[pianotech] Cresendo Punchings was RE: Hammer Blow

[Don Mannino]

I attempted a semi-blind test with the punchings in a Shigeru Kawai EX.
Now, this piano already has fairly firm front punchings, so the density
difference wasn't too great.

Another technician installed 4 of the Crescendo punchings in random notes
around the center of the action.  I didn't know which notes.  Paper
punchings were also changed to make sure the dip was correct.

First he played up and down the scale at different volume levels.  He knew
which keys of course, but I didn't know, and I could not hear any change in
tone from before they were changed.  He felt that maybe there was a slight
difference in sound, but he attributed it to a change in the impact noise of
the key.  Then I played the notes myself and still could not hear them, but
by slowly pressing down each key and feeling the nature of the punching
compression I was able to find them - they were slightly firmer than the
originals, and compressed differently, kind of a logarithmic increase in
resistance as you squeezed down.

So my friend replaced the Crescendo punchings with the originals, and I then
did the same process for him, in a different octave.  4 punchings changed,
paper punchings also to match dip.

Same results - I knew which notes I had changed, so I could slightly hear a
difference.  He was unable to figure out which notes were changed, either by
sound or by feel, until I took off the keyslip for him to see.

So this is one piano only, and it was a piano with fairly similar density of
punchings.  I can understand how different key wood, different keyframe and
keybed construction, and even the relative flushness of the front key
bushings would all have an effect on a perceived tonal difference.  But at
least for this piano, we decided that we could not justify changing them.

Subtle tonal differences can become more noticeable when an entire piano has
the same effect, also.   But truly blind testing something like this is
difficult, because there are always other factors which affect the sound. 2
actions in one piano?  They will always sound different.  Of course 2
different pianos have even more variables.  But those who have installed
many sets of these punchings can gradually build up a sense of the sound
difference from having heard it in different pianos over time.

I am in the camp that the impact sound and how it carries into the body of
the piano most definitely can be perceived as a change in the piano tone.
If you and your customers like it, that's reason enough to use them!

Don Mannino






-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Jon Page
Sent: Thursday, October 11, 2012 4:37 PM
To: pianotech at ptg.org
Subject: Re: [pianotech] Cresendo Punchings was RE: Hammer Blow

It must be mass hysteria then when other people standing near the piano hear
it.

 >Yes. A psycho-acoustic illusion. The world of piano is chock full of 'em.
DA

--
Regards,

Jon Page