humidity question (may be stupid but I'm curious...)

[Don]

Hi Stephen,

I have many case histories of upright pianos equipped with humidity control
systems with back covers where pitch will drop less than 2 cents in a year.
Some also change less than 2 cents in two years. This assumes the pitch of
the piano has been stabilized by frequent tunings when new. The magic
number for tunings to become this stable appears to be nine. (Hmmmm cats
and pianos?)

I also have case histories where the pitch on a piano will change at A4 by
4 cents for every 5% change in humidity. The rate change in pitch seems to
be similar whether humidity goes up or down.

I do have one case history of a piano with humidity control in a house
where a set back thermostat was in use. A new Yamaha P22. It would change
about 13 cents at A4 (28 cents worst note) every six months. The piano has
since been moved to a new home without set back. In the last year pitch
change was a measely .32 of one cent.

I hope this information is of assistance to you.

These measurements have been taken on pianos that vary from "decorative"
pianos to top of the line. The quality of the piano has very little to do
with the final results, assuming the pin block is tight enough to hold the
pins. If it is *not* then treating it with CA glue will make it so. 

At 10:36 PM 10/21/2001 -0700, you wrote:
>Two extremes here.
>
>One, you keep an average to good (maybe Steinway, but
>basically any piano rated 5 or higher on page 131 of
>the Piano Book 3rd edition(Larry Fine)) well-built
>full-size (52 to 60 inch) upright or medium size (6 to
>7 foot) grand in a very controlled room, with
>humidity, temperature, etc. control.  How fast/slow do
>you think the piano would go out of tune varying
>degrees if it's not played much (i.e. less than 4
>hours a week)?  like 10 cents / 20 cents / 50 cents /
>100 cents?
>
>Two.  Keep the same piano (although probably the
>upright for space reasons) in the bathroom next to the
>shower.  (provided the piano could even SURVIVE such
>awful treatment).  Would it be reasonable to say that,
>if someone takes a 15-minute (or long enough to
>totally fog up the mirrors) shower every day and runs
>heat lamps for a while (long enough to dry everything
>out) after the shower, once every day, do you think
>said piano in that room could go a half-step flat or a
>full step flat in the course of a few days? or how
>fast do you think it would go out?

Regards,
Don Rose, B.Mus., A.M.U.S., A.MUS., R.M.T., R.P.T.

mailto:drose@dlcwest.com

after Oct. 30 mailto:drpt@sk.sympatico.ca

http://donrose.xoasis.com/

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