English
In a loudspeaker unit, there is an unassuming but vital core component, the Voice Coil. The voice coil is the key component that converts electrical energy into mechanical energy and drives the diaphragm to produce sound, so it is not too much to call it the ‘heart’ of the speaker. The performance of voice coils in professional loudspeakers requires a very high level of performance, and one of the primary factors affecting the performance of voice coils is the choice of material.
What is a voice coil?
The basic structure and function of the voice coilThe voice coil is usually made of a coil of wire wound around a lightweight, heat-resistant sonic skeleton (voice coil frame). When audio current passes through the voice coil, it generates an electromagnetic force in the magnetic field, which pushes the speaker's diaphragm back and forth to produce sound. The choice of material for the voice coil affects the following key factors: conductive efficiency and power loss, heat dissipation, structural strength and deformation control, and transient response and expressiveness of the sound. In ZTZ SPEAKER products, these factors are often weighed against each other to achieve the best possible sound performance.
Common voice coil materials and their properties
Aluminum Alloy
Aluminum alloy is one of the most commonly used materials for voice coils. It has the following advantages: Easy to process and fix: anodised aluminium alloy is easier to bond with glue, which facilitates the stable fixing of voice coil coils. Excellent heat dissipation: it effectively reduces the risk of heat generation when working for long periods of time. High hardness and low deformation: maintains structural stability during high-speed vibrations. However, aluminium alloys have a fatal disadvantage - they are electrically conductive, which means that they are prone to electrical losses when driven at high power, leading to wasted energy.
Kapton (a special plastic film)
Kapton is a high-performance plastic material commonly used for high-end sonic skeletons. Its characteristics include: completely non-conductive, no electrical loss of lightweight, good rigidity and high temperature resistance However, Kapton's thermal performance is relatively poor, so it is mostly used for small-sized speakers or occasions where the volume demand is not high. In addition, due to the characteristics of the plastic material, it will have a slight damping when pushing the diaphragm, the sound style may appear relatively soft, rather than strong, sharp.
Titanium
Titanium is one of the most advanced materials available for voice coils: it is extremely hard, deformation-resistant, lightweight, fast-responding, has excellent heat dissipation and lower electrical losses than aluminium alloys. From a performance point of view, titanium is almost the ideal material for ‘getting the best of both worlds’, delivering higher maximum sound pressures and transient responses. However, the downside is obvious - it's very expensive. Titanium is an expensive material and more costly to process, so it is currently used in professional loudspeakers at the mid-to-high end of the range.
Sound Performance and Material Selection
Different materials also directly affect the sound style performance:
Kapton: slightly damped sound, soft texture, suitable for delicate medium and high frequency performance.
Aluminium alloy: direct and clear sound, good dynamics, suitable for scenes that require explosive power.
Titanium: hard and clean sound, rapid response, with excellent transient and dynamic performance, is the preferred material for top audio.
In professional speaker design, there is no absolute ‘best’ voice coil material, the most suitable is the best. Designers will be in accordance with the speaker size, purpose, target sound quality and cost control and other factors for selection. For example: small bookshelf speakers, the priority pursuit of lightness and sound density, often using Kapton voice coil; large floor standing or professional sound reinforcement speakers, the requirements of stability and heat resistance, will use aluminium alloy or even titanium voice coil.
Although the voice coil is small, determines the general direction of the sound voice coil as a speaker in a small but critical parts, not only bear the sound drive function, but also deeply affect the durability of the speaker, sound characteristics and overall performance. Professional brands such as Elac are able to develop and manufacture their own monoblocks, which allows them to perfectly integrate the voice coil material with other components to make the most optimal design for each speaker. So, if you are next time enjoying the wonderful sound quality of a pair of high-end speakers, don't forget that underneath the delicate shell, there is a small voice coil that quietly plays a huge role.