Disklavier

It is a natural trait of any technician to be able to beat their subject to 
death, myself included, but I cannot emphasize enough the role of friction 
and geometry in piano actions that determines the quality of playback you 
get on a Disklavier.

It was a good point brought up that many of these MIDI files are created on 
electronic keyboards and that their velocities do not always accurately 
reproduce on the DKV.  This is because real pianos have real working 
mechanical parts that produce the sound.

Both the key and hammer sensors on a DKV are for recording purposes only; 
not playback.  Playback-only models do not even have these sensors.  The 
measurements generated from these sensors create a Piano Tables Condition 
that record the speed (velocity)of both the hammer and key movement when 
recording.  There is no way these numbers can reflect actual volume as that 
is generated by the hammer hitting the string.  That is why the PPP value 
adjustment needs to be set on each piano for each key.  The factory defaults 
only put the piano in the ballpark, not the concert hall.

The volume generated on a piano, whether it is activated by playing the keys 
or the keys being pushed up from the rear by a firing solenoid, comes solely 
from the mechanical force of the hammer hitting the string.  A lot goes into 
this!  One of the nice things about regulating a piano action with an 
electronic player installed on it is that you can generate a constant blow 
and see how this is affected by varying amounts of friction in the piano 
action.

The areas most affected by friction are the whippen cushion felts (where the 
brass capstan screw on the back of the key contacts the piano action), and 
the leather knuckles on a grand piano or the leather on the hammer butts on 
an upright.  You can feel this friction when you try to play the piano 
softly.  It's amazing what a very light application of microfine teflon 
powder on these areas will do to make the piano play with more control.

The other important factor in piano volume is the density of the felt 
hammers that hit the strings.  This is a science all by itself, and most 
piano technicians spend their entire careers learning and  practicing the 
techniques of tone regulation.  Some pianos have hammers that are so hard 
they create a very loud tone on the softest of blows.  THese pianos need a 
lot of "voicing" to be able to play softly.

In conclusion, the volume of the Disklavier is controlled not only by the 
MIDI value of the velocity in the software, but by the physical, mechanical 
parts of the piano action generating the sound as well.  It is a complex 
adjustment of the geometry and friction of the piano action, the density of 
the piano hammer, and the re-computing of the DKV Tables in Maintenance 
Mode. You can't get the best results by emphasizing only one part of the 
process!  Those pianos that get tuning only will eventually have their 
dynamic range compromised.

Carol Beigel

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