In addition to the more traditional industrial and military applications, the people at Element 6 Composites also have a strong interest in the application of engineering analysis and carbon fiber composites to the field of music and acoustic resonance. Element 6 has been privileged to work with some of the preeminent instrument builders and researchers, leading to the development of many unique applications for carbon fiber to instrument building and sound amplification. The following paragraphs give brief summaries for a few of these projects.
Carbon Fiber D-Tube Neck Beam
The patented Carbon Fiber D-Tube Neck Beam™ has been specifically designed to stabilize instrument necks due to its unique D-Tube structure. The Carbon Fiber D-Tube Neck Beam replaces the truss rod, significantly increasing both bending and torsional stiffness and weighs less than the removed wood!
The D-Tube Neck Beam is available in 3/4″ in both straight and tapered versions and 1/2″ straight to fit virtually all necks. The 3/4″ tapered version is designed to be used on thin necks while the 1/2″ straight is designed for smaller necks such as a mandolin.
The D-Tube neck beam replaces the typical approach of truss rod and carbon fiber reinforcement beams with a one piece insert. Cutting the groove for the d-tube is a much simpler operation and requires less labor than fitting a truss rod and carbon fiber reinforcement strips.
More information can be found at GeminiMusical.com
Cello Neck Brace
Element 6 Composites worked with James Ham to develop a carbon fiber neck brace for cellos. This specialized neck reinforcement provides high stiffness without adding a large amount of weight to this part of the cello. Additional details about James Ham Luthier can be found at www.hamstringsmusic.com
Carbon Fiber Guitar Internal Bracing
Dave Bertoncini worked closely with the engineers at Element 6 Composites to develop carbon fiber bracing for a custom-built guitar. For this project, low mass and high strength and stiffness were important design parameters, for which carbon fiber provided the best solution.
Appalachian Mountain Dulcimer with Carbon Fiber Soundboard
Continuing a tradition of unique applications of composite laminates to acoustics, Element 6 Composites recently developed a carbon fiber soundboard for an Appalachian mountain dulcimer. Traditional all-wooden dulcimers produce a sweet, yet relatively quiet tone. The soundboard magnifies the sound made when the strings vibrate by coupling this sound to the body resonance chamber, thereby producing a quality musical tone; however, a wooden soundboard has a high degree of damping, and thus tends not to project well, particularly given the small size of the dulcimer and manner in which the strings are played. The solution to improving sound projection is to increase the stiffness of the soundboard, but without increasing the fundamental frequency. For example, if solid carbon fiber is used to create a musical instrument, the soundboard natural frequencies will be higher than their wooden counterparts. Although sound amplification is improved, the resulting tones are harsh and unpleasant. Through a combination of FEA analysis and acoustical testing, engineers at Element 6 Composites designed a custom composite laminate with drastically increased stiffness, but without increasing the fundamental of the plate. In fact, in the final design the fundamental was reduced by 2 Hz from 149 Hz to 147 Hz, producing an instrument with both excellent sound projection and a warm, full-bodied tone.
Carbon Fiber Musical Instrument Sound Board Patent
Element 6 Composites owns a patent for a carbon fiber music instrument sound board (US Patnet #7,276,868). This patent details a method of constructing a soundboard for a hollow-body stringed instrument made of layers of carbon fiber and resin surrounding a core of one or more layers of constant-thickness plywood, veneer, or paper. Additional shaped layers are utilized to produce a desired pattern of stiffness within the soundboard, allowing it to be tuned through customized thickness and material mass distribution.
Music Box Passive Amplifier
Amplification of sound is typically done actively using microphones and speakers; however, passive amplification using helmholtz resonation is a very nice alternative. This is particularly true for applications related to music, where an unaltered tone is ideal. Specifically aimed at music boxes and singing greeting cards, Element 6 Composites developed a small, yet deceptively complex carbon fiber stage to amplify the sound of these items, particularly in the lower frequency ranges. Due to its low mass and high stiffness, carbon fiber transmits sound extremely well. Interplay from several parameters was investigated using both acoustic and Nastran finite element analyses. The pictures show some of the results from these tests, where the goal was to provide a well distributed range of natural frequencies and clean mode shapes. Essentially acting as the soundboard for the music box stage, multiple composite layups were tested, each with a unique tonality. The effect is quite dramatic, since music boxes and greeting cards typically lack any bass due to their size. The result is an attractive carbon fiber piece with a rich, well balanced tone.
Sound Post Setter
Within the body of the violin family of stringed instruments, a small, typically round wooden rod, connects the top and bottom plates, allowing the instrument to resonate properly. Without a properly placed soundpost, these instruments do not produce quality musical tones, and will not project throughout a concert hall. For the majority of stringed instrument players, however, if the soundpost falls out of place, the only option is to bring the instrument to a repair shop and pay for it to be reset. Although preferable for professional musicians, for students, school music teachers, and casual players, the cost and hassle involved left a demand for an easy to use tool for setting your own soundpost. The engineers at Element6 Composites made several improvements to the current soundpost setting tools geared directly to improving ease of soundpost placement and tool retrieval. Specific patent-pending features of this tool include the internal locking mechanism and single-line soundpost securing and tool release.
The Gemini soundpost setter tool is a dramatic improvement over the traditional soundpost setter designs. Rather than piercing the soundpost with a sharp tip, the soundpost is instead held securely against the saddle at the tip of the tool without causing any damage. The sound post is then easily inserted through the f-hole and into proper position without risk of dislodging, a common problem with traditional soundpost tools. In addition, the fixed geometry of the soundpost and tool assembly allows the user to precisely locate the soundpost within the instrument. This tool is currently being used by teachers, students, and even luthiers around the world. In particular, for students and teachers, it allows them to quickly reset soundposts in student instruments, instead of sending them out for repair. For luthiers, reduced setting time is beneficial; however, this tool has also found wide acceptance as a means to hold the soundpost in place while it is measured for final length.
Carbon Fiber Clamps
Through interactions with stringed instrument luthiers, the opportunity presented itself to develop a series of lightweight carbon fiber clamps. These patent-pending tools, now marketed under the Gemini wood carving label, were designed to replace the heavy steel and aluminum clamps traditionally used in the construction and repair of instruments, as well as other fine wood working applications. When compared with traditional metal or plastic clamps, these carbon fiber clamps are nearly the weight of the latter, while maintaining the stiffness of the former. This is achieved by strategically placing the carbon fiber to resist the large bending stresses present when the clamp is utilized. Carbon fiber is light and extremely stiff in the direction of the fibers, so in the areas of highest bending moment, additional fibers were oriented axially. A special process was developed that allows the direct integration of both a non-uniform composite cross-section, as well as the clamping hardware, within a single part. The result is a lightweight, yet extremely robust tool that provides ample clamping force without the substantial weight load placed on the instrument typical of metal clamps.
Carbon Fiber Sound Posts
Another unique application of carbon fiber to musical applications was the design of a carbon fiber sound post for stringed musical instruments. Element 6 Composites worked with Michael Griffin, Assistant Principal of the Rochester Philharmonic Orchestra and owner of Luthier’s Care, to develop sound posts with reduced mass and higher stiffness compared with conventional wooden sound posts. Mr. Griffin found that the carbon fiber material, “resulted in a bass tone that was noticeably clearer, punchier, and speedy in production.” Mr. Griffin ascertained that, “the reduced mass of the CF sound post, compared to spruce, is responsible for allowing quicker sound post function of plate interaction, resulting in increased high frequency production. As a luthier and professional bassist, the CF sound post is an exciting alternative to traditional spruce.”