Article about bridge agraffes - function, types

[Calin Tantareanu]

Hi!
 
Read below:

> -----Original Message-----
> From: Cy Shuster [mailto:cy at shusterpiano.com] 
> Sent: sâmbătă, 18 noiembrie 2006 23:32
> To: Calin Tantareanu
> Subject: Fw: Article about bridge agraffes - function, types

> One improvement would be if you could add the time period 
> during which each 
> type of agraffe was used, for a given manufacturer (if you 
> know), or perhaps 
> a serial number or two.  For example, were the Sohmers from 
> the 1920's?  How 
> old was the Schumann?

I don't have this information, unfortunately.

> 
> It's also interesting that both Stuart and Paulello use the 
> "sound filter". 

Steingraeber uses it too. Look closely at the agraffes. They have a piece of
brownish felt that's hard to see.

> This seems to counter your original assumption about standard 
> bridge pins, 
> namely that the wood cap allows high frequencies to pass 
> through, where 
> bridge agraffes do not.  Is that what you meant?

It actually supports my assumptions. Wood caps are weaker and more flexible
than a bridge agraffe. So a bridge agraffe can be TOO EFFICIENT, in that it
can make higher partials audible than what you'd get with standard bridge
pins. Some of these higher partials are not always desireable (especially
above the 7th). That's why they use the filter, to "tune" the harmonic
content.

> 
> Another standard assumption is that the added weight of the 
> agraffes changes 
> the impedance of the bridge, like other mass-loading schemes.

Weight can have a role too, but I can't say how great.

> 
> Lastly, why exactly do the Sohmer agraffes split the bridge?  
> Isn't the 
> force on them straight down?  Why did they need the second 
> bearing point? 

The force of the string bearing on 2 points tends to rotate the agraffe, the
wood might have been too weak too. That's why it split.
I find the Sohmer agraffes the least desireable of the lot. Although I read
that they work fine.

> Couldn't they have just made the bridge narrower?  Is that 

They could, but then the string would bear only on the agraffe. Which is
fine as long as you have lots of downbearing, but if downbearing isn't
there...

> second bearing 
> point just a raised mound of wood?

Yes.

> 
> Thanks again,

You're welcome,

Calin Tantareanu
http://calin.haos.ro
--------------------



> 
> --Cy--
> 
> ----- Original Message ----- 
> From: "Calin Tantareanu" <calin1000 at gmail.com>
> To: "'Pianotech List'" <pianotech at ptg.org>
> Cc: "'Ray Klapwyk'" <rayklapwyk at msn.com>; "'Bill Hollinger'" 
> <billh96007 at mac.com>; "'Christoph Schreiber'" <tastenfreund at gmx.de>; 
> "'Hurstwood Farm Piano Studios'" 
> <dain at hurstwoodfarmpianos.com>; "'Daniel 
> Lindholm'" <daniel at instrumenttekniker.se>
> Sent: Saturday, November 18, 2006 12:52 PM
> Subject: Article about bridge agraffes - function, types
> 
> 
> > Hello all!
> >
> > I have uploaded an article on my website about the function 
> and different
> > types of bridge agraffes.
> > This is the direct link:
> > http://calin.haos.ro/c/instruments/bridge_agraffes/index.htm
> >
> > Let me know what you think. I'd also like to know if you 
> have any other
> > pictures & information which I could add to the article.
> >
> > Calin Tantareanu
> > http://calin.haos.ro
> > --------------------
> >
> > 
>