self tuning piano????

[Ron Nossaman]

>Hmm? I guess I better get my 2 cents in. Seems to me, if the principal by
>which this thingee works, is to heat the strings to lower them into pitch;
>then I suspect a change in the piano wire tempering would occur. If that
>were the case, then them puppies'd need restringing often.

Joe, if 95°F will compromise the temper of piano wire, then most pianos 
that have  spent a day in a truck being delivered anywhere, or been in a 
living room in direct sunlight for even one afternoon, are write offs. 
Suspecting I'd like to know the more official opinion on potential 
tempering changes, I looked it up in my Machinery's Handbook. It says:

"Most ferrous metals have a maximum strength at approximately 400° F, 
whereas the strength of nonferrous alloys is a maximum at about room 
temperature."

It also says: "The modulus of elasticity of metals decreases regularly with 
increasing temperatures above room temperature until at some elevated 
temperature it falls off rapidly and reaches zero at the melting point".

Perhaps a lightning strike...


>Also, the current
>running through the strings would need to be extremely low, else the usual
>"string strummers" would get a good jolt. :-)
>All this, to me, is an exercise in stupidity. Oh well, it's his money, let
>him throw it after naught.
>Regards,
>Joe Garrett, RPT, (Oregon)


He doesn't say what voltage and current levels he's running, only that it 
takes about 200 watts for the whole piano. Personally, I wouldn't mind a 
tingly waker-upper to remind string strummers to keep their sweaty little 
hands out of the piano. I'd guess I'm not qualified to score the idea on 
it's stupidity, since I think the basic concept is clever and interesting. 
The implementation will need some work before it's ready for prime time (if 
ever, considering it's reception by the techs who voiced opinions), but 
that will be a continuing education process. Impractical, maybe - we'll 
see. Stupid - hardly.

Has anyone mentioned the tuning problems resulting from the inharmonicity 
differences between struck and continuously excited strings?

Ron N