[pianotech] soundboard grain angle vs "faux"stiffness

[David Love]

Maybe not by itself.  But I think it might contribute.  I still think that
the hammer tolerance has to do with the tendency for these boards to enhance
the development of higher partials in the lower end of the piano and I think
that grain angle is one factor.  But so is a narrowing of the working
portion of the panel in the mid to low tenor.  But upper partial development
is only one part of the hammer tolerance issue.  The other factor might, as
I think you suggested in an earlier post, have something to do with
excursion rates and the tendency for some of these assemblies to "knock"
with harder hammers.  These boards tend to move more freely and that can
make the attack somewhat more percussive through the scale.  When you
combine that with an enhanced production of upper partials you get clang and
hard hammer intolerance, or matched right you get a board in which a soft
hammer produces ample attack and upper partial development.  That being said
there is a difference between hard and soft hammers producing what otherwise
would appear to be similar levels of attack on their appropriately matched
assemblies.  I think that some reactions against the difference in the power
curve have to do with how a soft hammer reacts when it's pushed versus a
hard hammer.  This is a bit difficult to articulate but perhaps you get my
drift.  Anyway, aside from introducing some compression, the solution
without pushing the rib scale up farther--which has other consequences,
seems to be to reduce the size of the cutoff across the lower end of the
tenor bridge and reduce the grain angle modestly.   

On a slightly separate track, I also wonder what it would sound like on one
of these light, hammer sensitive assemblies if the scale tensions were
further reduced say down in the 135 - 140lb range.  We tend to look at the
150lb scale as being low tension.  Maybe it's not quite low enough for some
of these designs.  Still looking for that research grant.     

David Love
www.davidlovepianos.com

I'm just not that sure 
grain angle has all that much to do with hammer hardness 
tolerance without some experience. I do know that folks making 
rib crowned boards with a higher level of panel compression 
are using Abels, Renner Blues, and other such rocks successfully.

Ron N