Russell Collection of Early
Keyboard Instruments

HS1-A1620.2: Single-manual harpsichord, anonymous. Naples, c.1620.

Re-stringing the anonymous single-manual Italian harpsichord

Stringing material:
The choice of stringing material for a harpsichord depends upon both the string scalings and the design pitch. At a pitch a¹ = 415.3Hz, a semitone flat to modern pitch, treble string scalings based on c² of about 345-355mm require iron stringing, and treble scalings of about 285-290mm require brass. The table below of the 8' strings scalings of the anonymous Russell Collection harpsichord shows that they are designed around a c² scaling of 266"mm (9" Florentine soldi = 266.6mm), so that b¹ has a scaling of 280mm instead of c². This suggests that brass is the appropriate stringing material with the instrument tuned to a pitch a semitone higher at a¹= 440Hz.

Long 8':
 

Notes	String Length	Plucking Point
d³	113	63½
c³	129	67
f²	201	80
c²	265½	90
f¹	385½	103
c¹	517½	112
f	768	121½
c	1010½	129
F	1412	136
D	1431	140½
C	1480	141½
D	1529	144

These scalings are plotted in the graph below. The red brass/yellow brass transition scaling at 217mm appropriate to the pitch a¹ = 440Hz has also been drawn in:

Hence the three notes on the separate bass section of the bridge should have strings of red brass a nd the whole of the rest of the instrument should be strung in yellow brass. The string diameters can be calculated from Taylor's formula (see the back page) using the standard string tensions for Italian harpsichords, modified for the pitch and compass of this particular instrument (see the graph on the back page). The table opposite shows the calculation of the 'ideal' diameters for each note, and the closest available diameters approximating these, both in mm:

Note	Frequency in Hz	Length in mm 8' Length		Tension in kg wt 8' Tension	'Ideal' Diameter	Available Diameter
d³	1175	113	2639	1.98	0.206	0.21
c³	1109	121	2639	2.05	0.208	0.21
c³	1047	129	2639	2.11	0.209	0.21
b²	987.8	137	2639	2.17	0.211	0.21
b²	932.3	146	2639	2.23	0.213	0.21
a²	880.0	156	2639	2.30	0.215	0.21
g²	830.6	166	2639	2.37	0.217	0.21
g²	784.0	177	2639	2.44	0.219	0.21
f²	740.0	189	2639	2.51	0.221	0.21
f²	698.5	201	2639	2.58	0.223	0.23
e²	659.3	213	2639	2.66	0.227	0.23
e²	622.3	225	2639	2.73	0.230	0.23
d²	587.3	238	2639	2.82	0.234	0.23
c²	554.4	251	2639	2.90	0.238	0.23
c²	523.3	266	2639	2.98	0.242	0.25
b¹	493.9	280	2639	3.07	0.247	0.25
b¹	466.2	295	2639	3.16	0.251	0.25
a¹	440.0	312	2639	3.26	0.256	0.25
g¹	415.3	329	2639	3.35	0.261	0.27
g¹	392.0	347	2639	3.46	0.267	0.27
f¹	370.0	365	2639	3.57	0.272	0.27
f¹	349.2	386	2639	3.68	0.277	0.27
e¹	329.6	409	2639	3.80	0.282	0.27
e¹	311.1	434	2639	3.93	0.286	0.30
d¹	293.7	460	2639	4.06	0.290	0.30
c¹	277.2	488	2639	4.20	0.295	0.30
c¹	261.6	518	2639	4.35	0.300	0.30
b	246.9	548	2639	4.50	0.305	0.30
b	233.1	579	2639	4.66	0.311	0.30
a	220.0	613	2639	4.83	0.317	0.33
g	207.7	648	2639	5.00	0.323	0.33
g	196.0	686	2639	5.17	0.329	0.33
f	185.0	726	2639	5.36	0.336	0.33
f	174.6	768	2639	5.54	0.342	0.33
e	164.8	811	2639	5.73	0.348	0.36
e	155.6	857	2639	5.92	0.355	0.36
d	146.8	905	2639	6.13	0.363	0.36
c	138.6	957	2639	6.33	0.369	0.36
c	130.8	1011	2639	6.54	0.377	0.36
B	123.5	1060	2639	6.74	0.386	0.40
B	116.5	1112	2639	6.92	0.395	0.40
A	110.0	1166	2639	7.10	0.404	0.40
G	103.8	1223	2639	7.27	0.413	0.40
G	98.00	1283	2639	7.39	0.421	0.44
F	92.50	1346	2639	7.48	0.428	0.44
F	87.31	1412	2639	7.56	0.434	0.44
E	82.41	1465	2639	7.62	0.445	0.44
E	77.78	1508	2639	7.65	0.459	0.44
D	73.42	1431	2780	7.65	0.499	0.48
C	69.30	1480	2780	7.62	0.510	0.52
C	65.41	1529	2780	7.56	0.521	0.52
	Total Tension	for the	long 8' choir:	234.99 kg wt

The standard Italian string tension curve above was drawn using an average of the string tensions found for a number of different Italian harpsichords with reliable string gauge markings¹. Instead of the standard tension curve, the modified tensions were used in the table on the previous page to calculate an 'ideal' string diameter which would give exactly these string tensions at a pitch based on a¹= 440Hz. This was done using Taylor's formula:

d = string diameter in metres

f = frequency in Hz

l = length of string in metres

T = string tension in kg wt

= string material density

g = acceleration of gravity = 9.8 m/sec²

= 2639 for yellow brass and 2780 for red brass

Footnotes:
¹ See Grant O'Brien, 'Some principles of eighteenth-century harpsichord stringing and their application', The Organ Yearbook, 12 (1981) 160-76.

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