At 6:54 PM -0800 12/8/01, Stephen Airy wrote: >What do you think is better in a piano with a 142cm >speaking length on low A? Singles all the way >through, or doubles from notes 1 to 10 and singles >(bichords) from 11 to 27, like the piano I'm talking >about is now? I've taken the bridge shape (string lengths) of an old 6"6" Bechstein as a basis for Sample Scale 1, added notes 26 and 27 and put the break after note 10, as on your piano. Your bridge could easily be very different, but the question is about the low bass, so it is probably be somewhat similar. Sample Scale 2 is a scale with similar targets but with a different bridge shape. As it is, you probably have on note A1 a No. 25 core with a 200 - 210 cover, the thickest normally used (Steinway go up to 220 but I can't get it because nobody asks for it). This will give you a tension roughly between 200 and 220 lbf with a strain left or right of 35%, which is low. On most pianos these bottom notes will not sound too good. Practical considerations prevent the spinning of a 210 cover on say a 22 core. It is just about possible, but noone would want to do it, so a 25 core is used mainly just to avoid breakages and the waste of a lot of copper as a result. There is also the question of the ratio of core to cover to consider; Too large a ratio will result in a string that vibrates in a peculiar way, giving rise to discordant partials. This 25/210 string will be pretty stiff at this length. I can't guess what your piano is, but it's probably American. I have just begun work on a 6'6" piano with 140 cm for A1, ten singles and 16 bichords. All the singles on this piano are double-covered, as opposed to the Bechstein which has all s/c like yours and a break at A13. I would prefer the break at 12 or 13 on these pianos in order to get a better transition. Very old pianos with the transition too low very often have a disproportionately rough sort of trombone quality about the lowest bichords. I already mentioned my preference for a single cover down to the point where the strain becomes too low and where it is possible to get a smooth transition. This introduces one more 'break' to deal with but proper treatment allows this to be smooth, just as proper treatment of the other transitions. In the example below, the length of the piano allows me to use a 1:3 under-:top-cover ratio, which gives a closer resemblance of the s/c properties than a closer ratio. I use three basic ratios, normally using one ratio only throughout the d/c section, though sometimes I use all three in succession -- it depends on the scale and what I'm aiming for in the light of various considerations. I make more strings for others than I make for myself and do not impose my own conceptions on customers I know have different tonal aims, though these happen to be in a tiny minority. When the strings are for my own stock pianos, which comprise only makes that I choose, then I tend to work within a fairly narrow range, having first determined the overall tonal qualities of the instrument as a whole. Here are the machine worksheets for the two scales. Sizes are New Westphalia for the steel (not much different from American) and 1/100 mm for the covers. The third column is the speaking length. For Scale 1 I have tapered off the tension from ca. 285 lbf on note 10 to ca. 250 at A1. Scale 2 is the nicer-shaped bridge, though I would put the transition at 12/13, and I have kept the tensions high right to the bottom on this one with almost 300 lbf on note A1. Both scales are simply hypothetical examples. ++++++++++++++++++++++++++++++ SAMPLE SCALE 1 A 1 142.5 23.5 65 175 A# 2 141.8 23.5 60 170 B 3 141.2 23.5 60 160 C 4 140.5 23.5 55 155 C# 5 139.8 23.5 55 150 D 6 138.8 23.5 50 140 D# 7 137.8 22.5 170 E 8 136.8 22.5 160 F 9 135.8 22.5 150 F# 10 134.2 22.5 140 G 11 132.7 20.5 100 G# 12 131.1 20.5 95 A 13 129.5 20 90 A# 14 127.4 20 85 B 15 125.3 19.5 80 C 16 123.2 19.5 75 C# 17 121.1 19 70 D 18 118.5 19 65 D# 19 115.9 18.5 60 E 20 113.3 18.5 55 F 21 110.7 18 50 F# 22 107.8 18 50 G 23 104.8 18 45 G# 24 101.9 18 45 A 25 98.9 17.5 40 A# 26 94.8 17.5 40 B 27 90.8 17.5 35 ====================================== SAMPLE SCALE 2 A 1 139.6 24 85 185 A# 2 139.0 24 80 175 B 3 138.5 23.5 75 160 C 4 137.9 23.5 70 150 C# 5 137.3 23.5 65 140 D 6 136.4 23.5 60 135 D# 7 135.5 22.5 175 - E 8 134.6 22.5 160 - F 9 133.7 22.5 150 - F# 10 132.6 22.5 140 - G 11 131.6 20 115 - G# 12 130.5 20 105 - A 13 129.4 20 100 - A# 14 127.9 19.5 90 - B 15 126.5 19.5 80 - C 16 125.0 19.5 75 - C# 17 123.5 19 70 - D 18 121.7 19 65 - D# 19 119.9 19 60 - E 20 118.1 18.5 55 - F 21 116.3 18.5 50 - F# 22 114.1 18.5 40 - G 23 111.9 18 40 - G# 24 109.6 18 35 - A 25 107.4 18 35 - A# 26 104.9 17.5 30 - B 27 102.1 17.5 25 -
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