String termination question

[Andrew and Rebeca Anderson]

Some piano makes have done this, such as Bosendorfer.  I believe 
someone is still doing "half agraffes" at the capo still.  Sohmer, 
Stewart and the Phoenix Steingraber have/do use agraffes on the 
bridge for precise termination/clamping.  This introduces a whole 
other dynamic to the sound requiring "filters" to moderate to 
traditionally accepted piano sound.

All these ideas have been visited, in the end economy does tend to 
eliminate those that are "more subtile"--where the benefit is not apparent.

Andrew Anderson


At 12:51 AM 1/14/2008, you wrote:
>David --
>
>I believe I used the term inharmonicity incorrectly. My apologies. 
>Inharmonicity is caused by the fact that the string doesn't 
>terminate at an exact or perfect point like, say, a hinge, but 
>rather through a bend that does not uniformly reflect the multiple 
>waveforms of the different partials created within a vibrating 
>string at a unique point.
>
>I don't think the primary purpose of a bridge pin is to prevent the 
>string from sliding around on top of the bridge. Like a guitar or 
>other stringed instrument that possibility is minimal. But just the 
>same, because of the high tension and subsequent high partial 
>content of a piano string the tolerance of any string movement 
>across the bridge would be much lower and a bridge pin is very 
>helpful in that regard.
>
>What I'm referring to is the need to make sure that the edge of the 
>notch on the bridge exactly matches the side of the bridge pin so 
>that the string termination at the bridge is the same in both the X 
>and Y axis. If it were not the same then the string is literally a 
>different length on one axis than it is in the other. Since a string 
>moves in all directions when vibrating, not just up and down, if 
>that termination is not exact then the partials created in one axis 
>are different than in the other, creating beats. This is one reason 
>why we make sure strings are seated correctly against the bridge 
>itself, and hope that the bridge notching and the pin placement has 
>been done accurately. It's another reason, in addition to stability, 
>why the movement of bridge pins in cracked bridges is such a problem.
>
>So I understand why matching the termination points for both X and Y 
>axis is important at the bridge. What I don't understand is why it's 
>not a consideration at the opposite end of the string. And like I 
>said, since this is a centuries old practice it's obviously not a 
>significant problem or else we would see X and Y axis termination at 
>both ends of the string. I'm just curious as to why it's not a 
>problem at the agraffe and capo bar end of the string.
>
>For a better understanding of my question check out Reblitz page 
>113, "Ringing, Jangling or False Beats in Treble Strings." I pulled 
>out my copy, (2nd ed), and looked this up and then posed my question 
>here because Reblitz just didn't address the effectiveness of the 
>agraffe/capo bar termination. Perhaps, as you suggest, it's because 
>the counterbearing is so severe that it's just not a problem. I'd 
>just like to understand it a little better. If that's possible.
>
>-- Geoff Sykes, Los Angeles
>
>
>
>-----Original Message-----
>From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] 
>On Behalf Of David Love
>Sent: Sunday, January 13, 2008 8:34 PM
>To: 'Pianotech List'
>Subject: RE: String termination question
>
>Are you asking why there aren't pins at the capo bar (or 
>agraffe)?  Part of the reason there are pins in the bridge is to 
>keep the strings from moving sideways.  The relatively low bearing 
>on the bridge (as compared with the counterbearing angle for the 
>agraffes or capo bar) combined with the bridge surface's natural 
>lubricity would allow the strings to move side to side quite easily 
>especially as the bridge moves up and down.  You don't want 
>that.  You might note, however, that on guitars and other stringed 
>instruments, the strings are not locked into place with vertical 
>pins at the bridge and they don't seem to move.  Anyway, the same 
>problem doesn't exist at the capo or agraffe though leakage can 
>occur where counterbearing angles are insufficient.
>
>
>
>Changing lengths, btw, will not necessarily cause an increase in 
>Inharmonicity, rather a difference between similar strings.  Also, 
>bass string do exhibit a tolerance for different speaking lengths 
>(and different winding lengths) without causing problems with 
>Inharmonicity as evidenced by the number of pianos in which the bass 
>bridge is not individually notched for each set of unisons.
>
>
>
>Of course, I'm not sure if that's what you are talking about.
>
>
>
>David Love
>davidlovepianos at comcast.net
>www.davidlovepianos.com
>
>-----Original Message-----
>From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] 
>On Behalf Of Geoff Sykes
>Sent: Sunday, January 13, 2008 8:05 PM
>To: 'Pianotech List'
>Subject: RE: String termination question
>
>
>
>Wim --
>
>
>
>BUT... As I understand it, one of the important reasons for the X 
>and Y axis to terminate at exactly the same point, (at the bridge), 
>is that if one axis is different than the other then the string is 
>essentially a different length in one axis than the other. This 
>increases inharmonicity and causes conflicting partials in the two 
>axis. This is a similar reason as to why the windings on bass 
>strings must be the same length and end at the same distance from 
>BOTH termination points. I understand that, among other things, 
>equal termination at the bridge equates to maximum transfer of 
>energy to the soundboard, but doesn't unequal termination at the 
>agraffe or capo bar cause distortion in the string waveform that not 
>only increases inharmonicity and unwanted conflicting partials but 
>also a loss in overall energy?
>
>
>
>I don't mean to start an argument. I'm really just interested in the 
>mechanical logic of this centuries old manufacturing practice. For 
>all I know the contribution of any errors at the agraffe or capo bar 
>may be so insignificant as to be unworthy of consideration. I'm just curious.
>
>
>
>-- Geoff Sykes, Los Angeles
>
>
>
>
>
>
>
>
>
>-----Original Message-----
>From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] 
>On Behalf Of Willem Blees
>Sent: Sunday, January 13, 2008 7:22 PM
>To: pianotech at ptg.org
>Subject: Re: String termination question
>
>Geoff
>
>
>
>As Annie indicated, the string needs to go over the bridge for the 
>vibrations to transfer from the string to the soundboard. The string 
>needs to be seated at both sides of the bridge, so that the 
>vibration is transferred without interference. If the string is not 
>seated, then there will not be a solid transfer of the vibrating string.
>
>See what happens when you start thinking.
>:
>
>
>Willem (Wim) Blees, RPT
>Piano Tuner/Technician
>Honolulu, HI
>Author of
>The Business of Piano Tuning
>available from Potter Press
>www.pianotuning.com
>
>
>
>-----Original Message-----
>From: Geoff Sykes <thetuner at ivories52.com>
>To: Pianotech at Ptg. Org <pianotech at ptg.org>
>Sent: Sun, 13 Jan 2008 3:42 pm
>Subject: String termination question
>
>Greetings All --
>
>
>
>I made the mistake of thinking the other day, and I started 
>wondering why piano strings are terminated at the bridge on both the 
>X and Y axis but at the capo bar, or agraffe, on only the X, (or 
>perhaps that's Y depending on how you are looking at it), axis. We 
>go to lengths to make sure the strings are seated properly at the 
>bridge so that there is a definite and precise termination in both 
>planes at the bridge and bridge pin. Why then is the lack of 
>termination in both planes not a problem at the agraffe and capo bar end?
>
>
>
>-- Geoff Sykes, Los Angeles
>
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