About Traditional and New Wood Species for String Instruments

Abstract

Traditional wood species used for violins and other instruments of this family are spruce resonance wood, also called Norway spruce, or spruce tonewood known under the scientific name of Picea abies that are used for the top, and curly maple (Acer pseudoplatanus) for the belly, ribs and neck. Macroscopically, resonance spruce for violins has a very regular structure without any defect (knots, resin pockets, stain). The width of the annual rings should have a low proportion of latewood. The raw wooden material for violins and other instruments, also called wedges should be naturally air dried for a long period of time (10 years). Resonance wood is very anisotropic. Other species, such as Sitka spruce, white spruce or red cedar are used for high quality instruments such as pianos, harps or guitars. Curly maple is characterised by flamed figures. Because of relative scarcity of these species there is a need to find replacement wood species with similar acoustical behaviour. Some Australian native species,such as King William pine and Huon pine were identified as substitutes for spruce. Blackwood, myrtle and sassafras as substitutes for curly maple. These new species should satisfy the acoustical requirements and aesthetical exigencies of luthiers and musicians. The tonal balance on violins made from Australian species is different from that obtained with European species because the high frequency damping is different. Building guitars with Australian species has been very successful and acoustical and aesthetical exigencies have been perfectly satisfied.

Appendices

Appendices

17.1.1 Appendix 1: Spruce with Indented Rings

Classes of indentations for “hasel” spruce with indented rings (data from Bonamini 2002)

Classes	Intensity of indentation			Classes as defined by Fukazawa and Ohtani (1984)
	Minimum	Geometric Average	Maximum
0—No. indentation				Class A
1	0.022098	0.03125	0.044194	Class B
2	0.044195	0.0625	0.08838	Class B
3	0.08839	0.125	0.17677	Class B
4	0.17678	0.25	0.35355	Class B
5	0.35356	0.5	0.70710	Class C
6	0.70711	1	1.41421	Class C
7	1.41422	2	2.82842	Class C
8	2.82843	4	5.65685	Class C
9	5.65686	8	5.65685	Class C
10	11.31371	16	11.31370	Class C
11	22.62742	32	22.62741	Class C
12	45.25484	64	90.50966	Class C
13 Maximum indentation	90.50967	128	181.0193	Class C

17.1.2 Appendix 2: Some Acoustic Properties of Australian Species

Acoustic impedance and acoustic radiation of some Australian species (Bucur 1991 unpublished data)

