Stringing practice

After all the verbiage in the previous post, the question still begs to be answered: how does one actually string a harpsichord?

The old makers often used a system of numerical progression. For Italian harpsichords with a scale of about c''=280 mm, they used a simple rule of thumb like this, starting from the top down:

10 wires of #10 gauge
9 of #9
8 of #8
...

and so on.

There is a certain numerological elegance to this system, and possibly that was part of its appeal. From a practical standpoint, as one descends the compass, the string gauges change more frequently. This makes sense because the sounding length of the strings changes rapidly as the bridge curvature straightens out, which the progressive stringing system takes into account.

Gauge numbers are sometimes found inked or stamped onto the wrestplanks of old harpsichords, showing which gauges were used and where they changed. The numbers in German and Italian harpsichords correspond to the old Nürnburg gauge system, which had at least 10 different diameters. Based on measurements of surviving wire fragments, the closest modern equivalent diameters are:

#10 = 0.008" = 0.20 mm
#9 = 0.009" = 0.23 mm
#8 = 0.010" = 0.25 mm
#7 = 0.011" = 0.27 mm
#6 = 0.012" = 0.30 mm
#5 = 0.013" = 0.33 mm
#4 = 0.014" = 0.36 mm
#3 = 0.016" = 0.40 mm
#2 = 0.018" = 0.46 mm
#1 = 0.020" = 0.52 mm

Note that the U.S. and metric units are not exact conversions of each other (for example, 0.020"=0.508 mm, not 0.52 mm). The chart is, as stated, a list of the closest available modern diameters.

Our knowledge of the Nürnberg gauges is complicated by the fact that exacting measurements of surviving wire are skewed by centuries of corrosion. Another significant issue is the gradual increase over time in the diameter of historical wire as the holes in the draw plates wore out and got larger. Draw plates were extremely valuable—literally worth their weight in silver—and wire makers were not anxious to dispose of them just because the wire was getting a tiny bit thicker. So, at best, the old gauge system represents a range of diameters instead of a single precise number.

I decided to use this system of numerical progression in stringing my own harpsichord, with one caveat. Several modern makers report that better results are obtained by stringing one gauge heavier, which means 10 wires of #9 and so on. I've adopted this modification as well.

Given the 50-note range of my keyboard, it should be clear that the stringing will end in the bass without having employed all 10 gauges shown above. An instrument with exactly 4 octaves will use 7 gauges. I'll need one more because of my extra low note. The extra pair of strings at the top (which provide c''' at A=440 Hz) are strung with #9 gauge but are not counted as part of my overall tally.

If you look at my tension chart in the previous post, you'll see two columns off to the right where I mapped out gauges by numerical progression, one column starting with #10 gauge, the other with #9. The equivalent gauge numbers are also listed horizontally just below each metric diameter along the top.

The very last wire for the note GG/BB needs a little extra thought. Since it is a third lower than the keyboard key assigned to it, I'm going to try stringing it in 0.56 mm/0.022" red brass. This is pretty thick stuff, but I have a German harpsichord here at home that has a similar GG string length, and it's strung that way. I'll find out whether that's a good idea once the instrument is up to pitch.