<!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 6.00.2800.1106" name=GENERATOR> <STYLE></STYLE> </HEAD> <BODY> <DIV><FONT face="Comic Sans MS" color=#000080>See = below:</FONT></DIV> <DIV><FONT face="Comic Sans MS" color=#000080></FONT> </DIV> <DIV>----- Original Message ----- <DIV>From: "David Love" <<A = href="mailto:davidlovepianos@earthlink.net"><FONT color=#000000>davidlovepianos@earthlink.net</FONT></A>></DIV> <DIV>To: "Pianotech" <<A href="mailto:pianotech@ptg.org"><FONT color=#000000>pianotech@ptg.org</FONT></A>></DIV> <DIV>Sent: July 14, 2003 10:37 PM</DIV> <DIV>Subject: Re: high or low?</DIV></DIV> <DIV><BR></DIV> <DIV>> Not being a scale design person, but judging from observation, = I would<BR>> think high or low tension has to do with the amount of = tension per string<BR>> on average calculated using speaking length, string = diameter and target<BR>> CPS.  Looking at various scale data, it seems that = on average, in the tenor<BR>> and treble sections, low tension pianos = come in around 150 lbs per string<BR>> while high tension pianos come in = around 160 - 165 lbs per string.  </DIV> <DIV> </DIV> <DIV><FONT face="Comic Sans MS" color=#000080>These classifications = are some arbitrary. I generally divide them up as follows:</FONT></DIV> <DIV><FONT face="Comic Sans MS" color=#000080>    Low = Tension <SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Symbol; mso-ascii-font-family: = 'Times New Roman'; mso-fareast-font-family: 'Times New Roman'; = mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times = New Roman'; mso-ansi-language: EN-US; mso-fareast-language: EN-US; = mso-bidi-language: AR-SA; mso-char-type: symbol; mso-symbol-font-family: = Symbol"><SPAN style="mso-char-type: symbol; mso-symbol-font-family: Symbol"><FONT size=3><STRONG><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Symbol; mso-ascii-font-family: = 'Times New Roman'; mso-fareast-font-family: 'Times New Roman'; = mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times = New Roman'; mso-ansi-language: EN-US; mso-fareast-language: EN-US; = mso-bidi-language: AR-SA; mso-char-type: symbol; mso-symbol-font-family: = Symbol"><SPAN style="mso-char-type: symbol; mso-symbol-font-family: Symbol"><FONT size=3><STRONG>ť</STRONG></FONT></SPAN></SPAN></STRONG> = </FONT></SPAN></SPAN>150 to 160 lbs. (68 to 73 kgf)</FONT></DIV> <DIV><FONT face="Comic Sans MS" = color=#000080>    Medium Tension <SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Symbol; mso-ascii-font-family: = 'Times New Roman'; mso-fareast-font-family: 'Times New Roman'; = mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times = New Roman'; mso-ansi-language: EN-US; mso-fareast-language: EN-US; = mso-bidi-language: AR-SA; mso-char-type: symbol; mso-symbol-font-family: = Symbol"><SPAN style="mso-char-type: symbol; mso-symbol-font-family: Symbol"><FONT size=3><STRONG>ť</STRONG> </FONT></SPAN></SPAN>160 to 180 lbs. (73 = to 82 kgf)</FONT></DIV> <DIV><FONT face="Comic Sans MS" color=#000080>    = High Tension <SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Symbol; mso-ascii-font-family: = 'Times New Roman'; mso-fareast-font-family: 'Times New Roman'; = mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times = New Roman'; mso-ansi-language: EN-US; mso-fareast-language: EN-US; = mso-bidi-language: AR-SA; mso-char-type: symbol; mso-symbol-font-family: = Symbol"><SPAN style="mso-char-type: symbol; mso-symbol-font-family: Symbol"><FONT = size=3><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Symbol; mso-ascii-font-family: = 'Times New Roman'; mso-fareast-font-family: 'Times New Roman'; = mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times = New Roman'; mso-ansi-language: EN-US; mso-fareast-language: EN-US; = mso-bidi-language: AR-SA; mso-char-type: symbol; mso-symbol-font-family: = Symbol"><SPAN style="mso-char-type: symbol; mso-symbol-font-family: Symbol"><FONT size=3><STRONG>ť</STRONG></FONT></SPAN></SPAN> = </FONT></SPAN></SPAN>180 to 200 lbs. (82 to 90 kgf)</FONT></DIV> <DIV><FONT face="Comic Sans MS" color=#000080>Note that these are = averages and apply only to the unwound tenor/treble scaling. In most existing pianos = tensions will vary all over the place with hills and valleys going well above and = well below these numbers.