Article about bridge agraffes - function, types

[Calin Tantareanu]

Ric,

All the things I wrote are based on 3 things: my reasoning of what can go on
with such s device, what I heard in pianos with and without bridge agraffes,
my own experiments with string terminations. So the whole article represents
my opinion. It is not based on the research of others because I am not aware
of such research.
Everybody is free to from his/her own opinion about what I say, I'm not
trying to present it as scientifically demonstrated, just as something that
seems quite sensible and logical.
I invite anybody who has such data or did such research to tell us where it
can be found.

Read below: 

> -----Original Message-----
> From: pianotech-bounces at ptg.org 
> [mailto:pianotech-bounces at ptg.org] On Behalf Of RicB
> Sent: duminică, 19 noiembrie 2006 14:42
> To: pianotech at ptg.org
> Subject: Article about bridge agraffes - function, types

> 
> 2nd you declare that the larger footprint of the agraffe on 
> the wood of 
> the bridge itself will cause the rest of the assembly to vibrate more 
> because the string will not be able to dig into the wood as 
> it vibrates. 
> This also needs documentation.   A couple of points on 
> this... I would 
> think this claim were were true... it would be true for all 
> frequencies 

It is not true for all frequencies. I stated repeatedly that a string
bearing against a wood cap/pin and digging into it mostly the highest
frequencies. As you go down the scale the effect decreases, to the point of
becoming probably negligible.

> and you would be able to measure a significant output increase across 
> the board.  I would also point out that the string is terminated at 

The significant output increase is in the top treble, not across the whole
scale.

> least as much by the pin itself, which while not having as big a 
> footprint in the wood of the bridge as an agraffe... certainly is far 
> harder then wood.  Then there is the matter of what degree 
> the presumed 
> lessened "efficiency" of the bridge/pin assembly becomes significant 
> enough to make a measureable difference in this context.

The pin is harder, but the wood which touches the string acts like a damper
for very high frequencies. I exaggerate this to make my point, but that's
what happens.
Piano makers have long used the hardest woods in the top treble caps. I
believe they recognized the need for a very stiff material there, to
minimize energy loss. The bridge agraffe is another quite efficient) way of
reducing energy losses where it matters most.

> 
> 3rd... which moves on a bit... you couple the above two to 
> the increase 
> in sustain seen in some agraffe pianos... presumably looking 
> away from 
> the added mass of the brass and other design issues that 
> accompany such 
> instruments that we already know significantly contribute to 
> sustain.  I 
> dont think you can do this without further ado without 
> qualifying this 
> as conjecture.


I'm not saying mass doesn't influence tone. It does. But I'm saying that
mass alone, while it can help, is not sufficient to get the most of the
piano's treble if you keep a traditional bridge cap/pin. A bridge agraffe
helps by wasting less energy.
Using a bridge agraffe doesn't mean one shouldn't take their weight into
account or use supplemental weights to adjust the soundboard's response to
the string scale's energy input.

> 
> Without supporting documentation, none of this can be substantiated, 
> and... if in the end it turns out you actually can not defend these 
> claims thus... you will end up in a rather uncomfortable position I 
> would think.


I am actually very comfortable in my position. I don't see a conflict or a
need to defend myself and I hope others will be encouraged by my article to
do further research on bridge agraffes, string terminations, mass loading
etc. 
I'm not attacking any theories, just presenting my opinion on a device which
I believe can help piano builders make a better piano.

Calin Tantareanu
http://calin.haos.ro
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