capo and V bar (was digest V1997#1919)

[Richard Brekne]

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Stephen Birkett wrote:

> Richard writes:
> > In theory two perfect circles touching will give an infinite contact point,
> > ( just imagine they don't touch, grin.)
> >
> You mean an infinitely small contact point. But that theory is far from
> reality as it assumes materials are incompressible, which is far from true.
>
> > A couple points from Ed's book are interesting in this regard.
> >
> What Ed? What book?

Ed McMorrow  "The Educated Piano" from 1989. Good reading.

>
>
> > The affect on the duplex makes sense, if we agree that the wider and
> > roundethe termination point is, the more this inhibits the power of the forward
> > duplex. This "power" can also be controlled by the tuning of the duplex scale.
> > I have done this as per Eds' specifications several times and it never fails.
> > A non harmonic duplex (ie tuned to a triple octave and a second above the
> > fundemental, or a triple or double octave and a 6th) allows for plenty of
> > duplex power, without robing energy from the fundemental.
> >
> > Still.. I would like to read Conklins material on this.. I dont think its part
> > of the Askenfelt lectures is it ?. If not can you suggest a place to find any
> > of his written material on this ?
> >
> You might get hold of "Design and tone in the mechanoacoustic piano.
> Parts I, II and III" J. Acoustical Soc. America Vol 100, 1286-1298,
> 695-708 and Vol 99, 3286-3296.

Thanks.. I will try and get ahold of it.

>
>
> There isn't much in these about capo and V bars, but he does comment that
> capo bars have major vibrational modes in the 1-2 KHz range. He also
> contradicts what you seem to be saying in the quote from the Ed book
> about tuning the front duplex.
> >From part II harold says: " Nothing touches the span betweent he two
> points (front termination). With this arrangement losses beyond the
> second deflection point have only a small effect on the tone. It has
> sometimes been believed that better tone can be achieved by tuning the
> intermediate spans to harmonics of the speaking length. Actually, it is
> best to tune the intermediate spans away from the fequencies of the
> speaking-length partials; if they reonate too near the speaking length
> partials, beats will be generated that can give a rough quality to the tone."
>

The underlined part is exactly what Ed is saying with regards to the duplex. He says
tuning the duplex (front) to harmonics of the fundemental of the speaking length is
bad, robs energy from the speaking length.

I am not sure what the first part of the paragraph is getting at. Will have to read
the article when I get it.

>
> Last bit from Part II Harols mentions the "alternative treble string
> terminating schemese have been used successfully in some contemporary
> grand pianos" and quotes his own patent: U.S. patnet # 3,477,331 "Forward
> termination means for the speaking length of piano strings and the like
> (11 November 1969).
>

Will read his patent to find out what the "alternative treble string terminating
scheme is"

>
> Stephen
>
> Stephen Birkett Fortepianos
> Authentic Reproductions of 18th and 19th Century Pianos
> 464 Winchester Drive
> Waterloo, Ontario
> Canada N2T 1K5
> tel: 519-885-2228
> email: birketts@wright.aps.uoguelph.ca

Thanks for the input Stephen. And for the references to the article and the patent #.

Richard Brekne
I.C.P.T.G.  N.P.T.F.
Bergen, Norway

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