Drifting Unisons

[Roger Jolly]

Fred and Ron,
                      A possible explanation, the bridge notching, has no
mass forward of the right string.
Therefore the string is less supported. Any given string will react in a
certain manner depending on how much tension is lying beside it. Some
experiments that I have conducted, (not too Scientific) tends to lead me to
believe sustain time is also very slightly increased on this string.
We all experience wandering pitch on the last tenor/bass string, as well as
the instability at the bridge notch on verticals. This tends to support
this hypothesis

On grands where the plate struts create quite a gap in the spacing between
notches, it's the left hand string that tends to wander on the upper note.
In the verticals where material has been removed for the plate web, the
upper note LH string is really unstable. Some manufacturers have added mass
in the form of a maple block to try to over come the problem, others will
try to align the rib with the notch to try and gain stability.

Harold Conklin's tone extender on the Baldwin model 6000 is there to fool
the last string into thinking it has mass and tension off to the left. If
you remove the weight the tone changes and the tuning becomes less stable.

I may be out to lunch but it's a reasonable half educated guess.

Roger


At 04:55 PM 07/11/99 -0600, you wrote:
>At 03:15 PM 11/07/1999 +0000, you wrote:
>>Ron,
>>	I agree we would have to account for the total "waste length" of every 
>>string (whether toward tuning pin or hitch pin), and their relative 
>>tensions, and the amount of friction involved, and bridge rise and roll, 
>>to come to a complete analysis. I have certainly considered all these 
>>factors in my musings while pitch raising/lowering for the ?thousandth 
>>time. 
>>	The puzzle for me is that uprights and grands both show the same 
>>tendency for the right string to move most, whether to a large or small 
>>degree. Hitch pin waste lengths vary, but typically not by much on any 
>>given piano. Tuning pin waste lengths vary pretty consistently, so that 
>>on all grands the right tuning pin's waste length is longest for the 
>>unison, while on an upright the right is shortest. So why isn't the 
>>pattern reversed for uprights? 
>>
>>Fred
>
>Fred,
>You got me there. I strip mute when tuning, and hadn't noticed the
>phenomenon. There has to be a real and rational cause and effect
>relationship of some sort though. Nothing happens arbitrarily (excluding
>the workings of people <G>). 
>
>
>Ron N
> 
Roger Jolly
Saskatoon, Canada.
306-665-0213
Fax 652-0505