[CAUT] pre-stretching new string?

[Michael Jorgensen]

>From observation, the amount of weather induced pitch change in a given
range is reasonably proportional to the amount of soundboard area and linear
bridge length per unison proportioned to the amount of string tension.
-Mike Jorgensen


On 6/7/07 7:13 PM, "Ron Nossaman" <rnossaman at cox.net> wrote:

> 
>> Where the bridge pin ends up relative to the front
>> termination is an open question, not one easily measured.
> 
> Hi Fred,
> No, not easily measured.
> 
>> One of the 
>> Fandrich's (I forget which, but think Darrell) wrote about pitch change
>> due to elongation of the bridge toward the tenor end about ten years
>> ago, citing speaking length change as a major factor.
> 
> That was Darrell, and his premise was based on strings not
> rendering through the bridge. An interesting thought though.
> 
> 
>> Soundboard movement in response to humidity change isn't just up/down.
>> The position of the bridge relative to the front termination may change
>> due to whatever is happening to the board. A bit sideways, a bit back or
>> forth, a bit of change in cant. It certainly isn't as simple as up and
>> down, increasing/decreasing bearing (and, hence, distance from a to b,
>> and, hence, tension).
> 
> Nothing is simple or isolated, and this isn't a discussion on
> every potential detail of why and how pianos go out of tune,
> is it? My initial intention was to illustrate that string
> stretch wasn't the likely primary reason for long term pitch
> drop. I don't have authoritative details on everything that
> happens in soundboards with moisture changes, and most likely
> never will. I've picked up what I think are a few clues, and
> reported why I think so. That's the best I can do.
> 
> 
>> You really think the moisture transfer from the bottom of the soundboard
>> into (and from) the bridges of a grand is enough to stabilize the
>> bridges to a significant degree?
> 
> When it rains outside, the humidity level in my house
> increases even though the doors and windows are closed.
> Dampp-Chasers are least effective when the lid is always wide
> open, with no bottom cover, and most effective with a top and
> bottom cover.
> 
> Ron N