Trichord -l inked file with illustrations

[Roger Jolly]

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Greetings Oleg,
                       Would it be possible to obtain this paper in English, I
have some problems with my High school French and over 35years of
forgetfullness.


>
> What they try to check anywway was the fact (theory) that a tuner doe's 
> not tune the three (yes they test 3 strings) unissons (fondamental) with 
> the same pitch, and why. Twoo strings are coupling in phase opposition 
> after a few seconds, so their fondamental are in tune so what do we do 
> of the third string ? 


This test would only be valid if the harmonic spectrum was checked at precise
dynamic levels on all three strings, a year ago I would have agreed with this
hypothisis, but now I'm not so sure. If you use your RCT to first ensure the
harmonic spectrum is even with a reproducable test blow, and then tune each
string to obtain full bloom on each string then the error is less than 0.1c. I
doubt very much that you would hear any out of tuneness.

>
> I too strongly suspect spectral differences because of the hammers, 
> strings, V-bar and so on. 
> I totally agree with the partias change corellated with the hammer 
> elasticity. A few weeks I tuned a piano (D S&S) for students recording a 
> CD in a conservatory. This D had been voiced without shaping of the 
> hammers, these are lively but with large grooves. 


The elasticity in the centre string area of the hammer is critical to even
unison voicing, and consistent unicorda tone quality.



>
> I was obliged to come back because they had big thump noises when using 
> the left pedal, due to the grooves of course. 
> In a hurry, I shape (!) the hammers quickly, voice a little, an then I 
> was obliged to tune again all the 5th octave and up to treble, with much 
> less strech, because of the change in sound wich did not allow the large 
> strech used before. I've done that aurally in 20' and all of that was 
> very natural to my ears. Did not have the time to check with RCT (but 
> this piano is very stable). 


If you had reshaped octave's 5,6,&7, you would have noticed a further drop in
stretch.

If your researchers are only using a Conn Stroboconn to do these measurements,
then appying theory of errors, this could explain why they are talking about
0.5 to 1.0c errors on one unison which seems wide to me.

Regulation is a big factor in these measurements, particularly jack height and
escapement. In my experiments I have found that ANY lost motion between the
jack and the knuckle (roller) makes reproducability next to impossible.

I would be interested in sharing imformation with these people.

Regards Roger


Roger Jolly
Baldwin Yamaha Piano Centre
Saskatoon and Regina
Saskatchewan, Canada.
306-665-0213
Fax 652-0505 
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