Why?

[Roger Jolly]

Hi Richard,
             I just knew some one would pick up on that statement, I'm
smiling.
If you have had the opportunity to study slow motion films of a travelling
hammer you will notice several things,  1. The shank starts to bend before
the hammer starts to move. 2. the hammer does not travel straight to the
string but tends to wobble like a drunken sailor in flight. This wobble is
far more pronounced on the angled hammers.
 I have just completed a test on a Yamaha U1 about 20 years old that was
showing the phasing problem at the bass tenor break. Hammers were well
traveled and nicely mated to the strings as well as evenly voiced. Both non
speaking lengths of the strings were braided to remove this item from the
equasion, the strings were seated to the bridges, and the bridge pins were
lightly tapped to eliminate false beats.
 Problem was still there, and I had duplicated John Woodrow's problem. I
then changed the centre pins, Making sure that about same amount of
friction was on each side of the flange yoke.  Yureka!!! the problem
disappeared.
 I think what is happening, is that with a slightly loose pin the flight of
the hammer is much more erratic, causing it to strike one string before the
other, therefore giving the phasing effect.
 I change a lot of centre pins in the killer octave region of grands prior
to voicing, and can hear the changes in harmonic structure long before the
centre pin starts to give the classic audiable click.  Down at the
bass/tenor break there is so much going on sound wise, that I have never
previously thought to check.
 Another thought for the reason on noticing it more on angled hammers is
that the weight not evenly distributed down the centre line of the shank,
adding to the wobbly flight pattern.
 Hope this sheds some light on your question.
regards Roger

 



At 11:09 AM 5/9/99 +0200, you wrote:
>
>
>Roger Jolly wrote:
>
>>
>> Similar instability can be noticed at the bass/tenor break, with the
>> addition of phasing due to the critical nature of angled hammers.
>> I'm sure others will add more reasons, but I would think this is the
>> primary cause.
>> Regards roger
>
>I'd like to hear more about this phasing in relation to angled hammers..
>
>Richard Brekne
>Sydneskleiven 1
>5010 Bergen, Norway
>
>E-mail Richard Brekne
>Richard Brekne Website
>
>
>>
>>
>> At 05:41 PM 5/8/99 -0400, you wrote:
>> >I am wondering who can provide a definitive answer to the question of why
>> most
>> >pianos seem to go out of tune the most at the treble break.  I have heard
>> >several versions of answers, and would like to hear from the best.  I am
>> new to
>> >the List, and inquiring minds just have to know!    Clark Sprague
Greenwich,
>> >Ohio
>> >
>> >
>> Roger Jolly
>> Balwin Yamaha Piano Centres.
>> Saskatoon/Regina.
>> Canada.
>
>Attachment Converted: "c:\eudora\attach\ReWhy.htm"
>
Roger Jolly
Balwin Yamaha Piano Centres.
Saskatoon/Regina.
Canada.