Article about bridge agraffes - function, types

[Calin Tantareanu]

 Hi John!

> -----Original Message-----
> From: pianotech-bounces at ptg.org 
> [mailto:pianotech-bounces at ptg.org] On Behalf Of John Delacour
> Sent: duminică, 19 noiembrie 2006 00:47
> To: Pianotech List
> Subject: Re: Article about bridge agraffes - function, types

> An interesting article, Calin.  Thank you.
> 
> I have a totally irrational aversion to these frightful things.  I 
> think you might mention the effect the various types have on the 
> tuning stability of the piano.  I have never met a tuner who does not 
> curse the Broadwood bridge agraffes.  You might also mention that 
> many of the better makers have capped the treble end of the bridge 
> with boxwood.

I don'ty know the Broadwood agraffes. I'd be very grateful if you could send
me some pictures and more info on them and I'll include them in the article.
I think there is no need for aversion to agraffes of the steingraeber or
stuart types 9can't speak for the otehrs as I didn't hear them).
I haven't heard anybody to complain about tuning instability caused by them.

> 
> No matter how shallow these devices they reduce the height of the 
> bridge compared with what it would be without them in a given piano, 
> and bridge height is a most important, and too often neglected, 
> factor in tone-building.

Well, the Steingraeber type agraffe does only reduce the bridge height by
maybe 3-4 mm. I think this can be easily compensated for by mounting the
plate higher, or the sounboard lower, whatever.

> 
> It might also be mentioned that whatever advantages at the 
> termination of the speaking length Stuart aims to gain, he is enabled 
> by the use of his 3-bearing stud to achieve the "floating 
> soundboard", with no down-bearing, to what advantage I was unable to 
> detect when I met one of his pianos.  At the same event he claimed 
> that these things favoured the vertical excursions of the vibrating 
> strings.  No movies were shown to back up this claim.

I am familiar with the Stuart claim about improved vertical vibration. But I
don't really think it is the case, at least not until I see more evidence.
To me, the only advantage of bridge agraffes lies in improved high frequency
transmission efficiency when compared to traditional terminations.
That's all, but it's enough to justify the expense in a good piano.

Calin Tantareanu
http://calin.haos.ro
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