Advantages of Carbon Fiber Musical Instruments
The choice of materials for building a musical instrument has a tremendous impact on the tone and character of the instrument and the musical experience of the musician. Even the most talented musician cannot make an injection molded plastic guitar sound rich and beautiful. Stringed instrument manufacturers have long sought to find the best materials for their instruments.
Carbon fiber has been proposed as a material for stringed instruments for decades. Ovation Guitar started using composites in their guitar designs back in 1965. The durability of composite structures, combined with the ability to produce complex geometries, made it an attractive option for guitar building. Before discussing the use of carbon fiber in building stringed instruments, an understanding of how materials affect the sound of instruments might be helpful.
The Role Of Resonance And Damping In Musical Instruments
Resonance is the tendency for structural components to vibrate at specific frequencies. One resonating object can transfer energy to a second object causing it to resonate as well. The strings in a musical instrument, such as a guitar, are typically the first to vibrate and then transmit that energy to the body. Resonance of the instrument body is important to the character of the instrument’s sound, including tone quality, timbre, and dynamic capabilities.
When the strings vibrate, the vibrations travel through the neck and body of the instrument. In an acoustic guitar, these vibrations will travel primarily through the bridge to the sound board. The soundboard drives the air in the body of the instrument, creating pressure waves that result in the sound that comes out through the sound hole.
Mathematically, the vibration of an instrument string can be represented in the following formula:
Where f= Frequency (Hz)
m = Mass (kg) or (sl)
T = Tension (N) or (lb)
L = Length of the string (m) or (ft)
Structures typically have a primary resonant frequency and many harmonics. For musical instruments, the key is finding a material that can be tuned to the right resonant frequencies. Fabricating components into different shapes and thicknesses can affect their resonant frequencies. Typically, flaws, imperfections and other discontinuities can have a negative effect on resonance and instrument tone.
Material damping plays a major role in the sound of a stringed instrument. Damping is the energy dissipation properties of a material or system under cyclic stress. For a stringed instrument, this can be seen when a string is plucked and the vibrations slowly dissipate until they stop. Musicians can skillfully make use of mechanical damping with their hands for artistic effect.
Material properties are important when selecting a material for a musical instrument.
Advantages of Carbon Fiber Musical Instruments
Compared to materials that are traditionally used in musical instruments, carbon fiber is very stiff, very light, and has very low damping. This leads to some interesting resonant properties. The increased stiffness and reduced weight of a carbon fiber part will typically raise the resonant frequency of a part while the reduced damping will allow it to vibrate longer.
Carbon fiber string instruments resonate differently than wood instruments and generally sound brighter and more powerful. There are other factors that can influence the resonant frequency of a carbon fiber component as well. For example, the orientation of the carbon fibers in the layup can tune the resonance in any specific axis. Low damping can contribute to a clearer sound and longer sustain.
The skilled luthier can use the unique properties of carbon fiber to fine tune the structure of an instrument for best resonance at specific frequencies, in specific areas. Many musicians have developed an appreciation for carbon fiber stringed instruments as an alternative to traditional wood instruments.
