated in this regard, as the Reblitz books points out. The first sentence of said book, when describing the regulation procedure for the dampers is "You are about to enter the most tedious and long process of regulating a piano" (quoting for memory, likely a paraphrase).

arc ave a listen at András Schiff playing the WTC at the BBC Proms 2018 for several examples.

There is a very long, edited (pitch shifted) and unofficial and monetized version on

Or the "official" page has only a 2 minute excerpt as far as I can tell.

https://www.bbc.co.uk/events/e92fbp

@arc If you could point out one particular example from either recording, that would be very appreciated