More CC vs RC questions was RE: Killer Octave & Pitch Raise

[David Love]

Just to clarify:  A lower spring rate means the board moves more easily
or less?

David Love
davidlovepianos@comcast.net 

-----Original Message-----
From: pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org] On
Behalf Of Ron Nossaman
Sent: Friday, February 18, 2005 7:21 AM
To: Pianotech
Subject: Re: More CC vs RC questions was RE: Killer Octave & Pitch Raise


>Well I meant that more as a question than a statement.  One thing that 
>does interest me is how CC vs RC&S methods influence, either in design
or 
>execution, the relationship between mass and spring rate and how that 
>might relate to proper hammer matching.  Which system,  for example,
tends 
>to have a thicker panel?

The CC board.


>It seems that the CC panel is generally thicker in the center and
tapered 
>toward the rim whereas the RC&S panel is slightly thinner and more
uniform 
>in thickness (except maybe around the bass perimeter).  Is that
correct?

Usually, but CC boards aren't necessarily tapered or diaphragmmed, and
RC&S 
boards could be if you wanted.


>Might not the difference in mass distribution of the CC panel explain 
>differences in hammer matching and potentially some tonal differences?

I don't think so.


>It seems that the CC panel requires a much denser and possibly less 
>flexible hammer than the RC&S board (at least in my experience).
Whether 
>the tone production potential between the two with appropriate hammers
is 
>net/net, is something I can't really answer but do wonder about.  The 
>subject might point to some differences.
>
>
>David Love


I think it is mostly spring rate differences. The RC&S board will have a

less progressive spring rate than the CC board (because of the lower
panel 
compression), and probably a lower spring rate as well (though not 
necessarily). Because of this, I think the amplitude of vibration will
be 
greater in the RC&S board, which might explain the different hammer 
requirements. An RC&S board with a laminated panel should have a more 
progressive spring rate (steeper gradient) than one with a planked
spruce 
panel because of the relative incompressibility of the laminated panel.

Ron N

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