Lack of low frequency response

[Richard Brekne]

Hi Greg

In the piano I am actually working on... we have a low tension scale, SB 
that starts at 9 mm at the belly rail and tapers very gradually and 
evenly to 5 mm at the tail.  Rib crowned board with ribs going roughly 
parallel to the long bridge... grain going roughly perpendicular... the 
ribs dimensions I'm going to have to dig out again.... but they are in 
general wide and shallow by modern standards.  Very long back scale as 
its an old straight strung instrument... Roughly 0.5 to 0.7 degrees 
residual downbearing in the bass and low tenor... about 1 to 1.2 degrees 
in the top.

I'm thinking there is too much downbearing... and will reduce.  This is 
a new board.  The thing is.... I've heard this sound before... and I've 
received very dependable advice that the reason has to do with too 
LITTLE stiffness in the middle part of the soundboard... front and left 
of the low tenor area.  The reasoning being that too little stiffness 
there will cause the soundboard to vibrate in many small individual 
areas... and poorly as a single whole. 

It might make sense if one stops to think that very old pianos may have 
had quite a bit more compression stiffness built into their panels with 
these shallow and wide rib structures.  Using the same rib structure on 
a new panel but using rib crowning to account for whatever cross grain 
stiffness instead would perhaps simulate an old panel that had lost its 
compression strength... and hence stiffness.

So... in general I'm looking for reasons in general for the way it is.  
But at the same time I want to build a bit more body into the tone. This 
despite the fact that all the folks who've played this so far have just 
loved the sound.  To my ears tho... its nasal and thin... just a bit 
more then I'd like to live with.

So I'm fishing for thoughts on the matter. 

Cheers, and thanks for your thoughts.  Please continue ! :)

RicB


    Ric,
        To be sure there are many factors that probably play in to this but
    how long is the backscale length? Is it short and trapping the bass
    bridge?
    I'd sure think that a thick board in the bass region would also
    produce a
    too stiff assembly. How much downbearing is there? Too much in the bass
    could choke the sound I should think. Can you tell if the board is
    tapered
    or not? If so, where? As a possible solution short of a new board
    could you
    rout a channel in it to make it more flexible? Are you rebuilding
    this or
    just looking for reasons that it is the way it is?

    Greg Newell
    Greg's Piano Forté
    www.gregspianoforte.com
    216-226-3791 (office)
    216-470-8634 (mobile)