You quoted from the letter from Jim Spriggs:

> The problem that you posed regarding "meantone tuning" for the
> Wurlitzer 150 has led to, I believe, a serendipitous solution. The
> solution is de Caus' "just" tuning scale, which for the Wurlitzer is
> ideal. The 150 can only play in the keys of "C" and "G", the latter
> only occasionaly being used.  This makes it possible for all of the
> chords normally used (tonic, dominant, and subdominant) to be totally
> without beats (eureka!). Much more information will follow. It would be
> well worth tuning the 150 in that fashion. I might write an article for
> the Bulletin on it if you find that it really sounds better.

Great!  That's just the conclusion I reached after staring at the real
frequencies.  In the table below I have _assumed_ a value for the D# so
that it is zero-beat in the C-minor chord.  I hope that this is
confirmed when you hear from Jim Spriggs.  The last two columns, "de
Caus frequency", may be multiplied by the standard pitch to get the
actual frequencies.  For example, for the best match with the equally
tempered scale based on A = 440 Hz, the note C may be adjusted to
zero-beat with a tuning fork at C = 261.63 Hz (which is 0 cents
deviation from the A440 standard).

•   note   Equal  de Caus   de Caus   de Caus
          cents   cents     freq      freq

     C       0      0      1.0         1/1
     C#    100     71      1.04167    25/24
     D     200    204      1.125       9/8
     D#    300   (315.5)   1.2         6/5
     E     400    386      1.25        5/4
     F     500    498      1.3333      4/3
     F#    600    590      1.40625    45/32
     G     700    702      1.5         3/2
     G#    800
     A     900    884      1.66667     5/3
     A#   1000
     B    1100   1088      1.875      15/8

•Because the "de Caus just tuning" is designed for zero beats, it is very
simple to tune "by ear".  Here is the algorithm:

   1. Strike the tuning fork, adjust C for zero-beat.

   2. Sound C, adjust G, and then E, all for zero-beat.   (the tonic chord)
(Then re-check that C and G are zero-beat.)

   3. Sound C and G, adjust D# for zero-beat.           (tonic minor chord)

   4. Sound G, adjust D, and then B, all for zero beat.    (dominant chord)

   5. Sound D, adjust F# for zero-beat

   6. Sound C, adjust F, and then A, all for zero-beat. (subdominant chord)

   7. Sound A, adjust C# for zero-beat.

I am eager to hear the "before and after" comparison recording of your
Wurlitzer 150 organ.  Steve Goodman tells me that "this is the way it
ought to be tuned!"

Cheers,

Robbie Rhodes