	Acoustic impedance 106 (v.ρ)				Acoustic radiation (v.ρ−1)
	Longitudinal [P] waves
	V LL .ρ	V RR .ρ	V TT .ρ	Ratio V LL /V RR	VLLρ−1	VRRρ−1	VTTρ−1	Ratio V LL /V RR
Cedar Melia azedarach	2.17	0.58	0.27	3.74	10.30	2.52	3.09	3.33
Queensland maple Flindersia brayleyana	2.43	0.88	0.78	2.76	9.72	3.52	3.16	2.76
Silky oak, brown Darlingia darlingiana	2.79	1.20	0.78	2.33	8.72	3.76	2.45	2.31
Queensland walnut Endiandra palmerstonii	2.90	1.17	1.02	2.48	7.43	2.99	2.62	2.48
Sassafras Doryphora sassafras	3.46	1.18	0.97	2.93	8.04	2.73	2.27	2.94
Blackwood Acacia melanoxylon	3.59	1.63	1.03	2.20	7.81	3.53	2.23	2.21
Silver ash Flindersia bourjotiana	3.48	1.43	0.83	2.43	6.70	2.76	1.60	2.42
Myrtle beech Nothofagus cunninghamii	3.41	1.62	1.46	2.10	5.47	2.59	2.35	2.11
Red gum (curly) Eucalyptus camaldulensis	3.11	1.63	0.84	1.90	4.37	2.30	1.18	1.90
Mountain ash Eucalyptus oreades	4.05	1.30	1.16	3.11	5.48	1.77	1.58	3.09
Jarrah Eucalyptus marginata	3.71	1.54	1.12	2.40	4.96	2.06	1.50	2.40
Shear waves
	V TR .ρ	V LT .ρ	V LR .ρ	Ratio V LR /V LT	V TR .ρ −1	V LT .ρ −1	V LR .ρ −1	Ratio V LR /V LT
Cedar Melia azedarach	0.27	0.53	0.64	1.20	1.31	2.52	3.04	1.21
Queensland maple Flindersia brayleyana	0.35	0.67	0.68	1.02	1.41	2.67	2.72	1.02
Silky oak, brown Darlingia darlingiana	0.37	0.59	0.69	1.15	1.15	1.81	2.16	1.19
Queensland walnut Endiandra palmerstonii	0.45	0.74	0.79	1.06	1.15	1.92	2.01	1.02
Sassafras Doryphora sassafras	0.52	0.84	0.83	0.98	1.22	1.96	1.92	0.97
Blackwood Acacia melanoxylon	0.51	0.88	1.03	1.17	1.11	2.00	2.24	1.12
Silver ash Flindersia bourjotiana	0.59	0.95	1.07	1.12	1.15	1.83	1.97	1.01
Myrtle beech Nothofagus cunninghamii	0.69	1.03	1.10	1.06	1.11	1.65	1.76	1.07
Red gum (curly) Eucalyptus camaldulensis	0.65	0.93	1.06	1.14	0.92	1.30	1.49	1.15
Mountain ash Eucalyptus oreades	0.68	0.96	1.09	1.14	0.91	1.29	1.47	1.14
Jarrah Eucalyptus marginata	0.64	1.00	0.99	0.99	0.85	1.34	1.33	0.99

17.1.3 Appendix 3: Moduli of Elasticity of Some Australian Species

Young’s modulus and shear modulus [10⁸ N/m²] of some Australian species (unpublished data Bucur 1991)

	Young’s moduli			Shear moduli			Anisotropy ratio
	E L	E R	E T	G TR	G LT	G LR	E L /E R	E L /G TR
Cedar Melia azedarach	102.77	18.95	7.42	1.66	6.12	8.95	5.4	66.3
Queensland maple Flindersia brayleyana	118.24	15.52	13.86	2.50	8.73	9.25	7.6	47.3
Silky oak, brown Darlingia darlingiana	138.12	25.67	10.87	2.43	6.16	8.49	4.8	56.8
Queensland walnut Endiandra palmerstonii	134.79	21.92	16.77	3.27	8.78	9.94	6.1	41.2
Sassafras Doryphora sassafras	182.53	21.16	14.54	4.19	10.79	10.43	8.7	43.6
Black wood Acacia melanoxylon	190.73	38.44	15.66	3.84	11.58	15.73	4.9	38.9
Silver ash Flindersia bourjotiana	167.65	28.51	9.57	4.96	12.65	14.49	5.9	33.8
Myrtle beech Nothofagus cunninghamii	147.31	33.15	27.35	6.09	10.92	15.37	4.4	24.18
Red gum (curly) Eucalyptus camaldulensis	114.78	31.72	8.43	5.13	10.20	13.34	3.6	22.4
Mountain ash Eucalyptus oreades	190.96	19.82	15.84	5.32	10.64	123.80	9.6	35.8
Jarrah Eucalyptus marginata	159.01	27.38	14.53	4.71	11.69	11.48	5.8	33.8

17.1.4 Appendix 4: Variability of Some Australian Species

Variability of some Australian species expressed by physical, acoustical and mechanical parameters (unpublished data Bucur 1991)

