Adjusting wippen assist springs

[Richard Brekne]

Sarah Fox wrote:

> This is true, but only if one looks at the input side, without regard to
> output.  With greater spring assist and less leading, that same 200 g of
> force will produce greater hammer velocity and therefore more sound.
>

One of the thing Jim Ellis keeps banging away at is that it is the hammers
interia that domninates this whole picture. The keys intertia is only a small
part relative to that. And his reasoning for discounting much of the touting of
reduced key inertia enthusiasts makes sense. The mass of the hammer remains the
same, so does the mass of the whippen. The actual amount of force needed to move
the added inertia at the key (assuming reasonable levels of key leading) is not
nearly so significant a factor as its made out to be then. And tho you do gain
some small amount in terms of overall action inertia, you still dont get around
the change in touchweight gradient.

Still the point you raise has never been quantified to my knowledge... and it
would be nice to get a "net result" figure to see just exactly what is gained,
what is lost, and what the side effects are.

Cheers
RicB


>
> How?  If a greater proportion of your counterbalancing is done by spring
> force, rather than key leading, there is considerably less inertia to fight
> in the key during hard playing.  Remember, the kinetic energy of the hammer
> is transferred to the strings (to a greater or lesser extent, depending on
> the resiliency of the hammers), while the kinetic energy of the keystick is
> transferred into the front rail, where it makes no sound but a "thud."  The
> higher the ratio of hammer inertia to keystick inertia, the lesser the input
> energy that must be delivered into the key to transfer a given amount of
> energy to the string.
>
> Peace,
> Sarah
>
> _______________________________________________
> pianotech list info: https://www.moypiano.com/resources/#archives

--
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