Acrosonic temperament tips w/ SAT Needed.

[Jim Coleman, Sr.]

Hi Dave:

I have an acrosonic temporarily. Its S/N is: 406219 probably made in 60's.

The FAC stretch numbers are 10.1, 7.6, & 6.4. These were stored on Page 1
On page 2 of memory I stored 20.0, 7.6, & 6.4

I used page 2 for all notes from G3 to C8. I measured G3 diff between 
4th and 8th partials and then stored them at F6 as though I were measuring
F3. The machine truncates the value of G3 which was 25.3 down to 20. Dr.
Sanderson says that if you use a higher number, the math gets messed up.
Therefore to even out the beating of the M3rds in the break between the
tenor wound strings and the lower plain wire, it is necessary to make the
SAT readings on page 2 a little lower on a graduated basis.
Here are the SAT reading taken for the 4ths partials of each note in area.

    Notes              G3   G#   A3   A#   B3   C4   C#   D4   D#   E4   F
    SAT values Page 2  0.0  0.6  1.3  1.8  2.4  3.0  3.6  4.3  5.1  5.6  6.3
    Additional corr.  -0.8 -0.6 -0.3 -0.1  
    Final value       -0.8  0.0  1.0  1.7  2.4  3.0  3.6  4.3  5.1  5.6  6.3

If you wished to make the M3rds come out even better, you could raise 
the highest wound strings in the tenor thusly:

       E3   F3   F#    Notes
      -0.9 -0.4  0.0   SAT values Page 1
       0.1  0.2  0.3   Additional corrections
      -0.8 -0.2  0.3   Final value

Caution! If you use these additions to the wound strings, the F3 5th will
beat even faster. Without these values, the 5th will beat more than 1 
bps already. and the G3 5th will already be on the wide side, but will 
sound good. People who tune primarily with 4ths and 5ths will always have
very fast F3 and F#3 M3rds and the G3 and G#3 M3rds will be way too slow.
That's just the problem with a scale like this. It can't be tuned in the
normal way. This is why I suggest to aural tuners that they tune their
temperament from A3 to A4 with a fairly good stretch, so that when they
work across the break, they can make judicious changes to smooth out the 
3rds. and still keep reasonably good octaves, 4ths and 6ths. Of course the
cost is in some variation in the minor 3rds and 5ths.

Just a side note for those who may not have read my previous post on this
particular piano, when I was at Baldwin I suggested to my boss that I could
redesign the tenor scale so that it would be easier for aural tuners. His
comment was: "Jim, that piano commands 40% of the market, we're not about
to change it." Well, maybe he was right. Everyone else has dropped out 
of the spinet market by now, I still think I was right. You still can't tune
the piano in that area. My figures above will give about the best 
compromise. I could raise the C4 and C#4 a little to help the too narrow
5th at F3 and F#3, but that would just cause some more uneveness higher up
where the scale is pretty good.

Jim Coleman, Sr.



On Sat, 14 Feb 1998 DGPEAKE@aol.com wrote:

> In a message dated 98-02-10 16:33:54 EST, you write:
> 
> << 
>  If you have difficulty figuring out what I have just tried to explain,
>  write me privately and I will give you some specific figures for each of 
>  the notes in that area along with FAC stretch numbers.
>  
>  Jim Coleman, Sr.
>   >>
> I would like a copy too.  I responded to Mark's post as well.
> 
> Dave Peake, RPT
> Portland, OR
>