Parameter	Units	Minimum	Maximum	Differences %
Density	kg/m3	459	859	87
Velocity VLL	m/s	3690	4940	33
Velocity VRT	m/s	603	883	46
Acoustic impedance ratio with P waves	106 kg m−2 s−1	1.90	3.11	63
Acoustic impedance ratio with S waves	–	0.99	1.17	18
Young’s modulus EL	108 N/m2	102.77	190.96	85
Young’s modulus ER	108 N/m2	15.52	38.44	83
Young’s modulus ET	108 N/m2	7.42	16.72	125
Shear modulus GTR	108 N/m2	1.66	6.09	266
Shear modulus GLT	108 N/m2	6.12	11.58	89
Shear modulus GLR	108 N/m2	8.95	15.73	75
Ratio EL/GRT	–	22.4	66.3	195
Ratio of Young’s moduli EL/ER	–	3.6	9.6	165
Ratio of Young’s moduli EL/ET	–	8.06	17.45	116

17.1.5 Appendix 5: Tasmanian Wood Species for Violins and Guitars

Acoustic impedance and acoustic radiation calculated from the values of velocities measured with P waves in three anisotropic directions of wood L, R and T (data from Perez-Pulido et al. 2010)

Species	Density (kg/m3)	Acoustic impedance (average values) expressed by the product velocity x density, in 3 principal directions of wood elastic symmetry, L, R, T [103 kg m−2 s−1]			Acoustic radiation (average values) expressed by the ratio velocity/density, in 3 principal directions of wood elastic symmetry, L, R, T [m4 kg−1 s−1]
		In axis L	In axis R	In axis T	In axis L	In axis R	In axis T
Softwoods
King Billy Pine	400	1536	803	584	9.60	5.02	3.65
Huon Pine	550	2319	861	742	7.67	2.84	2.45
Celery-top Pine	650	2798	1240	981	6.69	2.94	2.32
Spruce tonewood	435	2737	926	588	14.46	4.89	3.11
Hardwoods
Blackwood	640	3056	1277	946	7.46	3.07	2.31
Myrtle	700	3325	1144	1087	6.78	2.33	2.22
Sassafras	473	2249	925	718	10.04	4.13	3.20
Curly maple	650	2827	1683	1244	6.69	3.98	2.94

1. NB P waves—waves for which the propagation and polarization directions are parallel

17.1.6 Appendix 6: Tonewood Species

Mechanical parameters of tonewoods species determined with ultrasonic techniques and 1 MHz wide band transducers, on cubic specimens (25 × 25 × 25 mm). Terms of stiffness matrix [10⁸ N/m²] (Bucur 1987)

Species	Density (kg/m3)	Terms of stiffness matrix
		Diagonal terms						Off diagonal terms
		C 11	C 22	C 33	C 44	C 55	C 66	C 12	C 12	C 12
Softwoods for the top of the violins Picea spp.
Picea abies 7 years natural drying	400	102.01	16.00	10.24	0.36	7.56	8.12	17.53	13.20	12.14
Pitcea Sitchensis 7 years natural drying	430	130.07	22.75	9.77	0.53	9.42	9.68	25.66	19.34	10.81
Picea engelmannii Old ? years natural drying	352	106.48	17.43	12.04	0.37	6.76	6.52	26.91	20.79	14.13
Hardwoods for the back and other elements of the violins Acer spp.
Acer pseudoplatanus 1 years natural drying	670	141.34	41.87	23.43	5.73	15.68	22.54	32.44	30.72	18.53
Acer platanoides 15 years natural drying	740	180.59	45.91	27.90	7.20	13.68	21.34	54.17	43.70	16.26
Acer macrophyllus 7 years natural drying	600	121.50	32.85	14.42	4.86	10.77	17.75	12.45	11.39	8.39
Acer saccharum 15 years natural drying	700	160.27	39.52	22.33	2.82	12.79	21.09	43.47	32.19	20.18

1. Note the off diagonal terms were determined after optimisation procedure on experimental data obtained on specimens cut at 15°, 30°, 45°, 60° an 75° out of principal direction in each anisotropic plane. The specimens were provided by CM Hutchins and were cut for parts used for violins

17.1.7 Appendix 7: Anisotropy of Tonewood

Voigt and Reuss moduli averages and the compressive and shear anisotropy factors calculated from the data of Bucur (1987) for different tonewood species (Katz and Meunier 1990)

