Wapin revisited

[John Delacour]

At 12:02 am +0200 13/8/06, Ric Brekne wrote:

>...Wapin installation...A lot of unanswered questions remain in my 
>head about just what is going on.

Hello Ric,

The Wapin site shows only one small picture of a bridge fitted with 
the Wapin, and it's not quite clear to me how things are arranged. 
It looks as if the vertical front pin is positioned where the 
customary slanted front pin would be and very close behind, say 3mm 
clear of the notch, is a third pin at the same angle as the back pin. 
This third pin seems to have the sole function of preventing the 
string working its way up the vertical pin with time and use, as can 
happen, amazingly, even with a slanting pin -- one of the first 
things I do to a piano that has has no attention for a while is tap 
the strings down to the bridge, and this can sometimes cure the most 
unpleasant noises.

With the intermediate pin so close to the front vertical pin, I'd 
guess that the tendency for the string to ride up the front pin is 
very much reduced even though the front pin is vertical; the string 
is, I imagine, more tightly clamped to the bridge than in the 2-pin 
arrangement.  Is that so?

>Seems like the origional back bridge pin becomes actually superflous 
>and could be removed...

For several reasons I think not, the main one being that the side 
draft on the two front pins would be so great that they would be 
forced apart.

>... which then raises questions around why pianos traditionally 
>choose so much space between front and back bridge pins.

The greater the distance between them the less the crushing force on 
the top of the bridge, but some models of Steinway, for example, have 
the pins quite close together.  I'm not sure its very relevant to the 
matter of the Wapin pin.

>   Then there is this bit about sidebearing... or lack there of.  Ok 
>there is sidebearing in the wapin... but the initial pulse is not 
>inhibited nearly so much vertically as with a slanted pin.  I've 
>read back and forth comparisons between Wapin and bridge agraffes 
>employed by Stuart and others and it struck me that this is at least 
>one point they have a bit in common.  In a traditional slanted 
>bridge pin the pulse reflection is to no small degree affected by 
>that angle. It exerts a somewhat sideways force on the string which 
>might think right off would be itself conducive to longer sustain.

Doesn't Stuart claim that owing to his costly agraffe things the 
strings vibrate vertically?  I'd be interested to know what happens 
to a Wapin string under a forte-fortissimo blow.  When I tried such a 
thing once with a Stuart the result was rather shocking, and I'll say 
no more.

>  After all the soundboard moves more readily up and down and would 
>quickly absorb most strictly vertical motion... as the reasoning 
>goes.

Whose reasoning?

>   Yet there it is. In both the Wapin and the bridge agraffe the 
>vertical element is significantly less restrained... and in both 
>cases sustain goes up with no apparent loss of power... at least in 
>the case of the Wapin.

The longer sustain that you claim for it would be due, I think, only 
to the greater firmness of the clamping action of the two contiguous 
pins which assures a more definite termination to the speaking 
length.  It's my guess that if you added the intermediate pin without 
changing the front pin you might get just as great an improvement. 
That is my intuitive take on the matter and I could be quite wrong. 
Ideally one would weld the string to the bridge.  An improvemnt could 
probably be made by having a screw behind the front pin (which might 
be either vertical or angled) and as close as possible to it.  It all 
comes to the same thing : how securely unified with the bridge is the 
termination of the speaking length, in other words how little loss of 
energy is there at that point.

JD