Hi to all the faithful: Many have asked about tuning small spinets like the Acrosonics. When I worked for the company, I developed a method which always gave satisfactory results in the temperament area. This involved carefully setting the temperament between A3 and A4. Of course this involves listening to higher beat relationships is helpful. It helps to stretch this octave as much as possible. I found using the 6-3 type octave matching where the minor 3rd A3-C4 would beat the same as the M6th C4-A4. This can even be stretched a little more, so that the minor 3rd is just barely slower than the M6th. In tuning downward from this area, the next two notes need to be especially lowered so that their 5ths are pure (would you believe I have even tuned them on the wide side occasionally?). This helps to keep the M3rds G-B and Ab-C4 from slowing down too much due to their greater inharmonicity. Then when tuning the F#3 which is the highest wound string on an Acrosonic, it may be necessary to tune this with its octave F#4 as a pure 6-3 octave. This keeps its M3rd from being too fast. There may be a resultant 5th which is a bit narrower than you would like, but rejoice, the M3rds will fit better. Follow this same procedure on down into the Bass, trying to keep the M3rd decreasing in speed as you go, but giving some attention to the 5ths that they not be too busy. It's a compromise all the way, but give more attention to the overall sound of the octaves, letting the 3rds and 10ths guide you. Tuning the treble of the Acrosonic is a dream, one of the nice compensations in life and this is what has made the piano the most popular of all spinets. Below is a list of inharmonicity readings taken with the TuneLab program. In it you can see why so much juggling is necessary. 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 ? The lower partials of the notes around the break display quite a bit of irregularity. Wound strings were placed in the Tenor section in order to keep the tension level up. This was at the cost of a big jump in inharmonicity going from the wound to the plain wire. I put a space in the chart above to indicate the break between the wound and the plain strings and between the Bass and the Tenor. Other spinets which have wound strings in the Tenor have similar problems, but using the general rule that the lowest plain strings are to be tuned a little flatter and in some cases the highest wound strings to be tuned a little sharper usually will help in smoothing out the temperament area across the break. Jim Coleman, Sr.
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