High Treble Unisons - attack or sustain?

[Alex Galembo]

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There might be discussed several related phenomena to .
1. Sympathetic vibrations from undamped strings
2. Duplex scale if any
3. Non-accurate unison tuning
4. One not previously discussed theoretical hypothesis (not proven so 
far!!!!): Clavichord mode

In the treble range the strings are so short, that in physical sense 
they are the most distant from the ideal string model. In the highest 
(7^th ) octave strings are usually shorter than 100 mm, and for to 
transfer more energy to the string modes, the hammer contact has to be 
adjusted very close to the string support. In the extreme treble strings 
the striking ratio (the ratio of the striking distance to the speaking 
length of a string) decreases sharply down to 1/24 (0.042), or 
(according to Diakonov, 1964) 1/35 (0.029) or even less. In reality, in 
the extreme treble strings the striking distance is so small that in 
practice it is difficult to adjust and measure it precisely enough. 
More, it dynamically changes, because a real felted hammer contacts the 
string not at a point, but at a string fragment, and the length of this 
fragment is comparable with the striking distance

The highest octaves categorically differ from others by allowing having 
the contact duration between the hammer and strings exceed the period
of the string vibration. This situation may change the function of a 
hammer drastically.

First, the hammer remaining in contact with the string for extra long 
time, together with being an exciter of the string vibration becomes 
inevitably a damper of the same vibration, thus “killing the own child”. 
Instead being spent for supporting the string modes, the hammer energy 
contributes now primarily to the noisy knock element of the tone, making 
it louder and harsher at the price of weakening and shortening the 
pitch-conveying partials.

Second, the hammer for a significant contact time functions as an 
additional string support, a “striking support”, thus exciting the modes 
of the string fragment between the hammer contact point and the bridge. 
In other words, *the hammer in the attack phase might behave as a 
tangent of a clavichord*, exciting the pitch some sharper than the tail 
(sustain portion) of the tone

It is JUST A HYPOTHESIS so far, and I would appreciate any comments and 
opinions of the listers based on the tuning practice with facts 
suggesting pro and contra this hypothesis.

Thank you.

Alex Galembo



John Dorr wrote:

> Esteemed List,
>
> It seems I've noticed when setting unisons in the high treble area 
> that sometimes each string can seem to have its own direction it 
> wanders off into, independent of the frequency on its initial strike. 
> One string may go flat during its sustain period even when the "lights 
> stand still" (I use an SAT) on attack. Another of the unisons may 
> strike well but go MORE flat, or sharp first, then flat... yadayada. 
> So I find myself trying to make a decision as to whether to tune the 
> strike or the sustain. Has anybody else noticed this phenomena? (I 
> think you'd hafta be deaf not to)
>
> My conclusion: Whereas: those higher treble notes don't have very much 
> sustain, and the sustain is probably less listened to than the attack.
>
> AND, those notes oft-times are played very quickly, and with plenty of 
> other notes, high and low, going on in the music at the same time.
>
> Therefore, I resolve to tune the attack rather than the sustain, 
> compromising if need be by making the sustain as inoffensive as 
> possible while giving preference to the attack intonation.
>
> I realize I've made no reference to "wild" strings here. Maybe those 
> are another topic. I recognize them, too.
>
> Am I on the right track? What are your thoughts?
>
> Thanks in advance,
> John Dorr
>
>
>
> _______________________________________________
> pianotech list info: https://www.moypiano.com/resources/#archives




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