String coils affect stability?

[RicB]

Interesting.  Don is one of those guys that pays attention to this kind 
of detail... so if he says he's measured and observed some small 
difference I certainly wont discount his claim out of hand.

I dont see the mechanism that would achieve this tho... at least not 
clearly.

Cheers
RicB

    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