S&S D Duplex

[Richard Brekne]

Hi Phil, there are a couple points I seem a bit unclear on below.

Phillip Ford wrote:

>
> 2.  CFT seems pretty clear that he intends the rear duplex to deal with
> longitudinal vibrations, not transverse vibrations.  If I am not mistaken, the
> people who are talking about tuning the rear duplex are talking about moving
> the aliquot to make the back scale length such that its TRANSVERSE vibration
> is a harmonic of that of the speaking length.  Once again, this seems to be at
> odds with the sacred patent.  One could make an argument that doing this type
> of tuning is a good idea and will yield positive results, but it seems to me
> that one would not be justified in using this patent as beatification of that
> practice.

I'm not really sure I see the correlation here. I read the idea that "the back
length is to be some multiple of  1/2 the speaking length" as something one
arrived at empirically. That at the same time this results in this length being a
harmonic relative to transverse vibrations is coincidental to the desired effect
on longitudinals.

>
> 4.  Assuming that you could tune this portion of the string for longitudinal
> vibration, how do you go about tuning something that only your dog can hear?
> And, assuming that we now have machines that could hear this for us, how did
> they go about doing this back in CFT's day?

Low enough in the scale you can certainly hear the longitudinals. I suppose if one
found certain modifications have certain affects down there one could extrapolate
that these same results would be applicable over the rest of the scale. Further
the "whilstling" sound that is supposed to be a result of an inappropriate
configuration is certainly hearable, and certainly responds to variations in
duplex lengths, and for that matter the condition of the termination. Whether this
is indeed has anything to do with longitudinal frequencies is another matter.

> Phil F
>

--
Richard Brekne
RPT, N.P.T.F.
UiB, Bergen, Norway
mailto:rbrekne@broadpark.no
http://home.broadpark.no/~rbrekne/ricmain.html