[pianotech] Self-tuning piano

[Ben Bradley]

I remember this guy from many years ago. He was asking technical 
questions on the Usenet newsgroup sci.electronic.design in 2003 (in this 
thread: 
http://groups.google.com/group/sci.electronics.design/browse_thread/thread/ef0e2159cd4b5477/b84432b209be336). 
He posted this article in the New York Times about it, and this has a 
more detailed description than in the video:

http://www.nytimes.com/2003/01/02/technology/what-s-next-a-piano-that-runs-hot-and-cold-to-keep-itself-in-tune.html

I guess after nine years it's about time he got a working (or 
approximately working) prototype.

On 1/25/2012 4:32 PM, David Boyce wrote:
> Well I'm glad it's not just me - you all think the unison was "off" too!

    I heard it too but I was kind of thinking/hoping it had to do with 
the cheap microphone in the camera and bad room acoustics.

>
> The other thing is, who's going to keep the piano sharp, so that it 
> can self-tune by flattening (by heating).  It's bound to go gradually 
> flat, without the intveration of..... the piano tuner?

    Yes, exactly. As he states in the NYT article, the piano is tuned 
with current going through all the strings to bring them up to about 95 
degrees F, and with the piano in tune the computer records the pitch of 
each string. When the power is turned off, the strings cool down to room 
temperature and the pitch (and tension in ALL the strings) goes up. When 
the system is turned on again, the string are again heated to the point 
that they make the same pitch as when originally tuned. This heating and 
cooling (and tension change of every string) every time the system is 
turned on and off can't be good for stability. I'd think it would be 
much more stable if the strings were heated all the time.  Eventually 
the pitch of a string drops to where it's below the tuned pitch at room 
temperature, and since heating a string can only lower its pitch, that's 
when a tuner (person) needs to be called back.

>
> David.
> www.davidboyce.co.uk

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