According to theory the human ear can recognise time distances of 1/130 sec.
The key at forte has a speed of about 1m/s. (I measured about 1,5m/s for velocity 127 with my Kawai keyboard)
If a key at pianissimo level has a velocity of 100mm/s and if the total key travel is 10mm then this is 100ms key travel time. Now, if the sound is not triggered at 10mm, but at 8mm depth, then this is 20ms before the key bottoms out and 20ms are easily perceptible. (This is equivalent to a sound distance of 6m)
From playing software pianos I know, that 20ms of latency feels really bad and sluggish. Even 10ms is perceptile and somewhere below 10ms there is a point where it is ok.
Now, what happens, when the key is hit even slower? I was unable to measure the key speed for pianissimo level.
Also I measured about 3mm or 4mm distance between both switch points with my Kawai keyboard. The sound was triggered a little bit before the key bottoms out.
Now, the Kawai hammers can be readjusted and I readjusted them in this way that the sound is triggered exactly when the key bottoms out. It was also necessary to add an additional felt to the hammer bar.
And I think that is pretty good realistic now. But I would prefer to have 1,5mm for the switch distance instead. Unfortunately this is impossible to change.
I started this work some months ago, still experimenting, but I believe I have now the optimum that is reachable with this keyboard.
This adjustment cannot be done in the factory, because it is sensible to tolerances and needs several hours of work.
But I am quite happy with this.
Peter
Last edited by hpeterh; 03/18/10 08:43 AM.