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Reconstruction of the Urbino Clavichord
Jubilee Symposium 2012 of the Nederlands Clavichord Genootschap
Leiden, 28-30 September 2012
pierre.verbeek@skynet.be
27/09/2012 1 Urbino clavichord Leiden 28-30 Sep 2012
Urbino in the Marche Region
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Outline
1. Detailed photographs of the intarsia and technical drawings
2. Perspective of Federico's studiolo
3. Technical drawings of the ‘real’ instrument
4. Fretting, intonation
5. Acoustical properties, scaling, pitch, stringing
6. Tentative conclusions and open questions
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Main findings
• Perspective of the North wall of Federico’s studiolo
• Centric point, distance point
• Construction method
• Dimensions of the clavichord • 1005 mm x 216 mm x 82 mm
(w/o keyboard)
• Wall thickness 12 mm (± .5 mm)
• Keyboard dimensions • Octave span 177.5 mm
• Width of naturals 25.3 mm
• Width of sharps 14.0 mm
• Projecting keys 81.5 mm
• Key dip 4 – 6 mm
• Bridge position & string lengths • Pythagorean lengths except
lower octave
• 2 x 17= 34 strings; 36 tuning pins
• Tangents • All tangents in the form of
cramps
• Two tangents missing
• Fretting scheme • 3 - 4 - 3 - 4 - etc. consistently
• Temperament • Pythagorean tuning
• Wolf’s fifth B-F#
• Pitch • a’’ 440 Hz or higher
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1. Technical drawings and detailed photographs of the intarsia
• Federico (III) da Montefeltro: 1422 – 1482
• Building of the Urbino ducal palace: c. 1450 – 1482
• Painting of the Famous Man of studiolo by Giusto di Gand (Juste de Gand): 1473 – 1475
• Engineering of the Urbino intarsia by Baccio Pontelli, architect & cabinet maker: 1479 – 1482
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Photo: © Museo del Metauro, Communità Montano dell’Alto e
Medio Metauro
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Challenge: to avoid mistakes during measurements
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• Note: – The trompe-l’œil is of such a quality that mistakes are very easily
made when measuring dimensions
– A specific vocabulary is required to avoid confusion between measurements on the intarsia and interpretation for the ‘real instrument’
• Suggested vocabulary convention: – mm-I : measurements of dimensions on the intarsia
– mm-R : interpretation of same for the ‘real’ instrument
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Photo: © Soprintendenza per i Beni Storici, Artistici ed Ethnoantropologici delle Marche
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Inner dimensions of Federico’s studiolo
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Main external dimensions of clavichord on intarsia (mm-I)
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Main internal dimensions of clavichord on intarsia (mm-I)
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Position & dimensions of bridge (mm-I)
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Main dimensions of keys (mm-I)
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Hitchpin cover block?
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Dimensions in mm-I
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Method used for measuring the slot positions on rack / fimbrie
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Dimensions in mm-I
Slot positions on rack / fimbrie, as measured mm-I from right corner – see previous slide – tolerances ±1 mm
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Note Position mm-I
Note Position mm-I
Note Position mm-I
Note Position mm-I
f’’’ 156 f’’ 240 f’ 396 f 640
e’’’ 161 e’’ 249 e’ 407 e 670
eb’’’ 167 eb’’ 259 eb’ 430 eb 710
d’’’ 173 d’’ 270 d’ 450 d 723
c#’’’ 177 c#’’ 284 c#’ 460 c# 768
c’’’ 184 c’’ 294 c’ 481 c 805
b’’ 190 b’ 307 b 500 B 817
bb’’ 199 bb’ 321 bb 531 Bb 830
a’’ 204 a’ 334 a 541 A 843
ab’’ 213 ab’ 345 ab 573 G 853
g’’ 222 g’ 359 g 599 F 863
f#’’ 232 f#’ 380 f# 609 bridge 81 mm-I
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2. Perspective of Federico’s studiolo
• A primer on Alberti’s central perspective
• From the clavichord on the intarsia to the ‘real clavichord’
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Anamorphic effect
(North-East corner
of studiolo)
Leon Battista Alberti Della pittura (1435-6)
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Cast bronze medal of
Leon Battista Alberti by
Matteo de’Pasti (ca.
1450-5) © Trustees of
the British Museum
Principle of L.-B.
Alberti’s perpective
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Construction of a box in central perspective with distance point – Phase 1
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Construction of a box in central perspective with distance point – Phase 2
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Construction of a box in central perspective with distance point – Phase 3
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Construction of a box in central perspective with distance point – Phase 4
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Construction of a box in central perspective with distance point – Phase 5
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Central perspective of North wall
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Photo: © Soprintendenza per i Beni Storici, Artistici ed Ethnoantropologici delle Marche
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Central perspective of North wall
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Determination of ‘real’ clavichord width
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Determination of ‘real’ clavichord width
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Indirect proof : dimensions of lifted-up shelf
302 mm-R = 166 mm-I (± 2 mm)
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Direct proof : existence of a wooden patch at distance point
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A closer look at the wooden patch at distance point
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Why a wooden patch at the distance point?
