una corda tone question

Please pardon what may be a trivial question regarding the sound of a grand when the una corda pedal is depressed. Why exactly is the sound mellower? Is it because the hammers are striking the strings outside of their normal contact points, and are therefore softer at the new contact points? Or is it solely due to the fact that (for the two- and three-stringed notes) there is now one less string vibrating?

Can easily be both things contributing. The exception would be if the hammers are kept freshly filed and voiced, then it's mainly the 2 vs 3 strings. In that case, the change in tone is less drastic. When the hammers are not freshly filed or voiced, the change is more drastic.

Two strings vibrate in profoundly different ways from three. That is, it's not just 'one less string,' it's a *system* which behaves completely differently. See 'The Coupled Motions of Piano Strings,' a valuable article by G. Weinreich in Scientific American, Jan., 1979, pp. 118-127.

I've been startled to learn recently that some top technicians

Your email doesn't work, so:

Go to my web page:
http://members.aol.com/chang8828/contents.htm

and look up section II.24.

C. C. Chang

<<I've been startled to learn recently that some top technicians approve

I'm so glad you've posted this. I've been telling my piano students about this article for years. But I couldn't remember what year it was. I read it circa 1979 for a basic University science elective called 'Light and Sound.' It's great to have a deeper understanding of the una corda pedal. This article is highly recommended!!! This article also explains why bigger is better when it comes to pianos. (string length!!!)

I'd like to know if many technicians have read this, and what they think of it.

Mark (just a piano player) Eisenman

Mark Eisenman To order my CD 'The Chant' go to
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It is an excellent review article, but as an investigative science, it has no value, since it is just a rehash of known principles. The authors make it sound like they did original science, but they did not. I have a critique of this article in my Reference section:
http://members.aol.com/cc88m/reference.htm C. C. Chang

I asked a distantly related question on another thread that got no response:

Is there a change in the touch of the keyboard when you depress the damper pedal? If so, why? If not, is it an illusory effect?

<<Is there a change in the touch of the keyboard when you depress the damper pedal? If so, why? If not, is it an illusory effect?>>

Yes, lifting the underlevers out of the way on a grand reduces the effort to depress the keys. Your foot is doing some of the work.

Ed Foote Nashville, Tennessee

There is a change in touch on some uprights, which use a different mechanism to achieve soft, than the shift of the hammers to the right on grand pianos. The uprights IIRC, move the hammers closer to the strings, so that they cannot strike them as hard. At least, I think that's what I remember. That shift usually affects the touch of the upright pretty profoundly. Greg

One of the main reasons why the soft pedal seems to change the touch for grands is that the strings are hitting a softer part of the hammer. So the difference in feel is like the difference between a new and old hammer, which can be considerable for some pianos. C. C. Chang