Killer Octave Question

[Delwin D. Fandrich]

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Re: Killer Octave Question
  ----- Original Message -----=20
  From: Isaac OLEG=20
  To: Pianotech=20
  Sent: Sunday, April 20, 2003 11:58 PM
  Subject: RE: Killer Octave Question


  =20
  Building and installing crown compressed soundboards have been told me =
as being far way more difficult than rib crowned ones, and I see no =
advertising about the method nowhere (and indeed most pianist should not =
understand the difference). Seems unfair to me to talk as you do.

I have bellied soundboards using both systems and must disagree that =
compression-crowning is any more difficult than rib-crowning. Both =
require equal control over moisture content. Both require equal =
attention to detail. If anything, properly rib-crowning a soundboard =
assembly has a couple of additional steps. One must figure out just how =
much crown radius to put where and then carefully machine (or otherwise =
obtain) precisely that radius. Rib crowning is inherently more =
consistent and controllable.


  I have the impression too that everyone there is focusing on crown and =
durability, while not many are comparing  the response characteristics =
of the methods.=20
It was the degradation of tone quality over what I considered to be a =
very short period that caused me to investigate other crowning methods. =
For a number of years during the 1970s and early 1980s I serviced new =
pianos using the compression-crowning technique exclusively. While some =
of these instruments did indeed sound quite marvelous, too many others =
did not. I did not keep track of percentages, but I'd say from memory =
that probably two-thirds to three-fourths of them were marginal as they =
came from the factory. Generally through the upper half to one-third of =
the scale. Sustain would be short and the tone would be percussive. Even =
back then this company was using a considerable amount of shaping and =
hardening in their hammers to mask this tonal drop-off. It wasn't =
working then and it doesn't work now.=20

When I started putting in soundboards of my own I originally patterned =
my procedure after that used by the factories I had visited. Primarily =
the one mentioned above. I built a wood conditioning room to maintain my =
spruce at 4.0% moisture content. I bought my spruce from the same source =
and to the same or better grade. I edge-glued the stock in the same way. =
I planed it to the same thickness. I cut the ribs to the same dimensions =
and glued them up the same way. And I got the same results. Some sounded =
great, some deteriorated much more rapidly than I thought they should. =
Ultimately, in spite of the impressive marketing I came to realize there =
were some inherent problems. Problems which were inherent to the =
process, not to the control over the process or the quality of =
workmanship involved. The more I learned about the nature of wood the =
more I realized that this process simply asked more from the wood that =
God ever intended--it's compression strength is simply not adequate to =
support the loads the process imposes on it.=20

That realization led me to investigate alternative methods and I =
gradually switched over to a nearly 100% rib-crowned system. But it was =
the tone performance of the two systems that led me to make the switch. =
Not just the idea of crown.

So, yes, we have and continue to compare the tone quality of the two =
systems. From experience I would say that given two systems working =
equally well the tone quality of the two systems is approximately equal. =
I've not really been able to isolate much in the way of real =
differences. But--and here is the big but!--the rib-crowned system is =
inherently more predictable, more consistent and more reliable. =
Especially over the long term. And when I walk into the showroom of a =
store selling instruments with purely compression-crowned soundboards =
and I find eight out of ten with the upper third of their scales =
sounding seriously short and percussive to the point of being =
unacceptable yet carrying price tags in the $50,000 plus range I have to =
think there is a problem there somewhere. And, no, I don't buy the =
notion that it is simply poor workmanship. I've been in that factory and =
have seen their workers on the job. They are as good at what they do as =
any others. It is the design and the system that is at fault--not the =
men and women working to the design.


  While building soundboard that are supposed to travel and be installed =
in a repaired instrument far from the soundboard building place it is =
understandable that crown compression (and not only  if I understand =
well) is used, but how can you attain an internal assembly tension as =
high and then a delay in springiness response with the ribs as the most =
active elements?
I don't understand this comment/question. A compression-crowned =
soundboard assembly will begin to degrade immediately upon being exposed =
to normal room temperature and humidity. Installing the assembly in a =
piano rim and loading it simply speeds up the degradation. It doesn't =
really matter where the board is ribbed or where it is installed. A =
rib-crowned soundboard assembly is not really stressed until it is =
installed in the rim and then loaded with string bearing.


  Are not we using this process to build the internal spring rate of the =
soundboard ?=20
Well, stiffness, anyway.


   Being not experienced in these process I certainly will not argue on =
those matters with you, but I seem to recall that even Del was building =
so called "compression crowned soundboard in its early stages"  BTW =
thanks, Del for your clearing on the "neutral fiber laying" it was =
exactly that concept I was talking of .
Yes. But it was because of my experience with the compression-crowning =
technique, both my own and studying the product of the factories using =
it, that I began looking for alternatives.

  Everybody agrees we could build pianos without any crown if necessary, =
so the presence of crown is not the only proof of the taste of the =
pudding I'd say!
Well, we could. But we might have to alter our perception of the kind of =
tone quality we are after.


   Well the next soundboard I will build I will use S shaped ribs and a =
compressssed sssshaping method . Or we'll do again a soundboard with =
strings on the 2 sides to produce eventually a double vertical (for twin =
brothers or sisters that should be nice).
Just build a nice compression-crowned soundboard assembly and it will =
develop automatically.

Del

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