[pianotech] Soundboard deflection - Pitch raise

[David Nereson]

----- Original Message ----- 
From: "Ron Nossaman" <rnossaman at cox.net>
To: <pianotech at ptg.org>
Sent: Tuesday, August 04, 2009 8:15 PM
Subject: Re: [pianotech] Soundboard deflection - Pitch raise


I'm confused, and having to re-learn almost everything I was 
taught about humidity changes and how they affect or don't 
affect the tuning.
This statement:

> Exactly. Just like soundboard rise and fall with humidity 
> swings

says that the soundboard does rise and fall with humidity 
changes.  But the rest of it:

>has very little to do with pianos going out of tune, soundboard 
>deflection has very little to do with the pitch drop requiring 
>overshoot when pitch raising. The required angle and load 
>changes just aren't there.
> Ron N
>

says that those rises and falls don't affect tuning much.  Then 
what DOES make the low tenor strings go 25 cents sharp during 
the summer, and drop back down after the heat's been running for 
a couple weeks?

    On a related note (pun intended), a new customer just moved 
their grand from Boston to Denver.  Typically pianos go way flat 
when moved to dry Colorado from more humid places.  Are you 
going to say that's not the soundboard falling?  Also the 
soundboards often crack after being here a while, and many techs 
advise that they get a room humidifier and/or Dampp-Chaser 
system.  But in Boston, when the furnace is running all the time 
during a cold winter, aren't most homes there just as dry?
        --David Nereson, RPT