[pianotech] PR brohaha!???

[Ron Nossaman]

Don wrote:
> Hi all,
> 
> So what order would you place on instability factors during a pitch
> correction. Here is a non ordered list of a few I can think of. Please add
> any other factors that may be significant. 

Hey Don,
I thought we'd pretty much pounded this into the ground 
(again) a couple of weeks ago, but apparently not. You didn't 
differentiate between pitch drop with the pitch correction, 
and instability after the tuning is accomplished, which if we 
are to have any hope at all of understanding anything 
connected with the process, we need to do. They ain't the same 
thing.

My "opinion", such as it's worth.


> plate flex  

Very likely, with initial pitch drop. Not with instability.


> sound board compression

Not with pitch drop, not with instability. Basically - not.


> changes in bends in wire 

Not with initial pitch drop. Reasonably possible long term.


> hitch pin movement
> tuning pin angle change

Very unlikely, either initially, or later.


> main wooden frame dimensional change

Possible, but involving plate deformation, which puts it with 
the first one.


> pin block torsional change

Lacking any evidence whatsoever, no.


> twisting of bridge horizontally

???


> twisting of bridge vertically

Ah yes, bridge roll. A traditional favorite industry mirage. 
If this is a factor, it's in conjunction with strings 
rendering through bridges, reluctance of, being the culprit 
for possibly both (some) initial pitch drop with the pitch 
raise, or later instability. If the bridge actually rolls, 
it's because of insufficient support (soundboard failure), or 
a pathological failure of strings rendering through the bridge 
pins with the pitch raise. I'm currently convinced that the 
biggest factor in instability after the fact is strings not 
reliably rendering through bridges (or utterly incompetent 
tuners, which seem to be less all pervasive than render 
challenged bridges). Even if this results in "bridge roll", 
that makes bridge roll an effect of inadequate rendering, and 
not a cause of instability. IOW, a mirage.

There will be more and differing opinions, as usual, and 
probably some intuitive stuff.
Ron N