Steinway "pinning" dilemma

[Ed Sutton]

Ed Foote writes-

> Hmm,  there is more to be explored here than I have time to, but there are
> some divergent ideas in my mind about how pinnng affects tone.  I don't totally
> accept that it is wobble in the hammer during its approach to the string, nor
> loss of contact between knuckle and jack.
>    I think it is wobble during contact, caused by the restorative forces of
> the displaced string imparting some energy back to the hammer/shank structure.
> I think the pinning is responsible for supplying a degree of impedance to the
> hammer and shank.  Without this "anchoring mechanism", the shank absorbs the
> transient shock of contact and by its unfettered vibration, causes a short
> interference between the hammer and string.  Perhaps the shank goes into a
> momentary random oscillation during contact which causes the tone to suffer, I
> dunno.  I do know that pinning up from 1 gram to 5 makes a clear difference in
> tone.
>
>    I say this because the sound of a loose pin is readily apparent on a very
> soft blow, where I wouldn't expect a lot of hammer wobble or shank flex to be
> in play.  I asked a tympanist about controlling the sound by how firmly he
> gripped the mallets and he said "Of course, there is a wide range of tone
> available depending on how firmly you hold the sticks".  (that may or may not be
> germane).

IF I understand Donald Hall's lectures on "The Hammer and the string" in _Five
Lectures on the Acoustics of the Piano_ correctly, the hammer doesn't rebound from
the string in a simple, smooth push.  Rather, the wave from the front of the
hammer reflects from the agraffe or capo, strikes the hammer again, partially
pushing the hammer, and partially reflecting back to the agraffe, and repeating
this process several times.  It is a "pulsing" push rather than a "smooth" push.
The harder the hammer, the more high harmonics are produced.  Softer hammers
almost work as dampers to reduce higher partials.  (See his figures 11 & 12)

Note that his curves are for linear hammers.  To imagine a rebound of a
well-voiced hammer, we would probably have to graft the end of a "soft" curve onto
the start of a "hard" curve with a "medium" middle.
www.speech.kth.se/music/5_lectures/hall/theory.html

Simplifying, this seems to say it is not the hammer strike so much as it is the
complex rebound that shapes the tone.

If looser pinning allows the hammer to rebound too quickly, the rebound pattern
would be changed, most likely eliminating some of the damping effect. (Assuming my
hypothesis that the non-linear hammer actually changes hardness during the
rebound.)

Ed Sutton