Here is a simple suggestion for tuning Acrosonic spinets using the new Sanderson Accutuner III. Later I will write on doing something similar for the SAT I and SAT II. Measure the FAC Stretch numbers in the normal way, except instead of measuring the F3 which is a wound string, measure the difference between the 4th and 8th partials of G3. This will usually be 25.3 cents. Just before storing this stretch value change the note to F so that the machine will think you measured F3 Stretch. Your values for F3, A4 and C6 will be 25.3, 8.1, 10.1 respectively. After selecting a Page of Memory and doing the rollover technique between the Strech button and the Mem button, begin tuning downward from A4. When you get to C4, hold down the blue shift button and touch the UP CENTS button one time to increase the Double Octave stretch by .1 cents DOB. At B3, increase the DOB to .2 cents, At A#3 increase the DOB to .3 cents. At A3 increase the DOB to .4 beats stretch in the double octave. At G#3 increase the DOB to .6 cents. At G3 increase the DOB to .8 cents. At F#3 eliminate the DOB by holding down the blue SHIFT button and hitting the Dn CENTS button until it is at zero. The wound string in the Tenor can be tuned without any other change. However, you may wish to tweak the F#3 with a -.1 DOB and a -.2 DOB for the F3. THis type tuning will keep the major 3rds well inline and the octaves will sound good. a couple of the 5ths will be a little narrower than usual and a couple of 4ths will be just a little busier, but this is about as good as can be had with this scale. When you run the minor 3rd - Major 6th tests for the octaves, you will find them to be rather consistent throughout this area. The outside 6ths and inside M3rds will also be improved. Below are the inharmonicity values which were taken with TuneLab. You can see from this why it is necessary to alter the tuning of the lowest plain string notes due to their high inharmonicity. partials 2 3 4 5 6 7 8 9 10 C3 0.00 0.6 0.75 0.35 1.72 2.80 4.21 5.95 11.06 14.76 C#3 0.00 2.59 2.01 5.02 7.20 10.21 13.09 16.53 24.01 33.44 D3 0.00 2.17 4.08 4.62 7.29 10.21 13.31 4.93 24.76 34.80 D#3 0.00 2.76 4.69 6.20 8.73 11.64 14.69 18.15 26.42 36.20 E3 0.00 2.26 2.88 4.49 5.41 8.37 10.37 13.91 20.26 ? F3 0.00 2.77 3.57 4.81 6.33 8.53 10.94 13.00 19.79 11.99 F#3 0.00 4.10 4.81 5.95 7.44 9.20 11.33 14.03 ? ? G3 0.00 2.27 5.71 9.38 14.73 20.90 28.42 ? ? 48.43 G#3 0.00 0.83 4.57 8.12 13.18 19.05 26.12 33.99 30.65 32.10 A3 0.00 1.57 3.90 7.34 11.92 17.17 23.72 30.99 48.19 68.96 A#3 0.00 0.48 2.77 6.53 10.91 16.50 21.63 30.26 47.52 -8.25 B3 0.00 1.85 3.86 7.23 11.31 16.40 22.25 28.90 44.30 -12.07 C4 0.00 0.78 2.83 6.40 10.53 15.63 21.79 28.62 45.87 64.74 C#4 0.00 1.55 3.86 7.54 11.77 17.07 23.31 30.44 5.34 -7.28 D4 0.00 1.90 4.70 8.62 13.14 18.68 25.52 32.65 50.60 45.12 D#4 0.00 1.10 5.03 8.33 12.85 18.14 24.62 30.49 48.92 69.20 E4 0.00 0.30 4.00 7.83 12.35 17.89 24.54 32.07 49.80 -8.34 F4 0.00 2.01 4.81 8.65 13.62 19.34 26.49 34.14 52.94 38.55 F#4 0.00 2.26 5.04 9.14 14.80 21.07 28.79 37.34 57.94 29.03 G4 0.00 3.51 6.72 11.18 16.84 24.03 32.06 41.64 ? ? G#4 0.00 4.32 8.11 12.87 19.61 27.02 36.41 46.38 -2.35 23.31 A4 0.00 1.06 4.87 9.31 15.72 22.86 31.78 41.64 -5.44 ? I have place a space between the wound strings and the plain strings. If you look at the 6th partials at the break, you will see that there is twice as much inharmonicity in the plain string as in the F#3 wound string. This shows why the lower plain strings need to be lowered in pitch for better matching. You can also notice that there is more irregularity between the lowest partials than there is among the higher partials. This is a good reason for using the higher partials in tuning, i.e. controlling with the Major 3rds and 6ths, etc. This particular piano is very difficult to set a good temperament using only 4ths and 5ths because of the irregularity of the lower partials. Jim Coleman, Sr.
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