Seasonal pitch change:

[Andrew and Rebeca Anderson]

Ric,
My oberservations are that DCs do help, more with an undercover, and 
a whole lot more with a stringcover.  I have two Sauters here, one a 
Delta and one an Omega.  The Delta has a stringcover, the Omega 
doesn't.  We just had a big swing here with dry arctic weather.  The 
Omega needs unison cleanup and the Delta doesn't know anything 
happened; it is going on over four months with a pretty near concert 
level tuning still surviving on it.

Andrew Anderson

At 01:47 PM 3/8/2007, you wrote:
>Hi Don
>
>A couple things to remember... these are all based on same size wire
>0.9 mm (seemed like a good average) and short back lengths.  Still 
>they give a good enough picture.  Longer back lengths end up 
>requiring even larger deflection changes for any given pitch change, 
>but downbearing levels are lowered.  Still... no soundboard/bridge 
>is going to rise 5 + mm me thinks.
>
>I am also curious as to why damppchasers have an obvious positive 
>affect.  Obviously wood is involved.  In grands however... I cant 
>see the bridge itself being to awfully much affected by the DC unit 
>(perhaps I am wrong).  And the bridge is where most of my attention 
>is focused on this issue at the moment, for a couple 3-4 reasons as 
>I've stated in other posts.
>
>Rim, pinblock, and frame could all conspire to alter the end points 
>somewhat.  I still dont quite get why this should effect the lowest 
>tenor strings sooooo much more then others.
>
>btw... it always seems to me like there are 4 independent sections 
>and they all respond pretty similarly to each other.  Pitch drops 
>most in the lowest notes of each section.   The bass and top 
>sections behave a little differently then the middle to... but not 
>all that much.  That points me back to the bridge..... grin.
>
>Cheers
>RicB
>
>
>    Hi Ric,
>
>    Most interesting figures. I've not believed soundboard moving up and
>    down
>    had much to do with pitch corrections for some years.
>
>    What I *do not* understand is *why* damppchasers work to ameliorate
>    seasonal pitch change. Clearly they don't have much effect on metal.
>    That
>    leaves the rim and the main frame as possibilities.