Killer Octave & Pitch Raise

[Arnold Duin]

Richard mijn jongen

Thanks for the compliment and blowing my cover 
(you already know that I don't like you  that much 
:))

I can see that it is somewhat confusing but I am 
only referring to the fact that the name K  isn't 
mentioned as such in Fenner 's book.
Steingraeber and Fenner  employ different crowning 
methods at least in the way of  the total amount 
of crown and where to put the highest point of the 
soundboard. The both use the cc method for their 
boards. When you talk to Udo Steingraeber he will 
emphasize that his company is not constructing the 
board the Fenner-way but uses a different 
approach. How that approach is in detail I don't 
know but I know they achieved good results. Now 
about the Fenner approach, at least as I perceive 
the method he describes is his book.
Fenner is (was) an advocate for using stress in 
the board as an effective possibility to change 
the different frequencies in the various areas of 
the board to get a better match with the string 
frequencies. The goal is to achieve an uneven 
stress in the board more towards the treble and 
less towards the bas. He is also talking about the 
bending stress along  the grain which is a 
effective way to raise the frequency analogous to 
a singing saw. Fenner constructs his boards 
following this principle and doesn't want a 
uniform crown but an uneven crown with more stress 
with a highest point shifted to the treble. In his 
book he explains how to do achieve this and 
calculate the radii for the ribs etc. which are 
used for the board and the mould.
To help achieving a shift in frequency bending the 
board along the grain will not help that much so 
he is compressing the board in  that direction. 
One possibility is (before gluing)to lift he board 
at the highest point with a  block temporary fixed 
to the braces about max. 2 times the expected 
crown and then fix the board to the rim. After 
gluing the block is removed and the board will 
have some extra compression. Or you can combine it 
with pressing  the board into the cavity of the 
outer rim which is more easily done before fixing 
the bridge to the board. Extra compression along 
the grain can also be achieved by gluing the long 
bridge (straight not curved) after the board is 
glued in. Yet another approach is to glue a 
heavily dried (cooked) bridge on the board first, 
before gluing the ribs to achieve a crown and add 
some extra stress.
So much for now

This  time a friendly salute

Arnold



----- Original Message ----- 
From: "Richard Brekne" 
<Richard.Brekne@grieg.uib.no>
To: "Newtonburg" <pianotech@ptg.org>
Sent: Sunday, February 13, 2005 12:26 AM
Subject: Killer Octave & Pitch Raise


> Arnold my friend !!
> For those of you who dont know, Arnold is the 
> fellow who works together with André.  Arnold 
> works alot with soundboard rebuilding projects 
> and is IMHO an all around great guy.
>
> Thanks for chirping in, but I am afraid you lost 
> me a bit... first you say there is no K point, 
> then you say there is. Then you say Klaus and 
> Udo use different crowning methods, and then you 
> say they use the compression method.  Begins to 
> sound like the strawman in the Wizard of Oz just 
> after the goons raided them in the haunted 
> forest and flew off with Dorothy ! :)
>
> Seriously tho... would you mind going into a 
> little more detail. I'd loveto have this whole K 
> point thing clarified for me. I've been a bit 
> curious ever since I first heard about it, and 
> havent seen the subject pop up here before at 
> all.  Also... I remember distinctly Udo talking 
> about crown and compression along the grain 
> being << essential >>... so if you know more 
> about what he meant there I'd love to hear that 
> as well.
>
> And for what its worth, your use of the word 
> Tension should (I believe) be interepreted as 
> general Stress by readers.  Correct me if I am 
> wrong Arnold.. but you didnt mean actually 
> stretching something... just applying different 
> stresses.. yes ?
>
> Thanks for the post !
>
> RicB
>
>
>
>
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