• Goal of the wooden patch: to cover and hide the hole of a nail used for drawing the construction lines of intarsia
• In practical terms, the creation of the intarsia requires that the distance point and the centric point be inside the room and not somewhere in the walls.
• From those points, straight construction lines can be drawn (and/or cords can be tightened) very accurately and the objects can be represented precisely, without any distortion.
• Theoretically, using hundreds of proportions and trapeziums would achieve the same result, but at the cost of a significant loss of accuracy and a huge calculation work. The Quattrocento engineers used geometry, not algebra. Trigonometry was not yet invented.
• The intarsia of Urbino shows other wooden patches having a similar purpose, as aides for drawing open doors of cabinets, shelves, armour, books, astronomical instruments, etc.
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3. Technical drawings of the ‘real’ instrument
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Main dimensions of the ‘real’ clavichord
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Dimensions in mm-R
Main dimensional ratios
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Length / width Height / width Soundboard height / width
Urbino clavichord (present work)
(1005 mm-R/216 mm-R=)
13.96/3 (82 mm-R/ 216 mm-R =)
1 / 2.26
( 51mm-R / 216 mm-R =)
1/4
Arnaut de Zwolle secundum librum Baudeceti
14/3 1/2 1/6
Geneva MS 80 Volens facere clavichordium
(5/1 = )
15/3 -
1/9
Major assumption of present work: It is assumed that the front panel of the clavichord intarsia represents the front panel of the ‘real’ instrument at a 1:1 scale
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Main dimensions of the rack / fimbrie
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Dimensions in mm-R
Slot positions on ‘real’ rack / fimbrie mm-R from right corner - rounded - tolerances ±1 mm
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Note Position mm-R
Note Position mm-R
Note Position mm-R
Note Position mm-R
f’’’ 180.5 f’’ 270.5 f’ 437.5 f 699.0
e’’’ 186.0 e’’ 280.0 e’ 449.5 e 731.0
eb’’’ 192.5 eb’’ 291.0 eb’ 474.0 eb 774.0
d’’’ 199.0 d’’ 302.5 d’ 495.5 d 788.0
c#’’’ 203.0 c#’’ 317.5 c#’ 506.0 c# 836.0
c’’’ 210.5 c’’ 328.5 c’ 528.5 c 875.5
b’’ 217.0 b’ 342.5 b 549.0 B 888.5
bb’’ 226.5 bb’ 357.5 bb 582.0 Bb 902.5
a’’ 232.0 a’ 371.0 a 593.0 A 916.5
ab’’ 241.5 ab’ 383.0 ab 627.0 G 927.0
g’’ 251.0 g’ 398.0 g 655.0 F 938.0
f#’’ 262.0 f#’ 420.5 f# 665.5 bridge 101 mm-R
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String lengths on ‘real’ clavichord mm-R from right corner – rounded - tolerances ±1 mm
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Note String length mm-R
Note String length mm-R
Note String length mm-R
Note String length mm-R
f’’’ 79.5 f’’ 169.5 f’ 336.5 f 598.0
e’’’ 85.0 e’’ 179.5 e’ 348.5 e 630.0
eb’’’ 91.5 eb’’ 190.0 eb’ 373.0 eb 673.0
d’’’ 98.0 d’’ 202.0 d’ 394.5 d 687.0
c#’’’ 102.0 c#’’ 216.5 c#’ 405.0 c# 735.0
c’’’ 109.5 c’’ 227.5 c’ 427.5 c 774.5
b’’ 116.0 b’ 241.5 b 448.0 B 787.5
bb’’ 125.5 bb’ 256.5 bb 481.5 Bb 801.5
a’’ 131.0 a’ 270.5 a 492.0 A 815.5
ab’’ 140.5 ab’ 282.0 ab 526.0 G 826.0
g’’ 150.5 g’ 297.0 g 554.0 F 837.0
f#’’ 161.0 f#’ 319.5 f# 565.0
Lengths of c2 string compared - a few examples
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Instrument c2 length (mm) Source
Urbino c. 1479 227.5 (±1 mm) Present work
Pisaurensis clavichord 1543 234.5 O’Brien, Magnano 2001
Leipzig n° 2 c. 1540 176 Brauchli, The Clavichord, 1998
Leipzig n° 3 c. 1540 205 Brauchli, The Clavichord, 1998
Anon. Tagliavini, c. 1550 210 Tagliavini, Magnano 1993, 1995
Boston ‘Tosi’ early 17th c. 218 Koster, Magnano 1993
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Keyboard
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Keyboard of the ‘real’ clavichord octave span: 177.5 mm-R Stichmass: 532.0 mm-R
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Dimensions in mm-R
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Keyboards compared
Urbino clavichord (c. 1479) Width of naturals: 25.4 - 25.3 mm
Ghent altar piece (c. 1432) Width of naturals: 25.5 mm
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Photo:
Wikimedia
Foundation
Cross section of the ‘real’ clavichord (tentative)
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Dimensions in mm-R
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Bridge
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Section of the ‘real’ bridge
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Dimensions in mm-R