Species	Bulk moduli		Shear moduli		Anisotropy
	Voigt bulk modulus	Reuss bulk modulus	Voigt shear modulus	Reuss shear modulus	Compression	Shear
	K v	K R	G v	G R	A compression	A shear
	GPa	GPa	GPa	GPa	%	%
Picea abies	2.38	0.839	0.890	0.0820	47.8	83.2
Picea sitchensis	2.30	0.771	1.00	0.127	49.7	77.5
Picea Engelmannii	2.88	0.827	0.764	0.054	55.3	86.7
Acer pseudoplatanus	4.11	2.19	1.71	0.996	30.6	26.4
Acer platanoides	5.15	2.15	1.85	1.17	41.1	22.6
Acer saccharum	4.60	2.10	1.57	0.662	37.3	40.8

1. Note
2. Voigt parameters were calculated as
3. ${\text{K}}^{\text{v}} = \left[ {{\text{C}}_{ 1 1} + {\text{C}}_{ 2 2} + {\text{C}}_{ 3 3} + 2\left( {{\text{C}}_{ 1 2} + {\text{C}}_{ 1 3} + {\text{C}}_{ 2 3} } \right)} \right]/ 9$
4. ${\text{G}}^{\text{V}} = \left[ {{\text{C}}_{ 1 1} + {\text{C}}_{ 2 2} + {\text{C}}_{ 3 3} + 3\left( {{\text{C}}_{ 4 4} + {\text{C}}_{ 5 5} + {\text{C}}_{ 6 6} } \right) - \left( {{\text{C}}_{ 1 2} + {\text{C}}_{ 1 3} + {\text{C}}_{ 2 3} } \right)} \right]/ 1 5$
5. Reuss parameters were calculated as
6. $\begin{aligned} {\text{K}}^{\text{R}} = &\Delta /[{\text{C}}_{ 1 1} \cdot {\text{C}}_{ 2 2} + {\text{C}}_{ 2 2} \cdot {\text{C}}_{ 3 3} + {\text{C}}_{ 3 3} \cdot {\text{C}}_{ 1 1} - 2\left( {{\text{C}}_{ 1 1} \cdot {\text{C}}_{ 2 3} + {\text{C}}_{ 2 2} \cdot {\text{C}}_{ 1 3} + {\text{C}}_{ 1 2} \cdot {\text{C}}_{ 3 3} } \right) \\ & + \, 2\left( {{\text{C}}_{ 1 2} \cdot {\text{C}}_{ 2 3} + {\text{C}}_{ 2 3} \cdot {\text{C}}_{ 1 3} + {\text{C}}_{ 1 2} \cdot {\text{C}}_{ 1 3} } \right) - \left( {{\text{C}}_{ 1 2}^{ 2} + {\text{C}}_{ 1 3}^{2} + {\text{C}}_{ 2 3}^{2} } \right)] \\ \end{aligned}$
7. $\begin{aligned} {\text{G}}^{\text{R}} = & 1 5/( 4\{ \left( {{\text{C}}_{ 1 1} \cdot {\text{C}}_{ 2 2} + {\text{C}}_{ 2 2} \cdot {\text{ C}}_{ 3 3} + {\text{C}}_{ 3 3} \cdot {\text{C}}_{ 1 1} + {\text{C}}_{ 1 1} \cdot {\text{C}}_{ 2 3} + {\text{C}}_{ 2 2} \cdot {\text{C}}_{ 1 3} + {\text{C}}_{ 1 2} \cdot {\text{C}}_{ 3 3} } \right) \\ & + \,\left[ {{\text{C}}_{ 1 2} \cdot \left( {{\text{C}}_{ 1 2} + {\text{C}}_{ 2 3} } \right) + {\text{C}}_{ 2 3} \left( {{\text{C}}_{ 1 3} + {\text{C}}_{ 2 3} } \right) + {\text{C}}_{ 1 3} \left( {{\text{C}}_{ 1 3} + {\text{C}}_{ 1 2} } \right)} \right]\} / \left( {{\text{C}}_{ 1 2}^{ 2} + {\text{C}}_{ 1 3}^{ 2} + {\text{C}}_{ 2 3}^{ 2} } \right)]\} /\Delta \\ & + \, 3\left( { 1/{\text{C}}_{ 4 4} + 1/{\text{C}}_{ 5 5} + 1/{\text{C}}_{ 6 6} } \right) \\ \end{aligned}$
8. $\Delta = {\text{C}}_{ 1 1} \cdot {\text{C}}_{ 2 2} {\text{C}}_{ 3 3} + 2 {\text{C}}_{ 1 2} \cdot {\text{C}}_{ 1 3} \cdot {\text{C}}_{ 2 3} - \left( {{\text{C}}_{ 1 1} \cdot {\text{C}}_{ 2 3}^{ 2} + {\text{C}}_{ 2 2} \cdot {\text{C}}_{ 1 3}^{ 2} + {\text{C}}_{ 1 2}^{ 2} \cdot {\text{C}}_{ 3 3} } \right)$
9. Anisotropy
10. ${\text{Ac}}(\% ) = \left( { 100\,{\text{K}}^{\text{v}} - {\text{K}}^{\text{R}} } \right)/\left( {{\text{K}}^{\text{v}} + {\text{K}}^{\text{R}} } \right)$
11. ${\text{As}}(\% ) = \left( { 100\,{\text{G}}^{\text{v}} - {\text{G}}^{\text{R}} } \right)/\left( {{\text{G}}^{\text{v}} + {\text{G}}^{\text{R}} } \right)$
12. It notifying that when the strain is uniform across the interface, Voigt modulus represents the upper bound of the elastic properties of a multiphase system, whereas the Reuss modulus represents the lower bound

