Full frequency speakers are also called broadband speakers. Earlier, they generally refer to speakers that can cover the frequency range of 200-10000hz, which is called full frequency. In recent years, full frequency speakers have been able to cover the frequency range of 50-25000hz. For the sake of proper address, the "full frequency speaker" is hereinafter referred to as "full frequency unit" or simply "speaker" or "unit" according to industry practice. What kinds of diaphragm are used for full frequency horn? The diaphragm used by the full frequency unit mainly includes the following types:

1. Paper. Because paper has appropriate internal damping and basically sufficient strength, it has been widely used in loudspeaker diaphragm. However, due to the low strength / modulus, even if new shape design and some new materials are used, the initial frequency of sound quality degradation caused by split vibration is still much lower than that of other new materials. However, considering the low cost and the continuous process inheritance, paper can still be used in some less demanding occasions.
2. Plastic. The strength of polymer material itself is higher than that of paper, and the effective strength of diaphragm can be continuously improved by adding various fillers / structural reinforcement, but its density is large, so its weight is strictly controlled in actual use, resulting in smaller thickness, so the overall specific stiffness is less than that of paper and other materials. In addition, its internal damping is generally lower than that of paper, so it is basically difficult for people to accept the sound quality. The advantage is that polymer materials are easy to form and low cost, so they are widely used in low-grade products.
3. Metal. Metal materials make people love and hate. Its specific stiffness is higher than that of other materials, so the split vibration starting frequency of a suitable metal diaphragm is much higher than that of ordinary materials, and the cone of pure be metal is even higher than 40KHz. However, its internal damping is small and it is easy to form higher peaks. If this frequency falls in the auditory sensitive area, the sound will be quite unnatural.
Therefore, to make good use of the metal diaphragm, we must use additional damping means, including coating damping glue, joint edge anti damping treatment, and some physical treatment of cone. At the same time, through certain shape treatment, push the peak to even higher after 15KHz, which is insensitive to human ears, and reduce the peak at the same time, so as to cover a very wide frequency range. The full frequency unit that can cover the frequency of 50-25000hz mentioned above uses metal materials.
4. Others. Composite materials including some ceramic materials. There are few applications, basically immature, and very rare in the market.