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4. Fretting, intonation
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Fretting scheme 3-4-3-4 etc., except unfretted first half-octave
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octave c'''- f''' octave c'''- c'' octave c''- c' octave c'- c and lower
c#''' ? tangent missing
c'''
b'' b'
bb'' ? tangent missing bb'
a'' a' a
ab'' ab' ab
g'' g' g
f#'' f#' f#
f''' f'' f' f
e''' e'' e' e
eb''' eb'' eb' eb
d''' d'' d' d
c#'' c#' c#
c'' c' c
b B
bb Bb
A
G
F
Anomalies : two missing tangents c#’’’ & bb’’ and two tuning pins in excess
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Another anomaly on the North wall of studiolo : two broken lute strings
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String lengths (mm-R)
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Determination of intonation Semitones and tones in pythagorean tuning
All fifths pure except wolf’s fifth on B-F#
Semitone Interval in cents
F-E 90.2
E-Eb 113.7
Eb-D 90.2
D-C# 113.7
C#-C 90.2
C-B 90.2
B-Bb 113.7
Bb-A 90.2
A-Ab 113.7
Ab-G 90.2
G-F# 113.7
F#-F 90.2
Tone Interval in cents
F-Eb 203.9
E-D 203.9
Eb-C# 203.9
D-C 203.9
C#-B 180.4
C-Bb 203.9
B-A 203.9
Bb-Ab 203.9
A-G 203.9
Ab-F# 203.9
G-F 203.9
F#-E 180.4
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Minor seconds (fretted notes)
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Major seconds (fretted notes)
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Minor thirds (fretted notes)
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5. Acoustical properties, scaling, pitch, stringing
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Soundboard
design proposal -orthotropic plate in cypress, slightly
bended upwards in order to enhance
radiation power at low frequencies
-gaps between soundbars
proportional to prime numbers, in
order to avoid too strong eigenmodes
- 63 mm diameter rose for efficient
Helmholtz resonator and improved
air/soundboard coupling (with internal
volume of soundbox 5 ~ 6 litre)
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Proposed stringing brass 30% Zn (type Stolberg / Marc Vogel 2011 or equivalent Malcolm Rose)
Course Proposed diameter mm
F .563
G .533
A .506
Bb .478
B .478
c-c#-d .453
eb-e-f-f# .429
g-ab-a .406
bb-b-c’-c#’ .384
Course Proposed diameter mm
d’-eb’-e’ .364
f’-f#’-g’-ab’ .344
a’-bb’-b’ .326
c’’-c#’’-d’’-eb’’ .293
e’’-f’’-f#’’ .277
g’’-ab’’-a’’-bb’’ .262
b’’-c’’’-c#’’’ .248
f’’’-e’’’-eb’’’-d’’’ .248
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Estimated string tensions as a function of pitch brass 30% Zn (type Stolberg / Marc Vogel 2011 or equivalent Malcolm Rose)
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Local units of measurements
• On the wall of the entrance hall of the Palazzo del Comune of Urbino: ‘Misure lineari e di superficie della Città XV secolo’
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Photo: © Comune Urbino
6. Conclusions and open questions (1/2)
Technical conclusions
• Perspective of the North wall of Federico’s studiolo
• Dimensions of the clavichord
• Keyboard dimensions
• Bridge position & string lengths
• Pythagorean scaling
• Fretting scheme
• Pythagorean tuning with wolf’s fifth B-F#
• Pitch a’’ 440 Hz or higher
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Conclusions and open questions (2/2)
Open questions :
• Influence of the Urbino clavichord on the making of Italian keyboard instruments of the 16th c.?
• Service of Lorenzo Gusnasco da Pavia to the Montefeltro at Urbino 1505: any influence of the Urbino clavichord on the instruments built by Lorenzo Gusnasco da Pavia for Isabelle d’Este and other celebrities?
• Interesting anomalies? – rebus well in the spirit of the first Italian Renaissance?
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Acknowledgements
• I wish to acknowledge the support, assistance and co-operation of:
– Dr. ssa Vittoria Garibaldi, Sopraintendente, Soprintendenza per i Beni Storici, Artistici ed Ethnoantropologici delle Marche
– Dr. ssa Agnese Vastano, Direttor storico dell’arte, Urbino, Soprintendenza per i Beni Storici, Artistici ed Ethnoantropologici delle Marche
– Sig. Massimo Fabbri , Ufficio Tecnico, Soprintendenza per i Beni Storici, Artistici ed Ethnoantropologici delle Marche
– Bernard Brauchli, performer, musicologist, president of Musica Antiqua a Magnano
– Peter Bavington, clavichord maker, chairman of the British Clavichord Society
– Didier Jarny, luthier, secrétaire adjoint de l’Association Française du Luth
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