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Hi all,
Ron N wrote;
>No, because you aren't relying solely on panel compression for that
>stiffness increase. You can make the ribs as stiff or as flexible as
>you like to build in whatever spring rate you think you want with
>the RC&S assembly. In the RC&S assembly, you can also easily produce
>considerably different spring rates in different parts of the scale.
Indeed, the spring rate must vary throughout the scale. It must have
a lower rate in the bass to allow wider panel excursions, and stiffer
in the treble to accommodate the much small amplitude of panel
movement required for a given sound pressure level.
This is the second time that Ron N has mentioned spring rates and it
is a most important point IMO. The spring rate, mass
combination/distribution and the hysteresis characteristics of the
sound board assembly (which Sarah Fox mentioned in her thoughtful
post) will come together to produce the resultant tonal
characteristics, to a large extent.
Rick B wrote;
>Oh it holds up,,, as far as the reasoning goes. But stiffness, as
>you know, and for that matter spring rate is not all one is
>concerned with.
Agreed, it isn't.
> You have the mass side of the equation to figure in.... at the very least.
Yes we do, plus hysteresis.
> You can easily achieve similar stiffness levels I would assume...
>with two different assemblies ( a CC and an RC&S) at least for a
>given RH,
This should be do-able.
> but achieving that and at the same time the same stiffness to mass
>relationships is another matter.
It is not a 'another matter'. If you have determined a certain spring
rate but would like more mass you can use more, lower and wider ribs,
and your mass will be increased at a given stiffness. If you want
less mass for the same stiffness (spring rate) you can use less,
deeper and narrower ribs. Its a simple matter to arrive at the spring
rate and mass relationship required, using RC construction.
Furthermore, I believe that the stiffness of ribs should ideally be
varied along their length. The rib should be stiffer under the
bridges (where most CC boards collapse in short order), getting
gradually weaker as we move from the bridges to the ends of the rib.
The tapering of rib strength is a cake walk when building an RC& S
board. While the CC building school can contour the panel thickness
to increase the stiffness under the bridges, it is more of a 'blunt
instrument'.
>So varying panel thickness to achieve similar stiffness would
>probably insure dissimilar mass.
Varying the panel thickness, to achieve a certain level of stiffness,
has been the most usual method of controlling stiffness for the CC
building school. The hysteresis loss matter, which Sarah raised, is
an interesting one as well.
At 2:28 PM +0100 14/2/05, Richard Brekne wrote:
>
>When someone makes a RC&S board and puts it into a Steinway D rim,
>and puts the darned thing on the stage of Carnegie Hall and fools
>everyone with its <<authentic Steinway sound>>
Outside of the extensive 'cloning' school, who would want to build an
authentic Steinway sound - I certainly don't? And I don't expect to
see an RC&S boarded instrument on the Carnegie Hall concert platform
anytime soon. I certainly have no interest in fooling anybody.
Besides, if you built a different design into a Steinway piano and
failed to acknowledge it on the piano, you'd have the S&S legal team
trying to put you out of business ASAP. I and a number of others have
experience this potential drama first hand. Fortunately, I always fix
a label to the piano stating any modifications, so their team had
nothing to stand on in 1996. I've already built an RC&S board into a
D and, as expected, it certainly didn't sound like a Steinway.
I think folks should stop worrying about the risk of RC & S
construction causing the sky to fall in. Let's give the idea a
serious evaluation. At present the mainstream manufacturers have
joined in, in condemning the RC & S idea. There was a time when
shaped ribs were being similarly condemned. Today, many manufacturers
are profiling their ribs. Some are even doing it to the actual ribs,
and not just in the brochure.
Today is the second recording day (of 5) of Scott Davie's second CD
to be recorded on an Overs 225 piano. In this case the piano is the
RC&S boarded Overs no. 5 (the samples on the website are of no. 3).
For this CD, Scott is recording Massorgsky's Pictures at an
Exhibition and Rachmaninoff's first piano sonata (a monster work). It
should be available for sale sometime around mid year 05. Yesterday,
the recording team spent the first 2.5 hours getting the recorded
sound to a close match of the piano. Five of us finally agreed on the
balance, Scott Davie (recording artist), Lyle Chan (ABC Classics
executive producer), Thomas Grubb (producer), Christian Huff-Johnston
(engineer) and myself as piano technician. Scott recorded Pictures
from memory yesterday. I was most impressed when Tom would make
suggestions to Scott," from bar *** to ***", and he would just pick
up from that point for another 'take' without referring to the score.
Its wonderful to observe real talent in mid-career.
Ron O.
--
OVERS PIANOS - SYDNEY
Grand Piano Manufacturers
_______________________
Web http://overspianos.com.au
mailto:ron@overspianos.com.au
_______________________
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