What matters most?

[Richard Brekne]

Hi David

I think I see where you are going with this, and I again agree. However it seems
apparent the main thrust of the thread is going off in two directions. The first
is along the lines of  most of what you say below... ie different component
ratio combinations yeilding same overall ratio feeling differently. I aggree
that this seems unlikely. On the other hand we are asking whether or not two
such differing combinations that yeild the same total action inertia will feel
the same. This is not the same question as I think you will agree. And I am not
really sure that its a valid one to begin with. We'd first have to calculate
total action inertia for both cases to see if its really possible to have equal
total inertia for significantly different ways of achieving the same overall
static ratio.

Mark and Bill seem to think (if I read them correctly) that X units of total
inertia will feel the same reagardless of the individual component amounts. I
see the reasoning... as it all is << sensed >> as it were at the front of the
key by a single finger. But I wonder... intuitively this idea is uncomfortable
to me... and thats assuming its possible to achieve the condition in the first
place.  You touch on some of the reasons why I feel that way...when you say "my
hypothesis would be that at a
certain level of acceleration the various levers will handle inertia in
different ways". And Bill mentioned the possible configuration that would tend
toward fly away hammers.

I suppose I could buy Mark and Bills reasoning better if the coupling between
the levers was not free as it is.... still even then.. In anycase.. More to
think about

Cheers
RicB



David Love wrote:

> I wish I could elaborate more, but I don't really have any data.  I stands
> to reason that there will be differences in response to a 10 gram hammer on
> the end of shank if the shank is being accelerated 16 mm from the center
> pin or 17 mm from the center pin.  The idea of inertia seems simple on the
> surface.  A body at rest wants to stay at rest.  Add mass, it wants to stay
> at rest more.  While we use the strike weight as measured from the center
> pin flange which works in the static system we are using, what about the
> difference in strike weight as measured from the knuckle where the force is
> actually being applied.  Wouldn't that contribute to varying degrees of
> inertia?  While the combination of different hammer shank ratios and key
> ratios may make no difference in a static analysis, I would need to see the
> dynamic analysis to believe that it makes no difference through
> acceleration.  And while Ed's point that the differences will depend on how
> much you are accelerating the system, my hypothesis would be that at a
> certain level of acceleration the various levers will handle inertia in
> different ways.  In addition, it seems that you would have to take into
> account the deflection of the different levers with different setups.  How
> does shank deflection fit into all this when you start moving the knuckle
> toward the center pin while keeping the hammer weight the same.  Can the
> pianists sense that little bit extra lag due to increased deflection
> through the first part of the stroke?  It seems to me that there are a lot
> of unanswered questions.  For myself, I've found a system that works quite
> well: combinations of hammer weight, knuckle position and overall ratio.  I
> haven't begun to read Birkett's available research and I'm looking forward
> to it when I have the chance and when it becomes available.  For right now,
> I've got my nose buried in soundboard stuff.
>
> David Love
> davidlovepianos@earthlink.net
>
> >

--
Richard Brekne
RPT, N.P.T.F.
UiB, Bergen, Norway
mailto:rbrekne@broadpark.no
http://home.broadpark.no/~rbrekne/ricmain.html
http://www.hf.uib.no/grieg/personer/cv_RB.html