Wapin Bridge

[Richard Brekne]

Clark wrote:

> Bill, et al.
>
> I think the Wapin bridge termination is intriguing.

Me too.. and I would like to see more specifics about this thing. Contacting him
late last year didnt make me "secure" enough to invest any money, and reading the
info on his web-site was no more then reading a page of claims with a few graphs
attached. I certainly look forward to finding more about just how this thing does
what it claims.

> Now Richard Brekne's postings about the other end of the string at the capo bar
> provide more than adequate background for visualizing the function of the Wapin
> bridge. Is it found that its more hinged arrangement lowers inharmonicity
> compared with traditional clamped types?

I dont want this overstated, Clark. Fact is the whole buisness has not been really
thoroughly investegated as far as I can see. What is known is that in theory there
are two possibilities, and there is plenty of math to describe each (clamped and
hinged). It is also known that real termination points (front) always fall somewhere
in the middle (the main thrust of Coltmans article) Coltmans experiment did not use
differeing termination points, but was more concerned with changing parameters for
string characteristics. Exactly to what degree inharmonicity is effected by altering
the profile of the front termination is not (as far as I know) known nor been
explored. What seems clear to me is that approaching one or the other type of
"theoretical" terminations by altering the profile of the termination should result
in inharmonicity measurements that also approach (to some degree) the results
expected from mathamatical models of these theoretical terminations. To what degree
this can be useful, is an unknown and to my knowledge has not been researched.

That being said.. McMorrow states outright that the hinged profile lowers
inharmonicity, by allowing the string to flex at the termination point... thereby
loweing stiffness. I believe his source from this is McFerrin but I am not sure.

I will write down a bibliography of papers, pages etc of the different papers and
books I have that touch on all this and send along.

>
> These tests would be interesting to make, but I'm not really willing to pay a
> licensing fee to do them myself; it might be illuminating to do them outside of
> pianos, in more controlled situations.
>

aggreed ... grin

>
> Looking forward to further information,
>
> Clark

--
Richard Brekne
Associate PTG, N.P.T.F.
Bergen, Norway