The basin frame is the “skeleton” of the cone speaker. It can combine the diaphragm, ring, centering piece, magnet, magnetic conductive element, etc., and it can also play the role of installing the speaker on the box. When the loudspeaker is working, the diaphragm will transmit the vibration to the ring, and then the ring will transmit the vibration to the basin frame, and then to the box. This conduction will also propagate in the opposite direction and interfere with other waves. The vibration situation is very complicated. . Suppose we have an ultra-high-speed macro camera, what will we see when we shoot the vibration of the pot frame? The diaphragm will be slightly deformed with the vibration of the pot frame… Therefore, an ideal high-quality pot frame should have good strength and require “solidity”.
Steel is a material with a long history. In addition to the perfection of smelting technology, iron also has advantages that other materials cannot replace:
1. Good processing performance, iron is the pot frame with the longest history, and its processing technology has developed to a fairly stable level.
2. High strength. From the above, we can see that the strength of steel under the same volume is much greater than that of aluminum alloy, so the strength of a qualified iron frame can be reassuring.
Of course, the iron frame also has its insurmountable shortcomings:
1. Deformation. During transportation, it is very likely that the basin frame will be slightly deformed due to collisions. Large professional speakers will hardly use iron frames.
2. Rust, compared with other materials, iron is relatively easy to rust. Rust will greatly reduce the strength of iron and reduce its service life. Therefore, various measures must be taken to prevent iron from rusting.
3. Resonance, iron is often processed in the form of cold pressing and stamping. Many low-end speakers use thin materials, and resonance is easy to occur when playing dynamic music.
4. Influence on the magnetic circuit. Iron is a magnetic conductor. In actual use, the frame itself may affect the design of the magnetic circuit, especially the frame with a high thickness.
The rigidity and strength of aluminum are not high, but aluminum can make up for this shortcoming by increasing the material per unit volume, and the thick cast aluminum frame has strong rigidity. At present, in order to ensure the strength, the aluminum materials used on the high-end pot frames have adopted the method of using thicker cast aluminum and increasing the cross-sectional area, so most of the aluminum pot frames look very rough.
1. The appearance of aluminum does not change much after long-term use. It is not easy to detect changes in appearance,
2. The internal damping of aluminum is higher than that of iron, so it is not easy to resonate.
3. Aluminum is easy to dissipate heat, especially for temperature-sensitive NdFeB magnets, and the basin frame can become an important factor for temperature stability.
The above are the advantages of aluminum, but this material also has two disadvantages. The metal fatigue of aluminum is very poor, and aluminum has no elasticity, so the aluminum basin frame sometimes breaks when it is dropped, but the speaker is generally not dropped by anyone.
Plastic can also be used in the manufacture of pot frames. In the design of special speakers, such as automotive speakers, many use plastic basin frames.
Of course, there are also a small number of high-end engineering plastic speakers. With the research of materials science, engineering plastics can be used to design and manufacture basin frames similar to cast aluminum, but there is still a long way to go before large-scale popularization.