Martin Turesson
What do a Formula 1 car, NASA’s Mars helicopter, and next-generation high-end loudspeakers have in common? They all rely on TeXtreme® Thin-ply carbon.
So, what is Thin-Ply Carbon and what is Thin-Ply Carbon Diaphragm (TPCD®) technology?
What is Thin-Ply Carbon Fiber?
Thin-Ply Carbon is created by spreading carbon fiber tows into wide and thin layers, or plies.
Figure 1: The Spread Tow process, spreading round carbon tow (left) into an ultra-thin, flat tape (right).
The defining characteristics of this material include:
- Weight reduction: Each individual ply is extraordinarily thin, enabling extremely thin and lightweight constructions.
- Increased stiffness: Because the thin-ply carbon material is constructed from thin and wide tapes, the fiber undulations are minimized and the fibers are presented much straighter than traditional carbon fiber, resulting in higher stiffness [1].
- Tailored properties: The microscopic ply thickness allows stacking layers in tailored, multi-directional orientations to fit specific performance demands without adding unnecessary mass or thickness [1]. This also enables tailored properties in different areas of the composite part.
- Durability: Carbon-fiber composites have better fatigue resistance per unit weight than metals [2]. Thin-Ply Carbon in turn has even better fatigue resistance than traditional carbon fiber. Where traditional thick carbon layers are prone to developing microscopic cracks inside the material when flexed, thin-ply carbon reinforcements bypass this issue through a mechanism called "in situ strength" [1]. In situ strength means that many thin layers work together, preventing microscopic cracks from physically forming and propagating. This results in outstanding durability and fatigue resistance, something that has for instance been proven when TPCD® compression driver diaphragms are in principle unbreakable.
To understand the difference between thin-ply carbon and traditional carbon fiber, imagine the traditional carbon fabric as a yarn sweater with bundles of carbon threads over and under each other. When a mechanical load is applied to the sweater (the traditional carbon fabric) the undulations in the threads act like springs that need to be straightened before the carbon fiber engages and starts carrying the load [1]. Conversely, in the Thin-Ply Carbon material, the fibers are already straight and will immediately react to the load being applied.
In a speaker diaphragm, the traditional carbon material results in a low speed of sound through the diaphragm. In contrast, the stiffness of the carbon fiber in a Thin-Ply Carbon Diaphragm (TPCD®) immediately kicks in, resulting in a high speed of sound and wide range of pistonic motion. This in turn enables clear and detailed sound.
TeXtreme® thin-ply carbon offers a stiffness-to-density ratio that far exceeds titanium, aluminum and conventional woven carbon fiber, creating a new baseline for diaphragm design.
Figure 2: Stiffness to density ratio (Young’s modulus GPa/Density g/cm3)
Source: Standard engineering material specifications and internal testing. Values reflect typical properties for Titanium (Grade 5, Ti-6Al-4V), Aluminum (6061-T6), Conventional Woven Carbon Fiber (standard modulus twill/epoxy matrix in component configuration), and Composite Sound TPCD®.
What is a Thin-Ply Carbon Diaphragm (TPCD®)?
Speaker and headphone diaphragms are traditionally made using a uniform sheet of material. This is suboptimal leaving some areas of the diaphragm too thin and weak whereas other areas will be unnecessarily thick and heavy.
As shown above, Thin-Ply Carbon provides exceptional material properties for speaker and headphone diaphragms. However, the true breakthrough comes when this material is combined with application-specific diaphragm engineering, unlocking TPCD® solutions and performance levels that traditional diaphragm designs cannot achieve.
Composite Sound’s mission is to redefine diaphragm technology, enabling solutions and performance levels that traditionally have not been possible. To Composite Sound, an optimal diaphragm eliminates the traditional trade-off between stiffness and damping.
The engineering process involves optimizing thickness and stiffness in every point of the diaphragm. This enables:
- Increased stiffness
- Reduced mass
- Controlled resonances
To explain how resonances can be controlled, we need to understand how varying thickness and stiffness in different parts of the diaphragm influences resonances. Anytime thickness or stiffness is changed in any point in the diaphragm, the modal behavior and thereby how resonances occur are also changed. This means that by optimizing thickness and stiffness in every point of the diaphragm, resonances can be controlled.
Composite Sound's philosophy is that a diaphragm should be engineered such that stiffness and mass are strategically distributed where they contribute most to performance, ensuring structural integrity under mechanical load while maintaining the lowest practical moving mass possible.
Figure 3: TPCD® Thin-Ply Carbon diaphragm
Below, two examples of Composite Sound's engineering approach are presented – a tweeter and a woofer.
Figure 4: One inch tweeter with: Uniform thickness, varied thickness across the diaphragm [3].
Figure 5: 6.5 inch woofer comparing magnesium, TPCD® non-engineered and an engineered TPCD® diaphragm
Explore the potential of TPCD®
To help you explore the potential of Composite Sound’s TPCD® technology in your product, we have developed a three-step process:
- Explore: We use simulations to show the potential performance of TPCD® in your application quickly and efficiently. Alternatively, we will provide you with data and information if you prefer to simulate yourself.
- Experience: To experience the difference, we provide sample diaphragms tailored for you.
- Realize: Together we will turn your vision into a new benchmark product, providing you with TPCD® diaphragms engineered for performance, efficiency and quality.
Contact us today via the form below to explore the potential of TPCD® in your product.
References
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Ohlsson, F. (2016). Weight reduction by optimized reinforcement structures. In J. Njuguna (Ed.), Lightweight Composite Structures in Transport: Design, Manufacturing, Analysis and Performance (pp. 191–215). Kidlington: Elsevier Limited.
- Callister, W. D., & Rethwisch, D. G. (2021). Materials Science and Engineering: An Introduction (10th Australia & New Zealand ed.). John Wiley & Sons.
- Turesson, M. (2026, February). A Case Study on Thin-Ply Carbon Diaphragm 25mm Tweeter Domes. audioXpress.