</FONT></DIV> <DIV><FONT face="Comic Sans MS" color=#000080></FONT> </DIV> <DIV><FONT face="Comic Sans MS" color=#000080>Pianos like the = Steinway Model L and Model O are typical of relatively low tension scales. Both of these = scales nearly identical scales are in the 125 to 145 lb (57 - 66 kgf) range in = the top treble section, the 150 to 155 lb (68 - 70 kgf) range (the L is a bit = longer and higher) in the low treble section, and from the 155 to 160 lb (70 - 73 = kgf) range at the top of the tenor section down to something less than 120 = lbs (54.5 kgf) in the Model O and something less than 130 lbs (59 kgf) in the = Model L. The low tenor of the Model L's that I've measured are some longer than that = of the Model O. But these were probably all N.Y. built instruments--my notes = don't tell me if any of them were Hamburg-built and they may well be somewhat different.</FONT></DIV> <DIV><FONT face="Comic Sans MS" color=#000080></FONT> </DIV> <DIV><FONT face="Comic Sans MS" color=#000080>By the way, I must = assume that the figure given in the Steinway web site for the overall scale tension of = the current Model O is incorrect. I doubt the plates of the recent Hamburg = Model O's I have examined would long tolerate a scale tension of 19,000 kgf. This = works out to something like 41,850 lbf. Even if the bass has been cleaned up = this figure seems quite high. Our own rescale for this model (assuming = original bridges, etc.) works out to about 37,500 lbs (17.0 kgf). Even our = <EM>Killer O</EM> scale, complete with transition bridge, is only about 38,400 lbs = (17.4 kgf). Given the relatively short backscale found in these instruments = 19,000 kgf would pretty effectively tie the soundboard down and make for a pretty = tight sound.</FONT></DIV> <DIV><FONT face="Comic Sans MS" color=#000080></FONT> </DIV> <DIV><FONT face="Comic Sans MS" color=#000080></FONT> </DIV> <DIV>></DIV> <DIV>> ... Bass<BR>> string scaling seems then to be calculated to = create a smooth transition in<BR>> total tension note for note through the bass.  The question as it pertains<BR>> to this thread and ETD = users (and scale designers for that matter) is how<BR>> these differences = effect inharmonicity and loudness.  Different scale<BR>> designers seem = to choose to balance the effects of tension in terms of<BR>> loudness = and inharmonicity in different ways while keeping other limiting<BR>> = factors in mind (such as breaking points).    </DIV> <DIV> </DIV> <DIV><FONT face="Comic Sans MS" color=#000080>I can only speak for = myself, but my criteria for bass scaling are (in order of = importance):<BR>    1)    Unison tension<BR>    = 2)    Unison "power"<BR>    3)    String inharmonicity.<BR>If these three are balanced within acceptable ranges, = string breaking points will take care of themselves. </FONT></DIV> <DIV><FONT face="Comic Sans MS" color=#000080></FONT> </DIV> <DIV><FONT face="Comic Sans MS" color=#000080>The problem, from a = scaling perspective, is found in the low tenor. In both of these scales the = strings at the low end of the tenor bridge are excessively "foreshortened." From = E-32/F-33 in the Model O and from D-30/D#-31 in the Model L the length (and the = resultant string tensions) deviate significantly from anything resembling a log = curve. This results in a string tension at B-27 (the last unison on the tenor = bridge) of approximately 115 lbs (52.2 kgf) in the Model O and approximately 125 = to 130 lbs (56.8 - 59.0 kgf) in the Model L. It is possible to even out the = string (and, of course, the unison) tensions by simply increasing the wire = diameters of these lower strings--#20 wire in the Model L and #21 wire in the Model O = will do it--but the result will be a significant spike in the inharmonicity = curve. Still, this is the usual choice; go for smoother unison tensions (hence, = more uniform acoustical power) at the sacrifice of inharmonicity. (Uneven inharmonicity bothers the tuner, uneven power bothers the = pianist.)</FONT></DIV> <DIV><FONT face="Comic Sans MS" color=#000080></FONT> </DIV> <DIV><FONT face="Comic Sans MS" color=#000080>Even in short = scales like these, by using a transition bridge it is usually possible to blend all = three parameters in such a way that string inharmonicity will yield a smooth, = uniform tuning curve.</FONT></DIV> <DIV><FONT face="Comic Sans MS" color=#000080></FONT> </DIV> <DIV><FONT face="Comic Sans MS" color=#000080>Del</FONT></DIV> <DIV><FONT face="Comic Sans MS" color=#000080>Delwin D = Fandrich<BR>Piano Designer & Builder<BR>Hoquiam, Washington  USA<BR>E.mail:  = <A href="mailto:pianobuilders@olynet.com">pianobuilders@olynet.com</A><BR>= Web Site:  <A href="http://www.pianobuilders.com">www.pianobuilders.com</A></FONT></D= IV></BODY></HTML>