stability, heat and DC systems

[Don]

Hi,

I have often wondered how DC systems reacted to changes in heat. Here are
some results that are not scientific--yet may have some indication of what
may be happening.

The piano is a Samick SU-121b Serial # INJ00157, equipped with smart bar
system, plastic back cover and fabric back cover to protect the plastic.
First plain steel is d#3 (#31).

It was shoved UP against a perimeter heating unit (steam) and was receiving
direct sunlight on the back each day. I deliberately made a decision to
tune it *at* the pitch it had drifted to--which was -5 cents at D3 (#30),
on March 2, 2000. A4 (#49) was at -7.6 after doing a pitch correction of
between 11 and 24 cents.

The piano was then moved i.e. swung away from window so no more direct
sunlight and bass end 4 feet from perimeter heating. If we assume general
pitch level was -7.6 cents, pitch at D3 had risen only .6 cents, however
the pitch at A4 had risen 7 cents, and the pitch at D#3 rose 13 cents (i.e.
was 6 cents sharp). A0 went up about 3.5 cents, A1 2, A2 2, a3 5, A4 7, a5
2,a6 0.3, a7 2.

As usual, I hope some one else will be able to add to this information. I'm
sorry it is not so scientific this time--but it still may be useful.
Regards,
Don Rose, B.Mus., A.M.U.S., A.MUS., R.M.T., R.P.T.

Tuner for the Saskatchewan Centre of the Arts

drose@dlcwest.com
http://donrose.htmlplanet.com/

3004 Grant Rd.
REGINA, SK
S4S 5G7
306-352-3620 or 1-888-29t-uner