On Jan 18, 2011, at 8:16 PM, Ron Nossaman wrote: > This has been addressed on Pianotech (that other list). An > additional kilo of agraffe mass on the bridge will increase sustain > and change the tonal envelope without any inherently magical > properties of the agraffe. Just a couple thoughts about this statement: I assume it is a summary of the collective conclusion, essentially discounting any effect beyond that of the added mass. First, about the "extra kilo." How much does an agraffe weigh? Anybody actually weigh one? I am guessing somebody thought they would be about 10 grams each, hence a total of 880 grams added, nearly a kilo. Or does someone actually know? Also, does somebody actually know how much mass is subtracted from the bridges to install agraffes? (Or, more precisely, not included in the bridges, if it is a new install). Taking a normal bridge as a starting point for comparison, they will be machined down maybe 4 mm, so there is some wood mass removed, and there will be no bridge pins. If we are doing seat of the pants estimating, we might suppose that the agraffes _could_ weigh from 7 to 12 grams, and that 3 to 5 grams per unison _might_ be removed, which leaves us with a net increase of 200 to 800 grams round figures for the agraffe system. This is top of the head, just to illustrate the dangers of doing this kind of figuring without "getting real." But let us suppose that, in fact, nearly 1000 grams are added to the bridges. That means about a third of it will be added to the top three octaves, or 350 grams. Just adding 350 grams in some ways, whether a weight screwed to the bottom of the bridge or insertions of lead or whatever, will certainly have an effect on sustain. Will it be the same spreading it out unison by unison? I don't know, does someone else? Has it been tried? It could be, by using "earth magnets," that are relatively inexpensive and easily reversible (put them on the strings on top of the bridge). Without having these questions answered, and based on the physical experience of listening to that Baldwin retrofit, I'd have to say that I believe there is more to it than just added mass. Others may feel free to hold their own differing opinions. Regards, Fred Sturm fssturm at unm.edu http://www.cdbaby.com/Artist/FredSturm
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