FAC numbers

[Joe & Penny Goss]

Hi again Jim,
Thanks for the answer. It relay does not cover what I hoped it would. You
see, about three years ago ( after becoming better at listening because of
the SAT ) I bought the 160 tunings that are available from Inventronics and
started using those with the reading from F4. This allowed me to bypass the
lack of stretch numbers from C3-A0 and F6-C8. Now ( last week ) I have
updated my list of Stretch Numbers to C1 C2 C3 C4 C5 C6 F6 C8. Finding a
page to use is done by tuning the C's and checking the octaves that the
page produces. Looking at the length of C88 also helps me.
In general it seems that old uprights ( that is what most of the work I do
is ) come closest to matching F4 readings with a little tweak to the sharp
side in the bass and need to be flatter  in the treble above C7. The SAT111
should make this easier for me as the change can be made to the program on
the fly. We are almost getting violent: our expectations  for the new
machine are quite high.
Joe Goss

> From: Jim Coleman, Sr


 
> Hi Joe:
> 
> For a few strange pianos the F4 stretch number works better, but then you
> have to pigtail on the treble and Bass. If you see a problem with the
FAC,
> then switch over to the F4 Stretch system. Sometimes the F3 just doesn't 
> fit the rest of the piano.
> 
> Jim Coleman, Sr.
> 
> On Sun, 23 Aug 1998, Joe & Penny Goss wrote:
> 
> > HI Jim,
> > What are the advantages of tuning FAC as opposed to F4?
> > Was the F4 curve better for some scaled pianos?
> > Joe
> > 
> > ----------
> > > Hi richard:
> > > 
> > > The F, A, and C were chosen for very important reasons. If you know
what
> > the
> > > inharmonicity of F3 is and can locate that note, you know how you
want to
> > > tune Bb0 (it is the 6th partial of Bb0). If you know the
inharmonicity of
> > > A4, you can accurately locate A4, A3, A5, A6 and A7. If you know the 
> > > inharmonicity of C6, you can locate C6, C7, and C8. If you can locate

> > > all of these, then you can do a mathematical smooth curving of the
> > plotted
> > > points and have a complete tuning for the piano. Sure, you could
measure
> > > all of the notes and make a more precise tuning (maybe), but it is
not 
> > > practical except in Lab work. It takes a very lengthy computer
program to
> > > do this. There is another wise choice Dr. Sanderson made in choosing
> > these
> > > notes and the partials by which all notes are to be tuned. The Bass
is
> > tuned
> > > from A0 thru B2 using the 6th partials. The section from C3 thru B4
is 
> > > tuned using the 4th partial. The section from C5 thru B5 is tuned
using
> > the
> > > 2nd partial. In each of these section these are the most important
and 
> > > usually the strongest partials to be heard.
> > > 
> > > The reason for measuring the difference between the 4th and 8th
partials
> > > of F3 is because you get more consistent answers as to the the
general 
> > > inharmonicity of that note. The same goes for the A4 (using 2nd and
4th 
> > > partials) and for C6 (using 1st and 2nd partials).
> > > 
> > > There is no attempt to try to tune the 5ths. If the scale of the
piano
> > > is rather decent, they will come out pretty good. If the scale is not
> > good,
> > > you cant do much better anyway. Oh sure, you could give more
attention 
> > > to the 5ths, but this would be at the expense of consistency in 3rds,

> > > double octaves, 10ths etc. You can't have it all on a poor scale even
as
> > > "you can't make a silk purse out of a sow's ear".
> > > 
> > > Once an inharmonicity curve is plotted, you can tune any note by any 
> > > partial you wish. Just think how many intervals are controlled by the
4th
> > > partial which is used in the most critical part of the tuning.
Octaves 
> > > (4-2 relationship), M3rds (4-5 relationships), 5ths (6-4
relationships),
> > > P4ths (3-4 relationships), m7ths (4-7 relationships). I just can't
think
> > of
> > > any other partial which affects so many intervals. Oh, I forgot
Double 
> > > Octaves (4-1 relationships).
> > > 
> > > Tuning Octave 5 by the 2nd partials gives more accuracy than tuning
by 
> > > the fundamental. Above that, the fundamental is strongest and best to
> > tune
> > > by.
> > 
> > 
> >