New Old Bluthner Soundboard

[RicB]

Hi Stéphane

As I understand it there is a whole school of piano making that does 
just this. One method still in use in some places is to spread fine 
corned sand on the panel and use a device to input vibration to the 
soundboard in order to find the resonant modes and to identify the modal 
nodes and lines.  Thining of the soundboard at various areas is then 
used to manipulate the location of these line and frequencies of the 
lower resonant modes to what the manufacturer considered desirable.

Petrof uses a lot of modern technology today to accomplish basically the 
same kind of thing. Just exactly all the specifics of that I cant tell 
you, but Jan Skala of Petrof is a very amiable fellow who loves to 
discuss piano technology with folks...so drop him a line if you are 
interested in more.

There are several approaches to  localized impedance matching problems 
and I am sure I havent a clue as to more then a few of them.  But Ron 
O's description of mass loading is definantly one.  A kind of seat of 
the pants approach as well I might add.

Cheers
RicB


    So I can't help but thinking about the soundboard tuning (flame suit
    on).  I
    read that Ron O does this after stringing by adding mass to the
    bridge, if I
    understood well.  But couldn't a belly man fine tune the board
    before it is
    glued in the rim ?  I mean, I don't think of a F or a F# as lowest
    proper
    resonance frequency (as was recently suggested, grin), but more
    achieve a
    certain proportionnality between the proper modes of the board, in
    the same
    way that violin makers still do.  Localy adjust the panel or the ribs
    stiffness (not only letting the bass move more freely) could bring
    some of
    the otherwise inharmonic modes of the board into a partially more
    harmonic
    pattern that I suspect helping the whole thing breathe with more ease.
    Ok, the board is not a xylophone, and is first designed to achieve
    structural integrity and provide a surface for air contact, but
    eventually
    the board will resonate, and all of it's modes will respond in some
    amount
    to any note or chord input by the strings.  Wouldn't it be
    beneficial if
    those modes themselves are sympathic to each other ?  And the impedance
    holes problems, if any, wouldn't they be less obvious if all the
    modes were
    a bit higher, so the "distance" between the modes would be lineary
    reduced ?
    Couldn't the "one note kills" effect have to do with this ?
    Again, just a thought hoping to raise good comments from the list.

    Best regards.


Stéphane Collin.