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Why is Kevlar Used in Speaker Manufacturing?

Why is Kevlar Used in Speaker Manufacturing?

29 Mar 2021 | 4 min read

Quick Summary

Surprised that Kevlar is used in the manufacture of speakers? Here's why it makes such a great build material for speaker woofers.

Kevlar As a Build Material In Speaker Manufacturing

Kevlar is, as you’re no doubt aware, a material best known for its use in bulletproof vests and other armoured clothing. It is also used as a friction material in the automotive industry and in the aerospace industry to protect against fire due to its being a poor conductor of heat. A fibre, Kevlar is flexible during manufacture but, once formed, is tremendously durable under tension (a property known as ‘tensile strength’).

Its slash resistance, heat resistance and high tensile strength make Kevlar a highly durable material, as is no doubt evident given its applications. So why is Kevlar used in the manufacture of speakers?

Since kevlar is so stiff under tension, it is tremendously efficient at pushing air whilst the cone is in motion and coming to a dead-stop with very little transfer of energy to vibration within the cone’s material. This is known as ‘damping’ and, in the engineering of a speaker, the unobtainable, ideal material would be one that doesn’t flex at all since the purpose of the woofer is to act as a perfect piston, driving forward and back to compress and decompress air into sound waves.


Lithe Audio use woven Kevlar as their build material of choice for speaker cones.

Kevlar Speakers vs Polypropylene and Paper Speakers

Kevlar is used as an alternative to both paper and polypropylene in the manufacture of speaker woofers, though other fibres including glass fibres can be used as well.

Paper is often used as it is cheap and offers great flexibility in the manufacturing process, capable of being shaped and formed in a variety of ways. It is also light but, with the right treatment, stiff, lending itself well to the efficient transfer of kinetic energy (the motion of the speaker cone) to mechanical energy (the sound waves subsequently produced).

Both Kevlar and Polypropylene, unlike paper, are poor heat conductors and also non-absorbent, making them resistant to changes in environmental temperature. This results in reliable, consistent performance no matter where the Kevlar or Polypropylene speaker is situated. This is especially important for humid environments like indoor swimming pools and bathrooms, for which speakers with paper woofers will be poorly suited.

Polypropylene, while cheaper than Kevlar, is less stiff. Kevlar’s tensile strength is more than 14 times greater than that of Polypropylene. Remember, for the most accurate representation of sound quality, you want a woofer to be made of a material that has low mass, but great stiffness, with low absorbency and high heat resistance. Kevlar has all of these properties.


Speakers with cones of polypropylene are cheaper to produce than Kevlar, but have lower tensile strength, resulting in greater distortion.

Lithe Audio Ceiling Speakers

Lithe Audio’s range of Bluetooth ceiling speakers and WiFi ceiling speakers incorporate a Kevlar cone and titanium woofer. As we’ve learned, kevlar is a material that lends itself extremely well to a long-lasting, durable speaker. When it comes to the tweeter, you have to be even more careful to use a material that is very strong and stiff but of very low mass. In order to produce very high frequencies, tweeter cones are often driven tens of thousands of times a second. Even the smallest discrepancies are liable to negatively affect sound quality in a big way, making titanium a superb choice for its lightness and strength.

The superb build quality of Lithe Audio ceiling speakers, no doubt, contributed to their products winning the 2020 Cedia Awards, as well as winning the Smart Home Innovation of the Year award 2019 and the Build 2019 Design & Build award.

What’s more, your Lithe Audio ceiling speakers will sound consistent no matter where you place them, due to Kevlar’s property of being resistant to changes in humidity and changes in temperature. That’s why their IP44 rated bathroom speakers are so popular with homeowners, and owners of health spas and indoor swimming pools.

If you’d be interested in purchasing Lithe Audio’s ceiling speakers, you can do so with us and, if you have any questions, we’d be more than happy to assist you so please don’t hesitate to contact us with your queries.

Why is Kevlar Used in Speaker Manufacturing?