Seasonal pitch change: was -- Long term pitch drop, was: Type O

[PAULREVENKOJONES]

"If you want to know the truth, stop having opinions" (Chinese fortune cookie)


In a message dated 03/04/07 08:52:16 Central Standard Time, rnossaman at cox.net writes:

>      > Ron: 
>      >   
>      > Certainly the dimensional changes you suggest would create a pitch 
>      > difference, but what about the not so inconsequential friction 
>     systems 
>      > of the front scale: bearing cloth, counterbearing bar, agraffe or 
>     capo, 
>      > etc. 
> 
>     The friction levels of the front scale are usually just that - 
>     relatively inconsequential compared to that at the bridge. 
> 
> They're inconsequential compared with lots of things which doesn't make 
> them per se inconsequential when it comes to the string "rendering" past 
> them; the friction exists and is eminently measurable. My question 
> stands. Could the "couple of thousandths" move sufficiently and in such 
> "even" patterns past those friction points and create the various and 
> varied effects we find in piano pitch change? 

I didn't say they were inconsequential at the capo, just 
relatively so compared to the bridge friction levels, and 
don't claim to be able to provide infinite details describing 
the cause and effect of every pitch anomaly we find in pianos. 

If your question refers to pinblock movement of a couple of 
thousandths make a difference, past the counterbearing 
friction points, to the tuning, I'd say yes it can and does. 
Always? Obviously not or we wouldn't get those strings that 
ping when you bump them down. To what degree depends on other 
details. Is it the ONLY, or even the PRIMARY cause of pianos 
going out of tune, no, I don't think so. 
Agreed. My speculation is that it is at best very little of the major components that cause truly massive seasonal shifts in, e.g. spinets. Not that we care so much about stability of these pianos, but they are maybe worth looking at more closely just for the mechanics. Here in Chicago, among my clientele (and yes, I still tune a few spinets), these pianos move regularly between 435 and 445 even with my attempts to "float" the pitch. The older they are, the more "volatile" they get. Is this pinblock movement? Maybe to some wee degree. But I can't believe that it would account for the large-scale pitch movement.



The one think I'm sure is NOT the primary cause is soundboard 
rise and fall, as we were all taught. 

We do have soundboard rise and fall, which will make some 
difference. We do have bridge movement fore and aft, through 
soundboard distortion and bridge length changes which cause 
speaking length changes that will make some difference. We 
have bridge caps shrinking and swelling, changing string 
lengths by both changing bearing and moving strings up and 
down slanted bridge pins, which will make a difference. We 
have pinblocks experiencing dimensional changes which change 
string lengths and will make a difference. We also have a 
number of friction points that will help to disguise what we 
think we see happening, which will make a difference. We have 
different lengths of wire outside the speaking lengths of 
every single string, which will make a difference. We then 
have every warping, twisting, bending, and rotating scenario 
anyone can dream up whether there's any plausibility to it or 
not, that might possibly make a difference. Then throw in 
thermal effects, individual tuning styles, and more than a 
little Voodoo, and the piano's out of tune again.
All true. Especially the voodoo. Until we have data, that is. And yet, there is still measurable bearing change at the bridge from season to season. This in no way argues for "rise and fall" but certainly some movement of the major structures that correlates with pitch. It could be any and all (I suspect the latter) of the things you mention above, although there are some forces which oppose rather than complement. 



>     I'd love to hear Jim Ellis chime in on this. 
>      >   
>      > Paul 
> 
>     Then you'd better cross post to Caut. He doesn't read Pianotech. 
> 
> My sentiment was out of respect for Jim, Ron. 

And mine wasn't out of disrespect, Paul, it was factual and 
informative. The fact is that he doesn't read Pianotech, and 
if you are sincere in wanting to have his opinions on this it 
would seem the sensible thing to do would be to make him aware 
of it. 

Ron N 
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