Stiffness versus mass (was Compression ridges...)

[David Love]

It's more that the requirements are that there's a minimum amount of
stiffness for the treble and a maximum amount for the bass--to put it in a
simple way.  It's the tweeter/woofer thing.  That's why the bass end is
thinned out or floated and backscale lengths are maximized: to make sure it
achieves its requisite flexibility and freedom of movement.  In the treble
(and bass too) since it's much more difficult to change stiffness after the
fact than mass many opt to overbuild stiffness in the treble and rely on
mass loading to get the balance between stiffness and mass correct.
Increasing the backscale lengths in the treble also works (if the stiffness
is there from either panel compression or the rib assembly or both) because
the bridge still benefits from freedom of movement.   

You want to avoid the bass sounding tight and constricted from being too
stiff.  In the treble you want to avoid "plink" (not stiff enough), and
"scream and jangle" too stiff without enough mass to balance.  The "scream
and jangle", however, can be brought under control by adding mass.  The
"plink" can't. 

That's the simplified version anyway. 
  

David Love
davidlovepianos at comcast.net 
www.davidlovepianos.com



    
    I don't think what we are saying is all that different (I know, it's
    happened before), except you are adding that there is a minimum
    threshold of
    mass desirable for the bass and a minimum threshold of stiffness
    desirable
    for the treble. I would just like to explore what those minimum
    thresholds
    are.

    You are saying stiffness is more important in the bass and mass is more
    important in the treble. By inference then mass is less important in the
    bass and stiffness less important in the treble. That is basically
    the same
    thing I remember Del saying.

    Dean

    Dean May             cell 812.239.3359

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