String coils affect stability?

[Ron Nossaman]

> I certainly would not let down the tension to tighten coils.
> 
> With respect, I have measured the difference in unison stability with
> sloppy coils. There is a small but measureable difference, after lifting
> coils and tapping them down to form nice tight coils on upright pianos that
> are 50 years old and equipped with humidity control systems.
> 
> I routinely check each new client's piano by testing three pins. If there
> is no pitch drop then I accept the coils. If any of the three change pitch
> then I take the time to address the coils.


Don,
This sounds to me like you're talking about tapping and 
settling coils. I'm not. Tapping coils and getting measurable 
pitch changes is *not* tuning instability any more than 
dumping a piano down a flight of stairs and finding wavy 
unisons afterward is. Untouched, those non-neat coils will 
themselves manifest no tuning stability problem at all year 
after year after year unless someone disturbs them by tapping 
and settling. That is, of course, after the initial settling 
after stringing. The neatest coils you ever saw will likely 
produce a pitch change when tapped if coils haven't been 
touched since it was originally strung and settled. This 
doesn't mean to me that they need tapped, or the customer 
needs to pay for it, because they'll not be a problem left alone.
Ron N