Disklavier

On Sat, 8 Mar 2003, Carol Beigel wrote:
> MIDI numbers of 1 to 128 are only valid for electronic generated data.
> Remember, a piano is a "mechanical" instrument with friction.  No matter how
> many sensors are in the keys and hammers, the actual velocity of the hammer
> hitting a piano string is not as accurately measureable as an
> electronic-only measurement of the key velocity. Also, there is probably a
> translation somewhere in the software to accommodate for the fact that it is
> a piano and not an electronic keyboard. I think that is why the default
> value of the Pianosoft music you buy for Disklaviers is automatically set to
> 100.  I would hope that a fine piano action would NOT generate any value
> over 100!  If you really need numbers from 0 to 128, try an electronic
> keyboard.

I'm not sure that's quite the case - the way the hammer speed is measured
is basically exactly the same as how a digital keyboard measures the speed
of the key.

On the disklaviers there are beams that are broken and unbroken by the
hammers. Since the distance between the beams (on 4 position models) and
thickness of the hammer / shank is known, it's possible to calculate the
velocity from the length of time it took the hammer to travel between the
beams. I believe the extra sensor on each key is used to detect the
release of a note more than anything else, but it is feasable it is also
used in the velocity calculation. On the models with continuous position
sensing, things are obviously slightly different.

On a digital keyboard there are two contacts under each key very
close together and the time it takes for the two circuits to be made is
measured and velocity calculated in the same way as the hammers on a
disklavier.

I'd have thought the most important thing was to capture the performance
as accurately as possible. If the instrument currently can't play back
that accurately, so what - the chances are future instruments will be able
to.

If Yamaha are limiting the range of velocities output by the disklavier,
they are reducing the expressiveness of the instrument - the full scale
should be used, and then rescaling of the velocities used if necessary at
playback time. Midi is regularly criticised for its lack of controller
expressiveness; if the disklavier only handles velocities between 20 and
100 (about 60% of what MIDI is capable of) then no wonder a lot of people
don't like their performances being recorded on it.

I think playback on the disklavier is a different matter - the only way to
get more expression here is to use solenoids with faster response and more
power, which I beleive the Mark III Pro series of grands have.

Regards,

James