>Hi Phil, > >I intended to respond to this way back when it was written but didn't get >around to it then. I hope you're still interested.... Hi Del, Yes, I'm still interested. I appreciate your comments. >One of the early complaints I had with metal (aluminum) action rails was >what I perceived to be an increase in transmitted action noise. Now this is >not something I have done any real study on and don't have any numbers to >give you, but my perception was, back when I was doing a substantial amount >of field work, that actions converted directly from wood to aluminum tended >to sound somewhat noisier than their predecessors. This was most noticeable >during the transition period when pianos of same model would be side-by-side >one with wood action rails and another with aluminum action rails. The >brighter and harder the sound of the piano, of course, the more this noise >gets lost in the mix. Good point. I hadn't really focused on the noise aspect. I was thinking mainly in terms of strength and stability. A case in point. Over the weekend I serviced a Yamaha CF-III. The hammer rail is aluminum. Also, the letoff buttons are attached directly to the hammer rail - they are the wooden dowel type threaded onto studs on the hammer rail. The pianist was complaining about a 'clicking sound' on a couple of notes. As it turned out the problem was that the felt on the letoff button had gotten hard or rough. The sound of the jack tender rubbing on the letoff button was quite audible to the pianist. When I had the action out in my lap I could rub lightly with my finger or fingernail on the side of the letoff button and make quite an audible noise. When I put the action back onto the keybed the noise was even more pronounced. When I focused on it I did hear that the action of this piano is fairly noisy. But, as you say, you don't really notice it when playing because the piano is so bright. >Piano actions in motion are inherently noisy devices....Not only are >vibrations set up in the strings, a veritable cacophony of vibrations are >set up within the hammer and hammershank. Some of this is transmitted back >to the action rail, through the action brackets and keyframe, into the >keybed and, ultimately, into the air as sound...... > >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. >Wood >tends to dampen at least some of the higher frequency vibrations inherent in >the piano action function, aluminum tends to transmit them freely. The >Kranich & Bach unified action frame casting (that is, the keyframe center >rail, back rail, action brackets and both main action rails were all cast as >a single unit out of gray iron) dampened them quit nicely. I'm not familiar with that, but leave it up to that company to come up with something like this. > Nearly thirty >years after removing that action to my shop for repairs and regulation, my >back has still not completely forgiven me--but it was a quiet action. Other >quiet actions of my acquaintance have been found in certain early actions >having wooden action rails and wooden action brackets. I can see that wooden action brackets could be good in this respect. If they were laminated they could also be stable. > 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. >Stability in both wood action frames and rails can easily be achieved by >making them out of cross-laminated veneers. Of course, this also reduces >their vibration-damping characteristic and increases their vibration >transmission efficiency. Life's a compromise. The Decker piano I am >remanufacturing for myself has, and will retain, nicely crafted three-ply >cross-laminated maple action brackets. The only change is that they are now >epoxy saturated for stability and to insure their long-term structural >integrity. After all, they are nearly 120 years old--someday they may >develop structural problems. > >Del 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 Phillip Ford Piano Service & Restoration 1777 Yosemite Ave - 215 San Francisco, CA 94124
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