Henry, It seems to me (maybe I'm wrong) that you would want the damper at a NON-nodal point. (The nodes of the string vibration are the intersection points of where the partials separate and divide themselves.) Having a damper on a node would only help the string to ring-on at that partial. Getting the damper OFF the node seems to be the way to go, but I don't design pianos. Maybe one could simply measure the string length and estimate where the nodes occur? The best way, though, to locate the nodes is to excite the string while lightly touching your finger along its length, listening for the partials. Hear a partial? You found a node. Bill Spurlock has written an entire dissertation on dampers and damper "reinvention." I've not had a need to use it yet, but a fellow tech did use it on an old, ever-ringing upright, very successfully. It invloves, quite literally, designing your own dampers. Raising the action up on the action brackets will have an effect on the strike point, probably in a negative fashion. It's a valid idea, though, that might work - never tried it. I suspect that the reason some pianos work better than others is that some pianos are designed better than others. Hope this helps, John Piesik, RPT I hope the following will launch some useful discussion. This morning after a rather urgent call from a favorite customer I went to look at her Steinbach under-damper over strung. This piano has a case of ringing on after dampers return. Not specific notes, or individual dampers failing, but a slight echo effect. For example when striking individual notes in the bass, you get a secondary partial singing on, usually an octave above the fundamental. I have isolated the offending strings within the same break of strings, by placing a hand over the group of strings, and stopping the singing within the break from either the string itself, or one of its neighbors. Yet, the dampers come home clean, and the strings are blocked. But I think this must be due to the possibility that the dampers aren't quite meeting the node point of the string. I found by resetting a few of the dampers that made this condition most apparent I was able to get rid of most of the singing on, but not all of it. Several things occurr to me. As the piano ages, and the strings get older is it possible that the node point changes to a point where the dampers will begin to have less of an effect? In the cases I found, I had to raise individual dampers a fraction of a centimeter and the effect seemed to be cured. What about the expedient of raising the height of the action standard by a fraction to raise the general level of the dampers in question? Short of going back to basics, and replacing all of the dampers, or at least rebuilding all of the damper levers with slightly longer damper wires and repositioning all of the dampers, I can't see any other solution. How can one find the "right" node point. Seems to me this will be a real pains taking procedure. I know that one quick thought will suggest that the dampers are worn, and should be replaced. But, I think that the dampers need to rather than be replaced, will most likely need to be repositioned to find this node point. I have seen very old pianos with very poor dampers with no singing on what soever. I am nterested in any thoughts Thanks regards -- Henry Brugsch Editor Piano Technician's Quarterly http://www.airtime.co.uk/forte/brugsch.htm Net-Tamer V 1.08.1 - Registered
This PTG archive page provided courtesy of Moy Piano Service, LLC