<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META http-equiv=Content-Type content="text/html; = charset=iso-8859-1"> <META content="MSHTML 6.00.2800.1400" name=GENERATOR> <STYLE></STYLE> </HEAD> <BODY bgColor=#ffffff> <DIV><FONT face=Arial size=2>Ok, here goes: I'm going to paraphrase = David Stanwood from memory. Scary thought.</FONT></DIV> <DIV><FONT face=Arial size=2></FONT> </DIV> <DIV><FONT face=Arial size=2>I've gone to his classes several times = and my recollection is that his SW curves are not based on any mathematical = principle. His SW curves do not have anything to do with the original hammer = weights. But rather, his SW curves were developed from analyses of <EM>THOUSANDS</EM> = of "very good" pianos.</FONT></DIV> <DIV><FONT face=Arial size=2></FONT> </DIV> <DIV><FONT face=Arial size=2>Over a period of ten (or more???) = years, David sought out high quality, good sounding pianos. "Good" meant good tonal = qualities along with evenness along the entire scale. He would borrow = the action from these pianos and analyze the SWs (among other action parameters also).</FONT></DIV> <DIV><FONT face=Arial size=2></FONT> </DIV> <DIV><FONT face=Arial size=2>David is a smart guy, with good ears, = and I suspect a good judge of what a good piano sounds like. IMHO, being that his = curves were likely developed mostly from Steinways, and the fact that your piano is = a Steinway clone, I have little doubt that it would be a better basis to = base your SWs on a Stanwood curve rather than where some hammer maker happened to = run a saw across a set of hammers.</FONT></DIV> <DIV><FONT face=Arial size=2></FONT> </DIV> <DIV><FONT face=Arial size=2>I've done several pianos to his curves = and have been thrilled with the results. Ric B. and others could offer more = experienced advice than I as to which curves to follow. However, with your 9-foot = piano, I would imagine you will want one of the heavier curves.</FONT></DIV> <DIV><FONT face=Arial size=2></FONT> </DIV> <DIV><FONT face=Arial size=2>Terry Farrell</FONT></DIV> <BLOCKQUOTE dir=ltr style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; = BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px"> <DIV style="FONT: 10pt arial">----- Original Message ----- </DIV> <DIV style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: = black"><B>From:</B> <A title=sarah@graphic-fusion.com = href="mailto:sarah@graphic-fusion.com">Sarah Fox</A> </DIV> <DIV style="FONT: 10pt arial"><B>To:</B> <A = title=pianotech@ptg.org href="mailto:pianotech@ptg.org">Pianotech</A> </DIV> <DIV style="FONT: 10pt arial"><B>Sent:</B> Sunday, August 22, 2004 = 1:30 AM</DIV> <DIV style="FONT: 10pt arial"><B>Subject:</B> SW heresy?</DIV> <DIV><BR></DIV> <DIV><FONT face=Arial size=2>Hi all,</FONT></DIV> <DIV><FONT face=Arial size=2></FONT> </DIV> <DIV><FONT face=Arial size=2>Thanks for the advice about = techniques to even out the SW curve!  That should give me a variety of techniques to = use/combine in order to even out the jags.</FONT></DIV> <DIV><FONT face=Arial size=2></FONT> </DIV> <DIV><FONT face=Arial size=2>But the question is one of what my = target curve should *really* be.  Hmmmm....  My thoughts:</FONT></DIV> <DIV><FONT face=Arial size=2></FONT> </DIV> <DIV><FONT face=Arial size=2>The unmodified SW curve is = obviously very linear.  (Yes, I know what linear means.  I = "minored" in mathematics, sort of -- except that my U. didn't officially recognize minors).  Stanwood's curves, OTOH, are all concave downwards.</FONT></DIV> <DIV><FONT face=Arial size=2></FONT> </DIV> <DIV><FONT face=Arial size=2>I was advised off list that I = shouldn't force the hammers to artificially conform to a standardized Stanwood curve but = to simply even out the jags to make the action smooth from bottom to top.  = There's something to be said for this idea.</FONT></DIV> <DIV><FONT face=Arial size=2></FONT> </DIV> <DIV><FONT face=Arial size=2>But as I got to thinking about the SW = curves, I was wondering, where do they REALLY come from?  That is, where = does the shape come from?  I suspect the hammer manufacturing people might = be able to enlighten me as to this.  (Ray???)  I'm *guessing* that = the felt is denser than the molding, and when the hammer becomes skinnier, it = loses more felt than molding, resulting in a more precipitous dropoff = in weight at the higher end.  This would occur with a constant hammer = length and a linear variation in hammer and molding (and felt) width.  Am I = anywhere close on this idea???</FONT></DIV> <DIV><FONT face=Arial size=2></FONT> </DIV> <DIV><FONT face=Arial size=2>Contrast this function with other = functions that might actually relate to optimal hammer mass:  String length and = mass both decrease with the note number, with a function that is concave upwards.  Note frequency increases with a function that is = concave upwards.  Note period (inverse of frequency) increases with a = function that is concave upwards.  The Stanwood curve seems rather = meaningless with regard to any of these functions.  For instance, it might be = good to match hammer mass to string mass by some proportion.  = Right?  As the scale goes up, string length and mass approach an asymptote of = zero.  Therefore, shouldn't hammer mass approach an asymptote of zero?  = Instead, the curve starts taking a dive in the treble.  If the scale went = up well past 88, hammer mass would eventually crash to zero.  Because = these curves do not have the same form, the relationship between hammer and = string mass is anything but constant.  That doesn't make = sense.</FONT></DIV> <DIV><FONT face=Arial size=2></FONT> </DIV> <DIV><FONT face=Arial size=2>So is this something that is the way = it is just because of tradition -- because the cauls are built that way, and = that's what ya' get?  </FONT></DIV> <DIV><FONT face=Arial size=2></FONT> </DIV> <DIV><FONT face=Arial size=2>Now that I look at my linear SW curve = (with jags), I'm wondering if this isn't REALLY a closer match to something meaningful (like string mass) than the idealized Stanwood = curves.  Any thoughts, y'all?</FONT></DIV> <DIV><FONT face=Arial size=2></FONT> </DIV> <DIV><FONT face=Arial size=2>Peace,</FONT></DIV> <DIV><FONT face=Arial size=2>Sarah</FONT></DIV> <DIV><FONT face=Arial size=2></FONT> </DIV> <DIV><FONT face=Arial size=2></FONT> </DIV> <DIV><FONT face=Arial = size=2></FONT> </DIV></BLOCKQUOTE></BODY></HTML>