:is made of aluminum, nickel, cobalt, iron and magnetic materials cast and sintered at 600℃. Aluminium-nickel-cobalt magnets are more expensive than iron oxide, and cobalt is scarce. Alnico magnets are the earliest magnets used in trumpets, such as trumpets (known as tweeters) in the 50s and 60s. Generally made of internal magnetic horn (external magnetic type is also available). Its disadvantages: power is also small, the frequency range is narrow, hard and very brittle, processing is very inconvenient, need grinding processing or electric spark processing. The horn magnet.
: by magnetic material powder and iron powder as the material sintered at about 1200℃. Generally made of magnetic loudspeaker, cheap, high sex price. Its disadvantages: large volume, small power, narrow frequency range.
:is made of Neodymium iron boron material (rare earth) and neodymium nickel cobalt and other rare materials made by high temperature sintering after electroplating. The performance of Ndfeb magnet is far better than that of iron oxide magnet. By far the most used magnet on speakers. The magnetic force intensity in the same volume is more than 10 times that of general iron oxide. Its characteristics: under the same magnetic flux, it has small volume, large power and wide frequency range. At present, HiFi earphones basically use such magnets. The downside: Rare earths are widely used in high-tech applications (military, electronics, etc.), but their use has been tightly controlled by the government in recent years, and prices have skyrocketed.
