pianotech-digest V1997 #2032

[Mark Bolsius]

G'day Stan,

Keeping this as simple and short as possible

The low tenor strings in shorter pianos are usually strung at lower tensions
particularly regarding percentage of breaking strain. It's difficult to get
this area right or even reasonable. As a result these strings have more
stretch or give compared to those a little higher up (which are strung at a
higher percentage o their breaking strain.

So when the soundboard moves, these strings will actually move or give
further than those that are closer to their breaking strain.

The GH1 (I can't speak for the Baldwin) is a low tension scale-challenged
piano which doesn't help!

I'm sure there will be more scientific explanations, but that's as simple as
I can put it...besides I'm tired and I'm going to bed
Night All
--
Mark Bolsius
Bolsius Piano Services
Canberra Australia

----------
>From: owner-pianotech-digest@ptg.org (pianotech-digest)
>To: pianotech-digest@ptg.org
>Subject: pianotech-digest V1997 #2032
>Date: Thu, 30 Sep 1999 11:40 AM
>

> From: "Stan Kroeker" <stan@pianoexperts.mb.ca>
> Subject: Bald Ham Pitch Swing
>
> Apologies for the abbreviated subject line.
>
> Not quite sure I fully understand what is going on when humidity changes
> cause pitch fluctuation.  Ya, ya...I know...humidity goes up, soundboard
> swells, crown rises, string tensions increase...but... it is always the
> lowest tenor strings (10-15 unisons?) which are affected disproportionally
> to the rest of the scale.  Many claim that these strings sit on the portion
> of the bridge close to the center of the soundboard but the last time I
> looked the low end of most tenor bridges was pretty close to the rim.
> Almost as close as the bass bridge.  Weird things often happen on either
> side of the treble (strut) break as well.
>
> Some pianos exhibit extraordinary pitch swings (a client's Yam GH1 comes to
> mind) but none as peculiar as a Baldwin Hamilton (<10 yrs) on which the
> entire tenor/treble section fluctuates 25-30 cents each seasonal change.
> The bass remains within 5 cents of pitch on this piano.  Is there more to
> this phenomenon than the soundboard swells or shrinks?
>
> Regards to all,
>
> Stan Kroeker
> Registered Piano Technician