17.1.8 Appendix 8: Australian Species for Violin and Guitar

List of Australian wood species for violin and guitar parts (data from Morrow 2007)

Genus and species	Common name	Soundboard	Bridge and fret boards	Neck and hell
Acacia aneura	Mulga	–	Guitar, violin	–
Acacia harpophylla	Brigalow	–	Guitar, violin	–
Acacia cambagei	Gidgee	–	Guitar, violin	–
Acacia melanoxylon	Blackwood	Guitar	–	Guitar
Acacia papyrocarpa	Myall	–	Guitar, violin	–
Acacia pendula	Boree	–	Guitar, violin	–
Agathis robusta	Kauri pine	Guitar, violin, cello	–	–
Agonis juniperina	Warren river cedar	–	–	Guitar
Araucaria bidwillii	Bunya pine	Guitar	–	–
Araucaria cunninghamii	Hoop pine	Guitar violin	–	–
Atherosperma moschatum	Sassafras	Guitar	–	–
Athrotaxis selaginoides	King William pine Or “King Billy”	Guitar	–	–
Cardwellia sublimis	Northern silky oak	–	Guitar, violin	–
Dysoxylum fraseranum	Rose mahogany	–	–	Guitar
Erythrophleum chlorostachys	Cooktown ironwood	–	Guitar, violin	–
Eucalyptus marginata	Jarrah	–	Guitar, violin	Guitar
Eucalyptus regnans	Victorian ash	–	–	Guitar
Eucalyptus wandoo	wandoo	–	Guitar, violin	–
Flindersia brayleyana	Qld. maple	Guitar	–	Violin, guitar
Flindersia australis	Crows ash	–	Guitar, violin	–
Flindersia schottiana	Silver ash	–	–	Violin, guitar
Grevillea striata	Beefwood	–	Guitar, violin	–
Lagarostrobos franklinii	Huon pine	Guitar	–	–
Phebalium squameum	Satinwood	Violin, guitar	–	–
Phyllocladus aspleniifolius	Celery-top pine	Guitar	–	–
Podocarpus aramus	Black pine	Violin	–	–
Podocarpus neriifolius	Brown pine	Violin	–	–
Toona australis	Australian red cedar	Guitar	–	–