Re : INNOVATIVE FRETBOARDS

Estimado John Thaden :

Regarding programs for calculating fret placement:

>Anyway, this thing has been programmed already. First in Basic, by
>Eduardo Sabat and later in Ada, by me, in Scala (the command SHOW
STRINGLEN).
>It calculates fret positions for one string at a time, taking the
>string stretching into consideration. But getting the parameters
>right is rather cumbersome. Also, string stiffness is not taken into
>account and I don't know if its influence can be neglected.
>
>Manuel Op de Coul coul@ezh.nl
----------------------------------------------------

According to my experience with the Dinarra, I can make the following
comments.
In order to deduct my equation I take into account the three physical
states of the chord.
The chords weight the same in each of the different states..
State 0 : Is the chord "as per", before stretching. It has, let's say, 3
to 5
milimeters less than in state 2.
State 1 : Tuned chord in normal tuning. The first chord is tuned at 660
Hz,
the fifth at 110 and so on. The length of the chords are the standard
for the instrument.
I use a length of 650 mm for Dinarra.
State 2 : Pushed string. The value of the total length is the addition
of both
cathetus of the "triangle". The hypotenuse is in this case always 650.
When I handle the physical formulas, the "Modulus of Young" (M of Y) is
eliminated.
I believe this procedure is legitimate. The final formula is formed ONLY
by
lengths. The streching of the chord from state zero to one is related
with the M of Y
which is hidden. M of Y is the relation of length and weight. The
streching of the
chord from state zero to one is the realtion of length and "note"..
This streching of the chords is a constant mathematical value of each
chord.
I call this "Delta L sub zero-one". It has a value of 3 to 5 mm. wich is
the same for
plastic or steel chords, be them torched or not. This value is easily
measured
in steel chords. Both in the Dinarra and in the ordinary guitar the
using of the chords
increases this value till it stabilizes for a reasonable period of time.

The practical solution to have a trustworthy and accurate Dinarra is
making the
length of each chord variable. Bear in mind that the words trustworthy
and
accurate have in this case the same physical meaning than the one they
have
in the study of scales.
The bridge of electrical guitars generally have inside movable bridges
for each
of the chords. There is for acoustic Dinarra a special device wich makes
it
possible to vary the length of each of the chords easily. This device is
very
light and is of my invention.
I have not yet analized mathematically this practical solution but for
now it
is the only one we have got and it works very well in practice.
Working with harmonical echoe in the different chords I was able to
value the
accuracy and trustworth of this device I mentioned above, even thought
I do not have a frequencymeter of direct reading. The result is
efficient enough.

Eduardo
--
Eduardo Sabat-Garibaldi
Simon Bolivar 1260
11300 Montevideo
URUGUAY
email: esabat@adinet.com.uy

URL: http://members.xoom.com/dinarra/dinarra.html