String leveling as related to tuning

[Bill Ballard]

On Wed, 08 Apr, Michael Jorgensen <Michael.Jorgensen@cmich.edu>wrote:
>Hello List
>   Fast test blows help level strings?

If fast test blows could level strings, what would prevent them from
continuing to push all three string in a trichord upwards. Not to suggest
that as a result we would be constantly be raising the hammer line, let-off
and drop to keep up with this steady upwards creep in the string height.
But possibly to suggest that a slightly blocking let-off could be cleared
up with a couple of strong test blows. That seems to fly in the face of the
wire's elasticity.
Test Blows are another subject, and on that, my opinion is that as long the
tuning pin friction and the string frixction have the proper relationship,
it's all in the hand on the hammer, very little of it in the test blows.
Although my theory gets blown out of the water every once in a while, too.

On Wed, 8 Apr , "Richard Moody" <remoody@easnet.net>
>Well it is kind of hard to evalute tone when the strings are at rest. : )
>On the other hand it is impossible to detect unlevelness when the strings
>aren't at rest. Although there is one method that claims it does.....

The only point at which I care about the level ness of the strings is the
point whenthe hammer first hits them. That's when levelitude has its effect
on tone. Sure you'll be alerted to an open string when the hammer hits the
trichord and flies immediately away. If you're lifting the hammer up to the
strings with the jack tender, you have unlimited time (far more than the
milisecond of collision/rebound) to study what's happening between hammer
and strings.

Someone with an engineering back ground can help me out of my confusion
about phase shift. I thought that if you had two adjacent tone generaors
tuned to the same pitch (in our case, two pieces of wire on the same note)
their motion would be out of phase with each other if they were excited at
different points of time AND if the interval of that delay werwas not an
even multiple of their common period. Would that make the degree of phase
shift (read: interval of delay in excitations) a function of the difference
in string heigtht (one way to expreess out-of-levelness) and the average
velocity of the hammer as it travels through that difference in height?

Or would this phase shift be further modulated by  the fact the different
strike forces would yield different amounts of prompt time, and further,
different indiviudal behavior during the transition between prompt and
aftersound? The person who can really answer this is Barney Ricca. In 11/96
he mentioned that he was going to build a complex of magnetic plates to
measure both vertical and horizontal modes of vibration on three string
simlutaneously. (Six, read'em, six continuous measurements) Hopefully by
now, he's got that up and running.

Bill Ballard, RPT
New Hampshire Chapter, PTG

"May you work on interesting pianos."
Ancient Chinese Proverb