Speakers are one of the electroacoustic materials. The basic material for making loudspeakers is a permanent magnet. Rare earth permanent magnet neodymium alloy is a very good material for making loudspeakers.
The working principle of loudspeaker
The permanent magnet generates a magnetic field in the annular air gap of the magnetic circuit through the yoke iron, and the voice coil connected with the speaker paper basin is inserted into the annular air gap. The permanent magnet is surrounded by the external yoke iron, thus avoiding the interference of the external stray magnetic field. In turn, it can reduce the influence of the magnetic field of the permanent magnet on the outside world. When the sound passes through the magnetic field in the form of current, the coil is formed. It will produce different frequencies of vibration due to the change of current intensity, and then drive the paper basin to emit different frequencies and strong sounds. The use of rare earth permanent magnet NdFeB instead of traditional ferrite or AlNiCo magnets can not only improve the sensitivity of loudspeakers but also greatly reduce the number of magnets used.
The loudspeaker’s two favorite magnet materials are neodymium magnet and ferrite. Both are very strong, but they come with their own unique features.
NdFeB has the advantages of high-cost performance and good mechanical properties, while its disadvantages are low Curie temperature, poor temperature characteristics and easy to be powdered and corroded.
The manufacturers of bass headphone loudspeakers must adjust their chemical composition and adopt surface treatment methods to improve them. Only in this way, can the manufacturers of medium and high-pitch headphone loudspeakers meet the requirements of the practical application.
NdFeB belongs to the third generation of rare earth permanent magnets. It has the characteristics of small size, lightweight, and strong magnetism. It is a magnet with good performance-price ratio and is known as the king of magnets in the field of magnetics.
The advantages of high energy density make NdFeB permanent magnets widely used in modern industry and electronic technology. In the bare magnetic state, the magnetic force can reach about 3500 Gauss.
Ferrite is a kind of metal oxide with ferromagnetism. As far as electrical properties are concerned, the resistivity of ferrite is much larger than that of metal and alloy magnetic materials, and it also has higher dielectric properties. The magnetic properties of ferrite also show higher permeability at high frequencies.
Therefore, ferrite has become a non-metallic magnetic material widely used in the field of high frequency and weak current.
Ferrite is a kind of non-metallic magnetic material. It is a composite oxide of magnetic ferric oxide and one or more other metal oxides. The magnetic force is usually 800-1000 Gauss. It is often used in loudspeakers and other instruments.