----- Original Message ----- From: "Phillip Ford" <fordpiano@earthlink.net> To: <pianotech@ptg.org> Sent: February 18, 2003 11:57 AM Subject: Re: Wooden action parts and frames > >I doubt that your Bechstein representative intended to imply that certain > >vibrations were essential, or desirable, to the overall sound mix, but that > >they were not. Much gets lost in the translation between languages. > > Quite likely. But it did get me to thinking about where the vibrations that you feel in the key are coming from. In my opinion, one of the characteristics that distinguishes a really good piano from a mediocre one is this ability to transmit vibration to the keys. On a good piano you have the sensation that you are feeling the sound as well as hearing it. This is an attribute that I value highly, and many pianists do as well. I'm not sure what the path for this is. I had always assumed that the vibration was coming from the rim, through the keybed, and through the keyframe to the keys. The conversation mentioned above made me wonder if some of this 'vibration' wasn't coming from the hammer back through the action rails and frame and into the keys. > > There has been some discussion on the list in the past about whether the pianist can actually feel the hammer hitting the string. The transmission of this impact feel back to the key is probably different for aluminum and wood rails. Which would be superior I suppose is an open question. If it's aluminum, then it becomes a tradeoff between this feel and the noise associated with the aluminum rail. > > Also, the letoff feel that is detected in the key I assume is coming through the jack, whippen, capstan, and into the key. Whatever impact transmitted through the letoff button, rail, and frame to the key is insignificant. If that is the case, I can see that it could be a good idea to isolate the letoff buttons as much as possible from the brackets and frame to prevent the noise problem that I encountered on the CF-III. ----------------------------------- I rather doubt that what you feel at the key would be all that much different in either case. Anything your fingers are physically capable of picking up would be pretty low-frequency, high-magnitude stuff which probably wouldn't be damped much even by the most punky wood. The bothersome action noise is typically fairly high-frequency stuff that is readily transmitted by aluminum but tends to be absorbed, or damped, by wood. > > > I once encountered an > >action key frame resting on three strips of felt--one each for the front, > >center and back rail nicely set into a machined recess. I don't recall > >knowing enough about piano function at the time to properly evaluate the > >system in terms of action efficiency, but it was a quiet action. > > I would worry about this dampening the transmission of vibration to the keys, which I mentioned above. Were the strips of felt wider than the action rails? In other words, was all the weight of the action supported by the felt strips. If so, I would also worry about stability of the regulation. -------------------------------- I don't recall there being any problems of this kind. If memory serves, the felt strips (actually woven felt cloth) were about 25 mm wide. One each under the front rail, center rail and directly under the capstan line, not the back of the back rail. (I've no idea just how significant that was.) I expect that any instability would work itself out in the first few months as the wool fibers settled themselves in. After that I would expect the setup to be fairly stable. > > In my original post I also talked about metal flanges, but you made no comments on those. How do you think that these would affect action noise? What I had in mind was not something like the brass flanges of various sorts that we have seen in actions. But rather a direct replacement of a wood part with a metal part. As an example, a whippen flange made of aluminum having the same dimensions as a conventional wooden flange and having a felt bushing of the same sort as the wooden flange. If these were mounted on a wooden rail do you think that they would be noisier than a wooden flange mounted on the same rail? > > Phil F Well, I have no experience with them other than with early Chickerings. And those were brass which at least has the advantage of mass. I expect aluminum flanges would be some noisier, especially as the felt (bushing) takes on compression-set over the years and leaves room for a slight amount of slop. Wood is inherently a better damper. Though, I suppose the argument could be made that the transmission path is so short between the flange tongue and the edge of the rail that there would be no practical (audible) difference. On the other hand, how often have you come across hammer flange screws that were slightly loose. Enough that the flanges had to be moving slightly each time the note was played. Yet there was little or no audible clacking or clicking. I expect there would be some of both with an aluminum flange. Of course, on yet the other hand, without the expanding and contracting wood fibers the screws might not loosen up in the first place. Del
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